Detection device, program, and calculation method

Abstract

To provide a detection device, a program, and a calculation method capable of increasing calculation precision of a load acting on a rotor.SOLUTION: A detection device is applied to a wheel unit. The wheel unit comprises a hub bearing 40 having an outer wheel member 50, an inner wheel member 60, and a rolling element 41. The detection device comprises: a ring-like target member 80 that is provided in the inner wheel member 60 and extends in a circumferential direction of the inner wheel member 60 with the rotation center of the inner wheel member 60 as a center; a sensor board 100 for detecting a voltage signal corresponding to the relative potential of the target member 80 relative to itself; and a calculation section. The calculation section calculates relative displacement in a specific direction relative to a wheel on the basis of the detected voltage signal. The calculation section calculates a load acting on the wheel on the basis of the calculated relative displacement in the specific direction and a calculation parameter related to a load acting on the wheel.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a detection device, a program, and a calculation method. [Background technology]

[0002] A hub bearing with a sensor is known that detects displacement by utilizing the relative displacement of an inner ring member with respect to an outer ring member of the hub bearing. A hub bearing with a sensor is described in, for example, Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-275508 Summary of the Invention [Problem to be solved by the invention]

[0004] A detection device that is applied to a mechanical device that includes a rotating body is known. The mechanical device includes a bearing member. The bearing member includes a first bearing portion (e.g., an outer ring member), a second bearing portion (e.g., an inner ring member), and a rolling element. The first bearing portion is fixed to a base portion. The rotating body is fixed to the second bearing portion. The rolling element is provided between the first bearing portion and the second bearing portion. In this way, the bearing member supports the rotating body rotatably relative to the base portion.

[0005] The detection device includes a detection target and a sensor substrate as components for detecting displacement or force. The detection target is annular and extends in the circumferential direction of the bearing member around the center of rotation of the first bearing portion. The sensor substrate is provided at a position facing the detection target and the bearing member in the axial direction. The sensor substrate outputs a voltage signal corresponding to the relative displacement of the detection target with respect to the sensor substrate. The displacement is calculated based on the output voltage signal. The load acting on the rotating body is calculated based on the calculated displacement.

[0006] There is a demand for a technique that improves the accuracy of calculating the load acting on a rotating body.

[0007] A primary object of the present disclosure is to provide a detection device, a program, and a calculation method that can improve the accuracy of calculating a load acting on a rotating body. [Means for solving the problem]

[0008] The present disclosure provides: In a detection device applied to a mechanical device having a rotating body, the mechanical device includes a bearing member that rotatably supports the rotating body relative to a base portion, The bearing member is a first bearing portion extending in an axial direction, which is a direction in which a rotation center axis of the bearing member extends, and fixed to the base portion; a second bearing portion provided at a position facing the first bearing portion in a radial direction perpendicular to the axial direction, and to which the rotating body is fixed; a rolling element provided between the first bearing portion and the second bearing portion; the second bearing portion is rotatably supported relative to the base portion, a ring-shaped detection target portion provided in one of the first bearing portion and the second bearing portion and extending in a circumferential direction around a rotation center of the bearing member; a signal detection unit provided at a position facing the detection target in the axial direction; A calculation unit; Equipped with the signal detection unit detects a voltage signal corresponding to a relative displacement of the detection target portion with respect to the signal detection unit; The calculation unit calculating the relative displacement in a specific direction with respect to the rotating body based on the detected voltage signal; A load acting on the rotating body in the specific direction is calculated based on the calculated relative displacement in the specific direction and a calculation parameter related to the load acting on the rotating body.

[0009] In the present disclosure, a load acting on a rotating body in a specific direction is calculated based on a relative displacement in the specific direction with respect to the rotating body and a calculation parameter related to the load acting on the rotating body. This makes it possible to calculate the load acting on the rotating body in a specific direction while taking into account changes in the state of the bearing member due to the load acting on the rotating body. As a result, it is possible to improve the calculation accuracy of the load acting on the rotating body. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. [Figure 2] FIG. [Figure 3] FIG. 10 is an enlarged view of a portion near the hub bearing of the wheel unit. [Figure 4] FIG. [Figure 5] FIG. [Figure 6] FIG. [Figure 7] FIG. 2 is a diagram showing the electrical configuration of a sensor substrate and a processing unit. [Figure 8] FIG. 4 is a diagram showing the relationship between lateral force and axial displacement when the vehicle is stationary. [Figure 9] FIG. 4 is a diagram showing the relationship between vertical load and vertical displacement when the vehicle is stationary. [Figure 10] 4A and 4B are diagrams showing the relationship between lateral force and axial displacement in various driving modes; [Figure 11] 4A and 4B are diagrams showing the relationship between vertical load and vertical displacement in various driving modes. [Figure 12] FIG. 10 is a diagram for explaining factors that cause variations in load relative to displacement. [Figure 13] FIG. 4 is a diagram illustrating the deformation direction of a hub bearing. [Figure 14] 5A and 5B are diagrams for explaining changes in the state of a hub bearing. [Figure 15] FIG. 10 is a diagram showing a response variable and explanatory variables set in multiple regression analysis. [Figure 16]FIG. 10 is a diagram showing an example of the results of multiple regression analysis. [Figure 17] 10 is a flowchart showing the procedure of processing executed by a processing unit. [Figure 18] FIG. 10 is a diagram showing an example of a calculation result of a lateral force acting on a left front wheel. [Figure 19] FIG. 10 is a diagram showing an example of a calculation result of a vertical load acting on a left front wheel. [Figure 20] FIG. 10 is a diagram showing an example of calculation parameters according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, one embodiment of a detection device according to the present disclosure will be described with reference to the drawings. The detection device of this embodiment is configured to be able to calculate the force acting on wheels (drive wheels or driven wheels) as rotating bodies. A vehicle equipped with wheels is, for example, a four-wheeled passenger vehicle (for example, private or commercial use) having two front wheels and two rear wheels. However, the vehicle is not limited to this, and may be a vehicle other than a four-wheeled vehicle, such as a two-wheeled vehicle. Furthermore, the use of the vehicle is not limited to passenger use.

[0012] The wheel unit 10 as a mechanical device will be described using Figures 1 to 5. Figure 1 is a perspective cross-sectional view in which the wheel unit 10 is partially cut away, and Figure 2 is a cross-sectional view in which the wheel unit 10 is cut along a plane that passes through the center of rotation of the wheel unit 10 and extends vertically. Figure 3 is a partially enlarged view of Figure 2. Figures 4 and 5 are exploded perspective views of the wheel unit 10.

[0013] As shown in Figures 1 and 2, the wheel unit 10 includes a wheel 11 and a tire 14 that constitute a wheel. The wheel 11 includes a cylindrical rim portion 12 and a disc portion 13 provided at the outer end of the rim portion 12 in the vehicle width direction. The disc portion 13 includes a disc mounting portion 18 located in the center of the disc portion 13, and spoke portions 19 that extend radially from the disc mounting portion 18 to the rim portion 12. The tire 14 is mounted on the outer periphery of the rim portion 12.

[0014] As shown in Figures 1 to 5, the wheel unit 10 includes a brake device 20 and a hub bearing 40 as a bearing member. The brake device 20 is a disc-type friction braking device and includes a disc rotor 21 that is disk-shaped overall, and a brake caliper 33. The brake caliper 33 is operated by hydraulic pressure, an electric signal, or the like, and includes a pair of disc pads that come into contact with the disc rotor 21 to generate braking force, a piston that presses the disc pads against the disc rotor 21, and a caliper body that supports the brake pads and the piston. As shown in Figure 4, the brake caliper 33 is fixed to the knuckle 15, which is a base portion, by a bolt 34.

