JP2008216017A - Rotation angle calculating device and displacement amount calculating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotation angle calculating device for calculating a relative rotation angle of an inside rotator to an outside rotator by using a small number of sensors. <P>SOLUTION: The rotation angle calculating device includes a rotating body, measured members, a plurality of displacement sensors, and an operating means. The rotator includes inside and outside rotators disposed so that their inside and outside rotation axes are concentric with each other in a no load state, and connected by an elastic member deformed according to load so that they can be relatively displaced at least in a surface orthogonal to the inside rotation axis. The measured members rotate integrally with either the inside rotator or the outside rotator, and are provided at a plurality of different circumferential positions on the rotating inside or outside rotator. The displacement sensors rotate integrally with the other inside or outside rotator, and are disposed at a plurality of circumferential positions equidistant from the center of the rotating axis of the other rotator to detect distances to a measured part of a measured member disposed opposite thereto in a circumferential direction. The operating means calculates a relative rotation angle between the inside and outside rotators based on a plurality of distances detected by the displacement sensors. <P>COPYRIGHT: (C)2008,JPO&INPIT

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 at least 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 connected to each other, and one of the inner rotating body and the outer rotating body, and rotates around the inner rotating body or the outer rotating body. Rotate integrally with the part to be measured provided at a plurality of different locations in the direction and the other inner rotating body or the outer rotating body, and are arranged at different locations on the other rotating body, Based on the plurality of displacement sensors that detect the distance to the measurement site of the measurement target portion that is arranged facing the circumferential direction of the rotating body, and the plurality of distances detected by the plurality of displacement sensors, Inside rotating body and outside Displacement amount calculation apparatus characterized by comprising a calculating means for calculating the relative rotation angle 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. Rotate integrally with the inner rotator or the outer rotator at a plurality of different locations on either the inner rotator or the outer rotator, and place the measurement target at different locations on the other rotator. Since the plurality of displacement sensors for detecting the distance to the measurement site of the measurement target portion arranged opposite to each other in the circumferential direction are provided on the other rotary body, the gap between the inner rotary body and the outer rotary body is provided. The relative rotation angle can be calculated. As a result, the relative rotation angle can be calculated with a small number of displacement sensors.

FIG. 1 is a block diagram including a load calculation device 1 according to an 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 detector 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 shown in FIG. 2, the displacement detection device 2 includes displacement detection means 10 # 1, 10 # 2, 11 # 1, 11 # 2, filters 12 # 1, 12 # 2, 12 # 3, 12 # 4 and data. A transmission unit 14 is included.

  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. As shown in FIGS. 3 to 4, the wheel 32 includes a wheel disk 20, an elastic member 22, a rim 24, and a displacement sensor 26 that constitutes the displacement detection devices 10 # 1, 10 # 2, 10 # 3, and 10 # 4. # 1, 26 # 2, 26 # 3, 26 # 4 and a part to be measured (member to be measured) 28 # 1, 28 # 2, 28 # 3, 28 # 4.

  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 disc 20 and the rim 24, connects the wheel disc 20 and the rim 24, and is transmitted from the tire 30 through the rim 24 in the x-axis, y-axis, and z-axis directions. It is deformed according to the magnitude and the direction of the force My around Fx, Fy, Fz and the y-axis.

  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 sensors 26 # 1, 26 # 2, 26 # 3 and 26 # 4 measure the distances D1, D2, D3 and D4 to the measured members 28 # 1, 28 # 2, 28 # 3 and 28 # 4. An electric signal corresponding to the distance is output, for example, a non-contact type displacement sensor such as an eddy current type, a capacitance type or a laser type, or a contact type displacement sensor such as a linear potentiometer.

  FIG. 5 shows displacement sensors 26 # 1, 26 # 2, 26 # 3 and 26 # 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). 4 and the arrangement of measured members 28 # 1, 28 # 2, 28 # 3, and 28 # 4. In the present embodiment, the displacement sensors 26 # 1, 26 # 2, 26 # 3, and 26 # 4 are shown on the same plane, but are not necessarily on the same plane. FIG. 6 shows the arrangement of the displacement sensor 26 # 1 and the member to be measured 28 # 1.

