CN118286006A - Wheelchair structure capable of ascending and descending steps and intelligent control method thereof - Google Patents

Abstract

The invention provides an intelligent wheelchair and a control method for the ascending and descending path edges of the intelligent wheelchair. The intelligent wheelchair comprises a structure of the intelligent wheelchair and a measurement and control device. The intelligent wheelchair structure comprises a wheelchair body, a linear motor, a laser radar, a driving wheel, an auxiliary supporting wheel, an inclination sensor and the like. The method of the invention is as follows: the laser radar is used for measuring the terrain around the wheelchair and steps or similar obstacles to be passed, and the linear motor is controlled in turn to accurately control the body and the driving wheel of the wheelchair to lift so as to adapt to the current terrain characteristics, thereby controlling the wheelchair to smoothly pass through the steps. The inclination angle sensor has the function of monitoring the safety of the wheelchair in the process and protecting the wheelchair. The intelligent wheelchair can assist the wheelchair to safely go up and down the road edge, has stronger terrain passing capability, is an intelligent control device and method, and can meet the safety and comfort requirements in the process of going up and down steps which are needed to be faced when the wheelchair occupant widely goes out.

Description

A wheelchair structure capable of going up and down stairs and its intelligent control method

Technical Field

The present invention relates to the field of intelligent device control and perception, and in particular to a wheelchair structure capable of ascending and descending stairs and an intelligent control method thereof.

Background technique

The problem of population aging has become a global trend. At the same time, there are still a considerable number of disabled people due to diseases, disasters and other reasons, which has led to a rapid increase in the demand for wheelchairs. Due to the improvement of living standards, wide-area travel has become a basic need for the elderly and disabled. In order to realize the functions of wheelchairs such as climbing steps and stairs, scientific and technological workers and inventors have done a lot of work. For climbing stairs alone, nearly 200 patents have been applied for in China. Due to the lack of cost-effectiveness, coupled with the promotion of small high-rise elevators and the widespread installation of wheelchair ramps in public places, the demand for wheelchairs to climb stairs for the elderly and disabled has been greatly reduced.

However, in many cases, it is still necessary for the wheelchair to be able to smoothly go up and down the steps like curbs. At present, there are two main ways to solve this type of problem: one is to use a tracked wheelchair, such as the patent "An all-terrain walking wheelchair" (202310708467.0) proposes a tracked all-terrain walking wheelchair, which improves the terrain passability of the wheelchair. The second is to use high-power and large-diameter walking wheels to improve the passability of the wheelchair. Although these two types of wheelchairs can realize the function of going up and down stairs, there are still the following problems: First, the wheelchair will have a serious backward tilt when going up the stairs, which not only puts great psychological pressure on the occupants, but also there is indeed a possibility of rollover that the occupants cannot detect and control; second, when going down the stairs, there will be a serious feeling of falling. Both types of problems will not only make the wheelchair occupants feel uncomfortable, but also damage the wheelchair structure. In response to this problem, the present invention proposes an effective and low-cost intelligent control solution.

Summary of the invention

To solve the above problems, the present invention discloses a wheelchair structure that can go up and down stairs and an intelligent control method thereof: the intelligent wheelchair state perception and control system designed by the method can identify the curb and obtain the curb distance and height information, and then use the auxiliary support frame to achieve the purpose of going up and down the curb, which can effectively improve the accuracy and safety of the wheelchair going down the curb and has a strong terrain passing ability.

A wheelchair structure that can go up and down stairs, comprises a wheelchair body, walking wheels, and auxiliary support wheels, wherein the wheelchair body is composed of a seat plate, foot pedals, and a backrest plate, and is characterized in that; it also includes linear motor 1, linear motor 2, linear motor 3, linear motor 4, linear motor 5, a laser radar, and an inclination sensor; wherein linear motor 1, linear motor 2, linear motor 3 and linear motor 4 are exactly the same in structure, and the centers of the four linear motors are arranged in a rectangle, and the size of the rectangle is adapted to the seat plate; linear motor 5 is connected and adapted to the foot pedals; the inclination sensor is fixedly connected to the seat plate to measure the inclination angle of the seat plate relative to the horizontal plane; wherein the laser radar includes a left front radar and a right front radar.

Furthermore, the linear motor five comprises an electric cylinder five fixedly connected to the foot pedal and a telescopic rod five matched therewith. The movement direction of the telescopic rod five is parallel to the foot pedal, and the telescopic amount is recorded as L202.

Furthermore, the linear motor 1 includes an electric cylinder 1 fixedly connected to the seat plate and a telescopic rod 1 matched thereto, the movement direction of the telescopic rod 1 is perpendicular to the seat plate, and the telescopic amount is recorded as L212; the linear motor 2 includes an electric cylinder 2 fixedly connected to the seat plate and a telescopic rod 2 matched thereto, the movement direction of the telescopic rod 2 is perpendicular to the seat plate, and the telescopic amount is recorded as L222; the linear motor 3 includes an electric cylinder 3 fixedly connected to the seat plate and a telescopic rod 3 matched thereto, the movement direction of the telescopic rod 3 is perpendicular to the seat plate, and the telescopic amount is recorded as L232; the linear motor 4 includes an electric cylinder 4 fixedly connected to the seat plate and a telescopic rod 4 matched thereto, the movement direction of the telescopic rod 4 is perpendicular to the seat plate, and the telescopic amount is recorded as L242; linear array laser radars are fixedly installed on the electric cylinder 1 and the electric cylinder 2, respectively, and the corresponding numbers are left front radar and right front radar, respectively.

Furthermore, the telescopic rod includes a telescopic part and a mounting part; the telescopic part is a component that matches the electric cylinder and forms a linear motion; the mounting part is used to mount the support wheel; the support wheel rotates freely around the mounting part, the center of the support wheel is at a height of h5 from the ground, and the height difference between the foot pedal and the ground is h12.

Furthermore, telescopic rod 1, telescopic rod 1, telescopic rod 1, and telescopic rod 1 are respectively equipped with an electrically driven left front drive wheel, right front drive wheel, left rear drive wheel, and right rear drive wheel; the radius of the four drive wheels is R; when the drive wheels are not powered, they can rotate freely around their own axes; after power is supplied, the speed and angle of the drive wheels can be controlled.

Furthermore, the fixing position of the inclination sensor is not limited to directly above the seat board or below the seat board or other positions.

A method for intelligently controlling a wheelchair that can go up and down stairs, wherein the method for controlling the wheelchair to go up stairs includes a left front laser radar and a right front laser radar, the distance between the coordinate origins of the two is L14, and it is assumed that the distance from the wheelchair to the stairs measured by the left front laser radar is d31, and the distance from the wheelchair to the stairs measured by the right front laser radar is d32; the heights of the stairs measured by the left front laser radar and the right front laser radar are both h; based on the above measurement values, the following describes a method for smoothly controlling the wheelchair to go up stairs:

Step 1: Walking normally on a flat road; when walking on a flat road, the wheelchair linear motor is in the retracted state, and the laser radar measurement value meets the criteria for a flat road;

Step 2: After finding the step, if one laser radar detects the step above the road surface and the other does not, it means that the wheelchair is not moving perpendicular to the step. The wheelchair slows down and adjusts its direction of travel to ensure that both the left front laser radar and the right front laser radar detect the step, and the measured distances d31 and d32 are the same. At the same time, the distance is greater than L15 to prevent the pedal from hitting the step. The distance from the pedal 11 to the center of the left front drive wheel 41 and the right front drive wheel 42 is L15.

The third step is to lift the vehicle body; at an appropriate position where d31=d and d>L15, such as d-L15=10cm, telescopic rod 1 on linear motor 1, telescopic rod 2 on linear motor 2, telescopic rod 3 on linear motor 3 and telescopic rod 4 on linear motor 4 are extended at the same time, and the extension amount is the step height h, so that the footrest is higher than the step; the wheelchair continues to move forward slowly; at this time, the vertical height of the left front laser radar and the right front laser radar relative to the ground is: L0=hs+h, where hs is the vertical height of the left front laser radar and the right front laser radar relative to the ground in the initial state;

Step 4: Go up the stairs directly; when the measured step height h < R/3, the wheelchair can continue to move forward and go up the stairs directly; and jump to step 8;

Step 5: The auxiliary support wheel extends. When d≤L54, it indicates that the auxiliary support wheel is already above the step. Then the telescopic rod 5 supporting the linear motor 5 is controlled to extend by an amount of h/cosα, where α is the angle between the telescopic rod 5 and the vertical direction. The auxiliary support wheel contacts the step and is allowed to leave the step surface slightly, generally by less than 10 mm. The wheelchair continues to move forward.

