JP2008216016A - Rotation angle calculation device and displacement amount calculation device - Google Patents

Abstract

【Task】
Provided is a rotation angle calculation device that calculates a relative rotation angle of an inner rotating body with respect to an outer rotating body with a small number of sensors.
[Solution]
The inner rotating shaft and the outer rotating shaft are arranged concentrically with no load, and have an inner rotating body and an outer rotating body connected by an elastic member that is deformable in accordance with the load so as to be relatively displaceable in a plane orthogonal to the inner rotating shaft The rotating body and one of the members to be measured that rotate integrally with one of the inner rotating body and the outer rotating body, and are provided on the rotating inner rotating body or the outer rotating body, and the other inner rotating body or The distance to the measured part of the member to be measured that rotates integrally with the outer rotating body and that is provided on the other rotating inner rotating body or outer rotating body and faces in the direction orthogonal to the circumferential direction of the rotating body One displacement sensor to be detected, and calculation means for calculating a relative rotation angle between the inner rotator and the outer rotator based on a local median in the time variation of the distance detected by the displacement sensor. It comprises and comprises.
[Selection] Figure 5

Description

  The present invention relates to a rotation angle calculation device or a displacement amount calculation device that calculates a relative rotation angle or a relative displacement amount of an outer rotating body with respect to an inner rotating body.

  In a rotating body such as a wheel used for a wheel, a force acting on the rotating body, for example, a force in the x-axis direction parallel to the road surface due to a frictional force on the road surface, a vertical direction (z Stabilize the turning behavior of the vehicle such as anti-lock brake system (ABS) and traction control system (TCS) of the vehicle based on the axial force and the torque My around the y axis perpendicular to the x and z axes. In a vehicle stability assist system (VSA) or the like, vehicle braking control is performed.

  Prior art relating to estimation of forces Fx, Fy, Fz applied to the rotating body in the x, y, and z-axis directions and torques Mx, My, Mz acting around these axes includes the following patent documents.

  In Patent Document 1, four tangential displacement sensors and four vertical displacement sensors are provided at the boundary between the rim and the wheel disk in a point-symmetric manner on the circumference, and the rim displacement sensor is based on the outputs of the four tangential displacement sensors. It is described that the relative displacement amount α in the tangential direction with respect to the wheel disk is calculated, and the eccentric amount D in the vertical direction of the rim shaft center with respect to the wheel disk shaft center is calculated based on the outputs of the four vertical displacement sensors. Has been.

In Patent Document 2, each of the first and second sensing beams constituting each of the four T-shaped arms arranged in a dodecagonal shape between the wheel rim mounting frame and the hub mounting frame is provided. It is described that the forces Fx, Fy, Fz and torques Mx, My, Mz acting around these axes are estimated based on the outputs of the eight strain gauges.
WO2003 / 008246 Publication JP-A-2005-249772

  However, in Patent Document 1, the amount of tangential relative displacement α and the amount of eccentricity in the vertical direction D are calculated using eight sensors, and the tangential and vertical components of the force are calculated from these. Due to the estimation, there is a problem that many sensors are expensive. In Patent Document 1, the rim has a tangential relative displacement amount α and a vertical direction on the premise that the rim axis is displaced in the z-axis direction but not in the x-axis direction with respect to the center of the disk. Although the amount of eccentricity in the direction D is calculated, there is a problem that an error occurs when the elastic body provided at the boundary between the rim and the disk is displaced in the x-axis direction. Further, since the tangential displacement sensor and the vertical displacement sensor are provided at the narrow boundary between the rim and the disk, there is a problem in the detection accuracy of the displacement amount.

  In Patent Document 2, eight strain gauges provided in each of the first and second sensing beams constituting each of at least three T-shaped arms, a total of at least 48 (3 × 8 × 2). Since the forces Fx, Fy, and Fz and the torques Mx, My, and Mz acting around these axes are estimated based on the output of the above, there is a problem that many sensors are expensive. Further, Fx, Fy and Mx, Mz other than Fz and Mz need to be corrected based on the rotation angle of the wheel detected by the angle detection unit, and there is a problem that the processing becomes complicated.

  The present invention has been made in view of the above problems, and does not require rotation correction and calculates the relative rotation angle and relative displacement amount of the inner rotating body with respect to the outer rotating body with fewer sensors, and calculates the relative rotation angle and relative An object of the present invention is to provide a rotation angle and displacement amount calculation device that estimates forces Fx, Fy, and My based on displacement amounts.

  According to the first aspect of the present invention, the inner rotary shaft and the outer rotary shaft are arranged concentrically with no load, and are connected by an elastic member that is deformable according to the load so as to be relatively displaceable in a plane orthogonal to the inner rotary shaft. A rotating body having an inner rotating body and an outer rotating body, and the inner rotating body or the outer rotating body that rotates integrally with one of the inner rotating body and the outer rotating body. Provided in the other part of the inner rotating body or the outer rotating body that rotates integrally with the other inner rotating body or the outer rotating body, and is arranged around the rotating body. Based on one displacement sensor for detecting the distance to the measurement site of the measured part facing the direction orthogonal to the direction, and a local median in the time change of the distance detected by the displacement sensor The inner rotating body and the front Displacement amount calculation apparatus characterized by comprising a calculating means for calculating the relative rotation angle and the relative displacement between the outer rotating member is provided.

