CN114839876A - A kind of electromagnetic force control method of magnetic adsorption cable climbing robot - Google Patents

Abstract

The invention discloses an electromagnetic force control method for a magnetic adsorption cable climbing robot. The vibration of a bridge cable detection robot on the bridge cable is used as interference, and an attitude sensor is used to detect the motion state of the robot; the magnetic adsorption robot moves on the inclined cable. Vibration, the attitude sensor will detect the acceleration signal, and use the industrial computer to read the acceleration signal value, and then adjust the voltage value of the output port according to the size of the signal; finally, use the buck boost module to amplify the voltage value of the output port of the industrial computer. Access both ends of the electromagnetic mechanism. The sliding mode control method is used to control the voltage of the output port of the industrial computer to control the current passing through the coil of the electromagnetic mechanism. The robot of the invention can automatically select the most suitable electromagnetic force for control according to the detected vibration signal.

Description

A kind of electromagnetic force control method of magnetic adsorption cable climbing robot

technical field

The invention relates to the technical field of robot control, in particular to an electromagnetic force control method for a magnetic adsorption cable climbing robot.

Background technique

In the field of industrial technology, the inspection of cable bridge cables is a very important task. This type of task is an operation carried out under extremely dangerous conditions. If it is performed manually, it is not only inefficient and has a long cycle, but also faces great risks and challenges. The application of magnetic adsorption robots for maintenance can not only improve work efficiency, but also reduce the incidence of maintenance accidents, which is of great significance to the field of industrial technology.

The magnetic adsorption robot is a special robot that can perform continuous crawling operations on the magnetically conductive surface, which can effectively replace humans to perform these dangerous and complicated surface inspection tasks. The magnetic adsorption robot is adsorbed on the surface of the cable by the adsorption force generated by the magnetic adsorption unit, and the robot is driven by the motor to climb upward. During the climbing process of the robot, the electromagnetic force will fluctuate due to factors such as wind force or the surface of the inclined cable, which will cause the robot to fall. At present, the commonly used method is PID control, but PID control cannot quickly rise to the required voltage, and the robot is easy to fall during the climbing process. In order to better control the robot, the present invention relates to a new electromagnetic force control method for a magnetic adsorption robot, that is, a sliding mode control method in robust control.

Sliding mode control is mainly a control idea that appears in the controlled system for a class of control problems where there is unknown disturbance and the disturbance has an upper bound. In a broad sense, sliding mode control is similar to methods such as H-infinity and disturbance observer, and is a form of robust control, which enables the control system to still ensure a certain control performance under disturbance. From the perspective of system dynamics, the key to the design of the sliding mode control algorithm is:

1) For a controlled system that exhibits a specific dynamic behavior, how to design a sliding mode surface or select a sliding mode variable (or whether there is such a sliding mode surface) to ensure the performance of the control system (such as the control error under disturbance conditions) Convergence) to meet expectations;

2) How to design the control rate to ensure that the system trajectory starting from the initial state can reach the sliding mode surface within a limited time, and can stay in the sliding mode surface all the time after arriving, and ensure that the system state variables converge as soon as possible.

For the magnetic adsorption robot, the disturbance comes from the vibration of the robot affected by various factors. The sliding mode control method of the present invention can effectively keep the robot stable during the maintenance process, thereby achieving the effect of completing tasks safely and efficiently.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is aimed at the deficiencies of the above-mentioned prior art, and provides a method for controlling the electromagnetic force of a magnetic adsorption robot based on sliding mode control of bridge cables, which can control the magnitude of the magnetic adsorption force in time, and uses an electromagnetic mechanism to design Adsorption structure, the magnetic force of the electromagnetic mechanism is easy to control, and the value of the magnetic attraction force can be controlled by controlling the size of the current passing into the coil of the electromagnetic mechanism.