Step 6: The left front driving wheel and the right front driving wheel are lifted; the telescopic rod 1 of the linear motor 1 and the telescopic rod 2 of the linear motor 2 are controlled to retract, and the retraction amount is the step height h; at this time, the left front driving wheel and the right front driving wheel are lifted and leave the ground; the wheelchair actually continues to move forward by relying on the left rear driving wheel and the right rear driving wheel; at this time, the vertical height of the left front laser radar and the right front laser radar relative to the ground is: L0=hs+h;

In the seventh step, the left front driving wheel and the right front driving wheel climb up the steps; the wheelchair moves forward intermittently and slowly, and when L0=hs, it indicates that the left front driving wheel and the right front driving wheel just touch the road surface on the steps; in the eighth step, the left rear driving wheel and the right rear driving wheel begin to retract; when the measurement values of the left front laser radar and the right front laser radar are d31=d32=L13-R, it indicates that the rear driving wheels are very close to the steps; let the forward speed of the wheelchair be v1, the speed of the retracting telescopic rod three of the linear motor three and the retracting telescopic rod four 242 of the linear motor four be v2, and the retraction amount be L234:

When L234+R-h<R/2, V2＝2V1

When R/2<L234+R-h<1.7R, V2＝V1

When L234+R-h>1.7R, V2＝V1/2

Step 9: Reset the wheelchair; when the measurement values of the left front laser radar and the right front laser radar are d31=d32>L13, it indicates that the wheelchair has climbed up the steps; linear motor 1, linear motor 2, linear motor 3, linear motor 4, and linear motor 5 retract all telescopic rods to restore the wheelchair to its starting state; return to step 1.

The present invention is further improved in that the method for the wheelchair to go down the stairs specifically includes:

Step 1: Walking normally on a flat road; when walking on a flat road, the linear motor of the wheelchair is in the retracted state, and the measurement value of the laser radar meets the criteria for a flat road;

Step 2: Find the steps and adjust the walking posture of the wheelchair; assuming that one laser radar has detected a step below the road surface in the forward direction, while the other has not, it indicates that the forward direction of the wheelchair is not perpendicular to the step; the wheelchair slows down and approaches the step until both laser radars can detect the step; adjust the direction of the wheelchair so that the measurement values d31 of the left front laser radar 31 and the right front laser radar 32 are d31=d32, and d31>R;

Step 3: Go down the steps directly; when the height of the steps h is measured to be less than 0.3R, the wheelchair moves forward directly and makes all the driving wheels go down the steps to enter the eleventh step.

Step 4: The auxiliary support wheel 5 is extended; the wheelchair moves forward intermittently and slowly, and when d31=R, it indicates that the front running wheel has approached the step, and the telescopic rod 5 202 supporting the linear motor 5 20 is controlled to extend, and the extension amount is h/cosα, where α is the angle between the telescopic rod 5 202 and the vertical direction, so that the auxiliary support wheel 5 contacts the road surface under the step, and the auxiliary support wheel 5 is allowed to leave the step surface a little, generally less than 10mm; the wheelchair continues to move forward, and d31=d32;

Step 5: The front wheel goes beyond the step; the wheelchair moves forward slowly and intermittently. When d31 = 0 and L0 = hs + h, it indicates that the center line of the front wheel has reached the edge of the step; prepare to drop the front wheel;

Step 6: The front running wheel begins to fall; assuming that the forward speed of the wheelchair is v1, the speed at which the linear motor 1 21 extends the telescopic rod 1 212 and the linear motor 2 22 extends the telescopic rod 2 222 is v2, and the extension amount L212＝L222≈h-10, the telescopic rod 1 212 of the linear motor 1 21 and the telescopic rod 2 222 of the linear motor 22 are controlled according to the following rules, so that the front running wheel is close to the ground but does not fall to the ground:

When L212<0.3R, V2＝V1/2

When 0.3R<L212<0.7R, V2＝V1

When L212>0.7R, V2＝2V1

During this process, the wheelchair is driven forward by the left rear driving wheel 43 and the right rear driving wheel 44; after this process is completed, the front running wheels are only very close to the road surface but have not yet completely landed, so the friction between the front wheels and the ground will not affect the movement of the rear wheels in the subsequent process, but the wheelchair can be prevented from tipping over;

Step 7: Adjust the direction of the wheelchair and lower the front wheel; adjust the direction of the wheelchair so that the wheelchair can maintain balance when the next running wheel goes down the steps; control the differential speed of the left rear drive wheel and the right rear drive wheel of the wheelchair to make the wheelchair rotate around the left front drive wheel; and use the left front laser radar 31 and the right front laser radar 32 to measure the distances d31 and d32 of the steps;

When 0.9R<d31<1.1R and 0.9L13<d32<1.1L13 are satisfied, the right front wheel of the wheelchair is equivalent to being stationary, but will not touch the steps behind. Make d32≈L13, so that the wheelchair's forward direction forms an angle with the steps The optimal theoretical value of is: In this way, the left rear drive wheel is already at the edge of the step, ready to go down the step;

By the same principle, the wheelchair can also be made to rotate around the right front driving wheel, and the process is exactly the same as above, so that the right rear wheel is ready to go down the steps; then, the linear motor 1 21 is controlled to extend the telescopic rod 1 212 and the linear motor 2 is controlled to extend the telescopic rod 2 222, and the extension amount L212 = L222 = h, so that the front wheel of the wheelchair lands and can provide forward power;

Step 8: One rear drive wheel exceeds the step and touches the ground; control the wheelchair to move forward slowly, the left front drive wheel 41 and the right front drive wheel 42 have completely landed, providing the main walking power, and one of the two rear drive wheels close to the step is about to exceed the step and is ready to land; the left rear drive wheel 43 is close to the step, and when the wheelchair moves forward, the left rear drive wheel 43 will first exceed the step and land. During this process, it is necessary to control the linear motor 3 23 to extend the telescopic rod 3 232, thereby driving the left rear drive wheel 43 to descend, and the extension amount is recorded as L232; let the wheelchair forward speed be v1, and the speed at which the linear motor 3 23 extends the telescopic rod 3 232 is v2. Control v2 according to the following rules:

When L232<0.3R, V2＝V1/2

When 0.3R<L232<0.7R, V2＝V1

When L232>0.7R, V2＝2V1

Until the extension amount L232 = h, the left rear driving wheel 43 falls to the ground;

Similarly, the right rear driving wheel 44 is close to the step. When the wheelchair moves forward, the right rear driving wheel 44 will first exceed the step. During this process, the linear motor 424 needs to be controlled to extend the telescopic rod 4242, thereby driving the right rear wheel to descend. The extension amount is recorded as L242. Assume that the speed of the wheelchair moving forward is v1, and the speed of the linear motor 424 extending the telescopic rod 4242 is v2. Control v2 according to the following rule:

When L242<0.3R, V2＝V1/2

When 0.3R<L242<0.7R, V2＝V1

When L242>0.7R, V2＝2V1

Until the extension amount L242 = h, the right rear drive wheel falls to the ground;

Step 9: The other rear drive wheel approaches the step and is ready to fall and touch the ground. At this time, you need to move the last drive wheel on the step to the vicinity of the step. Continue to control the wheelchair to move forward slowly at the same speed until the last drive wheel approaches the step;

Step 10: The last rear drive wheel falls and touches the ground; continue to control the wheelchair to move forward slowly until the last drive wheel touches the ground.

Step 11: The wheelchair returns to the initial state. When all the driving wheels have finished descending the steps, the extended telescopic rods 5 202, 1 212, 222, 3 232 and 4 242 need to be retracted at the same time to make the wheelchair seat fall and return the wheelchair to the initial state.

