Wheel load estimation device and program

Abstract

The center of gravity inertia calculation unit (36, 236) calculates information related to the center of gravity of the vehicle, including the load, and calculates the vehicle's inertia tensor (J) which includes the principal axes of inertia around the center of gravity and the product of inertia. all The wheel load variation calculation unit (40, 240) is based on the inertia tensor (J). all ), angular velocities (P, Q, R) and angular accelerations (P) of a vehicle carrying cargo around three axes. · Q · R · ), the vehicle's longitudinal and lateral accelerations (G) xall G yall ), the weight of the vehicle including its cargo (M) all ), and information related to the center of gravity of vehicles containing cargo (h R_CG h CG t l t r l f l r The wheel load variation is calculated, and the wheel load estimation unit (42, 242) estimates the wheel load based on the wheel load variation and the static load.

Description

Technical Field

[0001] This invention relates to a wheel load estimation device and a wheel load estimation procedure. Background Technology

[0002] In the past, in vehicles such as forklifts that lift loads while moving, the load on each wheel supporting the vehicle was estimated in order to avoid dangers such as wheels lifting or vehicle tipping over due to the imbalance of the vehicle's center of gravity.

[0003] For example, a technique has been proposed for measuring the front-to-back and lateral accelerations, as well as the roll and pitch angular velocities, of a four-wheeled vehicle (see Patent Document 1). In this technique, the load on each wheel is estimated based on consideration of the vertical stiffness of each wheel, its front-to-back behavior, the tilt angle of the roll inertia axis, the pitch moment due to the gyroscopic effect, and the roll moment considering the lateral behavior.

[0004] Additionally, for example, a technique has been proposed for measuring the front-to-back and lateral acceleration, roll acceleration, and pitch acceleration of a four-wheeled vehicle (see Patent Document 2). In this technique, the load on each wheel is estimated based on the pitch moment caused by the front-to-back movement and the roll moment caused by the lateral movement, as well as the vehicle's pitch inertia and roll inertia.

[0005] Additionally, for example, a technique has been proposed for measuring the load on each wheel and the wheel speed of the two drive wheels of a forklift (see Patent Document 3). In this technique, the wheel speed is used to calculate the turning radius, and the steering input and braking torque are adjusted accordingly to any decrease in the measured wheel load value.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2004-58960

[0009] Patent Document 2: Japanese Patent Application Publication No. 2013-216278

[0010] Patent Document 3: Japanese Patent Application Publication No. 2001-63991 Summary of the Invention

[0011] The problem the invention aims to solve

[0012] However, the technologies described in Patent Documents 1 and 2 are designed for general four-wheeled vehicles and do not take into account situations where vehicles, such as forklifts, are traveling with heavy loads in various configurations. Therefore, the technologies described in Patent Documents 1 and 2 have the problem of not being able to properly estimate the wheel loads of vehicles traveling with heavy loads in various configurations.

[0013] Furthermore, in the technology described in Patent Document 3, the strain of the loading part of the load is used to measure the wheel load. However, in order to obtain the strain, the rigidity of the loading part of the load needs to be reduced, which poses a safety risk.

[0014] The present invention was made in view of the above circumstances, and its object is to provide a wheel load estimation device and program that can accurately estimate wheel loads without reducing the rigidity of the rigid body, even when the center of gravity of the rigid body changes.

[0015] Solution for solving the problem

[0016] To achieve the above objectives, the wheel load estimation device of the present invention comprises: an acquisition unit that acquires the angular velocity, angular acceleration, forward and backward acceleration (as the travel direction of the rigid body), and lateral acceleration (as the width direction of the rigid body) of a rigid body including an element that causes a change in center of gravity about three axes, the weight of the element, and the position of the element including its height, of the element; a center of gravity inertia value calculation unit that calculates information related to the center of gravity of the rigid body and calculates the inertia value of the rigid body including the principal axis of inertia about the center of gravity; a wheel load variation calculation unit that calculates the variation of wheel loads acting on each of a plurality of wheels supporting the rigid body based on the angular velocity, angular acceleration, and forward and backward acceleration acquired by the acquisition unit, the information related to the center of gravity of the rigid body and the inertia value calculated by the center of gravity inertia value calculation unit; and a wheel load estimation unit that estimates the wheel load based on the variation of wheel loads calculated by the wheel load variation calculation unit and the static loads acting on each of the wheels.