[0015] In the following, the direction in which the rotational center axis of the hub bearing 40 (specifically, for example, the inner ring member 60 of the hub bearing 40) extends is referred to as the axial direction, the direction extending radially from the rotational center axis is referred to as the radial direction, and the direction extending circumferentially around the rotational center axis is referred to as the circumferential direction.

[0016] The disc rotor 21 of this embodiment is a ventilated disc having an internal cavity for ventilation. The disc rotor 21 has a hat portion 22 and a sliding portion 23. The hat portion 22 is attached to the hub bearing 40. The hat portion 22 has a disk-shaped bottom surface portion 24 and a disc peripheral wall portion 25. A mounting hole 26 is formed in the center of the bottom surface portion 24. Bolt insertion holes 27 that axially penetrate the bottom surface portion 24 are formed in a circumferential direction around the mounting hole 26. The disc rotor 21 is connected to the hub bearing 40 using the mounting holes 26 and the bolt insertion holes 27. The disc peripheral wall portion 25 is cylindrical and extends from the outer circumferential edge of the bottom surface portion 24, forming the peripheral surface of the hat portion 22.

[0017] A sliding portion 23 is connected to the end of the disc peripheral wall portion 25 opposite the bottom surface portion 24. The sliding portion 23 is formed to protrude outward in an annular shape from the disc peripheral wall portion 25. The front and back surfaces of the sliding portion 23 form a pair of sliding surfaces that are pressed against by the disc pad.

[0018] The sliding portion 23 includes an inner disk portion 28, an outer disk portion 29 disposed on the outer side of the inner disk portion 28, and fins 30. The fins 30 connect the inner disk portion 28 and the outer disk portion 29 at multiple locations in the circumferential direction. The fins 30 extend radially, and the space surrounded by the inner disk portion 28, the outer disk portion 29, and the fins 30 forms an air passage penetrating in the radial direction (diameter direction). The air passage is a passage that extends from an air intake port 31 formed on the radially inner side of the sliding portion 23 to an air exhaust port 32 formed on the radially outer side.

[0019] The hub bearing 40 is a rolling bearing (specifically, a radial ball bearing) and includes an outer ring member 50 (corresponding to the "first bearing portion"), an inner ring member 60 (corresponding to the "second bearing portion"), and a plurality of rolling elements 41 (specifically, balls) arranged between the outer ring member 50 and the inner ring member 60. The hub bearing 40 of this embodiment has a structure in which the rolling elements 41 are arranged in two rows in the axial direction. Note that the hub bearing 40 may also be a radial roller bearing provided with rollers as the rolling elements 41.

[0020] The inner ring member 60 includes an inner cylindrical portion 61 extending in the axial direction, and a flange portion 62 extending radially from a first end of the inner cylindrical portion 61 in the axial direction. A shaft insertion hole 63 is formed in the inner cylindrical portion 61, penetrating it in the axial direction. A spline is formed on the inner peripheral surface of the shaft insertion hole 63. A shaft (not shown) to which rotational power of a driving power source such as a motor is transmitted is fitted in the shaft insertion hole 63.

[0021] The outer ring member 50 has an outer cylindrical portion 51 provided at a position facing radially outward from the inner cylindrical portion 61. The rolling elements 41 are provided between the outer cylindrical portion 51 and the inner cylindrical portion 61.

[0022] The flange portion 62 is disk-shaped and extends radially outward beyond the outer cylindrical portion 51. The flange portion 62 has bolt insertion holes 64 arranged in the circumferential direction, through which hub bolts 17 for fixing the wheel 11 are inserted. In this embodiment, as shown in FIG. 5, for example, five hub bolts 17 are arranged in the circumferential direction. Therefore, five bolt insertion holes 64 are also formed.

[0023] The wheel unit 10 is provided with a dust cover 70, which is a heat shield. The dust cover 70 is provided on the inner side in the vehicle width direction of the hub bearing 40 and the sliding portion 23 of the disc rotor 21. The dust cover 70 extends radially outward beyond the outer peripheral edge of the sliding portion 23.

[0024] The wheel unit 10 is equipped with a detection device. The detection device is provided in the inner space of the wheel 11 and includes a target member 80 (corresponding to the "detection target") and a sensor board 100 (corresponding to the "signal detection unit"). The detection device is a device for detecting the rotational speed of the wheel consisting of the wheel 11 and tire 14, the lateral force Fy acting between the ground contact surface (ground) GL and the wheel (specifically the tire 14), and the force acting between the ground contact surface GL and the wheel in a direction perpendicular to the ground contact surface GL (hereinafter referred to as the vertical load Fz). The direction in which the lateral force Fy acts is perpendicular to the direction in which the vertical load Fz acts.

[0025] In this embodiment, the detection device is mounted on a vehicle, which is a moving body, and a detection device is provided on each of the left and right front wheels of the vehicle. The rotational speed, lateral force Fy, and vertical load Fz calculated by the detection device are used for vehicle running control in a control device (specifically, an ECU: Electronic Control Unit) provided in the vehicle. The control device is a motor control ECU that controls a motor, which is a power source for running the vehicle.

[0026] The structure of the detection device will be described below.

[0027] The target member 80 is made of a metal material (e.g., aluminum or iron). The target member 80 has an annular shape extending in the circumferential direction around the central axis of rotation of the hub bearing 40. The target member 80 is provided in a position facing the sensor substrate 100 in the axial direction, without contacting the sensor substrate 100.

[0028] In this embodiment, the target member 80 is divided into two parts in the circumferential direction, as shown in Figures 4 and 5, more specifically, the two parts are divided into two parts with equal circumferential lengths. The reason for dividing the target member 80 is to facilitate the assembly of the target member 80 to the hub bearing 40. For example, the target member 80 can be attached to a completed hub bearing 40 later. Hereinafter, one of the divided parts of the target member 80 will be referred to as a first divided part 80A, and the other part will be referred to as a second divided part 80B.

[0029] The target member 80 has protrusions 81, which protrude inward in the vehicle width direction in the axial direction and have flat surfaces, lined up in the circumferential direction. The flat surfaces between the protrusions 81 lined up in the circumferential direction are recesses 82. The protrusions 81 and recesses 82 are arranged alternately in the circumferential direction. In this embodiment, 12 pairs of protrusions 81 and recesses 82 are provided.

[0030] 6, LCi indicates the center axis of the inner ring member 60. In this embodiment, the angle α1 formed by the axis passing through the center axis LCi and one circumferential end of the protruding portion 81 and the axis passing through the center axis LCi and the other circumferential end of the protruding portion 81 is equal to the angle α2 formed by the axis passing through the center axis LCi and one circumferential end of the recessed portion 82 and the axis passing through the center axis LCi and the other circumferential end of the recessed portion 82. Therefore, the circumferential length of the multiple protruding portions 81 and the circumferential length of the multiple recessed portions 82 are equal to each other.

[0031] Next, a configuration for fixing the target member 80 to the flange portion 62 will be described.

[0032] 5, a plurality of bolt insertion holes 62a (six are shown in the figure) that penetrate in the axial direction are formed in the flange portion 62 and aligned in the circumferential direction. The bolt insertion holes 62a are formed in positions that are shifted in the circumferential direction from the protruding positions of the hub bolts 17. The flange portion 62 is formed with a mounting surface 62b that is a flat surface with which the bottom surface portion 24 of the disc rotor 21 abuts (specifically, comes into surface contact with).