Beneficial effects of the present invention:

The intelligent wheelchair state perception and control system designed by this method can identify the curb, obtain the distance and height information of the curb, and then use the auxiliary support frame to achieve the purpose of getting on and off the curb, which can effectively improve the accuracy and safety of the wheelchair going off the curb, and has a strong terrain passing ability; at the same time, compared with the tracked wheelchair, the structure is simpler, making the wheelchair cost lower, while meeting the safety and comfort requirements of the wheelchair going on and off the curb, providing a more convenient travel method for the disabled. In addition, the method proposed by the present invention is related to the structural parameters of the wheelchair, but is not affected by the size of the wheelchair drive wheel. In fact, it also provides a universal design solution, which is conducive to expanding the design ideas of wheelchairs and improving the design level of wheelchairs.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a diagram of the wheelchair structure and the overall installation diagram of the sensor;

Fig. 2 is a schematic diagram of a telescopic rod;

Figure 3 is a projection diagram of the wheelchair structure (left: front view, right: left view);

Figure 4 is a schematic diagram of the laser radar road condition measurement principle;

Figure 5 is a schematic diagram of a step discovered by a laser radar;

FIG6 is a schematic diagram of accurately measuring step parameters;

FIG7 is a schematic diagram of the measurement of steps below the road surface;

FIG8 is a schematic diagram of backward measurement;

FIG9 is a schematic diagram of a wheelchair adjusting posture when it finds a step;

FIG10 is a schematic diagram of the walking direction approaching the steps;

Figure 11 is a schematic diagram of a wheelchair approaching a step;

Figure 12 is a schematic diagram of a wheelchair lifting the body;

FIG13 is a schematic diagram of a support wheel contact step;

Figure 14 is a schematic diagram of the front drive wheel climbing up the steps;

FIG15 is a schematic diagram of the rear drive wheel approaching the step;

Figure 16 is a schematic diagram of a wheelchair climbing up stairs;

Figure 17 is a schematic diagram of a step found below the road surface;

FIG18 is a schematic diagram of adjusting the walking direction of a wheelchair;

FIG19 is a schematic diagram of a foot pedal reaching the vicinity of a step;

Figure 20 is a schematic diagram of the support wheel landing;

FIG21 is a schematic diagram of the front driving wheel reaching the edge of the step;

Figure 22 is a schematic diagram of the front driving wheel falling;

Figure 23 is a schematic diagram of the left rear wheel preparing to go down the steps;

Figure 24 is a schematic diagram of the right rear wheel preparing to go down the steps;

Figure 25 is a schematic diagram of the front drive wheel landing;

Figure 26 is a schematic diagram of the left rear wheel reaching the edge of the step;

Figure 27 is a schematic diagram of the right rear wheel reaching the edge of the step;

Figure 28 is a schematic diagram of the right rear wheel reaching the edge of the step;

Figure 29 is a schematic diagram of the left rear wheel reaching the edge of the step;

Figure 30 is a schematic diagram of the right rear wheel falling down the steps;

Figure 31 is a schematic diagram of the left rear wheel falling down the steps;

FIG32 is a schematic diagram of a wheelchair adjusting its posture when it finds a step;

FIG33 is a schematic diagram of the walking direction approaching the steps;

Figure 34 is a schematic diagram of a wheelchair approaching steps;

FIG35 is a schematic diagram of lifting the wheelchair body;

FIG36 is a schematic diagram of a support wheel contact step;

Figure 37 is a schematic diagram of the front drive wheel climbing up the steps;

Figure 38 shows the angle between the wheelchair and the steps Schematic diagram;

Figure 39 is a schematic diagram of the right rear wheel ready to go up the steps;

Figure 40 is a schematic diagram of the left rear driving wheel climbing up the steps;

Figure 41 is a schematic diagram of the right rear drive wheel climbing up the steps;

Figure 42 is a schematic diagram of the right rear wheel approaching the step;

Figure 43 is a schematic diagram of the left rear wheel approaching the step;

Figure 44 is a schematic diagram of the wheelchair state perception and control process.

Detailed ways

The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. It should be noted that the words "front", "rear", "left", "right", "upper" and "lower" used in the following description refer to directions in the accompanying drawings, and the words "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively.

FIG1 is a schematic diagram of the structure of the intelligent wheelchair of the present invention. It is composed of a wheelchair body, a linear motor, a laser radar, a running wheel, an auxiliary support wheel 5, an inclination sensor 6, etc. Among them, the wheelchair body is composed of a seat plate 11, a footrest 12, and a backrest plate 13.

The linear motor of the present invention generally refers to various types of electric telescopic devices that can achieve linear motion, and its telescopic motion is like the motion of a piston cylinder and a piston, such as an electric push rod and a servo electric cylinder. In the present invention, such devices are abstracted as an electric cylinder and a telescopic rod that can perform linear motion relative to the electric cylinder, as shown in Figure 2:

The linear motor 5 20 comprises an electric cylinder 5 201 fixedly connected to the foot pedal 12 and a telescopic rod 5 202 matched therewith. The movement direction of the telescopic rod 5 202 is parallel to the foot pedal 12, and the telescopic amount is recorded as L202.

The linear motor 21 comprises an electric cylinder 211 fixedly connected to the seat plate 11 and a telescopic rod 212 matched therewith. The movement direction of the telescopic rod 212 is perpendicular to the seat plate, and the telescopic amount is recorded as L212.

The linear motor 22 includes an electric cylinder 221 fixedly connected to the seat plate 11 and a telescopic rod 222 matched therewith. The movement direction of the telescopic rod 222 is perpendicular to the seat plate, and the telescopic amount is recorded as L222.

The linear motor 3 23 comprises an electric cylinder 3 231 fixedly connected to the seat plate 11 and a telescopic rod 3 232 matched therewith. The movement direction of the telescopic rod 3 232 is perpendicular to the seat plate, and the telescopic amount is recorded as L232.

The linear motor 24 comprises an electric cylinder 241 fixedly connected to the seat plate 11 and a telescopic rod 242 matched therewith. The movement direction of the telescopic rod 242 is perpendicular to the seat plate, and the telescopic amount is recorded as L242.

The structures of linear motor 21, linear motor 22, linear motor 23 and linear motor 24 are exactly the same. The centers of the four linear motors are arranged in a rectangular shape, and the size of the rectangle is adapted to the seat plate.

The structure of the telescopic rod 5 202 is shown in the figure, which includes a telescopic part 2021 and a mounting part 2022. Its main features are: the telescopic part 2021 is a component that matches the electric cylinder and forms a linear motion, and 2021 itself can also rotate freely around its own axis; the mounting part 2022 is used to install the support wheel 5. The support wheel 5 can rotate freely around the mounting part 2022. It has no power and only plays an auxiliary supporting role. It can be seen that a universal wheel is formed by the support wheel and the telescopic rod 2021, and its function is equivalent to a universal caster. In fact, the support wheel 5 itself can also be replaced with a universal caster. Therefore, when the support wheel 5 contacts the ground and plays a supporting role, it does not affect the control of the walking direction of the wheelchair by other walking wheels. As shown in Figure 3, the height of the center of the support wheel 5 from the ground is h5, and the height difference of the foot pedal from the ground is h12.

The structures of telescopic rod 1 212, telescopic rod 2 222, telescopic rod 3 232, and telescopic rod 4 242 are similar to the structure of telescopic rod 5 202, and are respectively equipped with electrically driven left front driving wheel 41, right front driving wheel 42, left rear driving wheel 43, and right rear driving wheel 44. The radius of the four driving wheels is R. When the driving wheel is not powered, it can rotate freely around its own axis, which is equivalent to a follower wheel; after power is powered, the speed and angle of the driving wheel can be controlled. Therefore, when the left front driving wheel 41 and the right front driving wheel 42 are powered at the same time, the power for the wheelchair to move straight can be generated to drive the wheelchair to move; when the left rear driving wheel 43 and the right rear driving wheel 44 are powered at the same time, the power for the wheelchair to move straight can also be generated to drive the wheelchair to move; when the four driving wheels 41, 42, 43, and 44 are powered at the same time, a stronger power can be generated to complete the power required for climbing a slope, crossing obstacles, etc.; when the driving wheels on different sides move at different speeds, the wheelchair can be made to turn while walking.

The inclination sensor 6 is fixedly connected to the seat board to measure the inclination angle of the seat board relative to the horizontal plane. In the figure, the inclination sensor 6 is fixedly installed just above the seat board, but is not limited to just above the seat board. It can also be installed below the seat board or other positions. The inclination sensor is a MESM acceleration sensor, which can measure the acceleration of the wheelchair in addition to the inclination angle of the wheelchair seat.

In FIG1 , telescopic rod 5 202, telescopic rod 1 212, telescopic rod 2 222, telescopic rod 3 232, and telescopic rod 4 242 are all in the extended position. When the wheelchair is moving normally horizontally, all of these telescopic rods should be retracted to put the wheelchair in the initial state;

As shown in Fig. 3, there are the front view and left view of the initial state of the wheelchair, respectively. In this initial state, the height of the seat board 11 of the wheelchair from the ground is the lowest, and the center of gravity of the combination of the occupant and the wheelchair is also the lowest. This is the default state of the wheelchair and the normal walking state. At the same time, the distance between the footrest and the ground is also the lowest, which is convenient for the occupant to leave the wheelchair.