In order to solve the above-mentioned technical problems, the technical scheme adopted in the present invention is:

A method for controlling electromagnetic force of a magnetic adsorption cable climbing robot, comprising the following steps: Step 1, establishing an electromagnetic force correlation model according to the number of coil turns, contact area, current size and air gap length:

为保险系数(其值在0.05～0.15之间)，μ₀为空气的导磁系数(其值为4π×10^-7H/m)，S表示磁极与斜缆索的相对面积，δ表示气隙平均长度；Among them, F _dc represents the magnitude of the electromagnetic force, I represents the magnitude of the current, N represents the number of turns of the coil,

is the insurance factor (its value is between 0.05 and 0.15), μ ₀ is the permeability coefficient of air (its value is 4π×10 ^-7 H/m), S represents the relative area between the magnetic pole and the inclined cable, and δ represents the air gap average length;

Step 2, the shape of the magnetic pole is an arc. According to the mathematical equation of the curve at the magnetic pole and the mathematical equation of the curve at the rope, the total length of the air gap is:

表示气隙总长度，X表示直角坐标系横坐标的值，Y₁表示直角坐标系中磁极曲线纵坐标的值，R₁表示磁极曲率半径，Y₂表示直角坐标系中绳索曲线纵坐标的值，R₂表示绳索半径大小，将步骤2得到的气隙总长度除以磁极的长度则可以得到步骤1的气隙的平均长度；in,

Indicates the total length of the air gap, X represents the value of the abscissa of the rectangular coordinate system, Y ₁ represents the value of the ordinate of the magnetic pole curve in the rectangular coordinate system, R ₁ represents the radius of curvature of the magnetic pole, and Y ₂ represents the value of the ordinate of the rope curve in the rectangular coordinate system , R ₂ represents the radius of the rope, and the average length of the air gap in step 1 can be obtained by dividing the total length of the air gap obtained in step 2 by the length of the magnetic pole;

In step 3, the vibration of the magnetic adsorption robot is used as a source of interference, and the attitude sensor is used to detect the acceleration change of the magnetic adsorption robot, and the information of the lateral acceleration and the longitudinal acceleration is received, and then the shaking state of the magnetic adsorption robot is detected;

的关系式：Step 4, use the industrial computer to read the two acceleration signal values in step 3, process the two values in the industrial computer, and obtain the average value of the total acceleration |a|; according to the difference of the average value, the shaking level is divided into 10 level, the average acceleration |a| and the output voltage reference value are obtained

The relation of:

Real-time comparison of the total acceleration average value |a| in the industrial computer to obtain the output voltage reference value

Step 5, design the sliding surface _sk as:

s _k =mE _k +v _k

Among them, m is the parameter to be designed, E _k is the voltage tracking gain, v _k is the output voltage error integral, and s _k >0, v _k >0, m>0. The output voltage error integral v _k can be further expressed as:

v _k = v _k-1 +GE _k-1

Among them, G is the integral gain;

Step 6, according to Step 5, the initial state of the system is configured on the sliding mode surface, and the initial value v ₀ of the output voltage error integral v _k is set as:

v ₀ = -mE ₀

Step 7, design the sliding mode voltage controller, and adopt the discrete equivalent control law:

s _k+1 -s _k =0

Among them, _sk+1 is the sliding mode surface recursively forwarding one sampling time step. When the sampling time step is small enough, it can be considered that the output voltage reference value remains unchanged in one sampling period:

The sliding mode control law of Buck circuit is obtained as:

是等效控制的滑膜控制率，C为电容值，R为电阻值，T为采样周期，u_ok为电压反馈值，f_k为集中扰动的估计值；in,

is the synovial control rate of the equivalent control, C is the capacitance value, R is the resistance value, T is the sampling period, u _ok is the voltage feedback value, and f _k is the estimated value of the concentrated disturbance;

To enable the system to always reach the quasi-sliding mode, a discontinuous switching control is added:

是附加切换控制项，C为电容值，T为采样周期K_sw为切换项增益，且K_sw>0，sgn(s_k)为滑模面s_k的符号函数；in,

is an additional switching control term, C is the capacitance value, T is the sampling period, K _sw is the switching term gain, and K _sw >0, sgn( _sk ) is the sign function of the sliding mode surface _sk ;

Finally, it is concluded that the complete form of the sliding mode voltage controller is:

Step 8, introduce the "delayed disturbance estimation" strategy, and approximate the disturbance at this moment by calculating the concentrated disturbance value _mfk at the last sampling moment:

作为输入变量之一，与实时输出电压u_o作差得出E_k且f_k-1输入到式中，得出电感电流参考值

Step 9, sample the output voltage u _o in real time, and set the reference value of the output voltage

As one of the input variables, the difference with the real-time output voltage u _o obtains E _k and f _k-1 is input into the formula to obtain the reference value of the inductor current

Among them, f _k-1 is the estimated value of the centralized disturbance;

作差，对差值进行电流内环PI控制，并对等效占空比进行PWM；Step 10, sample the inductor current i _L in real time and make it match the reference value of the inductor current

Make a difference, perform current inner loop PI control on the difference, and perform PWM on the equivalent duty cycle;

Step 11, the PWM signal controls the MOSFET in the Buck circuit to obtain the ideal voltage value. The ideal voltage value is output to the DC-DC boost module through the output port of the industrial computer, and finally the voltage is output to both ends of the electromagnetic mechanism to generate The corresponding current ensures that the electromagnetic mechanism generates enough electromagnetic force so that the magnetic adsorption robot will not fall in the vibration state.

As a further preference of the present invention, in step 2, the mathematical equation for obtaining the curve at the magnetic pole according to the radius of curvature of the electromagnetic mechanism is as follows:

The mathematical equation to obtain the curve at the rope according to the rope radius is as follows:

Among them, X represents the value of the abscissa of the rectangular coordinate system, Y ₁ represents the value of the ordinate of the magnetic pole curve in the rectangular coordinate system, R ₁ represents the radius of curvature of the magnetic pole, Y ₂ represents the value of the ordinate of the rope curve in the rectangular coordinate system, and R ₂ represents rope radius size;

After the two equations are subtracted and integrated, the mathematical equation of the total length of the air gap in step 2 is obtained.

其中E_k是电压跟踪增益，u_ok为电压反馈值，

为输出电压参考值。As a further preference of the present invention, in step 5

where E _k is the voltage tracking gain, u _ok is the voltage feedback value,

is the output voltage reference value.

As a further preference of the present invention, the attitude sensor is arranged on the magnetic adsorption robot, and the attitude sensor collects the information of the lateral acceleration and longitudinal acceleration of the magnetic adsorption robot to transmit signals to the industrial computer, and the output port of the industrial computer is connected in series with a DC-DC booster module, the ideal voltage value is output to the DC-DC boost module through the output port of the industrial computer, and finally the voltage is output to both ends of the electromagnetic mechanism to generate the corresponding current.

As a further preference of the present invention, an industrial computer is used as the core control unit to realize the automatic control of the current. Use simulink as the experimental platform in the industrial computer, use visual programming to input the program into the industrial computer, use the serial receive module in simulink to receive the data generated by the attitude sensor, process the data, and use this data as the control output voltage reference The input variable of the value, and then the output voltage reference value is involved in the sliding mode control, and then the ideal output voltage is obtained. The ideal output voltage is changed from the industrial computer to the voltage that can make the robot run smoothly through the DC-DC boost circuit.