[0033] Each of the divided members 80A, 80B constituting the target member 80 has a female threaded hole 84 extending in the axial direction formed on the side opposite to the surface on which the convex portion 81 and the concave portion 82 are formed, and a bolt 83 is inserted through the female threaded hole 84. With the divided members 80A, 80B abutting against the flange portion 62 and the bolt 83 inserted through the bolt insertion hole 62a, the male thread of the bolt 83 is screwed into the female threaded hole 84. In this way, each of the divided members 80A, 80B is fixed to the flange portion 62. Note that the side surface portion 85 of the target member 80 does not protrude beyond the flange portion 62 when viewed from the front of the mounting surface 62b. This makes it possible to suppress an increase in the radial dimension of the sensor-equipped bearing module.

[0034] Next, a configuration for fixing the wheel 11 and the disc rotor 21 to the flange portion 62 will be described.

[0035] As shown in Fig. 3, the disc mounting portion 18 has a bolt insertion hole 18a formed therethrough in the axial direction. With the bottom surface portion 24 and the disc mounting portion 18 overlapping the mounting surface 62b of the flange portion 62, a hub bolt 17 is inserted into the bolt insertion holes 27, 18a. A nut 35 is threaded onto the hub bolt 17, thereby fixing the disc mounting portion 18 and the disc rotor 21 to the hub bearing 40. This makes the target member 80, disc rotor 21, and inner ring member 60 coaxial, and causes the target member 80, disc rotor 21, and wheel 11 to rotate integrally.

[0036] The target member 80 is provided radially inward of the disk peripheral wall portion 25 that constitutes the disk rotor 21. This allows the disk rotor 21 to protect against foreign matter from the outside.

[0037] Next, the sensor substrate 100 will be described.

[0038] The sensor substrate 100 is a so-called eddy current inductive sensor. The sensor substrate 100 is disposed such that the plate surface of the sensor substrate 100 extends in the vertical direction. The sensor substrate 100 is disposed in an arrangement space that is adjacent to the flange portion 62 on the inner side in the vehicle width direction and that is radially outward of the inner cylindrical portion 61 and the outer cylindrical portion 51. In the arrangement space, a target member 80 is disposed at a position facing the sensor substrate 100 in the axial direction. In this embodiment, the sensor substrate 100 is disposed at a position facing the upper end of the target member 80 in the axial direction. The sensor substrate 100 is disposed between the flange portion 62 and the hub mounting portion 52.

[0039] The sensor substrate 100 has an arc shape that follows the target member 80. As shown in FIG. 7, the sensor substrate 100 includes an excitation coil 110 and a receiving coil. In this embodiment, the receiving coils are a first receiving coil 111 and a second receiving coil 112. Each of the coils 110 to 112 is a planar coil that follows the surface of the sensor substrate 100. The sensor substrate 100 is a multi-layer substrate. Each of the coils 110 to 112 is formed by wiring patterns, vias, etc., formed on each layer of the sensor substrate 100.

[0040] The sensor substrate 100 includes an excitation circuit 113 that supplies a high-frequency excitation voltage to the excitation coil 110, and a receiving circuit 114. When an excitation voltage is supplied to the excitation coil 110, an excitation current flows through the excitation coil 110, and a voltage having the same or equivalent frequency as the excitation voltage is induced in each of the coils 111 and 112. The receiving circuit 114 detects output voltage signals at both ends of each of the coils 111 and 112. When an excitation voltage is supplied to the excitation coil 110, the phase difference between the first output voltage signal of the first receiving coil 111 and the output voltage signal of the second receiving coil 112 is 90 degrees.

[0041] The sensor board 100 is provided with a connector 115 electrically connected to the excitation circuit 113 and the receiving circuit 114. The connector 115 is electrically connected to a processing unit 117 via a cable 116. The processing unit 117 may be provided on the vehicle body or may be built into the wheel unit 10. In this embodiment, the motor control ECU includes the processing unit 117.

[0042] The processing unit 117 includes a CPU (Central Processing Unit). The functions of the processing unit 117 can be provided by software stored in a physical memory device and a computer executing the software, by software alone, by hardware alone, or by a combination of these. For example, if the microcomputer of the processing unit 117 is implemented as a hardware electronic circuit, it can be implemented by a digital circuit including multiple logic circuits or an analog circuit. For example, the microcomputer executes a program stored in a non-transitory tangible storage medium serving as a storage unit of the microcomputer. The program includes, for example, a program for processing the program shown in FIG. 17 (described later). A method corresponding to the program is performed by executing a set of instructions constituting the program. The storage unit is, for example, a non-volatile memory. The program stored in the storage unit can be updated via a communication network such as the Internet, for example, via OTA (Over The Air).

[0043] The processing unit 117 performs calculation processing to calculate the load acting on the wheel, etc. In detail, the processing unit 117 includes a displacement calculation unit 117a, a force calculation unit 117b, and a rotational speed calculation unit 117c.

[0044] 2, when a lateral force Fy acts on the wheel, the inclination θ of the center axis LCi of the inner ring member 60 relative to the center axis LCo of the outer ring member 50 increases. In this case, the axial distance between each of the coils 111, 112 and the target member 80 changes, and the amplitude of the output voltage signals of each of the coils 111, 112 changes. The displacement calculation unit 117a calculates the axial displacement ΔYc of the target member 80 based on the change in amplitude of the output voltage signals of each of the coils 111, 112.

[0045] On the other hand, when a vertical load Fz acts on the wheel, the central axis LCi of the inner ring member 60 is displaced in a direction perpendicular to the central axis LCo of the outer ring member 50. As a result, the target member 80 fixed to the flange portion 62 is also displaced. In this case, the sensor board 100 is configured so that the amplitudes of the output voltage signals of the first receiving coil 111 and the second receiving coil 112 change. The displacement calculation unit 117a calculates the displacement of the target member 80 in the axial direction and the direction perpendicular to the vehicle length direction (hereinafter referred to as the up-down displacement ΔZc) based on the change in the amplitude of the output voltage signals of the coils 111, 112.

[0046] The vehicle is equipped with an acceleration sensor 140, a yaw rate sensor 141, a wheel speed sensor 142, and a strain sensor 143. The acceleration sensor 140 is installed near the center of gravity of the vehicle and detects the acceleration in the longitudinal and vertical directions of the vehicle. The yaw rate sensor 141 is installed, for example, at the center of the vehicle and detects the acceleration in the turning direction of the vehicle. The wheel speed sensor 142 detects the rotational speed of the wheels. The strain sensor 143 detects the axial displacement and radial displacement of the outer wheel. The sensors 140 to 143 and the processing unit 117 are capable of communicating with each other using a predetermined communication format (for example, CAN). The detected values ​​of the sensors 140 to 143 are input to the force calculation unit 117b.

[0047] The displacements ΔYc and ΔZc calculated by the displacement calculation unit 117a are input to the force calculation unit 117b. The force calculation unit 117b calculates the lateral force Fyc and the vertical load Fzc based on the calculated displacements ΔYc and ΔZc and the detection values ​​of the sensors 140 to 143. The process of calculating the loads Fyc and Fzc will be described later.