  The displacement sensor 26 # i (i = 1 to 4) has a distance measurement center point spaced apart from the center of the wheel disk 20 by a fixed distance r, for example, on a circumference separated from the center P1 by a distance r (for example, a wheel disk). 20 at a position shifted by 90 ° (on the outer periphery of the wheel 20), the direction in which the distance measurement is directed from the center P1 of the wheel disk 20 toward the rim 24 (radial direction of the wheel disk 20) Li (i = 1 to 4), (Circumferential direction). In the present embodiment, the displacement sensor 26 # i (i = 1 to 4) is shown as being disposed at a position spaced apart from the rotation axis center P1 of the wheel disk 20 by the same distance r, but the present invention is not limited to this.

  The x-axis and z-axis are stationary coordinate systems. The displacement sensors 26 # 1, 26 # 2, 26 # 3, and 26 # 4 are 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, the inner circumference of the rim 24). Above), the distance measurement direction may be arranged in the circumferential direction with no load.

  The member to be measured 28 # i (i = 1 to 4) is attached to the rim 24, and the opposing surface in the measurement direction of the displacement sensor 26 # i (i = 1 to 4) is the surface to be measured 28a # i (i = 1). To 4), which are displaced together with the rim 24. The material of the member to be measured 28 # i (i = 1 to 4) may be any material as long as the displacement sensor 26 # i (i = 1 to 4) can detect the distance Di (i = 1 to 4).

  The members to be measured 28 # i (i = 1 to 4) include those formed by processing a part of the rim 24 and the wheel disk 20. The shape is not limited as long as the measured surface 28a # i (i = 1 to 4) is as follows.

  The member to be measured 28 # i (i = 1 to 4) is the center of the distance measurement of the displacement sensor 26 # i (i = 1 to 4) of the surface 28a # i (i = 1 to 4) to be measured in the no-load state. The angle α (α> 0) formed by the straight line Mi (i = 1 to 4) and the straight line Li (i = 1 to 4) connecting the measured site Si (i = 1 to 4) and the center P1 of the wheel disk 20 And the member 28 # i (i = 1 to 4) to be measured so that the straight line Mi (i = 1 to 4) is in a fixed direction with respect to the straight line Li (i = 1 to 4), for example, counterclockwise. ) Is arranged on the rim 24.

  For example, the member to be measured 28 # i (i = 1 to 4) has a wheel disk 20 having a cross section by a plane including the x axis and the z axis of the surface to be measured 28a # i (i = 1 to 4) in a no-load state. Are processed so as to be a straight line Mi (i = 1 to 4) passing through the center P <b> 1 and disposed on the rim 24.

  The measured surface 28a # i (i = 1 to 4) is, for example, a single plane. FIG. 7 is a diagram illustrating an example of the member to be measured 28 # i (i = 1 to 4). The member to be measured 28 # i (i = 1 to 4) is, for example, a rectangular parallelepiped from the viewpoint of easy mounting and manufacturing, and the surface 28a # i (i = 1 to 4) is perpendicular to the circumferential direction. The surface 28b # i (i = 1 to 4) is perpendicular to the surface 28a # i (i = 1 to 4), and the surface 28b # i (i = 1 to 4) is placed on the rim 24 so as to be perpendicular to the radial direction. Install.

  When the displacement sensor 26 # i (i = 1 to 4) is provided on the rim 24, the member to be measured 28 # i (i = 1 to 4) is separated from the center of the wheel disk 20 by a distance r in the radial direction. The distance measurement direction is arranged in a circumferential direction perpendicular to the radial direction of the rim 24. The measured surface 28a # i (i = 1 to 4) is a distance measurement of the displacement sensor 26 # i (i = 1 to 4) of the measured surface 28a # i (i = 1 to 4) in the no-load state. The angle α (α>) formed by the straight line Mi (i = 1 to 4) and the straight line Li (i = 1 to 4) connecting the measurement site Si (i = 1 to 4) and the center P1 of the wheel disk 20 with the center of 0) is constant and the member 28 # i (i = 1 to 4) to be measured is placed on the wheel disk 20 so that the straight line Mi (i = 1 to 4) is in a constant direction with respect to the straight line Li (i = 1 to 4). To place.