[0017] According to the wheel load estimation device of the present invention, the acquisition unit acquires the angular velocity, angular acceleration, forward and backward acceleration (as the direction of travel of the rigid body), and lateral acceleration (as the width direction of the rigid body) of a rigid body including elements that cause changes in the center of gravity, as well as the weight of the elements and the position including the height of the elements. The center of gravity inertia calculation unit calculates information related to the center of gravity of the rigid body and calculates the inertia value of the rigid body including the principal axis of inertia around the center of gravity. The wheel load variation calculation unit calculates the variation of the wheel load acting on each of the multiple wheels supporting the rigid body based on the angular velocity, angular acceleration, forward and backward acceleration, and lateral acceleration acquired by the acquisition unit, and the information related to the center of gravity and the inertia value of the rigid body calculated by the center of gravity inertia value calculation unit. The wheel load estimation unit estimates the wheel load based on the variation of the wheel load calculated by the wheel load variation calculation unit and the static load acting on each wheel. Thus, even when the center of gravity of the rigid body changes, the wheel load can be estimated with good accuracy without reducing the rigidity of the rigid body.

[0018] Alternatively, the center of gravity inertia calculation unit may calculate the center of gravity positions of the rigid body containing the element and each of the constituent parts based on the weight and position of the element obtained by the acquisition unit, and the structure of each of the multiple constituent parts constituting the rigid body. The inertia value is then calculated using the difference between the center of gravity position of the rigid body containing the element and the center of gravity positions of the constituent parts. This allows for the appropriate calculation of inertia values ​​corresponding to changes in the center of gravity.

[0019] Alternatively, the center of gravity inertia calculation unit can calculate the inertia value that further includes the inertia product. This allows for a more appropriate calculation of the inertia value corresponding to the change in the center of gravity, and enables a more accurate estimation of the wheel load.

[0020] Alternatively, the acquiring unit acquires the lateral force and the front-rear force acting on the wheel, and the wheel load variation calculation unit further uses the yaw moment of the rigid body about its center of gravity, calculated based on the lateral force and the front-rear force acquired by the acquiring unit, to calculate the variation in the wheel load. Thus, the wheel load can be estimated by taking into account the yaw moment of the rigid body about its center of gravity.

[0021] Alternatively, the wheel load variation calculation unit can calculate the yaw moment of the rigid body around its center of gravity along with the wheel load variation, under the constraint that the sum of the variations in the wheel loads of the plurality of wheels is 0. Thus, the yaw moment can also be calculated along with the wheel load based on the information obtained by the acquisition unit.

[0022] Alternatively, the rigid body could be a vehicle, and the element that imparts a change in the center of gravity could be the load mounted on the vehicle. Alternatively, the vehicle could be a forklift, and the load could be mounted on forks that can move up and down. Thus, for vehicles such as forklifts that move while carrying loads in various configurations, wheel loads can be estimated with good accuracy.

[0023] Alternatively, the information related to the center of gravity of the rigid body may include the vertical distance between the center of gravity of the rigid body and the tilt center of the rigid body, the lateral position of the center of gravity of the rigid body, and the lateral distance between each of the plurality of wheels and the center of gravity of the rigid body.

[0024] Furthermore, the wheel load estimation program of the present invention is a program for enabling the computer to function as various parts of the aforementioned wheel load estimation device.

[0025] Invention Effects

[0026] According to the wheel load estimation device and procedure of the present invention, the wheel load can be estimated with good accuracy even when the center of gravity of the rigid body changes, without reducing the rigidity of the rigid body. Attached Figure Description

[0027] Figure 1 This is a schematic diagram that roughly illustrates the different principal axes of inertia caused by different lifting heights of the load.

[0028] Figure 2 It is a diagram used to illustrate the vehicle coordinate system relative to the ground coordinate system.

[0029] Figure 3 It is a diagram that shows the general outline of the various components of the vehicle, its center of gravity, and the origin of the coordinate system.

[0030] Figure 4 This is a block diagram showing the wheel load estimation device of the first embodiment and the various components connected to the wheel load estimation device.

[0031] Figure 5 This is a functional block diagram of the wheel load estimation device in the first embodiment.