为0.1，根据实物得知线圈匝数为3050匝，电磁机构与斜缆索相对面积为1500mm²，取气隙δ＝0.2mm则电磁力大小如下所示：

As a further preference of the present invention, take the insurance factor

It is 0.1. According to the actual object, it is known that the number of turns of the coil is 3050 turns, and the relative area between the electromagnetic mechanism and the inclined cable is 1500 mm ² . Taking the air gap δ = 0.2 mm, the magnitude of the electromagnetic force is as follows:

The present invention has the following beneficial effects:

(1) The robot of the present invention can introduce a "delayed disturbance estimation" strategy according to the detected vibration signal, realize online estimation of the centralized disturbance of the system, and integrate the estimation into the robust DISM controller to form compensation, so that the controller can The engineering implementation further enhances the immunity of the system output voltage to load changes, and weakens the chattering. The control effect of the electromagnetic force can meet the requirements for use.

(2) For the magnetic adsorption robot, the interference comes from the vibration of the robot affected by various factors. The sliding mode control method of the present invention can effectively keep the robot stable during the maintenance process, thereby achieving the effect of completing tasks safely and efficiently.

Description of drawings

Figure 1 is a rectangular coordinate system with a radius of curvature;

Figure 2 shows the relationship between the rope radius R2 and the air gap;

Figure 3 is a graph showing the change of electromagnetic force with current;

Fig. 4 is the electromagnetic force control flow chart;

Figure 5 is a schematic diagram of the sliding mode control algorithm;

6 is a structural diagram of a sliding mode control system;

Fig. 7 is the hardware principle diagram of sliding mode control system;

Figure 8 is a voltage simulation curve diagram after sliding mode control.

Detailed ways

The present invention will be described in further detail below with reference to the accompanying drawings and specific preferred embodiments.

In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "left side", "right side", "upper", "lower part", etc. are based on the orientation or positional relationship shown in the accompanying drawings, only For the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a particular orientation, be constructed and operate in a particular orientation, "first", "second", etc. importance, and therefore should not be construed as a limitation to the present invention. The specific dimensions used in this embodiment are only for illustrating the technical solution, and do not limit the protection scope of the present invention.

As shown in Figure 1-8, a sliding mode control method for electromagnetic force control of a magnetic adsorption robot, the robot is a magnetic adsorption robot and needs to be adsorbed on a cable, the cable is a diagonal cable, and the adsorption surface is a curved surface. In order to make the suction wheel perpendicular to the cable surface, the angle between the wheel arm and the robot body can be adjusted. The electromagnetic adsorption structure provides electromagnetic force, so that the robot can be stably adsorbed on the inclined cable surface. The drive motor and drive wheels provide power for the robot's movement.

The invention uses the function as part of the lifting electromagnetic mechanism, and the electromagnetic mechanism is placed at the bottom end of the robot and connected with the robot. Using the oblique cable as a ferromagnetic material, when the electromagnetic mechanism wire is energized, an electromagnetic force can be generated to adsorb the robot and the oblique cable together, so as to achieve the purpose of adsorption, so that the robot can be stably adsorbed on the oblique cable surface.

The magnetic adsorption robot attaches the robot to the inclined cable through the electromagnetic force. The most important thing to control the movement of the robot on the cable is the control of the electromagnetic force. Therefore, it is first necessary to carry out mathematical modeling of electromagnetic force for the designed electromagnetic structure.

Maxwell's equations are the most basic equations in electromagnetism. Maxwell's electromagnetic force formula is used to establish a mathematical model of electromagnetic force. After deduction, the following formula can be obtained:

为保险系数，其值在0.05～0.15之间，μ₀为空气的导磁系数且其值为4π×10^-7H/m，S为磁极与斜缆索的相对面积，δ为气隙平均长度。Formula (1-1) is the electromagnetic force model, where F _dc is the magnitude of the electromagnetic force, I is the magnitude of the current, N is the number of turns of the coil,

is the insurance factor, its value is between 0.05 and 0.15, μ ₀ is the permeability coefficient of air and its value is 4π×10 ^-7 H/m, S is the relative area between the magnetic pole and the inclined cable, δ is the average length of the air gap .