  According to the second aspect of the present invention, the inner rotary shaft and the outer rotary shaft are arranged concentrically with no load, and are elastically deformed according to the load so as to be relatively displaceable in a plane orthogonal to the inner rotary shaft. A rotating body having an inner rotating body and an outer rotating body connected to each other, and one of the inner rotating body and the outer rotating body is rotated integrally with the rotating inner body or the outer rotating body. The one measured part and the other inner rotating body or the outer rotating body rotate integrally with each other, and the other rotating inner rotating body or the outer rotating body is provided. One displacement sensor that detects a distance to the measurement site of the measurement target that faces in the circumferential direction, and the inner side based on a local median in the time change of the distance detected by the displacement sensor Rotating body and outside Displacement amount calculation apparatus characterized by comprising a calculating means for calculating the relative rotation angle and the relative displacement between the rotating member is provided.

  According to the first aspect of the present invention, when the rotating body receives torque, the torque is transmitted to the elastic member via the outer rotating body, the elastic member is deformed according to the torque, and the outer rotating body rotates inward. Rotates relative to the body. The distance measured by the displacement sensor, which is provided on the other rotating inner rotating body or outer rotating body and detects the distance to the measured portion of the measured part facing the direction orthogonal to the circumferential direction of the rotating body, Since the part to be measured and the displacement sensor rotate together with the rotating body, the time changes. The local median value of the distance detected by the change sensor is the distance R from the center of rotation of one inner rotating body or the outer rotating body to the measurement site without load, and the other inner rotating body to the displacement sensor. Alternatively, it is represented by the distance r from the rotation center of the outer rotating body and the relative rotation angle. Therefore, the relative rotation angle can be calculated from the local median in the time change of the distance and the known r and R. As a result, the relative rotation angle can be calculated by one displacement sensor.

  According to the invention of claim 2, when the rotating body receives torque, the torque is transmitted to the elastic member via the outer rotating body, the elastic member is deformed according to the torque, and the outer rotating body rotates inward. Rotates relative to the body. The distance measured by the displacement sensor, which is provided on the other rotating inner rotating body or outer rotating body and detects the distance to the measured portion of the measured part facing the direction orthogonal to the circumferential direction of the rotating body, Since the part to be measured and the displacement sensor rotate together with the rotating body, the time changes. The local median in the time change of the distance detected by the change sensor is represented by the distance r from the rotation center of the other inner or outer rotating body up to the displacement sensor and the relative rotation angle without load. . Therefore, the relative rotation angle can be calculated from the local median value of distance and the known r. As a result, the relative rotation angle can be calculated by one displacement sensor.

First Embodiment FIG. 1 is a block diagram including a load calculation device 1 according to a first embodiment of the present invention. As shown in FIG. 1, the load calculation device 1 includes displacement detection devices 2 #FL, 2 #FR, 2 #RL, 2 #RR, and displacement-load conversion calculation means 4. Displacement detector 2 # FL detects the displacement of the left front wheel. Displacement detector 2 # FR detects the displacement of the right front wheel. Displacement detection device 2 # RL detects the displacement of the left rear wheel. Displacement detector 2 # RR detects the displacement of the right rear wheel. The displacement detection means 2 may be provided for at least one of the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel.

  FIG. 2 is a block diagram of the displacement detectors 2 # FL, 2 # FR, 2 # RL, and 2 # RR in FIG. Since the displacement detection devices 2 # FL, 2 # FR, 2 # RL, and 2 # RR are substantially the same, the displacement detection device is denoted by reference numeral 2. As illustrated in FIG. 2, the displacement detection device 2 includes a displacement detection unit 10, a filter 12, and a data transmission unit 14.

  FIG. 3 is a wheel side view. 4 is a cross-sectional view taken along line AA of FIG. 3 in a state where the wheel 32 is attached to the axle hub 34. FIG. FIG. 5 is a cross-sectional view taken along line BB in FIG. 3 in a state where the wheel 32 is attached to the axle hub 34. As shown in FIGS. 3 to 5, the wheel 32 includes a wheel disk 20, an elastic member 22, a rim 24, a displacement sensor 26 that constitutes the displacement detection device 10, and a measured part (measured member) 28.

  The wheel disc (inner rotating body) 20 is disposed at the center of the wheel 32, passes through stud bolts 38 in through holes provided in the axle hub 34, the brake disc 40 and the wheel disc 20, and is fastened by a wheel nut 36. Thus, the wheel disc 20 and the brake disc 40 are attached to the axle hub 34 that rotates integrally with the axle 42.

  The wheel disc 20 is rotatable with the central axis of the axle hub 34 as a rotation axis (inner rotation axis). However, since the wheel disc 20 is fixed to the axle hub 34, the x axis parallel to the road surface and the rotation axis of the axle 42 ( (y-axis), movement in the z-axis direction perpendicular to the x-axis and the y-axis is restricted. The wheel disk 20 is, for example, a cast molded product made of an aluminum alloy.

  The rim (outer rotating body) 24 is disposed on the outer peripheral side of the wheel disk 20 and is mounted with a tire 30 to support the tire 30. In the unloaded state, the rotating shaft (outer rotating shaft) is It is concentric with the rotational axis of the wheel disc 20. Its shape is a ring. The rim 24 is, for example, a cast molded product made of an aluminum alloy.

  The elastic member 22 is disposed between the wheel disk 20 and the rim 24, connects the wheel disk 20 and the rim 24, and is transmitted from the tire 30 through the rim 24. The forces Fx and Fz in the x-axis and z-axis directions are transmitted. And it deform | transforms according to the magnitude | size of the torque My around y-axis, and the direction of force.