[0032] Figure 6 This is a block diagram showing the hardware configuration of the wheel load estimation device.

[0033] Figure 7 This is a flowchart illustrating an example of the wheel load estimation process in the first embodiment.

[0034] Figure 8 This is a block diagram showing the wheel load estimation device of the second embodiment and the various components connected to the wheel load estimation device.

[0035] Figure 9 This is a functional block diagram of the wheel load estimation device in the second embodiment.

[0036] Figure 10 This is a flowchart illustrating an example of the wheel load estimation process in the second embodiment.

[0037] Figure 11 This is a diagram illustrating an example of the estimated wheel load.

[0038] Figure 12 This is a diagram used to illustrate the effect of the change in inertia value caused by the increase in height.

[0039] Figure 13 This is a diagram used to illustrate a comparison of the estimated results of wheel loads with and without considering the product of inertia. Detailed Implementation

[0040] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0041] <First Embodiment>

[0042] First, the principle of the first embodiment will be explained. In the first embodiment, as an example of a rigid body that includes elements that cause changes in the center of gravity, the load on each wheel of a forklift with four wheels (front, rear, left, and right) that moves while loading a load onto forks that can move up and down will be described. Furthermore, in the first embodiment, the vehicle behavior, including the forklift's forward and backward acceleration, lateral acceleration, roll angular velocity, pitch angular velocity, and yaw angular velocity, is measured. Additionally, in the first embodiment, the weight of the load, the lifting height, and the loading position of the load relative to the forks are all detectable.

[0043] Unlike passenger vehicles, forklifts travel while lifting heavy loads at various heights. Furthermore, the loading position of the load may sometimes shift in the y-direction (lateral direction) relative to the forklift's center of gravity. Due to this loading state, the orientation of the principal axis of inertia changes relative to the axes of tilt, pitch, and yaw. Therefore, in the first embodiment, the principal axis of inertia and the inertia product are set accordingly to the loading state of the load. Figure 1 This is a schematic diagram that roughly illustrates the different principal axes of inertia caused by different lifting heights of the load. For example... Figure 1 As shown in (A), the case of a low-height elevator loaded with cargo is similar to... Figure 1 Compared to the case shown in (B), where the elevator is at a higher height, the direction of the principal axis of inertia changes.

[0044] In order to correspond to, Figure 1 The different loading states of the loads shown indicate the use of Figure 2 The vehicle motion is described using a 6-DOF model of the vehicle as shown in equations (1) to (3) below. Furthermore, equation (1) represents the rotational motion of the vehicle, equation (2) represents the translational motion of the vehicle, and equation (3) represents the vehicle coordinate system. Figure 2 The x, y, z coordinate system in the image is relative to the ground coordinate system. Figure 2 x in e y e , z e The expression for the orientation of the vehicle in a coordinate system. Furthermore, in the vehicle coordinate system, the forward / backward direction (driving direction) is the x-axis, the lateral direction (width direction) is the y-axis, and the vertical direction is the z-axis.

[0045] [Mathematical Expression 1]

[0046]

[0047]

[0048]

[0049] In equations (1) to (3), P, Q, and R are the angular velocities [rad / s] of roll, pitch, and yaw, respectively, and L... v M v and N v These are the moments of roll, pitch, and yaw [Nm]. Additionally, U, V, and W are the velocities [m / s] along the x, y, and z axes in the vehicle coordinate system, and φ, θ, and ψ are the attitude angles of the vehicle coordinate system relative to the ground coordinate system [rad]. Furthermore, X... v Y v and Z v These are the front-to-back, lateral, and vertical forces acting on the vehicle [N]. Additionally, J... all The inertial tensor [kg·m] is composed of the principal axes of inertia and their products in the x, y, and z axes. 2 ], M all It is the total weight [kg] of the cargo and the vehicle combined. Furthermore, the inertia tensor is an example of the "inertia value" of this invention.