[0048] The rotation speed calculation unit 117c calculates the rotation angle (specifically, the electrical angle or the mechanical angle) of the wheel based on the output signal of at least one of the first receiving coil 111 and the second receiving coil 112. The rotation speed calculation unit 117c calculates the rotation speed of the wheel based on the calculated rotation angle. Specifically, for example, the rotation speed calculation unit 117c may calculate the rotation speed based on the time differential value of the rotation angle.

[0049] The sensor substrate 100 and the calculation process are also described in, for example, Japanese Patent Application Laid-Open No. 2023-130285.

[0050] Next, a configuration for fixing the sensor board 100 to the knuckle 15 will be described with reference to FIGS.

[0051] The wheel unit 10 includes a board mounting member 120 as a component for fixing the sensor board 100 to the knuckle 15. The board mounting member 120 is plate-shaped and annular. The board mounting member 120 is made of, for example, synthetic resin or a metal material (e.g., aluminum). A circular (specifically, perfect circular) through-hole 122 is formed in the center of the board mounting member 120. The through-hole 122 penetrates in the axial direction from the first plate surface 121a to the second plate surface 121b of the board mounting member 120, and the outer cylindrical portion 51 is fitted into the through-hole 122.

[0052] A protrusion 130 for attaching the sensor board 100 is provided on the first plate surface 121a of the board mounting member 120. The protrusion 130 extends from the first plate surface 121a toward the flange portion 62 in the axial direction. A plurality of protrusions 130 (three are illustrated in the drawing) are formed spaced apart in the circumferential direction.

[0053] Each protrusion 130 has a bolt insertion hole that penetrates in the axial direction and through which a board mounting bolt 131 is inserted. Meanwhile, the sensor board 100 has the same number of female screw holes 101 as the bolt insertion holes, into which the male screws of the board mounting bolts 131 are screwed.

[0054] The board mounting member 120 and the sensor board 100 have a configuration that facilitates relative positioning of the sensor board 100 with respect to the board mounting member 120. More specifically, the sensor board 100 has a first plate surface 102a and a second plate surface 102b that is the back surface of the first plate surface 102a. Positioning pins 103 that extend axially toward the board mounting member 120 are provided at both circumferential ends of the second plate surface 102b. Of the multiple protrusions 130, the protrusions 130 at both circumferential ends have pinholes that extend axially and through which the positioning pins 103 are inserted.

[0055] By inserting the positioning pins 103 into the pin holes, the female screw holes 101 at both circumferential ends of the sensor board 100 are aligned with the bolt insertion holes of the protrusions 130. In this aligned state, the board mounting bolts 131 are inserted into the bolt insertion holes from the second plate surface 121b side of the board mounting member 120, and the male threads of the board mounting bolts 131 are screwed into the female screw holes 101. As a result, the sensor board 100 is fixed to the board mounting member 120 while maintaining a predetermined relative positional relationship between the sensor board 100 and the board mounting member 120. In this case, the plate surfaces of the sensor board 100 and the board mounting member 120 are parallel to each other. Furthermore, the sensor board 100 is supported by the protrusions 130 while spaced apart from the first plate surface 121a of the board mounting member 120.

[0056] The board mounting member 120 is formed with bolt insertion holes 123 that penetrate from the first plate surface 121a to the second plate surface 121b and through which the bolts 16 are inserted. In this embodiment, three bolt insertion holes 123 are formed spaced apart in the circumferential direction.

[0057] An extension 124 extending axially toward the dust cover 70 is formed on the periphery of the through hole 122 of the board mounting member 120. The extension 124 is formed over the entire periphery of the periphery of the through hole 122.

[0058] The dust cover 70 includes a first wall portion 73, a connecting portion 74, and a second wall portion 75. The connecting portion 74 extends radially outward from the radially outer end portion of the first wall portion 73. The second wall portion 75 extends radially outward from the radially outer end portion of the connecting portion 74.

[0059] The first wall portion 73 of the dust cover 70 has a circular (specifically, perfect circular) through-hole 72 formed therein, which extends in a direction perpendicular to the plate surface of the first wall portion 73 and into which the extension portion 124 of the board mounting member 120 is fitted. The knuckle 15 has a circular (specifically, perfect circular) through-hole 15a formed therein, which extends in the axial direction and into which the outer cylindrical portion 51 of the outer ring member 50 is fitted.

[0060] A bolt insertion hole 71 through which the bolt 16 is inserted is formed in the first wall portion 73 of the dust cover 70. A bolt insertion hole 15b through which the bolt 16 is inserted is formed in the knuckle 15.

[0061] The hub bearing 40 has hub mounting portions 52, the number of which is the same as the number of bolt insertion holes 123. The hub mounting portions 52 are spaced apart in the circumferential direction. Each hub mounting portion 52 has a female screw hole 52a that penetrates in the axial direction and into which the bolt 16 is screwed. Each hub mounting portion 52 has a flat surface 52b that extends in a direction perpendicular to the axial direction.

[0062] The board mounting member 120, the dust cover 70, and the knuckle 15 are provided with a configuration that facilitates relative positioning of the dust cover 70 and the knuckle 15 with respect to the board mounting member 120. More specifically, the knuckle 15 is provided with a positioning pin 15c that extends axially toward the board mounting member 120. The first wall portion 73 of the dust cover 70 is formed with a pin hole 76 that extends axially and through which the positioning pin 15c is inserted. The board mounting member 120 is formed with a pin hole 126 that extends axially and through which the positioning pin 15c is inserted.

[0063] The end of the through hole 15a of the knuckle 15 on the PCB mounting member 120 side in the axial direction is an expanded diameter portion 15d whose radial dimension is enlarged. The positioning pin 15c is inserted into the pin holes 76 and 126, and the extension portion 124 of the PCB mounting member 120 is fitted into the expanded diameter portion 15d. This aligns the centers of the through holes 15a, 72, and 122. The extension portion 124 and the expanded diameter portion 15d can improve the alignment accuracy.

[0064] The board mounting member 120, the first wall portion 73 of the dust cover 70, and the knuckle 15 are formed with cable insertion holes 127, 77, and 15e through which the cable 116 connected to the connector 115 of the sensor board 100 is inserted.

[0065] With the dust cover 70, board mounting member 120, and hub mounting portion 52 of the outer ring member 50 overlapping on the knuckle 15, the bolt 16 is inserted into the bolt insertion holes 15b, 71, 123, and the male thread of the bolt 16 is screwed into the female threaded hole 52a of the hub mounting portion 52. In this way, the sensor board 100 and the dust cover 70 are fixed to the knuckle 15.

[0066] In the above-described calculation process, it is desired to improve the accuracy of calculation of the load acting on the wheel.

[0067] FIG. 8 shows the relationship between the actual lateral force Fyr acting on the wheel and the actual axial displacement ΔYr when the vehicle is stationary. In this case, the relationship between the lateral force Fyr and the axial displacement ΔYr is linear, and the lateral force Fyr is uniquely determined from the axial displacement ΔYr. Therefore, it is conceivable to calculate the lateral force Fyc based on the axial displacement ΔYc calculated by the displacement calculation unit 117a and correspondence information (e.g., map information or mathematical formula information) that correlates the axial displacement ΔYc and the lateral force Fyc. The correspondence information is created from the lateral force Fyr and the axial displacement ΔYr measured when the vehicle is stationary.