  The force Fx is due to a frictional force in a direction horizontal to the road surface from the road surface to the tire 30 due to a braking force or the like, and is transmitted from the tire 30 to the elastic member 22 through the rim 24. The force (load) Fz is due to the reaction from the road surface of the load from the vehicle body, and is transmitted from the road surface to the elastic member 22 through the tire 30 and the rim 24. As for the torque My, a moment around the center P <b> 2 of the rim 24 due to the force Fx is transmitted to the elastic member 22 through the tire 30 and the rim 24.

  That is, the elastic member 22 expands / contracts (deforms) in the x-axis direction and the z-axis direction according to the forces Fx and Fz, and with the rotation of the rim 24 by the torque My around the axis parallel to the y-axis, The elastic member 22 extends in the direction perpendicular to the straight line connecting the points of the elastic member 22 and the rotation center P2 of the rim 24 (circumferential direction). It consists of a leaf spring. The transmission path of the forces Fx and Fz is tire 30 → rim 24 → elastic member 22 → wheel disk 20 → stud bolt 44 → axle hub 34 → axle 42.

  The elastic member 22 is fixed to the wheel disk 20 and the rim 24 by vulcanization adhesion or the like in the case of elastic rubber, or by welding or the like in the case of a leaf spring. By relative displacement with respect to the wheel disc 20 according to the forces Fx, Fz and torque My, the forces Fx, Fz and torque My are estimated from the relative displacement amount. The shape is a ring shape. The elastic member 22 only needs to be connected to the wheel disk 20 and the rim 24 while having sufficient elasticity so that they do not contact each other, and the specific shape thereof may be arbitrarily determined.

  The rim 24 is configured so that the elastic member 22 is displaced in the x-axis and z-axis directions according to the forces Fx and Fz, and is displaced in the circumferential direction of a circle around the center P2 of the rim 24 according to the torque My. While moving relative to the disk 20 in the x-axis and z-axis directions, the disk 20 rotates relative to the wheel disk 20.

  The displacement sensor 26 measures a distance D to the member 28 to be measured and outputs an electric signal corresponding to the distance D. For example, the displacement sensor 26 is a non-contact type such as an eddy current type, a capacitance type or a laser type. It is a contact-type displacement sensor such as a displacement sensor or a linear potentiometer.

  The displacement sensor 26 is spaced apart from the rotation axis center of the wheel disk 20 by a fixed distance r. For example, the distance measuring direction of the wheel disk 20 is on the circumference (for example, on the outer circumference of the wheel disk 20) separated from the center P1 by the distance r. It arrange | positions so that it may become the direction which goes to the rim | limb 24 side from the center P1. The x-axis and y-axis are stationary coordinate systems. In FIG. 5, the member to be measured 28 shows only the surface to be measured 28a. In addition, the displacement sensor 26 is spaced apart from the rotation axis of the rim 24 by a fixed distance R, for example, on the circumference of the distance R from the center P2 (for example, on the inner circumference of the rim 24). For example, you may arrange | position in the direction which goes to the center P1.

  The member to be measured 28 is attached to the rim 24, and the surface facing the measurement direction of the displacement sensor 26 is the surface to be measured 28 a and is displaced integrally with the rim 24. The material to be measured 28 may be any material as long as the displacement sensor 26 can detect the distance D.

  The member to be measured 28 includes those formed by processing a part of the rim 24 or the wheel disk 20. As long as the surface 28a to be measured is as follows, the shape is not particularly limited. In the measured member 28, a straight line L1 connecting the center P1 of the wheel disk 20 and the measurement point S1 on the measured surface 28a measured by the displacement sensor 26 is a perpendicular line from the center P1 of the wheel disk 20 to the measured surface 28a. A predetermined angle α (α> 0) is deviated from the perpendicular L1 ′ to the foot Q1.

  The measured surface 28a is, for example, a single plane. FIG. 6 is a view showing an example of the member 28 to be measured. For example, from the viewpoint of easy mounting and manufacturing, the member to be measured 28 is a rectangular parallelepiped whose angle between the diagonal and the base is α, and is divided into two diagonals, and the slope becomes the surface to be measured 28a, and there is no S1. The bottom surface 28b is attached to the rim 24 so that it becomes an observation point of the displacement sensor 26 in a loaded state and each side of the bottom surface 28b is perpendicular to the radial direction.

  When the displacement sensor 26 is provided on the rim 24, the member to be measured 28 is arranged at a distance r from the center of the rotation axis of the wheel disk 20, and the distance measurement direction is the rotation axis direction of the rim 24. The measured surface 28a is arranged so that the distance measuring direction of the displacement sensor 26 is deviated in a constant direction by a predetermined angle α (α> 0) with respect to the normal line from the center P2 to the measured surface 28a.

  The filter 12 in FIG. 2 removes a high frequency component from the electrical signal indicating the distance D output from each displacement sensor 26 of the displacement detection means 10 to cut noise. The data transmission unit 14 transmits the electrical signal output from the filter 12 to the displacement-load conversion calculation unit 4 by wireless or the like.

  The displacement-load conversion calculating means 4 in FIG. 1 is configured so that the displacement of the rim 24 will be described in detail later from the distance D transmitted from each of the displacement detection devices 2 # FL, 2 # FR, 2 # RL, 2 # RR. The relative rotation angle θ with respect to the wheel disk 20 is calculated (calculation means), and the forces Fx, Fz, and torque My are calculated from the relative rotation angle θ and output to the VSA system 6. The displacement-load conversion calculating means 4 is configured by a program that operates on an ECU (Electric Control Unit) having a CPU, a memory, and the like, for example.