[0050] In the first embodiment, the part of equation (1) related to the rotational motion of the vehicle is utilized. (Refer to...) Figure 3 To illustrate the inertial tensor J of equation (1) all The settings. Figure 3 This diagram shows a general outline of the constituent parts of a forklift (hereinafter referred to as the "vehicle assembly") 100 containing the load, as well as the center of gravity of each constituent part, the center of gravity of the vehicle assembly, and the origin of the coordinate system. Figure 3 In this example, the components of the forklift are envisioned as a body 102, a load 104, forks 106, an outer mast 108, and an inner mast 110. Furthermore, the components also include an IMU (Inertial Measurement Unit) 112, but here, the IMU 112 is extremely lightweight and is considered not to affect the center of gravity of the overall vehicle 100. Figure 3 In the diagram, the center of gravity of each component is indicated by a reference numeral ending with "A". Furthermore, the size of the circle representing the center of gravity roughly indicates the weight of each component.

[0051] The inertial tensor J is shown in equation (4) below. all The composition of . On the right side of equation (4), the diagonal terms are the principal axes of inertia, and the off-diagonal terms are the product of inertia.

[0052] [Mathematical Expression 2]

[0053]

[0054] In equation (4), the subscript j is the variable that determines each constituent part, N is the total number of constituent parts, and m j This refers to the weight of component j. When the center of gravity of the entire vehicle (100) is set as CG... all At that time, CG all Position (x) all y all , z all The load 104 can be calculated using its weight, lifting height, and loading position relative to the fork 106. In equation (4), Δx j Δy j and Δz j The center of gravity of the vehicle as a whole is 100 (CG). all The differences in each axial direction between position 100A and the positions 102A, 104A, 106A, 108A, and 110A of the center of gravity of component j are calculated by the following formula (5).

[0055] [Mathematical Expression 3]

[0056] Δx j =x j -x all Δy j =y j -y all Δz j =z j -z all (5)

[0057] Assuming that the IMU112 can measure the roll, pitch, and yaw accelerations (P, Q, and R), as well as the vehicle's center of gravity CG at 100°, all The yaw moment N can be obtained by detecting the front-to-back acceleration and lateral acceleration at the point of contact with the tire, and by measuring the front-to-back force and lateral force of the tire. v Furthermore, assume that P in equation (1) · (The mathematical expression contains a "· (dot)" above "P", and the same applies to Q and R below.) Q · and R · It is calculated by approximate differentiation of P, Q, and R measured at each sampling point. In this case, only the wheel load is an unknown parameter in equation (1).

[0058] The following is a more detailed explanation. The tilting moment L in equation (1) v And pitching moment M v The sum of the torques generated by the lateral and longitudinal forces of the tires acting on the vehicle and the torques generated by the reaction forces of the tire springs (upper and lower springs) can be expressed by the following equations (6) and (7).

[0059] [Mathematical Expression 4]

[0060] L v =M all ·G yall ·h R_CG +(ΔFL Z +ΔRL Z )·t l -(ΔFR Z +ΔRR Z )·t r (1)

[0061] M v =-M all ·G xall ·h CG -(ΔFL Z +ΔFR Z )·l f +(ΔRL Z +ΔRR Z )·l r (7)

[0062] G in equations (6) and (7) xall and G yall The center of gravity of the vehicle as a whole is 100 (CG). all Forward and lateral accelerations at [m / s] 2 Additionally, h R_CG It's CG all With the roll center h R z-direction distance between (=z all -h R [m], h CG It's CG all z-direction distance (=z all [m]. Additionally, t l and t r The left and right wheels are relative to CG. all The distance in the y direction [m], l f and l r It refers to the front and rear wheels relative to CG. all The x-direction distance [m]. Additionally, ΔFL z ΔFR z ΔRL z and ΔRR z It is the variation of the wheel load on each of the front, rear, left, and right wheels [N].

[0063] Equations (6) and (7) represent the overall vehicle 100 around the center of gravity CG. all The torque, using the vehicle's center of gravity CG all forward and backward acceleration G xall Lateral acceleration Gyall and weight M all This represents the sum of the frontal and lateral forces on each wheel. For example... Figure 3 As shown, with the IMU112 mounted at any position on the vehicle body 102, assuming the measured value G of the IMU112 is... x and G y Converted to the vehicle's overall center of gravity CG all The acceleration at the position. Yaw moment N v The front and rear force FL of the two drive wheels Fx FR Fx And the lateral force FL of each wheel's tires Fy FR Fy RL Fy and RR Fy The sum of the generated torques is represented by the following equation (8).