  The filter 12 # i (i = 1 to 4) in FIG. 2 is a distance Di output from each displacement sensor 26 # i (i = 1 to 4) of the displacement detector 10 # i (i = 1 to 4). A high frequency component is deleted from the electrical signal indicating (i = 1 to 4), and noise is cut. The data transmission unit 14 transmits the electrical signal output from the filter 12 # i (i = 1 to 4) to the displacement-load conversion calculation unit 4 by wireless or the like.

  The displacement-load conversion calculating means 4 in FIG. 1 will be described in detail later from the distances D1, D2, D3, D4 transmitted from the displacement detectors 2 # FL, 2 # FR, 2 # RL, 2 # RR. As described above, the relative rotation angle θ of the rim 24 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. 8 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. 8 and 9 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 # i (i = 1 to 4) rotates integrally with the wheel disk 20 around the point P1, the displacement sensor 26 # 1 rotates counterclockwise by φ from the x-axis at the time of observation. Suppose you are. The x-axis and z-axis are axes obtained by translating the x-axis and z-axis (a, b). Let Q1 be the observation center point of the displacement sensor 26 # 1. An observation point of the measured surface 28a # 1 by the displacement sensor 26 # 1 after the displacement of the rim 24 is 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 26 # 1 and the device under test are measured. From the arrangement of the member 28 # 1, the angle formed by the straight line P2Q3 and the straight line P2S1 is α.

  A perpendicular foot from the point P2 to the straight line P1Q1 is defined as V1. 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 + α). 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 D1 is the sum of the distance between the points S1 and T1 and the distance between the points T1 and Q1, the following equation (1) is established.

D1 = (b cos φ−asin φ) + {r− (acos φ + b sin φ)} tan (θ + α)
(1)
For D2, since (φ + π / 2) should be substituted for φ in equation (1), equation (2) holds.

D2 = (bcos (φ + π / 2) −asin (φ + π / 2)) + {r− (acos (φ + π / 2) + bsin (φ + π / 2)} tan (θ + α)
=-(Bsinφ + acosφ) + {r − (− asinφ + bcosφ)} tan (θ + α)
(2)
With respect to D3, since (φ + π) has only to be substituted for φ in equation (1), equation (3) holds.

D3 = (bcos (φ + π) −asin (φ + π)) + {r− (acos (φ + π) + bsin (φ + π)} tan (θ + α)
= − (B cos φ−cos φ) + {r + (cos φ + b sin φ)} tan (θ + α)
(3)
As for D4, since (φ + 3π / 2) is substituted into φ in the formula (1), the formula (4) is established.

D4 = (bcos (φ + 3π / 2) −asin (φ + 3 / 2π)) + {r− (acos (φ + 3π / 2) + bsin (φ + 3π / 2)} tan (θ + α)
= (Bsinφ + acosφ) + {r + (− asinφ + bcosφ)} tan (θ + α)
(4)
Expression (5) is established from Expressions (1) to (4).

tan (θ + α) = (D1 + D3) / 2r = (D2 + D4) / 2r = (D1 + D2 + D3 + D4) / 4r
(5)
Here, since α and r are known, the rotation angle θ is calculated from α, r and the measured values D1, D2, D3, and D4 without depending on the rotation angle φ of the wheel 32 from the equation (5). it can.

  When Xi = Di-rtan (θ + α) (i = 1 to 4), the following expressions (6), (7), (8), and (9) are established.

X ₁ = (a ² + b ² ) ^1/2 cos (A + φ + θ + α) / cos (θ + α) (6)
X ₂ = − (a ² + b ² ) ^1/2 sin (A + φ + θ + α) / cos (θ + α) (7)
X ₃ = − (a ² + b ² ) ^1/2 cos (A + φ + θ + α) / cos (θ + α) (8)
X ₄ = (a ² + b ² ) ^1/2 sin (A + φ + θ + α) / cos (θ + α) (9)
However, tanA = a / b.