  The VSA system 6 includes forces Fx, Fz and torque My, and a lateral acceleration sensor, a longitudinal acceleration sensor, a yaw rate sensor, and a pitch (not shown) for the wheels WFL, WFR, WRL, and WRR output from the displacement-load conversion calculation means 4. Based on the output of the rate sensor or the like, VSA control such as ABS control and TCS control is performed.

  FIGS. 7 to 11 are explanatory views of the operation of the displacement-load conversion calculating means 4 and show a state in which the wheel 32 is attached to the axle hub 34 and is moving on the road surface while rotating in the direction of arrow A. . The x-axis and z-axis in FIGS. 7 to 11 are the same as those in FIG. Here, for example, it is assumed that a force Fx is applied to the rim 24 from the road surface through the tire 30 when the driver depresses the brake pedal.

  When the brake pedal is depressed, a braking force acts on the brake disc 40 that rotates integrally with the axle hub 34 based on the hydraulic pressure from the brake pedal, and the friction force between the tire 30 and the road surface causes the rim 24 to pass through the tire 30. A force Fx is applied. The force Fx is transmitted from the rim 24 to the elastic member 22, and the elastic member 22 expands and contracts in the x-axis direction. As a result, the center P2 of the rim 24 is displaced with respect to the center P1 of the wheel disk 20 by a displacement amount a in the x-axis direction, and the rim 24 is rotated by the torque My acting on the rim 24 as a rotating body by the force Fx. It rotates relative to the wheel disc 20 by an angle θ.

  On the other hand, the rim 24 receives a force Fz in the z-axis direction due to the vertical reaction force Fz from the road surface to the tire 30 due to the load from the vehicle, the elastic member 22 expands and contracts in the z-axis direction, and the rim 24 moves in the z-axis direction. It is displaced by a displacement amount b. Thereby, the coordinates of the center P2 of the rim 24 are (a, b).

  Since the displacement sensor 26 rotates integrally with the wheel disk 20 around the point P1, it is assumed that the displacement sensor 26 is rotated counterclockwise by φ from the x-axis at the time of observation. The x-axis and z-axis are axes obtained by translating the x-axis and z-axis (a, b). Let Q1 be the leg of the perpendicular to the measured surface 28a from the center P2 (a, b) of the rim 24 to the measured surface 28a.

  The distance between the point P2 and the point Q1 is R. A straight line connecting the point P2 and the point Q1 around the point P2 (hereinafter referred to as the straight line P2Q1) is rotated by an angle α and the intersection of the measured surface 28a is S1, and the straight line P2Q1 is rotated by an angle (θ + α) around the point P2. Let T1 be the intersection of the straight line and the measured surface 28a. Further, an observation point after the displacement of the measurement target surface 28a by the displacement sensor 26 is U1. The distance measuring direction of the displacement sensor 26 is arranged so as to be shifted by α with respect to the normal line from the center P1 of the wheel disk 20 to the measured surface 28a, and the rim 24 is relative to the wheel disk 20 by θ. Since it is rotating, the straight line P2T1 is parallel to the straight line P1U1.

  As shown in FIG. 10 which is an enlarged view of the portion B in FIG. 9, the perpendicular foot from the point P2 to the straight line P1U1 is defined as V1. Let W1 be the intersection of the straight line T1U1 and the straight line P1U1 translated so that the point T1 coincides with the point P2. The distance between the point P2 and the point V1 is (b cos φ−asin φ). Since the angle W1P2V1 is (θ + α) and the distance between P2 and V1 is (bcosφ−asinφ), the distance between V1 and W1 is ((bcosφ−asinφ) tan (θ + α)).

  Since the distance between the foot of the perpendicular to the straight line P1V1 from the coordinate (a, 0) and the point P1 is (acosφ) and the distance from the coordinate (a, 0) to the straight line P2V1 is (bsinφ), P1 and V1 The distance of is (acosφ + bsinφ).

  Since the distance between P1 and W1 is (distance between P1 and V1) + (distance between V1 and W1), it is (acosφ + bsinφ + (bcosφ−asinφ) tan (θ + α)).

  On the other hand, since the distance from the point P2 to the measured surface 28a # 1 is R and the angle T1P2Q1 is (θ + α), the distance between P2 and T1 is R / cos (θ + α). Since the quadrilateral P2W1U1T1 is a parallelogram, the distance between W1 and U1 = the distance between P2 and T1 = R / cos (θ + α).

  P1 and U1 distance = P1 and W1 distance + W1 and U1 distance = (acos φ + b sin φ) + (b cos φ−asin φ) tan (θ + α) + R / cos (θ + α). On the other hand, since the observation point of the displacement sensor 26 # 1 is attached at the position of the radius r from the point P1, the distance between P1 and U1 = D + r.

  Therefore, the following expression (1) is established.

D = R / cos (θ + α) −r + (acos φ + b sin φ) + (b cos φ−asin φ) tan (θ + α)
= R / cos (θ + α) −r + (a ² + b ² ) ^1/2 sin (φ + θ + α + A) / cos (θ + α)
... (1)
However, A = tan ⁻¹ a / b.

As the wheel disk 20 rotates once, φ changes by 0 to 2π. If θ, α, and A are constant during a certain period of time, for example, while the wheel disk 20 makes one revolution, (φ + θ + α + A) changes from 0 to 2π, so (a ² + b ² ) ^1/2 sin (φ + θ + α + A) / cos (θ + α) is a sine wave whose period is the rotation period of the wheel disk 20 and amplitude (a ² + b ² ) ^1/2 / cos (θ + α) on the time axis. Therefore, the time change of the distance D is a sine wave having an amplitude of (a ² + b ² ) ^1/2 / cos (θ + α) and a center (median value) of R / cos (θ + α) −r.