[0068] 9 shows the relationship between the vertical load Fzr acting on the wheel and the vertical displacement ΔZr when the vehicle is stationary. In this case, the relationship between the vertical load Fzr and the vertical displacement ΔZr is linear, and the vertical load Fzr is uniquely determined from the vertical displacement ΔZr. Therefore, it is conceivable to calculate the vertical load Fzc based on the vertical displacement ΔZc calculated by the displacement calculation unit 117a and correspondence information that correlates the vertical displacement ΔZc and the vertical load Fzc. The correspondence information is created from the vertical load Fzr and the vertical displacement ΔZr measured when the vehicle is stationary.

[0069] However, when the correspondence information between the lateral force Fyc and the axial displacement ΔYc created from measurement data when the vehicle is stationary is used to calculate the lateral force Fyc during slalom running, the calculated lateral force Fyc may deviate from the actual lateral force Fyr. Furthermore, when the correspondence information between the vertical load Fzc and the vertical displacement ΔZc created from measurement data when the vehicle is stationary is used to calculate the vertical load Fzc during slalom running, the calculated vertical load Fzc may deviate from the actual vertical load Fzr. Therefore, it is considered that the relationship between the displacements ΔYr, ΔZr and the loads Fyr, Fzr changes depending on the state of the vehicle. Note that the actual loads Fyr, Fzr used for comparison with the loads Fyc, Fzc calculated by the force calculation unit 117b are measured values ​​from a six-component force sensor attached to the wheel.

[0070] Figure 10 shows the relationship between the lateral force Fyr acting on the wheel and the axial displacement ΔYr in various driving modes. Figure 11 shows the relationship between the vertical load Fzr acting on the wheel and the up-down displacement ΔZr in various driving modes. Specifically, Figures 10 and 11 show the relationships between the loads Fyr and Fzr acting on the wheel and the displacements ΔYr and ΔZr in the corresponding directions for the following cases: when the vehicle is running steadily, when the vehicle is accelerating straight, when the vehicle is braking straight, when the vehicle is accelerating while turning right, when the vehicle is running in a slalom at a low speed (e.g., 20 km / h), and when the vehicle is running in a slalom at a high speed (e.g., 50 km / h).

[0071] As shown in Figures 10 and 11, when the vehicle's driving mode differs, variations occur in the loads Fyr and Fzr acting in the directions of the displacements ΔYr and ΔZr relative to the displacements ΔYr and ΔZr. This raises concerns that the calculation accuracy of the loads Fyc and Fzc may be reduced. The factors explained below are thought to be involved in the variations in the loads Fyr and Fzr relative to the displacements ΔYr and ΔZr.

[0072] 12, it is believed that the force that the vehicle receives from the road surface is transmitted to each component in the following order: tire 14, wheel 11, hub bolt 17, inner ring member 60, rolling element 41, and outer ring member 50. In this case, if we assume that the wheel 11, hub bolt 17, and inner ring member 60 are rigid bodies with no backlash or loose bolts, it is believed that the hub bearing 40 is the cause of the variation in the loads Fyr and Fzr relative to the displacements ΔYr and ΔZr depending on the vehicle's driving mode.

[0073] 13, the hub bearing 40 can deform in the outward direction of the vehicle (hereinafter referred to as the y-axis direction) facing outward from the vehicle along the central axis of rotation LCo, in the direction of travel of the vehicle perpendicular to the outward direction of the vehicle (hereinafter referred to as the x-axis direction), and in the upward direction of the vehicle perpendicular to the outward direction of the vehicle and the direction of travel of the vehicle (hereinafter referred to as the z-axis direction).The hub bearing 40 can also deform in a direction of rotation around the x-axis (θx) and a direction of rotation around the z-axis (θz).

[0074] FIG. 14 shows the changes in the state of the hub bearing 40 that can occur when forces are applied in the x, y, and z axis directions relative to a reference state N. The reference state N is, for example, a stationary state of the vehicle. When forces are applied in each axial direction, the hub bearing 40 is compressed or extended. When the hub bearing 40 is compressed relative to the reference state N, the contact angle of the hub bearing 40 changes. When the hub bearing 40 is extended relative to the reference state N, the preload that was applied in advance is released. Note that when moments in the θx and θz directions act on the wheel, the hub bearing 40 can be compressed or extended depending on the direction of the moment.

[0075] If the contact angle of the hub bearing 40 changes or preload loss occurs, the rigidity of the hub bearing 40 changes. This is thought to change the relationship between the displacements ΔYr, ΔZr and the loads Fyr, Fzr acting in the directions of the displacements ΔYr, ΔZr.

[0076] In order to calculate the loads Fyc and Fzc taking into account changes in the state of the hub bearing 40, it is possible to use calculation parameters related to the force acting on the wheel in addition to the displacement in the direction in which the load acts. In this case, it is possible to use a multivariate analysis technique to create a calculation model that calculates the loads Fyc and Fzc based on multiple input values. Below, an example will be described in which a statistical analysis technique, specifically a multiple regression analysis technique, is used to create a calculation model that calculates the loads Fyc and Fzc.

[0077] As shown in Fig. 15, in order to create a calculation model for calculating the loads Fyc and Fzc, multiple regression analysis was performed by setting the loads Fy and Fz as response variables and setting the displacements ΔY and ΔZ as explanatory variables. As data for the loads Fy and Fz, which are response variables, the loads Fyr and Fzr measured in the various driving modes described in Figs. 10 and 11 were used. As data for the displacements ΔY and ΔZ, which are explanatory variables, the displacements ΔYc and ΔZc calculated by the displacement calculation unit 117a in the various driving modes were used.

[0078] Specifically, a multiple regression analysis was performed by setting the lateral force FL_Fy acting on the left front wheel as the dependent variable, and the axial displacement FL_ΔY of the left front wheel, the vertical displacement FL_ΔZ of the left front wheel, and the axial displacement FR_ΔY of the right front wheel as explanatory variables. Furthermore, a multiple regression analysis was performed by setting the vertical load FL_Fz acting on the left front wheel as the dependent variable, and the axial displacement FL_ΔY of the left front wheel, the vertical displacement FL_ΔZ of the left front wheel, the axial displacement FR_ΔY of the right front wheel, and the acceleration acting in the longitudinal direction of the vehicle (hereinafter referred to as longitudinal G) as explanatory variables. The value of longitudinal G was used as the detection value of the acceleration sensor 140.

[0079] As shown in Fig. 16, multiple regression equations (A) and (B) were obtained as a result of the multiple regression analysis. Multiple regression equation (A) is an equation that shows the relationship between the axial displacement of the left front wheel FL_ΔY, the vertical displacement of the left front wheel FL_ΔZ, and the axial displacement of the right front wheel FR_ΔY, and the lateral force FL_Fyc of the left front wheel. Multiple regression equation (B) is an equation that shows the relationship between the axial displacement of the left front wheel FL_ΔY, the vertical displacement of the left front wheel FL_ΔZ, the axial displacement of the right front wheel FR_ΔY, and the longitudinal G force, and the vertical load FL_Fzc of the left front wheel.

[0080] The lateral force FL_Fyc acting on the left front wheel calculated based on the multiple regression equation (A) using the displacements FL_ΔYc, FL_ΔZc, and FR_ΔYc calculated by the displacement calculation unit 117a as input values ​​was found to reproduce the actual lateral force FL_Fyr. The coefficient of determination in this case was confirmed to be 0.996.

[0081] The vertical load FL_Fzc acting on the left front wheel, calculated based on the multiple regression equation (B) using the displacements FL_ΔYc, FL_ΔZc, and FR_ΔYc calculated by the displacement calculation unit 117a and the detected value of the acceleration sensor 140 as input values, reproduced the actual vertical load FL_Fzr. The coefficient of determination in this case was confirmed to be 0.978.