Referring to FIG1 , linear array laser radars are fixedly installed on the electric cylinder 1 211 and the electric cylinder 2 221, and the corresponding numbers are left front laser radar 31 and right front laser radar 32. Considering that all four electric cylinders are fixedly connected to the seat plate 11, the two laser radars 31 and 32 are also fixedly connected to the wheelchair body, and the installation positions include but are not limited to the positions shown in the figure. The function of the laser radar is to measure and identify the road conditions in the direction of the wheelchair.

Linear array laser radar is a multi-point distance measuring instrument that can control the laser line to deflect at a certain angle in the same plane and measure the distance of each laser line from the target. According to the deflection angle and ranging value, the shape, distance and other information of the target can be measured. Since the deflection angle is known, partial measurement values of the linear array laser radar can also be used intentionally to obtain information about the target.

As shown in Figure 4, the measurement center of the laser radar is directed directly below the wheelchair. To facilitate the explanation of the principle of the present invention, L0 is taken as the vertical laser line, and 7 laser lines in the direction of the wheel are selected at equal intervals, which are called forward measurement values. Their ranging values Li are recorded as L0, L1...L6, L7 respectively, and the angle between every two laser lines is Therefore, the deflection angle of the 8th laser line L7 is Obviously, L0 can directly measure the installation height hs of the laser radar, hs=L0.

At the same time, R0 can also be taken as the plumb laser line, and then 7 laser lines emitted by the laser radar at equal intervals in the direction behind the wheelchair are selected, which are called backward measurement values. The ranging values are R0, R1...R6, R7 respectively, and the angle between each two laser lines is Therefore, the deflection angle of the 8th laser line R7 is Obviously, R0 can directly measure the installation height hs of the laser radar, hs=R0.

From the above description, it can be seen that L0 and R0 are the same laser line, that is, L0=R0.

The following describes the road condition measurement principle based on laser radar in conjunction with FIG. 4 .

1. How to determine whether the wheelchair is moving in a flat road:

When the road surface is flat, there are:

Li×cosΦLi＝L0＝hs and Ri×cosΦRi＝R0＝hs (i＝1,2,…7) (1)

2. Determine whether there are steps above the ground in the direction of the wheelchair, and measure the step parameters:

As shown in Figure 5, when there is a step in front of the wheelchair, the forward measurement value of the laser line measures the vertical plane of the step in the order of large number first and small number later. The laser line irradiated on the vertical plane of the step satisfies:

Li×cosΦLi<hs (i＝7，6，n) (2)

d＝Li×sinΦLi (i＝7，6，n) (3)

n is the smallest number of all laser lines irradiated on the vertical plane of the step, and the remaining laser lines satisfy equation 1. d is the distance from the vertical plane of the step to the origin of the laser radar coordinates.

As the wheelchair moves forward, the value of d gradually decreases. For example, in example Figure 5, n = 6, and:

L7×cosΦL7<hs(hs＝L0)

L6×cosΦL6<hs(hs＝L0)

L5×cosΦL5＝L4×cosΦL4＝L3×cosΦL3＝L2×cosΦL2＝L1×cosΦL1＝hs＝L0

L7×sinΦL7＝L6×sinΦL6＝d

Therefore, the criterion for whether there is a step in the direction of the wheelchair's forward movement is: starting from the laser line with a large number, at least one laser line measurement value satisfies Formula 2.

3. Determine the measured value of the step parameters in the direction of the wheelchair:

As shown in Figure 6, when there is a step in front of the wheelchair, the laser line measures the horizontal plane of the step above the ground in the order of large numbers first and small numbers later. The laser line irradiated on the horizontal plane of the step satisfies:

Li×cosΦLi<hs (i＝7，6，n) (4)

The laser line shining on the plumb plane of the step can be used to measure the distance d:

Li×sinΦLi＝d,(i＝n-1,n-2…m)

The laser line irradiated on the horizontal surface under the step meets

Li×cosΦLi＝hs,(i＝m-1,m-2…0) (5)

At this time, the step height h can be measured:

h＝L0-L7×cosΦLi (6)

As an example, in FIG6 , n=6, m=4. In the subsequent control of the wheelchair of the present invention, the step height h and the distance d need to be known. As can be seen from the above description, each parameter can be measured by multiple laser lines, and its optimal estimated value can be obtained by some method, so there is a high measurement accuracy.

4. When judging whether there are steps below the ground in the direction of the wheelchair, the measured value of the step parameters:

As shown in Figure 7, when there is a step in front of the wheelchair, the laser line illuminates the ground below the step in the order of large numbers first and small numbers later, and there are measurement values:

Li×cosΦLi>hs (i＝7，6，n) (7)

Li×cosΦLi＝hs＝L0,(i＝n-1,n-2…1) (8)

h＝L7×cosΦLi-L0 (9)

d＝Ln×sinΦLn-Ln _-1 ×sinΦLn _-1 (10)

According to the example of FIG7 , in the above formulas, n=4.

5. Backward measurement of the parameters of the step behind the lidar,

In the same way, the step parameters behind the lidar can be obtained using the backward measurement value, as shown in Figure 8:

Ri×cosΦRi<hs (i＝7，6，n) (11)

Ri×cosΦRi<hs (i＝n-1,m、n-2...m) (12)

Ri×cosΦRi＝hs (i＝m-1,m-2…0) (13)

d＝Ri×sinΦRi (i＝n-1,m、n-2...m) (14)

h＝hs-R7×cosΦR7＝hs-R6×cosΦR6＝……＝hs-Rn×cosΦRn (15)

n is the minimum number of laser lines irradiating the upper surface of the step, and m is the minimum number of laser lines irradiating the vertical surface of the step. As an example, in the above formulas, n = 6, m = 4

6. Control method of wheelchair climbing stairs

According to the above, the device of the present invention has two laser radars 31 and 32, and the distance between the coordinate origins of the two is L14.

Assume that the distance between the wheelchair and the steps measured by the left front laser radar 31 is d31, and the distance between the wheelchair and the steps measured by the right front laser radar 32 is d32. In real life, the height of the steps in a small range will not vary much, so the height of the steps measured by the two laser radars 31 and 32 is set to h. Based on the above measurement values, the method of the present invention for smoothly controlling the wheelchair to go up the steps is described below:

Step 1: Walk normally on a level surface.

When walking on a normal flat road, the linear motors of the wheelchair are in the retracted state, and the measurement values of the lidar meet the criteria for a flat road.

Step 2: Find the steps and adjust the walking posture of the wheelchair.

Combined with Figure 3, refer to Figure 9. Figure 9 shows a top view of the wheelchair when it is moving. Assume that one laser radar has detected a step above the road surface in the forward direction. The other one has not detected it, indicating that the forward direction of the wheelchair is not perpendicular to the step. Then the wheelchair slows down and continues to approach the step, and adjusts the walking direction so that both laser radars can detect the step and have the same distance measurement value, even if d31 = d32, as shown in Figure 10. At the same time, ensure that d31 is greater than L15 to ensure that the wheelchair pedal does not hit the step.

Step 3: Lift the car body

As shown in FIG11, when d31=d and d>L15 at an appropriate position, such as d-L15=10cm, the telescopic rods 212, 222, 232, 242 of the linear motors 21, 22, 23, 24 are extended at the same time, and the extension amount is the step height h. As a result, the seat plate 11, footrest 12, backrest 13, etc. of the wheelchair are all lifted up, so that the footrest is higher than the step. The wheelchair continues to move forward slowly, and d31=d32. At this time, the detection value of the laser radar L0 is: L0=hs+h. As shown in FIG12.

Step 4: Go up the stairs directly

When the measured step height h<R/3, the wheelchair can continue to move forward and go directly up the steps and jump to the eighth step.

Step 5: Auxiliary support wheel 5 extends

Combined with Figure 3, when d≤L54, it indicates that the support wheel 5 is already above the step, and the telescopic rod 202 supporting the linear motor 201 is controlled to extend, and its extension amount is controlled to be h/cosα, where α is the angle between the telescopic rod 202 and the vertical direction. As shown in Figure 13, the support wheel 5 is allowed to contact the step, and the support wheel 5 is also allowed to leave the step surface slightly, generally less than 10mm. The wheelchair continues to move forward and makes d31=d32.

Step 6: Lift the left front drive wheel 41 and the right front drive wheel 42

As shown in Figure 13, the auxiliary support wheel 5 has already contacted the road surface on the step. At this time, the telescopic rods 212 and 222 of the linear motor 1 21 and the linear motor 2 22 are controlled to retract, and the retracted distance is the step height h. At this time, the left front drive wheel 41 and the right front drive wheel 42 are lifted and leave the ground. The wheelchair actually continues to move forward by relying on the left rear drive wheel 43 and the right rear drive wheel 44, and makes d31=d32. At this time, since the front running wheel is already at a distance h from the ground, the detection value of the laser radar L0 is: L0=hs+h.