It can be seen from formula (1-1) that the magnitude of the electromagnetic force and the current, the number of turns around the iron core, the contact area between the electromagnetic mechanism and the oblique cable, and the length of the air gap are related. Among them, the number of coil turns, the relative area between the electromagnetic mechanism and the inclined cable are fixed, and the length of the air gap is related to the diameter of the inclined cable and the shape of the magnetic pole of the electromagnetic mechanism.

The relationship between the diameter of the inclined cable and the average air gap is analyzed below.

The length of the electromagnetic mechanism is 50mm, and its radius of curvature is 45mm. The diameter of the oblique cable is between 60mm and 180mm, and a rectangular coordinate system as shown in Figure 1 below is established. The abscissa and ordinate coordinates in Figure 1 are lengths, and the unit is mm. The radius of curvature of the magnetic pole is 45mm, so when the radius of the cable is greater than 45mm, both ends of the magnetic pole are in contact with the cable. When the cable radius is less than 45mm, the center of the magnetic pole is in contact with the cable.

The shape of the magnetic pole is an arc. Let the abscissa value of the rectangular coordinate system be X, the radius of curvature of the magnetic pole to be R ₁ , the rope radius to be R ₂ , and the ordinate value of the magnetic pole curve in the rectangular coordinate system to be Y ₁ . The value of the ordinate of the rope curve is Y ₂ . The mathematical equation of the curve at the magnetic pole is as follows:

The mathematical equation to obtain the curve at the rope according to the rope radius is as follows:

Because the length of the air gap is not the same everywhere, we need to find the total length of the air gap first. After subtracting the mathematical equation of the curve at the magnetic pole and the mathematical equation of the curve at the rope, and integrating, the total length of the air gap is:

The average length of the air gap is obtained by dividing the total length of the air gap by the length of the magnetic pole. According to the conditions, we know that the radius of curvature of the magnetic pole R ₁ =45mm, and the radius of the rope: 30mm<R ₂ <90mm. The average gap between the cable and the robot is obtained, and the curve with the radius of the inclined cable is shown in Figure 2 below.

为0.1，根据实物得知线圈匝数为3050匝，电磁机构与斜缆索接触面积为1500mm²。I的单位为A，取气隙δ＝0.2mm则电磁力大小如下式(3-1)所示：

From the previous analysis, we obtained the model of electromagnetic force as shown in formula (1-1), taking the insurance coefficient

It is 0.1. According to the actual object, it is known that the number of turns of the coil is 3050 turns, and the contact area between the electromagnetic mechanism and the inclined cable is 1500 mm ² . The unit of I is A, and taking the air gap δ=0.2mm, the magnitude of the electromagnetic force is shown in the following formula (3-1):

The graph of electromagnetic force changing with current is shown in Figure 3.

However, when the mass of the robot is large, only relying on the voltage of the output port of the industrial computer may not provide enough adsorption force to stabilize the robot on the slope. Therefore, in order to solve the problem of insufficient electromagnetic force, a DC-DC booster circuit can be connected in series with the output port of the industrial computer to increase the maximum value of the voltage, thereby increasing the electromagnetic force. The flow chart of electromagnetic force control is shown in Figure 4. The structure diagram of the sliding mode control system is shown in Figure 5.

During the climbing process of the robot, the electromagnetic force will fluctuate due to factors such as wind force or the surface of the inclined cable, and the lateral acceleration and longitudinal acceleration will change, which will cause the robot to fall. The attitude sensor is arranged on the magnetic adsorption robot, and the attitude sensor collects the information of the lateral acceleration and longitudinal acceleration of the magnetic adsorption robot and transmits signals to the industrial computer. The output port of the industrial computer is connected in series with a DC-DC boost module, and the ideal voltage value passes through The output port of the industrial computer is output to the DC-DC boost module, and finally the voltage is output to both ends of the electromagnetic mechanism to generate the corresponding current.