If the center (median value) is known, R, r, and α are known, so that the rotation angle θ can be known. Fx = K _a × a (K _a is _a constant determined by the extension of the elastic member 22 in the x-axis direction and the force Fx), My = K _θ × θ (K _θ is centered on the center P2 of the rim 24 of the elastic member 22). Since there is a relationship of constant in the circumferential direction and a constant determined by the torque My and My = Fx × R ₀ (R ₀ : dynamic radius of the rotating body), if the dynamic radius of the rotating body is a known R ₀ ,
_{a = Fx / K a = My} / (K a × R 0) = K θ × θ / (K a × R 0) ··· (2)
Thus, a can be obtained. Further, when the amplitude (a ² + b ² ) ^1/2 / cos (θ + α) is known, a is obtained from the equation (2), so that b is known.

The amplitude (a ² + b ² ) ^1/2 c / cos (θ + α) is obtained by, for example, sampling the distance D at a constant sampling period based on the minimum period of the sine wave determined by the prescribed maximum rotation period of the wheel disk 20 and the like. After the A / D conversion, the difference between the local maximum value (maximum value) of the distance D and the local minimum value (minimum value) following the maximum value is multiplied by 1/2. The center (R / cos (θ + α) −r) is calculated by, for example, obtaining an average value of the maximum value of the distance D and the minimum value subsequent to the maximum value.

  FIG. 11 is a diagram showing the center and amplitude of the distance D, with the horizontal axis representing time t and the vertical axis representing the distance D. From time t0 to time t3, a case is shown in which force Fx = 0, moment My = 0 (θ = 0, a = 0), and force Fz is small (b is small). In this case, the center is (R / cos α−r), and the amplitude b / cos α is small. From time t0 to time t3, the maximum value of distance D (R / cos α−r + b / cos α) is reached at time t1, and the minimum value of distance D is ((R / cos α−r−b / cos α) at time t2.

  From time t3 to time t6, a case is shown in which force Fx = 0, moment My = 0 (θ = 0, a = 0), and force Fz is large (b is large). In this case, the center is (R / cos α−r), and the amplitude b / cos α is increased. From time t3 to time t6, at time t4, the maximum value of distance D (R / cos α−r + b / cos α) is reached, and at time t5, the minimum value of distance D is ((R / cos α−r−b / cos α).

After time t6, force Fx ≠ 0, moment My ≠ 0 (θ ≠ 0, a ≠ 0), center (R / cos (θ + α) −r), amplitude (a ² + b ² ) ^1/2 / cos The case of (θ + α) is shown. After time t6, at time t7, the maximum value of distance D (R / cos (θ + α) −r + (a ² + b ² ) ^1/2 / cos (θ + α)), and at time t8, the minimum value (R / Cos (θ + α) −r− (a ² + b ² ) ^1/2 / cos (θ + α)).

  The displacement-load conversion calculating means 4 calculates the wheels WFL, WFR from the displacements a, b, the relative rotation angle θ and the following equations (3), (4), (5) for the wheels WFL, WFR, WRL, WRR. , WRL, and WRR, Fx, Fz, and My are calculated.

Fx = Ka × a (3)
Fz = Kb × b (4)
My = K _θ × θ (5)
However, _Kb is a value based on the elastic force of the elastic member 22 in the z-axis direction.

As described above, according to the present embodiment, the distance D to the measured surface 28a is measured by one displacement sensor 26, and the local median value of the distance D is calculated by the time change of the distance D. Thus, the relative rotation angle θ of the rim 24 with respect to the wheel disc 20 can be calculated. Then, a can be calculated from the relative rotation angle θ. By calculating the amplitude of the distance D based on the time change of the distance D, b can be calculated. Then, Fx, Fz, and My can be obtained from a, b, and θ. That is, the relative rotation angles θ, Fx, Fz, and My can be calculated with a small number of displacement sensors 26. Further, since there is a correlation between a and θ via the moving radius R ₀ of the rotating body, the forces Fx and Fz can be calculated without detecting the rotation angle φ of the wheel disk 20.

Second Embodiment FIG. 12 is a block diagram including a load calculation device 50 according to a second embodiment of the present invention. Components that are substantially the same as those shown in FIG. Yes. As shown in FIG. 12, the load calculation device 50 includes displacement detection devices 52 #FL, 52 #FR, 52 #RL, 52 #RR, and displacement-load conversion calculation means 54. Displacement detector 52 # FL detects the displacement of the left front wheel. Displacement detector 52 # FR detects the displacement of the right front wheel. Displacement detection device 52 # RL detects the displacement of the left rear wheel. Displacement detector 52 # RR detects the displacement of the right rear wheel. The displacement detecting means 52 may be provided for at least one of the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel.

  FIG. 12 is a block diagram of the displacement detection devices 52 # FL, 52 # FR, 52 # RL, and 52 # RR in FIG. 11, and components that are substantially the same as those in FIG. The sign is attached. Since the displacement detection devices 52 # FL, 52 # FR, 52 # RL, and 52 # RR are substantially the same, the displacement detection device is represented by reference numeral 52. As illustrated in FIG. 12, the displacement detection device 52 includes a displacement detection unit 60, a filter 12, and a data transmission unit 14.