Step 7: The left front driving wheel 41 and the right front driving wheel 42 climb up the steps

The wheelchair moves forward intermittently and slowly, and when L0=hs, it indicates that the left front driving wheel 41 and the right front driving wheel 42 just touch the road surface on the step. Continue to move forward and make d31=d32, keeping the walking direction perpendicular to the vertical plane of the step.

Step 8: The left rear drive wheel 43 and the right rear drive wheel 44 begin to retract.

Combined with Figure 3 and Figure 15, when the left front laser radar 31 and the right front laser radar 32 measure that the distance between the wheelchair and the step is d31 = d32 = L13-R, it indicates that the rear drive wheel is very close to the step. The wheelchair continues to move forward slowly, and at the same time, the linear motor 3 23 and the linear motor 4 24 are controlled to retract the telescopic rods 232 and 242 according to the following rules. Assume that the speed of the wheelchair moving forward is v1, the speed of the linear motor 3 23 and the linear motor 4 24 to retract the telescopic rods 232 and 242 is v2, and the retraction amount is L234:

When L234+R-h<R/2, V2＝2V1

When R/2<L234+R-h<1.7R, V2＝V1

When L234+R-h>1.7R, V2＝V1/2

Step 9: The wheelchair returns to its starting position

When the left front laser radar 31 and the right front laser radar 32 measure that the distance between the wheelchair and the step is d31=d32>L13, it indicates that the left front driving wheel 41, the right front driving wheel 42, the left rear driving wheel 43, and the right rear driving wheel 44 of the wheelchair have all climbed onto the step. The linear motor 1 21, the linear motor 22, the linear motor 3 23, the linear motor 4 24, and the linear motor 5 20 continue to retract all the telescopic rods to restore the wheelchair to the initial state. Return to step 1.

7. How to use a wheelchair down stairs

Based on the above measured values, the method of the present invention for smoothly controlling a wheelchair to go down stairs is described below: Step 1: Level the road surface and walk normally

When walking on a normal flat road, the linear motors of the wheelchair are in the retracted state, and the measurement values of the lidar meet the criteria for a flat road.

Step 2: Find the steps and adjust the wheelchair's walking posture

As shown in Figure 17, it is a top view of the wheelchair when it is moving. Assume that one laser radar has detected a step below the road surface in the forward direction, while the other has not detected it, indicating that the forward direction of the wheelchair is not perpendicular to the step. Then the wheelchair slows down and continues to approach the step until both laser radars can detect the wheelchair step. Adjust the direction of the vehicle so that the laser radars 31 and 32 have the same distance measurement value, that is, d31 = d32, and d31>R, as shown in Figures 18 and 19.

Figure 17 shows a step below the road surface; Figure 18 shows the wheelchair being adjusted in direction; Figure 19 shows the pedal reaching the vicinity of the step;

Step 3: Go straight down the stairs

As shown in FIG. 19 , when the wheelchair moves forward intermittently and slowly and the height of the step is measured to be h<0.3R, the wheelchair moves forward directly and makes all the driving wheels go down the steps to enter the eleventh step.

Step 4: Extend the auxiliary support

When the wheelchair moves forward intermittently and slowly, making d31 = R, it indicates that the front running wheel has approached the vertical plane of the step, and the telescopic rod 202 of the auxiliary support linear motor 5 extends, and its extension amount is controlled to be h/cosα, where α is the angle between the telescopic rod 202 and the vertical direction. As a result, the support wheel 5 contacts the road surface under the step, and the support wheel 5 is allowed to leave the step surface a little. The wheelchair continues to move forward and makes d31 = d32.

Step 5: The front wheels begin to extend beyond the steps

When the wheelchair moves forward intermittently and slowly, so that d31 = 0, and L0 = hs + h, it indicates that the center line of the front running wheel has reached the edge of the step. Then the front running wheel is ready to drop, as shown in FIG. 21 .

Step 6: The front wheel starts to fall

As shown in FIG. 22 , assuming that the forward speed of the wheelchair is v1, and the speeds of 212 and 222 are v2, the linear motor 1 21 and the linear motor 2 22 are controlled to retract the telescopic rods according to the following rules until the extension amount L212＝L222≈h-10, so that the front running wheels are close to the ground but not on the ground:

When L212<0.3R, V2＝V1/2

When 0.3R<L212<0.7R, V2＝V1

When L212>0.7R, V2＝2V1

During this process, the wheelchair is substantially driven forward by the left rear driving wheel 43 and the right rear driving wheel 44. After this process is completed, the front running wheels are only very close to the road surface but have not yet completely landed, so the friction between the front wheels and the ground will not affect the movement of the rear wheels in the subsequent process, but the wheelchair can be prevented from tipping over.

Step 7: Adjust the direction of the wheelchair and lower the front wheels

In order to keep the wheelchair balanced when the next wheel goes down the stairs, the wheelchair needs to adjust its walking direction. As shown in Figure 23, the wheelchair's left and right rear wheels are controlled to make the wheelchair rotate around the left front wheel. The backward measurement values of the left front laser radar 31 and the right front laser radar 32 are used to measure the distances d31 and d32 of the stairs.

As shown in Figure 23, when 0.9R<d31<1.1R and 0.9L13<d32<1.1L13 are satisfied, the right front wheel of the wheelchair is equivalent to being stationary, so that 0.9R<d31<1.1R, but the right front wheel will not touch the steps behind. So that d32≈L13, the wheelchair's forward direction forms an angle with the steps. The optimal theoretical value of is: In this way, the left rear wheel is already at the edge of the step, ready to go down the step.

In the same way, the wheelchair can also be made to rotate around the right front wheel, and the process is exactly the same as above, as shown in Figure 24, so that the right rear wheel is ready to go down the steps. The specific process will not be repeated.

Next, the telescopic rods 212 and 222 are controlled so that their telescopic amount L212=L222=h. As a result, the front wheels of the wheelchair are completely on the ground and can provide forward momentum, as shown in FIG. 25 .

Step 8: One rear drive wheel extends beyond the step and touches the ground.

The left front driving wheel 41, the right front driving wheel 42, the left rear driving wheel 43, and the right rear driving wheel 44 of the wheelchair are controlled to move forward slowly at the same speed. At this time, the left front driving wheel 41 and the right front driving wheel 42 have completely landed on the ground, providing the main walking power, and the one of the two rear driving wheels close to the step is about to go beyond the step and is ready to land.

Therefore, in FIG23, the left rear driving wheel 43 is close to the step. When the wheelchair moves forward, the left rear driving wheel 43 will first exceed the step and land on the ground, as shown in FIG26. In this process, it is necessary to control the telescopic rod 232 of the linear motor 3 23 to extend, thereby driving the left rear driving wheel 43 to descend. The extension amount is recorded as L232. Assume that the speed of the wheelchair moving forward is v1, and the speed of the linear motor 3 23 extending the telescopic rod 232 is v2. Control v2 according to the following rules:

When L232<0.3R, V2＝V1/2

When 0.3R<L232<0.7R, V2＝V1

When L232>0.7R, V2＝2V1

Until the extension amount L232 = h, the rear left driving wheel 43 falls to the ground.

Therefore, in FIG24 , the right rear drive wheel 44 is close to the step. When the wheelchair moves forward, the right rear drive wheel 44 will first exceed the step, as shown in FIG27 . In this process, it is necessary to control the linear motor 24 to extend the telescopic rod 242, thereby driving the right rear drive wheel 44 to descend. The extension amount is recorded as L242. Assume that the speed of the wheelchair moving forward is v1, and the speed of the linear motor 24 extending the telescopic rod 242 is v2. Control v2 according to the following rule:

When L242<0.3R, V2＝V1/2

When 0.3R<L242<0.7R, V2＝V1

When L242>0.7R, V2＝2V1

Until the extension amount L242 = h, the rear right drive wheel falls to the ground.

Step 9: The other rear drive wheel approaches the step and is ready to drop down to touch the ground

At this time, three driving wheels have already landed, and the last driving wheel on the step needs to be moved near the step. Therefore, the left front driving wheel 41, the right front driving wheel 42, the left rear driving wheel 43, and the right rear driving wheel 44 of the wheelchair are controlled to move forward slowly for a short distance at the same speed until the last driving wheel is close to the vertical surface of the step.