的关系式：The industrial computer will be used as the core control unit to realize the automatic control of the current. Simulink is used as the experimental platform in the industrial computer, and the program is input into the industrial computer by using visual programming. The serialreceive module is used in simulink to accept the data generated by the attitude sensor, and after processing the data, this data is used as the input variable to control the output voltage reference value, and then the output voltage reference value participates in the sliding mode control to obtain the ideal output voltage. The ideal output voltage is changed from the industrial computer to the voltage that can make the robot run smoothly through the DC-DC booster circuit, so that the robot will not be shaken or even dropped when working on the high-altitude cable. The attitude sensor outputs a signal to the industrial computer, and the industrial computer receives the acceleration information, processes the lateral acceleration and longitudinal acceleration, and obtains the average value of the total acceleration |a|, and the unit of |a| is m/s ² , according to the difference of the average acceleration value , divide the shaking grade into 10 grades, and obtain the average acceleration value |a| and the output voltage reference value according to the empirical value of multiple tests.

The relation of:

The graph of the piecewise function of the vibration level is shown in Figure 6. Using the relationship between acceleration and voltage, the greater the acceleration, the greater the current and the greater the adsorption force, which ensures the stability of the robot. Real-time comparison of the total acceleration average value |a| in the industrial computer to obtain the output voltage reference value

Next, the sliding mode control is performed, and the sliding mode surface _sk is designed as:

s _k =mE _k +v _k

其中E_k是电压跟踪增益，u_ok为电压反馈值，

为输出电压参考值，且s_k>0，v_k>0，m>0。Among them, m is the parameter to be designed, E _k is the voltage tracking gain, v _k is the output voltage error integral,

where E _k is the voltage tracking gain, u _ok is the voltage feedback value,

is the output voltage reference value, and s _k >0, v _k >0, m>0.

The output voltage error integral v _k can be further expressed as:

v _k = v _k-1 +GE _k-1

Among them, G is the integral gain.

The initial state of the system is configured on the sliding mode surface, and the initial value v ₀ of the output voltage error integral v _k is set as:

v ₀ = -mE ₀

The sliding mode voltage controller is designed, and the discrete equivalent control law is used:

s _k+1 -s _k =0

Among them, _sk+1 is the sliding mode surface recursively forward one sampling time step.

In the case where the sampling time step is small enough, that is, when the time interval is almost 0, the output voltage reference value can be considered to remain unchanged during one sampling period:

The sliding mode control law of Buck circuit is obtained as:

Among them, C is the capacitance value, R is the resistance value, T is the sampling period, u _ok is the voltage feedback value, and f _k is the estimated value of the concentrated disturbance.

To enable the system to always reach the quasi-sliding mode, a discontinuous switching control is added:

Among them, K _sw is the switching term gain, and K _sw >0, sgn( _sk ) is the sign function of the sliding mode surface _sk .

Finally, it is concluded that the complete form of the sliding mode voltage controller is:

Figure 7 is a hardware schematic diagram of the sliding mode control system. Introduce the "delay disturbance estimation" strategy, and approximate the disturbance at this moment by calculating the concentrated disturbance value mf _k at the last sampling moment, u _ok uses the voltage sensor sampling, u _o(k-1) is the voltage sampling value at the previous moment , i _L(k-1) is the sampling value of the inductor current at the last moment:

作为输入变量之一，与实时输出电压u_o作差得出E_k且f_k-1输入到式中，得出电感电流参考值

Real-time sampling of the output voltage u _o , the output voltage reference value

As one of the input variables, the difference with the real-time output voltage u _o obtains E _k and f _k-1 is input into the formula to obtain the reference value of the inductor current

Among them, f _k-1 is the estimated value of the centralized disturbance.

作差，对差值进行电流内环PI控制，并对等效占空比进行PWM。Sample the inductor current i _L in real time and match it with the inductor current reference

Make a difference, perform current inner loop PI control on the difference, and perform PWM on the equivalent duty cycle.