[0082] The multiple regression equation for calculating the loads FR_Fyc and FR_Fzc on the right front wheels can also be obtained by performing multiple regression analysis, as in the case of the left front wheel. Specifically, multiple regression analysis can be performed by setting the lateral force FR_Fy on the right front wheel as the objective variable, and setting the displacements FR_ΔY and FR_ΔZ of the right front wheel and the axial displacement FL_ΔY of the left front wheel as explanatory variables. In this case, a multiple regression equation for calculating the lateral force FR_Fy on the right front wheel can be obtained based on the displacements FR_ΔY and FR_ΔZ of the right front wheel and the axial displacement FL_ΔY of the left front wheel. Furthermore, multiple regression analysis can be performed by setting the vertical load FR_Fz on the right front wheel as the objective variable, and setting the displacements FR_ΔY and FR_ΔZ of the right front wheel, the axial displacement FL_ΔY of the left front wheel, and the longitudinal G force as explanatory variables. In this case, it is possible to obtain a multiple regression equation for calculating the vertical load FR_Fz of the right front wheel based on the respective displacements FR_ΔY and FR_ΔZ of the right front wheel, the axial displacement FL_ΔY of the left front wheel, and the longitudinal G-forces.

[0083] Therefore, in this embodiment, the force calculation unit 117b calculates the loads Fyc and Fzc based on the calculated displacements ΔYc and ΔZc and the detection value of the acceleration sensor 140. The force calculation unit 117b inputs the input values, such as the calculated displacements ΔYc and ΔZc and the detection value of the acceleration sensor 140, into the calculation model obtained by the above-mentioned multiple regression analysis, to calculate the loads Fyc and Fzc.

[0084] The procedure of the calculation process executed by the processing unit 117 will be described with reference to Fig. 17. This process is executed repeatedly at a predetermined control period, for example.

[0085] In step S10, the displacement calculation unit 117a acquires the output voltage signals of the coils 111, 112 from the receiving circuit 114. In this embodiment, the output voltage signals of the coils 111, 112 are acquired from the receiving circuits 114 of the sensor boards 100 provided in the wheel units 10 of the left and right front wheels.

[0086] In step S11, the displacement calculation unit 117a calculates the axial displacement ΔYc based on the acquired output voltage signal. In this embodiment, the axial displacements FL_ΔYc and FR_ΔYc are calculated for each of the left and right front wheels. More specifically, the axial displacement FL_ΔYc of the left front wheel is calculated based on the output voltage signal detected by the receiving circuit 114 of the sensor board 100 provided in the wheel unit 10 of the left front wheel. The axial displacement FR_ΔYc of the right front wheel is calculated based on the output voltage signal detected by the receiving circuit 114 of the sensor board 100 provided in the wheel unit 10 of the right front wheel.

[0087] In step S12, the displacement calculation unit 117a calculates the vertical displacement ΔZc based on the acquired output voltage signal. In this embodiment, the vertical displacements FL_ΔZc and FR_ΔZc are calculated for each of the left and right front wheels. More specifically, the vertical displacement FL_ΔZc of the left front wheel is calculated based on the output voltage signal detected by the receiving circuit 114 of the sensor board 100 provided in the wheel unit 10 of the left front wheel. The vertical displacement FR_ΔZc of the right front wheel is calculated based on the output voltage signal detected by the receiving circuit 114 of the sensor board 100 provided in the wheel unit 10 of the right front wheel.

[0088] In step S13, the force calculation unit 117b calculates the lateral force Fyc. In this embodiment, the lateral forces FL_Fyc and FR_Fyc are calculated for each of the left and right front wheels.

[0089] Specifically, the lateral force FL_Fyc of the left front wheel is calculated based on the displacements FL_ΔYc, FL_ΔZc of the left front wheel and the axial displacement FR_ΔYc of the right front wheel. Here, to calculate the lateral force FL_Fyc of the left front wheel, correspondence information correlating the displacements FL_ΔYc, FL_ΔZc, FR_ΔYc with the lateral force FL_Fyc of the left front wheel is used. The correspondence information is information for executing the calculation process of the lateral force FL_Fyc of the left front wheel based on the calculation model obtained by performing the multiple regression analysis described above. The correspondence information is, for example, map information or mathematical formula information, and is stored in the memory of the processing unit 117. The direction along the rotation center axis LCo corresponds to the "specific direction," and the displacements FL_ΔZc, FR_ΔYc correspond to the "calculation parameters."

[0090] Furthermore, the lateral force FR_Fyc of the right front wheel is calculated based on the respective displacements FR_ΔYc, FR_ΔZc of the right front wheel and the axial displacement FL_ΔYc of the left front wheel. Here, to calculate the lateral force FR_Fyc of the right front wheel, correspondence information correlating the respective displacements FR_ΔYc, FR_ΔZc, FL_ΔYc with the lateral force FR_Fyc of the right front wheel is used. The correspondence information is information used to execute the calculation process for the lateral force FR_Fyc of the right front wheel based on the calculation model obtained by performing the above-mentioned multiple regression analysis. Note that the direction along the central axis of rotation LCo corresponds to the "specific direction," and the respective displacements FR_ΔZc, FL_ΔYc correspond to the "calculation parameters."

[0091] In step S14, the force calculation unit 117b calculates the vertical load Fzc. In this embodiment, the vertical loads FL_Fzc and FR_Fzc are calculated for each of the left and right front wheels.

[0092] Specifically, the vertical load FL_Fzc of the left front wheel is calculated based on the displacements FL_ΔYc, FL_ΔZc of the left front wheel, the axial displacement FR_ΔYc of the right front wheel, and the longitudinal G-forces. Here, to calculate the vertical load FL_Fzc of the left front wheel, correspondence information is used that associates the displacements FL_ΔYc, FL_ΔZc, FR_ΔYc, the longitudinal G-forces, and the vertical load FL_Fzc of the left front wheel. The correspondence information is information used to execute the calculation process for the vertical load FL_Fzc of the left front wheel based on the calculation model obtained by performing the multiple regression analysis described above. The direction perpendicular to the contact patch GL corresponds to the "specific direction," and the displacements FL_ΔYc, FR_ΔYc, and the longitudinal G-forces correspond to the "calculation parameters."

[0093] Furthermore, a vertical load FR_Fzc on the right front wheel is calculated based on the respective displacements FR_ΔYc, FR_ΔZc of the right front wheel, the axial displacement FL_ΔYc of the left front wheel, and the longitudinal G-forces. Here, to calculate the vertical load FR_Fzc on the right front wheel, correspondence information is used that associates the respective displacements FR_ΔYc, FR_ΔZc, FL_ΔYc, the longitudinal G-forces, and the vertical load FR_Fzc on the right front wheel. The correspondence information is information used to execute the calculation process for the vertical load FR_Fzc on the right front wheel based on the calculation model obtained by performing the above-mentioned multiple regression analysis. Note that the direction perpendicular to the contact patch GL corresponds to the "specific direction," and the respective displacements FR_ΔYc, FL_ΔYc, and the longitudinal G-forces correspond to the "calculation parameters."