For FIG. 26 , the termination condition of this step is: the backward measurement value of the right laser radar 32 is measured as d32=L13, and the result is shown in FIG. 28

For FIG. 27 , the termination condition of this step is: the backward measurement value of the left laser radar 31 is measured as d31=L13, and the result is shown in FIG. 29 ;

At this time, the center of the last driving wheel is at the edge of the step.

Step 10: The last rear drive wheel falls down and touches the ground

Continue to control the left front driving wheel 41, the right front driving wheel 42, the left rear driving wheel 43, and the right rear driving wheel 44 of the wheelchair to move forward slowly at the same speed until the last driving wheel lands.

For Figure 28, the action flow is: the right rear drive wheel 44 is close to the step. When the wheelchair moves forward, the electric cylinder 4 241 is controlled to extend the telescopic rod 4 242, thereby driving the right rear drive wheel 44 to descend. The extension amount is recorded as L242. Assume that the speed of the wheelchair moving forward is v1, and the speed of the electric cylinder 4 241 extending the telescopic rod 4 242 is v2. Control v2 according to the following rules:

When L242<0.3R, V2＝V1/2

When 0.3R<L242<0.7R, V2＝V1

When L242>0.7R, V2＝2V1

Until the extension amount L242 = h, the right rear drive wheel 44 falls to the ground, as shown in FIG. 30 .

In Figure 29, the left rear driving wheel 43 is close to the step. The wheelchair will move forward and the left rear driving wheel 43 will go beyond the step. It is necessary to control the electric cylinder 3 231 to extend the telescopic rod 3 232, thereby driving the right rear driving wheel 44 to descend. The extension amount is recorded as L232. Assume that the speed of the wheelchair moving forward is v1, and the speed of the electric cylinder 3 231 extending the telescopic rod 3 232 is v2. Control v2 according to the following rules:

When L232<0.3R, V2＝V1/2

When 0.3R<L232<0.7R, V2＝V1

When L232>0.7R, V2＝2V1

Until the extension amount L232 = h, the left rear drive wheel falls to the ground, as shown in Figure 31.

Figure 30 The right rear wheel falls off the step; Figure 31 The left rear wheel falls off the step; Step 11: The wheelchair returns to its initial state

When all the driving wheels have finished going down the steps, it is necessary to move the extended telescopic rods 5 202 and 1

The telescopic rod 212, the second telescopic rod 222, the third telescopic rod 232, and the fourth telescopic rod 242 are retracted simultaneously, so that the wheelchair seat falls, and finally the wheelchair is restored to the initial state of walking along a flat road.

8. How to use small diameter drive wheels on steps

When the radius R of the driving wheel is greater than the step height h, as shown in FIG15 , the wheel can be made to pass over the step according to the above method. However, if the radius R of the driving wheel is significantly smaller than the step height h, the method in the sixth embodiment of the present invention may cause the wheelchair to vibrate violently or fail to climb the step at all. Therefore, the present invention provides a method for a wheelchair to pass over the step smoothly using a small-diameter driving wheel. The following is an explanation in conjunction with FIG3 .

Step 1: Walk normally on a level surface.

When walking on a normal flat road, the linear motors of the wheelchair are in the retracted state, and the measurement values of the lidar meet the criteria for a flat road.

Step 2: Find the steps and adjust the walking posture of the wheelchair.

Combined with Figure 3, refer to Figure 32. Figure 32 shows a top view of the wheelchair when it is moving. Assume that one laser radar has detected a step above the road surface in the forward direction. The other one has not detected it, indicating that the forward direction of the wheelchair is not perpendicular to the step. Then the wheelchair slows down and continues to approach the step, and adjusts the walking direction so that both laser radars can detect the wheelchair step and have the same distance measurement value, even if d31 = d32, as shown in Figure 33. At the same time, ensure that d31 is greater than L15 to ensure that the wheelchair foot pedal does not hit the step.

Step 3: Lift the car body

As shown in FIG35 , at the appropriate position of d31=d and d>L15, such as: d-L15=10cm, at this time, the footrest of the wheelchair is close to the step. The linear motor 1 21, the linear motor 22, the linear motor 3 23, and the linear motor 4 24 are controlled to extend the corresponding telescopic rods 1 212, 222, 3 232, and 4 242 at the same time, and the extension amount is the step height h+10mm. As a result, the seat plate 11, footrest 12, backrest 13, etc. of the wheelchair are all lifted up, so that the footrest is higher than the step. The wheelchair continues to move forward slowly, and d31=d32. At this time, the detection value of the laser radar L0 is: L0=hs+h. As shown in FIG35 .

Step 4: Auxiliary support wheel 5 extends

In conjunction with FIG3 and FIG36, when the wheelchair moves forward to d≤L54, it indicates that the support wheel 5 is already above the step, and the telescopic rod 5 202 of the electric cylinder 5 201 is controlled to extend, and its extension amount is controlled to be h/cosα, where α is the angle between the telescopic rod 202 and the vertical direction. As shown in FIG36, the support wheel 5 contacts the step.

Step 6: Lift the left front drive wheel 41 and the right front drive wheel 42

As shown in Figure 36, since the auxiliary support wheel 5 has already contacted the road surface on the step. At this time, the telescopic rod 1 212 of the linear motor 1 21 and the telescopic rod 2 222 of the linear motor 22 are controlled to retract, and the retracted distance is the step height h+Δh, where 5<Δh<20. In this way, the running wheels 41 and 42 leave the ground. The wheelchair actually continues to move forward by relying on the running wheels 43 and 44, and makes d31=d32. At this time, since the front running wheel is already at a distance h from the ground, the detection value of the laser radar L0 is: L0=hs+h+Δh.

Step 7: The left front driving wheel 41 and the right front driving wheel 42 climb up the steps

The wheelchair moves forward intermittently and slowly. When L0=hs, it indicates that the left front driving wheel 41 and the right front driving wheel 42 are just above the step but not in contact with the road surface, as shown in FIG37 .

Step 8: Adjust the direction of the wheelchair

In order to make the small diameter drive left rear drive wheel 43 or right rear drive wheel 44 at the back climb up the steps smoothly, the wheelchair needs to adjust its walking direction. In Figure 37, the front drive wheel is not in contact with the ground, so the left rear wheel and the right rear wheel differential of the wheelchair can be controlled, and the backward measurement values of the laser radar 31 and 32 are used to measure the distances d31 and d32 of the steps. When d31=L13-R is satisfied, the left rear wheel is close to the vertical plane of the step and is ready to go up the steps. At this time, d32=0-50 should also be set, so that the right front drive wheel 32 is on the side of the road surface on the step on the edge of the step, and is 0-50 away from the vertical plane of the step. This makes the wheelchair form an angle with the step. The optimal theoretical value of is: As shown in Figure 38.

In the same way, the right rear wheel can be placed at the edge of the step, ready to go up the step. As shown in Figure 39, the right rear wheel is ready to go down the step. The specific process will not be described in detail.

Next, the telescopic rods 212 and 222 are controlled to extend by Δh so that their total extension amount is L212=L222=h. As a result, the front wheels of the wheelchair are completely on the ground and can provide forward momentum.

Step 9: Raise the rear drive wheel near the step

The wheelchair continues to move forward slowly while raising the rear wheel closest to the step. For Figure 38, the left rear drive wheel 43 is closest to the step and needs to be raised and climbed up the step first. Assume that the speed of the wheelchair moving forward is v1, and the speed of the linear motor 231 retracting back to the telescopic rod 232 is v2. Control v2 according to the following rule:

When L232-R>10-40mm, V2＝max(V2). In this process, due to the symmetrical structure of the wheelchair, the center of gravity of the wheelchair and the occupant is near the diagonal of the centers of the four driving wheels. Since the center of the left rear drive 43 is lower than the upper surface of the step, the wheelchair is in a critical balance state. However, due to the forward momentum of the driving wheels 41, 42 and 44 at this time, the raised left rear drive wheel 43 is close to the vertical surface of the step, and the wheelchair will rely on friction to maintain balance. For safety, V2 should be made to reach the maximum speed of the linear motor so that the left rear drive wheel 43 can be raised as quickly as possible. After this process is completed, the center of the left rear drive 43 is 10-40mm higher than the upper surface of the step. Thereafter, v2 is controlled according to the following rules:

When R-L232>0.7R, V2＝2V1

When 0.3R<R-L232<0.7R, V2＝V1

When R-L232<0.3R, V2＝V1/2

After the above process is completed, the left rear driving wheel is lifted onto the step surface, as shown in Figure 40. In a similar way, the right rear driving wheel 44 in Figure 39 can be made to climb onto the step, as shown in Figure 41. In this way, there are already three driving wheels on the upper surface of the step that can provide power for the wheelchair to move forward, and the remaining driving wheel is still a certain distance away from the step.