  FIG. 14 is a side view of the wheel, and components that are substantially the same as those in FIG. 3 are given the same reference numerals. 15 is a cross-sectional view taken along the line AA of FIG. 14 in a state where the wheel 32 is attached to the axle hub 34. Components substantially the same as those in FIG. 4 are denoted by the same reference numerals. . As shown in FIGS. 14 and 15, the wheel 32 includes a wheel disk 20, an elastic member 22, a rim 24, and a displacement sensor 70 and a measurement target (measurement member) 72 that constitute a displacement detection device 60. The wheel disk 20, the elastic member 22, the rim 24, and the like are substantially the same as the components in FIG.

  The displacement sensor 70 measures the distance D to the member 72 to be measured and outputs an electrical signal corresponding to the distance. For example, a non-contact type such as an eddy current type, a capacitance type, or a laser type is used. It is a contact-type displacement sensor such as a displacement sensor or a linear potentiometer.

  FIGS. 16 and 17 are views showing the arrangement of the displacement sensor 70 and the member 72 to be measured located on a plane including the x-axis and the z-axis perpendicular to the axle 42 in a state where no load is applied to the wheel (no load). It is.

  The displacement sensor 70 measures the distance on the circumference (for example, on the outer circumference of the wheel disk 20) that is separated from the center P1 by a distance r from the center of the rotation axis of the wheel disk 20, for example, at a distance r from the center P1. The wheel disk 20 is disposed so that the direction is perpendicular to the radial direction L1 of the wheel disk 20 (circumferential direction). The x-axis and z-axis are stationary coordinate systems.

  The member 72 to be measured is attached to the rim 24, and the surface facing the circumferential direction of the displacement sensor 70 is the surface to be measured 72 a and is displaced integrally with the rim 24. The material of the member to be measured 72 may be any material as long as the displacement sensor 70 can detect the distance D.

  The member to be measured 72 includes a member formed by processing a part of the rim 24 or the wheel disk 20. As long as the surface to be measured 72a is as follows, the shape is not particularly limited. The member 72 to be measured has an angle α (α) formed by a straight line M1 and a straight line L1 that connect the measured site S1 and the center P1 of the wheel disk 20 at the center of the distance measurement of the displacement sensor 70 of the measurement surface 72a in the no-load state. > 0), the member 72 to be measured is arranged on the rim 24.

  For example, the member 72 to be measured is machined so that the cross section of the plane to be measured 72a including the x-axis and the z-axis becomes a straight line M1 passing through the center P1 of the wheel disk 20 in the no-load state and disposed on the rim 24. Has been.

  The measured surface 72a is, for example, a single plane. FIG. 18 is a view showing an example of the member 72 to be measured. The member to be measured 72, for example, a rectangular parallelepiped from the viewpoint of easy mounting and manufacturing, the surface 72 is perpendicular to the circumferential direction, the surface 72b perpendicular to the surface 72a is perpendicular to the radial direction, and S1 is unloaded The straight line in the radial direction on the measured surface 72a passing through S1 becomes the straight line M1, and the straight line M1 is deviated from the straight line L1 in a certain direction, for example, counterclockwise. Arrange as follows.

  When the displacement sensor 70 is provided on the rim 24, the member 72 to be measured is separated from the center of the wheel disk 20 by a distance r in the radial direction, and the distance measurement direction is a circumferential direction perpendicular to the radial direction of the rim 24. Arrange so that. In addition, the measured surface 72a has a straight line connecting the measurement point S1 of the measured surface 72a by the displacement sensor 70 and the center P1 of the wheel disc 20, the measurement center of the displacement sensor 70, and the center P1 of the wheel disc 20 in an unloaded state. The angle formed by the straight line connecting is set to α (α ≠ 0).

  The filter 12 in FIG. 13 removes a high frequency component from the electrical signal indicating the distance D output from the displacement sensor 70 of the displacement detection means 60, and cuts noise. The data transmission unit 14 transmits the electrical signal output from the filter 12 to the displacement-load conversion calculation unit 4 by wireless or the like.

  The displacement-load conversion calculating means 54 in FIG. 12 is configured so that the displacement of the rim 24 will be described in detail later from the distance D transmitted from each of the displacement detection devices 52 # FL, 52 # FR, 2 # RL, 52 # RR. The relative rotation angle θ with respect to the wheel disk 20 is calculated (calculation means), and the forces Fx, Fz, and torque My are calculated from the relative rotation angle θ and output to the VSA system 6. The displacement-load conversion calculating means 54 is configured by a program that operates on an ECU (Electric Control Unit) having, for example, a CPU and a memory.

  19 and 20 are explanatory diagrams of the operation of the displacement-load conversion calculating means 54, showing a state in which the wheel 32 is attached to the axle hub 34 and is moving on the road surface while rotating in the direction of arrow A. . The x-axis and z-axis in FIG. 16 are the same as those in FIG. Here, for example, it is assumed that a force Fx is applied to the rim 24 from the road surface through the tire 30 when the driver depresses the brake pedal.

  When the brake pedal is depressed, a braking force acts on the brake disc 40 that rotates integrally with the axle hub 34 based on the hydraulic pressure from the brake pedal, and the friction force between the tire 30 and the road surface causes the rim 24 to pass through the tire 30. A force Fx is applied. The force Fx is transmitted from the rim 24 to the elastic member 22, and the elastic member 22 expands and contracts in the x-axis direction. As a result, the center P2 of the rim 24 is displaced with respect to the center P1 of the wheel disk 20 by a displacement amount a in the x-axis direction, and the rim 24 is rotated by the torque My acting on the rim 24 as a rotating body by the force Fx. It rotates relative to the wheel disc 20 by an angle θ.