  Expression (10) is established from Expressions (6) to (9).

a ² + b ² = − (X ₁ X ₃ + X ₂ X ₄ ) cos ² (θ + α)
= (X ₁ ² + X ₂ ² ) cos ² (θ + α) (10)
As in equations (1) to (4), a and b depend on the rotation angle φ of the disc wheel 32. Therefore, an angle detection sensor for detecting the wheel rotation angle φ is required. However, Fx = K _a × a (K _a is _a constant determined by the elongation in the x-axis direction of the elastic member 22 and the force Fx), My = K _θ × θ (K _θ is the center P2 of the rim 24 of the elastic member 22). ) And a constant determined by the torque My, and My = Fx × R ₀ (R ₀ : dynamic radius of the rotating body), the dynamic radius of the rotating body is known as R ₀ . if there is,
_{a = Fx / K a = My} / (K a × R 0) = K θ × θ / (K a × R 0) ··· (11)
Thus, a can be obtained.

  Since tan (θ + α) is obtained from Equation (5) and a is obtained from Equation (11), b shown in Equation (12) is obtained from Equation (10).

b = {− (X ₁ X ₃ + X ₂ X ₄ ) cos ² (θ + α) −a ² } ^1/2
= {(X ₁ ² + X ₂ ² ) cos ² (θ + α) −a ² } ^1/2 (12)
b is calculated by substituting a, θ, α, X ₁ , X ₂ , X ₃ , and X ₄ into Equation (12).

A constant value may be used as the moving radius R ₀ used for the calculation, or a value corrected by the rotational speed of the wheel disk 20 or the load Fz may be used.

  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 (13), (14), (15) for the wheels WFL, WFR, WRL, WRR. , WRL, and WRR, Fx, Fz, and My are calculated.

Fx = Ka × a (13)
Fz = Kb × b (14)
My = K _θ × θ (15)
However, Ka is a value based on the elastic force of the elastic member 22 in the x-axis direction, and _Kb is a value based on the elastic force of the elastic member 22 in the z-axis direction.

  From equation (5), equation (16) holds.

D1 + D2 + D3 + D4 = 4rtan (θ + α) (16)
FIG. 10 is a diagram showing the relationship between (θ + α) and (D1 + D2 + D3 + D4) when r = 200 mm based on the equation (16), with the horizontal axis representing (θ + α) (unit degrees) and the vertical axis representing (D1 + D2 + D3 + D4). (Unit: mm). FIG. 11 is an enlarged view of a portion B in FIG. For example, when α = 5 ° and θ changes in the range of −3 ° to + 3 °, the difference between (D1 + D2 + D3 + D4) when θ is + 3 ° and (D1 + D2 + D3 + D4) when −3 ° is 84.5 mm. Thus, the detected displacement amount is large. This is because tan (θ + α) has a large change amount with respect to the change amount of θ, and thus the change amount of the distance Di (i = 1 to 4) becomes large.

  As described above, according to the present embodiment, the measured surface 28a is measured by the displacement sensors 26 # i (i = 1 to 4) arranged at four positions shifted by 90 ° with the center P1 of the wheel disc 20 being symmetrical. By measuring the circumferential distance Di (i = 1 to 4) up to #i (i = 1 to 4), the relative rotation angle θ and a, b of the rim 24 with respect to the wheel disk 20 can be calculated. . Fx, Fz, and My can be obtained from θ and a and b.

  In this embodiment, the output of the three displacement sensors (D1, D2, D3), (D1, D2, D4), (D2, D4, D1), (D2, D4, D3) gives θ ( It is clear that torque My), a (force Fx) and b (force Fz) can be calculated.