Step 10: The last drive wheel is close to the step

The wheelchair continues to move forward slowly, so that the driving wheel under the step approaches the vertical plane of the step. For Figure 40, when the rearward measurement value of the laser radar 32 measures d32 = L13-R, it indicates that the right rear drive wheel 44 has approached the vertical plane of the step, as shown in Figure 42; for Figure 41, when the rearward measurement value of the left front laser radar 31 measures d31 = L13-R, it indicates that the left rear drive wheel 43 has approached the vertical plane of the step, as shown in Figure 43.

Step 11: Raise the last drive wheel

Raise the last drive wheel as in step 9.

Step 12: Return the wheelchair to its original state

When all the driving wheels have finished going down the steps, the extended telescopic rods 202, 212, 222, 232, 242 need to be retracted at the same time to make the wheelchair seat fall down, and finally restore the wheelchair to the initial state of walking along a flat road.

9. Safety measurement and control of wheelchairs going up and down stairs

The present invention provides an independent safety protection mechanism to avoid errors in various wheelchair actions. The system structure logic is shown in FIG44 .

In FIG44 , the control electrical appliance of the wheelchair mainly refers to the computer processing unit and its corresponding communication bus necessary to complete the aforementioned various actions. The mechanical structure of the wheelchair and the corresponding measuring device include the aforementioned wheelchair body 1, linear motor 2, laser radar 3, driving wheel 4, auxiliary support wheel 5, etc. The software part includes the control of the intelligent wheelchair, the use of laser radar 3 for curb recognition, and the use of the inclination sensor 6 to measure the balance state of the wheelchair in real time. As can be seen from FIG44 , the inclination sensor 6 is independent of the movement of the wheelchair and can measure the balance and vibration of the wheelchair in real time. Therefore, the measurement of the inclination sensor 6 is not affected by the above methods and steps, and the balance state of the wheelchair can be obtained at any time in the above method steps. When it is found that the wheelchair is in a serious imbalance state or violent vibration occurs, it immediately enters the implementation of other fault handling processes in the intelligent wheelchair: possible process actions include: terminating the current action, giving an alarm signal, and other actions designed to ensure safety.

The technical means disclosed in the scheme of the present invention are not limited to the technical means disclosed in the above-mentioned implementation mode, but also include technical schemes composed of any combination of the above technical features.

Claims (7)

1. The wheelchair structure capable of ascending and descending steps comprises a wheelchair body, travelling wheels and auxiliary supporting wheels (5), wherein the wheelchair body consists of a seat plate (11), a pedal plate (12) and a backrest plate (13), and is characterized in that the wheelchair body comprises a seat plate (11); the system also comprises a first linear motor (21), a second linear motor (22), a third linear motor (23), a fourth linear motor (24), a fifth linear motor (20), a laser radar (3) and an inclination sensor (6); the linear motors I (21), II (22), III (23) and IV (24) have the same structure, the centers of the 4 linear motors are arranged in a rectangular shape, and the size of the rectangle is adapted to the seat plate; the linear motor five (20) is connected and matched with the pedal plate (12); the inclination angle sensor (6) is fixedly connected with the seat plate (11) and is used for measuring the inclination angle of the seat plate relative to the horizontal plane; the laser radars comprise a front left laser radar (31), a front right laser radar (32), a rear right left laser radar (33) and a rear right laser radar (34).

2. A wheelchair structure capable of ascending and descending steps according to claim 1, characterized in that: the linear motor five (20) comprises an electric cylinder five (201) fixedly connected with the pedal plate (12) and a telescopic rod five (202) matched with the electric cylinder five, the movement direction of the telescopic rod five (202) is parallel to the pedal plate (12), and the telescopic amount is recorded as L202.

3. A wheelchair structure capable of ascending and descending steps according to claim 1, characterized in that: the linear motor I (21) comprises an electric cylinder I (211) fixedly connected with the seat plate (11) and a telescopic rod I (212) matched with the electric cylinder I, the movement direction of the telescopic rod I (212) is perpendicular to the seat plate (11), and the telescopic amount is recorded as L212; the telescopic rod I (212) is connected with the left front driving wheel (41); the linear motor II (22) comprises a cylinder II (221) fixedly connected with the seat plate (11) and a telescopic rod II (222) matched with the cylinder II, the moving direction of the telescopic rod II (222) is perpendicular to the seat plate (11), and the telescopic amount is recorded as L222; the second telescopic rod (222) is connected with the right front driving wheel (42); the linear motor III (23) comprises a cylinder III (231) fixedly connected with the seat plate (11) and a telescopic rod III (232) matched with the cylinder III, the movement direction of the telescopic rod III (232) is vertical to the seat plate, and the telescopic amount is recorded as L232; the telescopic rod III (232) is connected with the left rear driving wheel (43); the linear motor IV (24) comprises an electric cylinder IV (241) fixedly connected with the seat plate (11) and a telescopic rod IV (242) matched with the electric cylinder IV, the movement direction of the telescopic rod IV (242) is perpendicular to the seat plate, and the telescopic amount is recorded as L242; the telescopic rod IV (242) is connected with the right rear driving wheel (44); the first electric cylinder (211), the second electric cylinder (221), the third electric cylinder (231) and the fourth electric cylinder (241) are respectively and fixedly provided with a linear array type laser radar, and corresponding numbers are respectively a left front laser radar (31) and a right front laser radar (32); a left rear lidar (33) and a right rear lidar (34).

4. A wheelchair structure capable of ascending and descending steps according to claim 1, characterized in that: the telescopic rod five (202) comprises a telescopic part (2021) and a mounting part (2022); the telescopic part (2021) is a component which is matched with the electric cylinder and forms linear motion; the mounting part (2022) is used for mounting the auxiliary supporting wheel (5); the auxiliary supporting wheel (5) freely rotates around the mounting part (2022), the height between the center of the auxiliary supporting wheel (5) and the ground is h5, and the height difference between the foot pedal (12) and the ground is h12.

5. A wheelchair structure capable of ascending and descending steps according to claim 1, characterized in that: the fixed position of the inclination sensor (6) is not limited to the position just above the seat plate or below the seat plate or other positions.

6. An intelligent wheelchair control method capable of ascending and descending steps is characterized in that: the control method for the wheelchair to go up the step comprises the steps of arranging a left front laser radar (31) and a right front laser radar (32), wherein the distance between the two coordinate origins is L14, and the steps are as follows: the distance from the wheelchair to the step is d31 measured by the left front laser radar (31), and the distance from the wheelchair to the step is d32 measured by the right front laser radar (32); setting the heights of steps measured by a left front laser radar (31) and a right front laser radar (32) to be h; based on the above measurement values, the following describes a method of smoothly controlling the steps on the wheelchair:

The first step: the road surface is leveled and normally walked; when the wheelchair walks on a flat road, the wheelchair linear motor is in a retracted state, and the measured value of the laser radar accords with the criterion of the flat road;

And a second step of: after the steps are found, if one laser radar detects the steps higher than the road surface and the other laser radar does not detect the steps, the wheelchair is not vertical to the steps in the advancing direction; the wheelchair decelerates and adjusts the travelling direction, so that the left front laser radar (31) and the right front laser radar (32) both detect steps, the measurement distances d31 and d32 are the same, and the distance is ensured to be larger than L15 so as to prevent the pedal from striking the steps; wherein the distance from the pedal (11) to the centers of the left front driving wheel (41) and the right front driving wheel (42) is L15;

Thirdly, lifting the vehicle body; in the proper position where d31=d, and d > L15, such as: d-L15=10cm, the telescopic rod I (212) on the linear motor I (21), the telescopic rod II (222) on the linear motor II (22), the telescopic rod III (232) on the linear motor III (23) and the telescopic rod IV (242) on the linear motor IV (24) extend simultaneously, the extending amount is the step height h, and the pedal is higher than the step; the wheelchair continues to slowly advance; at this time, the vertical heights of the front left lidar (31) and the front right lidar (32) with respect to the ground are: l0=hs+h, where hs is the vertical height of the front left laser radar (31) and the front right laser radar (32) with respect to the ground in the initial state;

fourth, directly ascending the step; when the measured step height h is less than R/3, the wheelchair can continuously move forward and directly go up the step; and jumping to an eighth step;