  On the other hand, the rim 24 receives a force Fz in the z-axis direction due to the vertical reaction force Fz from the road surface to the tire 30 due to the load from the vehicle, the elastic member 22 expands and contracts in the z-axis direction, and the rim 24 moves in the z-axis direction. It is displaced by a displacement amount b. Thereby, the coordinates of the center P2 of the rim 24 are (a, b).

  Since the displacement sensor 70 rotates integrally with the wheel disk 20 around the point P1, it is assumed that the displacement sensor 72 is rotated counterclockwise by φ from the x-axis at the time of observation. The x-axis and z-axis are axes obtained by translating the x-axis and z-axis (a, b). The observation center point of the displacement sensor 70 is Q1. An observation point of the measured surface 72a by the displacement sensor 72 after the displacement of the rim 24 is defined as S1.

  A straight line obtained by translating a straight line connecting the points P1 and Q1 (hereinafter, straight line P1Q1) by (a, b) is defined as a straight line P2Q2. Since the rim 34 rotates counterclockwise by θ with respect to the wheel disk 20, if the straight line P2Q2 is rotated counterclockwise by θ counterclockwise around P2, the displacement sensor 70 and the member 72 to be measured are assumed to be P2Q3. Therefore, the angle formed by the straight line P2Q3 and the straight line P2S1 is α.

  Let V1 be the leg of the perpendicular from the point P2 to the straight line P1Q1. The distance between the point P2 and the point V1 is (b cos φ−asin φ). Since the distance between the foot of the perpendicular line from the coordinate (a, 0) to the straight line P1V1 and the point P1 is (acosφ), and the distance from the coordinate (a, 0) to the straight line P2V1 is (bsinφ), the point P1 The distance of the point V1 is (acosφ + bsinφ).

  Since the distance between the point P1 and the point Q1 is r and the distance between the point P1 and the point V1 is (acos φ + bsin φ), the distance between the point V1 and the point Q1 is r− (acos φ + bsin φ). Since the distance between the point P1 and the point Q1 is r, the straight line V1Q1 is parallel to the straight line P2T1, and the straight line V2P2 is parallel to the straight line Q1T1, the distance between the point P2 and the point T1 is r− (acosφ + bsinφ).

  Since the distance between the point P2 and the point T1 is r− (acos φ + bsin φ), the angle S1P2T1 is (θ + φ), the angle S1Q1P1 is 90 °, and the straight line V1Q1 is parallel to the straight line P2T1, the distance between the point S1 and the point T1 is {r − (Acosφ + bsinφ)} tan (θ + φ). Since the straight line P2V1 and the straight line T1Q1 are parallel, and the straight line V1Q1 and the straight line P2T1 are parallel, the distance between the point T1 and the point Q1 is (b cos φ−asin φ). Since the distance D is the sum of the distance between the points S1 and T1 and the distance between the points T1 and Q1, the following equation (6) is established.

D = (b cos φ−asin φ) + {r− (acos φ + b sin φ)} tan (θ + α)
= Rtan (θ + α) + (a ² + b ² ) ^1/2 cos (A + φ + θ + α) / cos (θ + α) (6)
However, A = tan ⁻¹ a / b.

As the wheel disk 20 rotates once, φ changes by 0 to 2π. If θ, α, and A are constant during a certain period of time, for example, while the wheel disk 20 makes one revolution, (φ + θ + α + A) changes from 0 to 2π, so (a ² + b ² ) ^1/2 cos (A + φ + θ + α) / cos (θ + α) is a sine wave having an amplitude (a ² + b ² ) ^1/2 / cos (θ + α) on the time axis. Therefore, the distance D is a sine wave having an amplitude of (a ² + b ² ) ^1/2 / cos (θ + α)) and a median (center) of rtan (θ + α).

If the center is known, since r and α are known, the rotation angle θ is known. Fx = K _a × a (K _a is _a constant determined by the extension of the elastic member 22 in the x-axis direction and the force Fx), My = K _θ × θ (K _θ is centered on the center P2 of the rim 24 of the elastic member 22). Since there is a relationship of constant in the circumferential direction and a constant determined by the torque My and My = Fx × R ₀ (R ₀ : dynamic radius of the rotating body), if the dynamic radius of the rotating body is a known R ₀ ,
_{a = Fx / K a = My} / (K a × R 0) = K θ × θ / (K a × R 0) ··· (7)
Thus, a can be obtained. Further, when the amplitude (a ² + b ² ) ^1/2 / cos (θ + α) is known, a is obtained from the equation (7), so that b is known.

The amplitude (a ² + b ² ) ^1/2 / cos (θ + α) is obtained by, for example, sampling the distance D at a constant sampling period based on the minimum period of the sine wave determined by the prescribed maximum rotation period of the wheel disk 20 and the like. After the / D conversion, the difference between the local maximum value (maximum value) and the local minimum value (minimum value) following the maximum value in the time change of the distance D is multiplied by 1/2. The center (rtan (θ + α)) is calculated by, for example, obtaining the average value of the maximum value of the distance D and the minimum value following the maximum value.

  FIG. 20 is a diagram illustrating the center and amplitude of the distance D, where the horizontal axis indicates time t and the vertical axis indicates distance D. From the time t0 to the time t3, the force Fx = 0, the moment My = 0 (θ = 0, a = 0), and the force Fz is small (b is small). In this case, the center is rtanα and the amplitude b / cosα is small. At time t0 to t3, the maximum value of distance D (rtanα + b / cosα) is reached at time t1, and the minimum value of distance D (rtanα−b / cosα) at time t2.