The PWM signal controls the MOSFET in the Buck circuit to obtain the ideal voltage value. The ideal voltage value is the voltage value that the robot can stably adsorb on the cable. The ideal voltage value is output to the DC-DC boost module through the output port of the industrial computer. The DC-DC boost module amplifies the voltage value of the output port of the industrial computer, and finally outputs the voltage to both ends of the electromagnetic mechanism to generate the corresponding current. The size of the adsorption force is automatically controlled to ensure that the electromagnetic mechanism generates enough electromagnetic force to prevent the robot from falling under the vibration state. The voltage simulation curve graph after sliding mode control is shown in Figure 8. The abscissa of Figure 8 is time, and the unit is s; the ordinate is voltage, and the unit is V. The invention greatly reduces the risk and cost of the magnetic adsorption robot falling from a high altitude, and greatly improves the automation degree of the detection of the cables of the cable bridge.

The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details of the above-mentioned embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention. These equivalent transformations All belong to the protection scope of the present invention.

Claims (6)

1. A method for controlling electromagnetic force of a magnetic adsorption cable climbing robot, characterized in that: comprising the following steps: Step 1, establish the electromagnetic force correlation model according to the number of coil turns, contact area, current size and air gap length:

Among them, F _dc represents the magnitude of the electromagnetic force, I represents the magnitude of the current, N represents the number of turns of the coil,

is the insurance factor, its value is between 0.05 and 0.15, μ ₀ is the permeability coefficient of air, and its value is 4π×10 ^-7 H/m, S represents the relative area between the magnetic pole and the inclined cable, δ represents the average length of the air gap ; Step 2, the shape of the magnetic pole is an arc. According to the mathematical equation of the curve at the magnetic pole and the mathematical equation of the curve at the rope, the total length of the air gap is:

in,

Indicates the total length of the air gap, X represents the value of the abscissa of the rectangular coordinate system, Y ₁ represents the value of the ordinate of the magnetic pole curve in the rectangular coordinate system, R ₁ represents the radius of curvature of the magnetic pole, and Y ₂ represents the value of the ordinate of the rope curve in the rectangular coordinate system , R ₂ represents the radius of the rope, and the average length of the air gap in step 1 can be obtained by dividing the total length of the air gap obtained in step 2 by the length of the magnetic pole; In step 3, the vibration of the magnetic adsorption robot is used as a source of interference, and the attitude sensor is used to detect the acceleration change of the magnetic adsorption robot, and the information of the lateral acceleration and the longitudinal acceleration is received, and then the shaking state of the magnetic adsorption robot is detected; Step 4, use the industrial computer to read the two acceleration signal values in step 3, process the two values in the industrial computer, and obtain the average value of the total acceleration |a|; according to the difference of the average value, the shaking level is divided into 10 level, the average acceleration |a| and the output voltage reference value are obtained

The relation of:

Real-time comparison of the total acceleration average value |a| in the industrial computer to obtain the output voltage reference value

Step 5, design the sliding surface _sk as: s _k =mE _k +v _k Among them, m is the parameter to be designed, E _k is the voltage tracking gain, v _k is the output voltage error integral, and s _k >0, v _k >0, m>0; The output voltage error integral v _k is further expressed as: v _k = v _k-1 +GE _k-1 Among them, G is the integral gain; Step 6, according to Step 5, the initial state of the system is configured on the sliding mode surface, and the initial value v ₀ of the output voltage error integral v _k is set as: v ₀ = -mE ₀ Step 7, design the sliding mode voltage controller, and adopt the discrete equivalent control law: s _k+1 -s _k =0 Among them, _sk+1 is the sliding mode surface recursively forwarding one sampling time step. When the sampling time step is small enough, it is considered that the output voltage reference value remains unchanged in one sampling period:

The sliding mode control law of Buck circuit is obtained as:

in,

is the synovial control rate of the equivalent control, C is the capacitance value, R is the resistance value, T is the sampling period, u _ok is the voltage feedback value, and f _k is the estimated value of the concentrated disturbance; To enable the system to always reach the quasi-sliding mode, a discontinuous switching control is added:

in,

is an additional switching control term, C is the capacitance value, T is the sampling period, K _sw is the switching term gain, and K _sw >0, sgn( _sk ) is the sign function of the sliding mode surface _sk ; Finally, it is concluded that the complete form of the sliding mode voltage controller is:

Step 8, introduce the "delayed disturbance estimation" strategy, and approximate the disturbance at this moment by calculating the concentrated disturbance value _mfk at the last sampling moment:

Step 9, sample the output voltage u _o in real time, and set the reference value of the output voltage

As one of the input variables, the difference with the real-time output voltage u _o obtains E _k and f _k-1 is input into the formula to obtain the reference value of the inductor current

Among them, f _k-1 is the estimated value of the centralized disturbance; Step 10: Sample the inductor current i _L in real time and make it match the reference value of the inductor current

Make a difference, perform current inner loop PI control on the difference, and perform PWM on the equivalent duty cycle; Step 11, the PWM signal controls the MOSFET in the Buck circuit to obtain the ideal voltage value. The ideal voltage value is output to the DC-DC boost module through the output port of the industrial computer, and finally the voltage is output to both ends of the electromagnetic mechanism to generate The corresponding current ensures that the electromagnetic mechanism generates enough electromagnetic force so that the magnetic adsorption robot will not fall in the vibration state. 2. The electromagnetic force control method for a magnetic adsorption cable climbing robot according to claim 1, characterized in that: in step 2, the mathematical equation for obtaining the curve at the magnetic pole according to the radius of curvature of the electromagnetic mechanism is the following formula:

The mathematical equation to obtain the curve at the rope according to the rope radius is as follows:

Among them, X represents the value of the abscissa of the rectangular coordinate system, Y ₁ represents the value of the ordinate of the magnetic pole curve in the rectangular coordinate system, R ₁ represents the radius of curvature of the magnetic pole, Y ₂ represents the value of the ordinate of the rope curve in the rectangular coordinate system, and R ₂ represents rope radius size; After the two equations are subtracted and integrated, the mathematical equation of the total length of the air gap in step 2 is obtained. 3 . The electromagnetic force control method of a magnetic adsorption cable climbing robot according to claim 1 , wherein: in step 5

where E _k is the voltage tracking gain, u _ok is the voltage feedback value,

is the output voltage reference value. 4 . The electromagnetic force control method of a magnetic adsorption cable climbing robot according to claim 1 , wherein the attitude sensor is arranged on the magnetic adsorption robot, and the attitude sensor collects the information of the lateral acceleration and the longitudinal acceleration of the magnetic adsorption robot. 5 . The signal is transmitted to the industrial computer, the output port of the industrial computer is connected in series with a DC-DC booster module, the ideal voltage value is output to the DC-DC booster module through the output port of the industrial computer, and finally the voltage is output to both ends of the electromagnetic mechanism to generate the corresponding current. 5. The electromagnetic force control method for a magnetic adsorption cable climbing robot according to claim 4, characterized in that: using an industrial computer as a core control unit to realize automatic control of current; using simulink as an experimental platform in the industrial computer, and using a visualization Programming, input the program into the industrial computer, use the serial receive module in simulink to receive the data generated by the attitude sensor, process the data, use this data as the input variable to control the output voltage reference value, and then participate in the output voltage reference value Sliding mode control, and then obtain the ideal output voltage, the ideal output voltage is changed by the industrial computer through the DC-DC boost circuit into the voltage that can make the robot run smoothly. 6 . The electromagnetic force control method of a magnetic adsorption cable climbing robot according to claim 1 , characterized in that: taking the insurance factor

It is 0.1. According to the actual object, it is known that the number of turns of the coil is 3050 turns, and the relative area between the electromagnetic mechanism and the inclined cable is 1500 mm ² . Taking the air gap δ = 0.2 mm, the magnitude of the electromagnetic force is as follows:

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