Fifthly, the auxiliary supporting wheels (5) extend out; d is less than or equal to L54, indicating that the auxiliary supporting wheel (5) is positioned above the step, controlling the extension of the telescopic rod five (202) supporting the linear motor five (20), wherein the extension amount is h/cos alpha, and alpha is an included angle between the telescopic rod five (202) and the vertical direction;

The auxiliary supporting wheel (5) is contacted with the step, and the auxiliary supporting wheel (5) is allowed to leave the step surface a little, and the distance is generally less than 10mm; the wheelchair continues to advance;

a sixth step of lifting the left front driving wheel (41) and the right front driving wheel (42); controlling the first telescopic rod (212) of the first linear motor (21) and the second telescopic rod (222) of the second linear motor (22) to retract by the step height h; at this time, the left front driving wheel (41) and the right front driving wheel (42) are lifted up and separated from the ground; the wheelchair essentially continues to advance by means of the left rear drive wheel (43) and the right rear drive wheel (44); at this time, the vertical heights of the front left lidar (31) and the front right lidar (32) with respect to the ground are: l0=hs+h;

Seventh, the left front driving wheel (41) and the right front driving wheel (42) climb up the steps; the wheelchair intermittently and slowly advances, when L0=hs, the left front driving wheel (41) and the right front driving wheel (42) are indicated to be just contacted with the road surface on the step;

Eighth, the left rear driving wheel (43) and the right rear driving wheel (44) start to retract; when the front left lidar (31) and the front right lidar (32) measure d31=d32=l13-R, it is indicated that the rear drive wheel has been very close to the step; let the forward speed of the wheelchair be v1, the speed of the retraction telescoping rod three (232) of the linear motor three (23) and the retraction telescoping rod four (242) of the linear motor four (24) be v2, and the retraction amount be L234:

When l234+r-h < R/2, v2=2v1

When R/2< l234+r-h <1.7R, v2=v1

When l234+r-h >1.7R, v2=v1/2

Ninth step: resetting the wheelchair; when the measured values d31=d32 > L13 of the left front laser radar (31) and the right front laser radar (32), the wheelchair is indicated to climb up the step; the first linear motor (21), the second linear motor (22), the third linear motor (23), the fourth linear motor (24) and the fifth linear motor (20) retract all the telescopic rods, so that the wheelchair is restored to the initial state; returning to step 1.

7. The intelligent wheelchair control method capable of ascending and descending steps according to claim 6, wherein the method comprises the following steps: the method for descending the step of the wheelchair specifically comprises the following steps:

the first step: the road surface is leveled and normally walked; when a flat road surface walks, the linear motor of the wheelchair is in a retracted state, and the measured value of the laser radar accords with the criterion of the flat road surface;

and a second step of: finding steps and adjusting the walking posture of the wheelchair; assuming that one lidar has detected that the forward direction has a step lower than the road surface and the other lidar has not detected, indicating that the forward direction of the wheelchair is not perpendicular to the step; the wheelchair is decelerated to approach the step until both lidars can detect the step; adjusting the wheelchair direction so that the measured values d31=d32 of the left front laser radar (31) and the right front laser radar (32) are d31> R;

and a third step of: directly descending a step; when the height h of the step is measured to be less than 0.3R, the wheelchair directly advances, and all driving wheels are driven to go down the step to enter an eleventh step.

Fourth step: the auxiliary supporting wheel (5) stretches out; when d31=R indicates that the front travelling wheel is close to a step, the telescopic rod five (202) supporting the linear motor five (20) is controlled to extend, the extending amount is h/cos alpha, and alpha is the included angle between the telescopic rod five (202) and the vertical direction, so that the auxiliary supporting wheel (5) contacts the road surface under the step, and the auxiliary supporting wheel (5) is allowed to leave the step surface a little, and the general distance is less than 10mm; the wheelchair continues to advance and d31=d32;

Fifth step: the front travelling wheel exceeds the step; intermittent slow-speed travel of the wheelchair, when d31=0 and l0=hs+h, indicates that the center line of the front road wheel has reached the edge of the step; preparing to drop the front travelling wheel;

Sixth step: the front travelling wheel begins to fall down; let the forward speed of the wheelchair be v1, the speed of the first linear motor (21) extending out of the first telescopic rod (212) and the speed of the second linear motor (22) extending out of the second telescopic rod (222) be v2, the extending amount l212=l222≡h-10, the first telescopic rod (212) of the first linear motor (21) and the second telescopic rod (222) of the second linear motor (22) are controlled according to the following rule, so that the front travelling wheels are close to the ground but do not fall to the ground:

when L212<0.3R, v2=v1/2

V2=v1 when 0.3r < l212<0.7r

When L212>0.7R, v2=2v1

In the process, the wheelchair drives the wheelchair to advance by virtue of the left rear driving wheel (43) and the right rear driving wheel (44); after the process is finished, the front travelling wheel is only very close to the road surface, but not completely falls to the ground, so that the movement of the rear wheel in the subsequent process cannot be influenced due to the friction force between the front wheel and the ground, and the wheelchair can be prevented from tilting and turning over;

seventh step: adjusting the direction of the wheelchair, and falling down the front wheel; in order to keep the wheelchair balanced when the next walking wheel goes down the step, the direction of the wheelchair needs to be adjusted; controlling the differential speed of the left rear driving wheel and the right rear driving wheel of the wheelchair to enable the wheelchair to rotate around the left front driving wheel; measuring the distances d31 and d32 of the steps by using a left front laser radar (31) and a right front laser radar (32);

When 0.9r < d31<1.1r,0.9l13< d32<1.1l13 are satisfied, the right front wheel of the wheelchair corresponds to stationary in place but does not contact the step at the rear. The d32 is approximately equal to L13, and an included angle is formed between the advancing direction of the wheelchair and the step The preferred theoretical values of (2) are: (L13/L12); thus, the left rear driving wheel is already at the step edge and ready to go down the step;

The same reason is that the wheelchair can also rotate around the right front driving wheel, the process is exactly the same as the above, and the right rear wheel is ready to go down the step; then, the first linear motor (21) is controlled to extend out of the first telescopic rod (212) and the second linear motor is controlled to extend out of the second telescopic rod (222), the telescopic quantity L212=L222=h, and the front wheel of the wheelchair is enabled to fall to the ground and can provide forward power;

eighth step: a rear drive wheel extending beyond the step and contacting the ground; the wheelchair is controlled to slowly advance, the left front driving wheel (41) and the right front driving wheel (42) are completely landed, main walking power is provided, one of the two rear driving wheels, which is close to the step, is about to exceed the step, and the wheelchair is ready to land; when the left rear driving wheel (43) approaches to the step, the left rear driving wheel (43) firstly exceeds the step and falls to the ground, and in the process, the linear motor III (23) needs to be controlled to extend the telescopic rod III (232), so that the left rear driving wheel (43) is driven to descend, and the telescopic quantity is recorded as L232; let the forward speed of the wheelchair be v1, and the speed of the linear motor III (23) extending out of the telescopic rod III (232) be v2. V2 is controlled as follows:

When L232<0.3R, v2=v1/2

V2=v1 when 0.3r < l232<0.7r

When L232>0.7R, v2=2v1

Until the protruding amount L232=h, the left rear driving wheel (43) is landed;

Similarly, when the wheelchair moves forward, the right rear driving wheel (44) firstly exceeds the step, and in the process, the linear motor IV (24) needs to be controlled to extend the telescopic rod IV (242), so that the right rear wheel is driven to descend, and the telescopic amount is recorded as L242; the forward speed of the wheelchair is v1, and the speed of the linear motor IV (24) extending out of the telescopic rod IV (242) is v2; v2 is controlled as follows:

When L242<0.3R, v2=v1/2

V2=v1 when 0.3r < l242<0.7r

When L242>0.7R, v2=2v1

Until the projecting amount l242=h, the right rear drive wheel is landed;

ninth step: the other rear drive wheel approaches the step and is ready to drop to the ground at which point the last drive wheel on the step needs to be moved to the vicinity of the step. Continuously controlling the wheelchair to slowly advance at the same speed until the last driving wheel approaches the step;

Tenth step: the last rear driving wheel falls to contact the ground; and continuously controlling the wheelchair to slowly advance until the last driving wheel falls to the ground.

Eleventh step: returning the wheelchair to the initial state when all driving wheels finish descending steps, the extending telescopic rods five (202), the extending telescopic rod one (212), the extending telescopic rods two (222), the extending telescopic rods three (232) and the extending telescopic rods four (242) need to retract simultaneously, so that the wheelchair seat falls down, and the wheelchair is returned to the initial state.