  From time t3 to time t6, the force Fx = 0, the moment My = 0 (θ = 0, a = 0), and the force Fz is large (b is large). In this case, the center is rtanα and the amplitude b / cosα is large. From time t3 to time t6, at time t4, the maximum value of distance D (rtanα + b / cosα) is reached, and at time t5, the minimum value of distance D (rtanα−b / cosα) is reached.

After time t6, force Fx ≠ 0, moment My ≠ 0 (θ ≠ 0, a ≠ 0), center (rtan (θ + α)), amplitude (a ² + b ² ) ^1/2 / cos (θ + α) It shows a case. After time t6, at time t7, the maximum value of distance D (rtan (θ + α) + (a ² + b ² ) ^1/2 / cos (θ + α)), and at time t8, the minimum value of distance D (r tan (θ + α)) − (A ² + b ² ) ^1/2 / cos (θ + α)).

  The displacement-load conversion calculating means 4 calculates the wheels WFL, WFR from the displacements a, b, the relative rotation angle θ and the following equations (8), (9), (10) for the wheels WFL, WFR, WRL, WRR. , WRL, and WRR, Fx, Fz, and My are calculated.

Fx = Ka × a (8)
Fz = Kb × b (9)
My = K _θ × θ (10)
However, _Kb is a value based on the elastic force of the elastic member 22 in the z-axis direction.

As described above, according to the present embodiment, the distance D to the measured surface 72a is measured by the displacement sensor 70, and the center of the distance D is calculated based on the time change of the distance D. The relative rotation angle θ with respect to the wheel disk 20 can be calculated. Then, a can be calculated from the relative rotation angle θ. By calculating the amplitude of the distance D from the time change of the distance D, b can be calculated. Then, Fx, Fz, and My can be obtained from a, b, and θ. That is, the relative rotation angles θ, Fx, Fz, and My can be calculated with a small number of displacement sensors 26. Further, since there is a correlation between a and θ via the moving radius R ₀ of the rotating body, the forces Fx and Fz can be calculated without detecting the rotation angle φ of the wheel disk 20.

It is a block diagram of the load calculation apparatus by 1st Embodiment of this invention. It is a block diagram of the displacement detection apparatus in FIG. It is a side view of a wheel. It is the sectional view on the AA line in FIG. It is a figure which shows arrangement | positioning of the displacement sensor located on the plane containing the x-axis and z-axis in a no-load state, and a to-be-measured member. It is a figure which shows an example of a to-be-measured member. It is a figure which shows the wheel in a load state. It is operation | movement explanatory drawing of a displacement-load conversion calculating means. It is operation | movement explanatory drawing of a displacement-load conversion calculating means. It is operation | movement explanatory drawing of a displacement-load conversion calculating means. It is operation | movement explanatory drawing of a displacement-load conversion calculating means. It is a block diagram of the load calculation apparatus by 2nd Embodiment of this invention. It is a block diagram of the displacement detection apparatus in FIG. It is a side view of a wheel. It is the sectional view on the AA line in FIG. It is a figure which shows arrangement | positioning of the displacement sensor located on the plane containing the x-axis and z-axis in a no-load state, and a to-be-measured member. It is a figure which shows arrangement | positioning of the displacement sensor located on the plane containing the x-axis and z-axis in a no-load state, and a to-be-measured member. It is a figure which shows an example of a to-be-measured member. It is operation | movement explanatory drawing of a displacement-load conversion calculating means. It is operation | movement explanatory drawing of a displacement-load conversion calculating means.

Explanation of symbols

2 # FL, 2 # FR, 2 # RL, 2 # RR, 52 # FL, 52 # FR, 52 # RL, 52 # RR Displacement detecting device 4, 54 Displacement-load conversion calculating means 20 Wheel disk 22 Elastic member 24 Rims 26, 70 Displacement sensors 28, 72 Measuring members 28a, 72 Measuring surface 30 Tire 34 Axle hub

Claims (2)

An inner rotating body and an outer rotating body are arranged concentrically with no load, and are connected by an elastic member that is deformable according to the load so as to be relatively displaceable in a plane perpendicular to the inner rotating shaft. A rotating body having
One part to be measured that rotates integrally with one of the inner rotating body and the outer rotating body, and is provided on the rotating inner rotating body or the outer rotating body,
Rotating integrally with the other inner rotating body or the outer rotating body, provided in the other rotating inner rotating body or the outer rotating body, and facing the direction orthogonal to the circumferential direction of the rotating body One displacement sensor for detecting the distance to the part to be measured of the part to be measured;
An arithmetic means for calculating a relative rotation angle and a relative displacement amount between the inner rotator and the outer rotator based on a local median in the time change of the distance detected by the displacement sensor;
Displacement amount calculation apparatus characterized by comprising: An inner rotating body and an outer rotating body, which are arranged with no load, are arranged concentrically with each other and are elastically deformed according to the load so that they can be relatively displaced in a plane orthogonal to at least the inner rotating shaft. A rotating body having
One part to be measured that rotates integrally with one of the inner rotating body and the outer rotating body, and is provided on the rotating inner rotating body or the outer rotating body,
Of the part to be measured which rotates integrally with the other inner rotating body or the outer rotating body, is provided on the other rotating inner rotating body or the outer rotating body, and faces the circumferential direction of the rotating body. One displacement sensor for detecting the distance to the part to be measured;
An arithmetic means for calculating a relative rotation angle and a relative displacement amount between the inner rotator and the outer rotator based on a local median in the time change of the distance detected by the displacement sensor;
Displacement amount calculation apparatus characterized by comprising:

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