[0094] FIG. 18 shows a comparison of the lateral force FL_Fy of the left front wheel when the vehicle is slaloming at high speed, using the true value FL_Fyr, the calculated value FL_Fyc by the force calculation unit 117b, and the value FL_Fyd of a comparative example. FIG. 19 shows a comparison of the vertical load FL_Fz of the left front wheel when the vehicle is slaloming at high speed, using the true value FL_Fzr, the calculated value FL_Fzc by the force calculation unit 117b, and the value FL_Fzd of a comparative example. In FIGS. 18 and 19, the solid line indicates the transition of the true value, the dashed line indicates the transition of the value calculated by the force calculation unit 117b, and the dashed-dotted line indicates the transition of the value of the comparative example. The values ​​of the comparative example are calculated values ​​of the loads Fy and Fz acting in the corresponding directions from the displacements ΔYc and ΔZc based on the linear correspondence relationship described in FIGS. 8 and 9.

[0095] As shown in FIGS. 18 and 19, the results show that the loads FL_Fyc and FL_Fzc calculated based on the calculation model obtained by multiple regression analysis match the true values ​​FL_Fyr and FL_Fzr with high precision.

[0096] In this embodiment, a load acting on a wheel in a specific direction (e.g., Fyc) is calculated based on a relative displacement in the specific direction with respect to the wheel (e.g., ΔYc) and a calculation parameter related to the load acting on the wheel. Specifically, the calculation parameter is a displacement in an intersecting direction that is perpendicular to the specific direction (e.g., ΔZc). This makes it possible to calculate the load acting on the wheel in a specific direction, taking into account changes in the state of the hub bearing 40 due to the load acting on the wheel. As a result, it is possible to improve the accuracy of calculating the load acting on the wheel.

[0097] In order to calculate a load (e.g., FL_Fyc) acting in a specific direction on one of the left and right wheels, the displacement (e.g., FR_ΔYc) of the other wheel is also used as a calculation parameter. This makes it possible to accurately consider, when calculating the load acting in a specific direction, the change in the state of the hub bearing 40 that accompanies the load acting on the wheel. This further improves the accuracy of the load calculation.

[0098] To calculate the vertical load Fzc, the detection value of the acceleration sensor 140 is further used as a calculation parameter. This makes it possible to accurately take into account the change in the state of the hub bearing 40 as the load acts on the wheel when calculating the load acting in a specific direction. This further improves the calculation accuracy of the vertical load Fzc.

[0099] <Other embodiments> The above-described embodiments may be modified as follows.

[0100] In step S13 of Fig. 17, the axial displacement FR_ΔYc of the right front wheel does not have to be used to calculate the lateral force FL_Fyc of the left front wheel. Similarly, the axial displacement FL_ΔYc of the left front wheel does not have to be used to calculate the lateral force FR_Fyc of the right front wheel. Even in this case, it is possible to improve the calculation accuracy of the lateral forces FL_Fyc and FR_Fyc.

[0101] In step S14 of Fig. 17, the axial displacement FR_ΔYc of the right front wheel does not have to be used to calculate the vertical load FL_Fzc of the left front wheel. Similarly, the axial displacement FL_ΔYc of the left front wheel does not have to be used to calculate the vertical load FR_Fzc of the right front wheel. Even in this case, it is possible to improve the calculation accuracy of the vertical loads FL_Fzc and FR_Fzc.

[0102] Furthermore, the longitudinal G does not have to be used to calculate the vertical loads FL_Fzc and FR_Fzc. Even in this case, it is possible to improve the accuracy of calculating the vertical loads FL_Fzc and FR_Fzc.

[0103] The circumferential center positions of the first and second receiving coils 111, 112 may be located at positions axially facing the right or left end of the target member 80, rather than at positions axially facing the upper end of the target member 80. In this case, when a force acting between the ground contact surface GL and the wheel in the vehicle length direction (hereinafter referred to as the longitudinal load Fx) acts, the amplitude of the output voltage signal of each coil 111, 112 changes. This allows the displacement calculation unit 117a to calculate a displacement in the vehicle length direction (hereinafter referred to as the longitudinal displacement ΔXc) instead of the vertical displacement ΔZc. The direction in which the longitudinal load Fx acts is perpendicular to the direction in which the lateral force Fy acts and the direction in which the vertical load Fz acts.

[0104] The circumferential center positions of the first and second receiving coils 111, 112 may be provided at a position axially facing the upper end of the target member 80, and at a position axially facing the right end or left end of the target member 80. In this case, the displacement calculation unit 117a can calculate the forward / backward displacement ΔXc, the axial displacement ΔYc, and the up / down displacement ΔZc.

[0105] The force calculation unit 117b may calculate the longitudinal load Fxc based on the respective displacements ΔXc and ΔYc calculated by the displacement calculation unit 117a. In this case, by using a calculation model obtained by performing multiple regression analysis in the calculation process of the longitudinal load Fxc, the calculation accuracy of the longitudinal load Fxc can be improved. For example, when performing multiple regression analysis, it is possible to set the longitudinal load Fx as the objective variable and the respective displacements ΔX and ΔY as explanatory variables. Note that the longitudinal load Fxc is used in the control device for vehicle running control.

[0106] To calculate the front-rear load FL_Fxc of the left front wheel, the force calculation unit 117b may use the axial displacement FR_ΔYc of the right front wheel in addition to the displacements FL_ΔXc and FL_ΔYc of the left front wheel calculated by the displacement calculation unit 117a. In this case, by using a calculation model obtained by performing multiple regression analysis in the calculation process of the front-rear load FL_Fxc of the left front wheel, it is possible to improve the calculation accuracy of the front-rear load FL_Fxc of the left front wheel. For example, when performing multiple regression analysis, it is possible to set the front-rear load FL_Fxc of the left front wheel as the objective variable and the displacements FL_ΔX, FL_ΔY, and FR_ΔY as explanatory variables. Note that, similarly, when calculating the front-rear load FR_Fxc of the right front wheel, the axial displacement FL_ΔYc of the left front wheel may be used in addition to the displacements FR_ΔXc and FR_ΔYc of the right front wheel.

[0107] The force calculation unit 117b may use displacements ΔXc, ΔYc, and ΔZc in the corresponding directions and various calculation parameters to calculate the loads Fxc, Fyc, and Fzc. Even in this case, the calculation accuracy of the loads Fxc, Fyc, and Fzc can be improved by using a calculation model obtained by performing multiple regression analysis in the calculation process of the loads Fxc, Fyc, and Fzc. For example, when performing multiple regression analysis, it is possible to set the loads Fxr, Fyr, and Fzr as the objective variables, and set the displacements ΔXc, ΔYc, and ΔZc in the corresponding directions and various calculation parameters as the explanatory variables.

[0108] An example of calculation parameters used to calculate the loads Fxc, Fyc, and Fzc is shown in Fig. 20. For example, the calculation parameters are the detection values ​​of the sensors 140 to 143 provided on the vehicle.

[0109] To calculate the lateral force Fyc, the detection value of the acceleration sensor 140 may be used as a calculation parameter. Furthermore, to calculate at least one of the loads Fyc and Fzc, at least one of the detection value of the acceleration sensor 140 and the detection value of the strain sensor 143 may be used as a calculation parameter.

[0110] In order to calculate at least one of the loads Fxc, Fyc, and Fzc, at least one of the detection value of the yaw rate sensor 141 and the detection value of the strain sensor 143 may be used as a calculation parameter. In addition, in order to calculate at least one of the loads Fxc and Fyc, at least one of the detection value of the yaw rate sensor 141, the detection value of the wheel speed sensor 142, and the detection value of the strain sensor 143 may be used as a calculation parameter.