As shown in the modification formulas (1) to (4), by adding a part or all of the distance Di (i = 1 to 4) and canceling the terms of sin and cos depending on the angle φ, tan By calculating (θ + α), the relative rotation angle θ can be calculated. In order to calculate the relative rotation angle θ, the center P1 of the wheel disk 20 is symmetrical, two measurement parts and a displacement sensor are arranged at positions shifted by 180 °, and the distance in the circumferential direction to the measurement part is determined by the two distances. It is only necessary to measure with two displacement sensors and add the two distances measured by these displacement sensors. Accordingly, when only θ (torque My) and a (force Fx) are obtained, at least two are required.

  Further, the three distances D1, D2, and D3 measured by the three displacement sensors that measure the distance in the circumferential direction arranged at positions shifted by 120 ° about the center P1 of the wheel disc 20 are expressed by the equations (17) to ( 19), and when the expressions (17) to (19) are added, the sum of the three sin and cos terms whose phases are shifted by 120 ° is 0 as shown in the expression (20). Can be canceled, and the relative rotation angle θ can be calculated as shown in equation (21).

D1 = (b cos φ−asin φ) + {r− (acos φ + b sin φ)} tan (θ + α)
... (17)
D2 = (bcos (φ + 2π / 3) −asin (φ + 2π / 3)) + {r− (acos (φ + 2π / 3) + bsin (φ + 2π / 3)} tan (θ + α)
... (18)
D3 = (bcos (φ + 4π / 3) −asin (φ + 4π / 3)) + {r− (acos (φ + 4π / 3) + bsin (φ + 4π / 3)} tan (θ + α)
(19)
D1 + D2 + D3 = 3rtan (θ + α) (20)
tan (θ + α) = (D1 + D2 + D3 / 3r) (21)
Further, in order to calculate b (force Fz) from (a ² + b ² ), at least one displacement sensor is required in addition to the displacement sensor for calculating only θ (torque My) and a (force Fx). Become. At this time, in the embodiment, the two (X1, X2) or (X3, X4) arranged at positions shifted by 90 ° are squared and added to cancel the trigonometric function sin or cos depending on φ. However, (a ² + b ² ) can be calculated even in other arrangements.

For example, even when two displacement sensors are arranged at an angle ξ (ξ ≠ 90 °) other than 90 °, X1 = (a ² + b ² ) ^1/2 cos (A + φ + θ + α) / cos ( θ + α), (X1 = D1−rtan (θ + α)) and D2 = {bcos (φ + ξ) −asin (φ + ξ)} + {r− (acos (φ + ξ) + bsin (φ + ξ)} tan (θ + α), and X2 = ( a ² + b ² ) ^1/2 (cos (A + φ + θ + α + ξ) / cos (θ + α), (X2 = D2−rtan (θ + α)), and a ² + b ² = (X1 ² −2X1X2 cos ξ + X2 ² ) cos ² (θ + α) / From sin ² ξ, (a ² + b ² ) can be calculated.

It is a block diagram of the load calculation apparatus by 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 the wheel in a no-load state. It is a figure which shows arrangement | positioning of a displacement sensor 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. 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 Displacement detecting device 4 Displacement-load conversion calculating means 20 Wheel disk 22 Elastic member 24 Rim 26 # 1, 26 # 2, 26 # 3, 26 # 4 Displacement sensor 28 # 1, 28 # 2, 28 # 3, 28 # 4 member to be measured 28a # 1, 28a # 2, 28a # 3, 28a # 4 surface to be measured 30 tire 34 axle hub

Claims (1)

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
A unit to be measured that rotates integrally with any one of the inner rotating body and the outer rotating body, and is provided at a plurality of different locations in the circumferential direction of the rotating inner or rotating body;
The device under test that rotates integrally with the other inner rotating body or the outer rotating body, is disposed at a plurality of different locations on the other rotating body, and is disposed opposite to the circumferential direction of the other rotating body. A plurality of displacement sensors for detecting the distance to the part to be measured;
An arithmetic means for calculating a relative rotation angle between the inner rotating body and the outer rotating body based on the plurality of distances detected by the plurality of displacement sensors;
Displacement amount calculation apparatus characterized by comprising:

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