[0111] In addition to the detection values ​​of the various sensors described above, the calculation parameters may also be the detection values ​​of a steering angle sensor that detects the steering angle or turning angle of the front wheels to the left or right.

[0112] In addition to the detection values ​​of the various sensors described above, the torque of the motor that drives the wheels may also be used as a calculation parameter. For example, the command torque used to control the motor may be used as the motor torque.

[0113] In addition to the detection values ​​of the various sensors described above, the rotation angle or rotation speed calculated by the rotation speed calculation unit 117c may be used as the calculation parameter. For example, the calculated rotation angle or rotation speed may be used as the calculation parameter to calculate at least one of the loads Fxc and Fyc.

[0114] The processing unit does not need to execute the rotation speed calculation process.

[0115] In each of the above embodiments, the target member may be fixed to a base portion such as a knuckle rather than to the wheel, and the sensor board may be fixed to the wheel rather than to the base portion. In this case, when a force acts on the wheel, the sensor board fixed to the wheel is displaced relative to the target member fixed to the base portion.

[0116] The longitudinal load Fxc, lateral force Fyc, vertical load Fzc, and rotational speed calculated by the detection device may be used for purposes other than vehicle driving control. In this case, the processing unit may be provided in an ECU other than the motor control ECU among various ECUs provided in the vehicle.

[0117] The disc rotor is not limited to a ventilated disc, but may be, for example, a solid disc made of a single circular plate.

[0118] The mechanical device to which the detection device can be applied is not limited to a wheel unit, but may also be, for example, an aircraft equipped with a propeller as a rotating body, a ship equipped with a screw as a rotating body, an internal combustion engine equipped with a crankshaft as a rotating body, or a generator equipped with a turbine as a rotating body.

[0119] Furthermore, the rotating body is not limited to being used with the axial direction of the rotating body being horizontal, but may also be used with the axial direction being in a direction other than horizontal (for example, up and down).

[0120] The control device and method described herein may be implemented by a special-purpose computer configured with a processor and memory programmed to perform one or more functions embodied in a computer program. Alternatively, the control device and method described herein may be implemented by a special-purpose computer configured with a processor comprising one or more dedicated hardware logic circuits. Alternatively, the control device and method described herein may be implemented by one or more special-purpose computers configured with a processor and memory programmed to perform one or more functions in combination with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored in a computer-readable non-transitory tangible recording medium as instructions executed by a computer. [Explanation of symbols]

[0121] 10...wheel unit, 11...wheel, 14...tire, 15...knuckle, 40...hub bearing, 41...rolling element, 50...outer ring member, 60...inner ring member, 80...target member, 100...sensor board, 117...processing unit.

Claims

1. A detection device applied to a mechanical device (10) having a rotating body (11, 14), The mechanical device includes a bearing member (40) that rotatably supports the rotating body relative to a base portion (15), The bearing member is a first bearing portion (50) extending in an axial direction, which is a direction in which a rotation center axis of the bearing member extends, and fixed to the base portion; a second bearing portion (60) provided at a position facing the first bearing portion in a radial direction perpendicular to the axial direction, and to which the rotating body is fixed; a rolling element (41) provided between the first bearing portion and the second bearing portion; the second bearing portion is rotatably supported relative to the base portion, a detection target portion (80) provided in either the first bearing portion or the second bearing portion and extending in a circumferential direction around a rotation center of the bearing member; a signal detection unit (100) provided at a position facing the detection target in the axial direction; A calculation unit (117); Equipped with the signal detection unit detects a voltage signal corresponding to a relative displacement of the detection target portion with respect to the signal detection unit; The calculation unit calculating the relative displacement in a specific direction with respect to the rotating body based on the detected voltage signal; The detection device calculates a load acting on the rotating body in the specific direction based on the calculated relative displacement in the specific direction and a calculation parameter related to the load acting on the rotating body.

2. The calculation unit calculating the relative displacement in an intersecting direction that is a direction perpendicular to the specific direction based on the detected voltage signal; The detection device according to claim 1 , wherein the calculated relative displacement in the cross direction is used as the calculation parameter.

3. the mechanical device includes left and right wheels of a vehicle as the rotating bodies, the detection target portion and the signal detection portion are provided for each of the left and right wheels, The calculation unit calculating the relative displacement in the specific direction of the first wheel based on the voltage signal detected by the signal detection unit provided on a first wheel, which is one of the left and right wheels; calculating the relative displacement of the second wheel based on the voltage signal detected by the signal detector provided on the other of the left and right wheels, the second wheel; 3. The detection device according to claim 2, further comprising: a calculation parameter that is further configured to calculate the load acting on the first wheel in the specific direction, the calculated relative displacement of the second wheel being used as the calculation parameter.

4. The calculation unit calculating the relative displacement of the second wheel in the axial direction based on the voltage signal detected by the signal detector provided on the second wheel; The detection device according to claim 3 , wherein the calculated relative displacement of the second wheel in the axial direction is used as the calculation parameter.

5. the mechanical device includes a vehicle wheel as the rotating body, The detection device according to claim 2 , wherein the calculation unit further uses, as the calculation parameter, a detection value of an acceleration sensor that detects acceleration of the vehicle.

6. A program applied to a mechanical device (10) having a rotating body (11, 14) and a detection device, The mechanical device includes a bearing member (40) that rotatably supports the rotating body relative to a base portion (15), The bearing member is a first bearing portion (50) extending in the axial direction of the rotation center axis of the bearing member and fixed to the base portion; a second bearing portion (60) provided at a position facing the first bearing portion in a radial direction perpendicular to the axial direction, and to which the rotating body is fixed; a rolling element (41) provided between the first bearing portion and the second bearing portion; the second bearing portion is rotatably supported relative to the base portion, The detection device includes: a detection target portion (80) provided in either the first bearing portion or the second bearing portion and extending in a circumferential direction around a rotation center of the bearing member; a signal detection unit (100) provided at a position facing the detection target in the axial direction; Equipped with the signal detection unit detects a voltage signal corresponding to a relative displacement of the detection target portion with respect to the signal detection unit; The computer (117) a process of calculating the relative displacement in a specific direction with respect to the rotating body based on the detected voltage signal; calculating a load acting on the rotating body in the specific direction based on the calculated relative displacement in the specific direction and a calculation parameter related to the load acting on the rotating body; A program that executes a process including:

7. A calculation method applied to a mechanical device (10) including a rotating body (11, 14) and a detection device, The mechanical device includes a bearing member (40) that rotatably supports the rotating body relative to a base portion (15), The bearing member is a first bearing portion (50) extending in the axial direction of the rotation center axis of the bearing member and fixed to the base portion; a second bearing portion (60) provided at a position facing the first bearing portion in a radial direction perpendicular to the axial direction, and to which the rotating body is fixed; a rolling element (41) provided between the first bearing portion and the second bearing portion; the second bearing portion is rotatably supported relative to the base portion, The detection device includes: a detection target portion (80) provided in either the first bearing portion or the second bearing portion and extending in a circumferential direction around a rotation center of the bearing member; a signal detection unit (100) provided at a position facing the detection target in the axial direction; Equipped with the signal detection unit detects a voltage signal corresponding to a relative displacement of the detection target portion with respect to the signal detection unit; calculating the relative displacement in a specific direction with respect to the rotating body based on the detected voltage signal; calculating a load acting on the rotating body in the specific direction based on the calculated relative displacement in the specific direction and a calculation parameter related to the load acting on the rotating body; Calculation method, including

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