[0064] [Mathematical Expression 5]

[0065] N v =-FL Fx ·t l +FR Fx ·t r +(FL Fy +FR Fy )·l f -(RL Fy +RR Fy )·l r (8)

[0066] In addition, the front and rear tire forces (FL) Fx FR Fx and tire lateral force FL Fy FR Fy RL Fy RR Fy Let the value be the value after conversion to the vehicle coordinate system. When equations (4) to (8) are used to express equation (1) and the variation of the load on each wheel as an unknown parameter is obtained, the following equation (9) holds.

[0067] [Mathematical Expression 6]

[0068]

[0069] In equation (9), the '+' in the upper right corner of the first term on the right indicates the pseudo-inverse matrix, and the variation of the wheel load on the left can be obtained as an approximation. Therefore, the relationship between the left and right sides of equation (9) is expressed as '≈'. From now on, when using the pseudo-inverse matrix, the relationship between the left and right sides will be expressed entirely as '≈'. The subscript i indicates the sampling scale. The reason for the element in the third row being 0 is that the variation of the wheel loads in the vertical direction does not contribute to the yaw rotational motion. Regarding this, J all R· (i) N v(i) It does not affect the variation of the load on each wheel, so it can be any value. The load on each wheel can be estimated by the sum of the static load and the variation of the wheel load calculated by equation (9).

[0070] Furthermore, as a variation of equation (9), the variation in load on each wheel and the yaw moment can also be estimated as unknown parameters. In this case, equation (9) is modified as shown in equation (10) below.

[0071] [Mathematical Expression 7]

[0072]

[0073] In addition, the sum of the variations in the load of each wheel at each sampling time i is 0, so the constraint of the following equation (11) holds.

[0074] [Mathematical Expression 8]

[0075] ΔFL Z +ΔFR Z +ΔRL Z +ΔRR Z =0 (11)

[0076] When the constraint of equation (11) is added to equation (10), the following equation (12) holds, and the variation of the load on each wheel and the yaw moment can also be calculated using equation (12).

[0077] [Mathematical Expression 9]

[0078]

[0079] However, in equation (12), J all * It becomes the following equation (13) after transforming equation (4).

[0080] [Mathematical Expression 10]

[0081]

[0082] Furthermore, for equation (12), when using the upper and lower stiffness k based on the front and rear wheels... f k rThe roll stiffness distribution ratio a f a r When, the following equation (14) holds true.

[0083] [Mathematical Expression 11]

[0084]

[0085] The '-1' in the upper right corner of the first term on the right side of equation (14) indicates that it is the inverse matrix. Additionally, the roll stiffness distribution ratio a in equation (14) f a r It is calculated from the following equations (15) and (16).

[0086] [Mathematical Expression 12]

[0087]

[0088]

[0089] Additionally, in equation (14), J all2 * It becomes the following equation (17) after transforming equation (4).

[0090] [Mathematical Expression 13]

[0091]

[0092] Next, the configuration of the wheel load estimation device in the first embodiment will be described.

[0093] like Figure 4 As shown, the wheel load estimation device 10 of the first embodiment is connected to an IMU 112, a pressure sensor 114, an encoder 116, and an operation quantity sensor 118. The wheel load estimation device 10 is installed at any position on the vehicle (forklift).

[0094] As described above, IMU 112 is positioned at any location on the vehicle (forklift) to detect the angular acceleration and axial acceleration of each of the three axes around the vehicle coordinate system, and outputs the detected values. Pressure sensor 114 is a sheet-like sensor, for example, positioned on the entire loading surface of the fork 106 to which the load 104 is loaded, to detect the pressure applied to various locations on the loading surface and outputs the detected values. Encoder 116 detects the rotation angle of the unloading hydraulic motor used to move the inner mast 110 up and down, and outputs the detected values. Operational quantity sensors 118 detect the accelerator pedal depressing amount, brake pedal depressing amount, and steering angle, respectively, and output the detected values.

[0095] like Figure 5As shown, the wheel load estimation device 10 functionally includes a front-rear acceleration acquisition unit 12, a lateral acceleration acquisition unit 14, a roll rate acquisition unit 16, a pitch rate acquisition unit 18, and a yaw rate acquisition unit 20. Additionally, the wheel load estimation device 10 includes a load acquisition unit 22, a load position acquisition unit 24, a lift height acquisition unit 26, a tire front-rear force acquisition unit 28, and a tire lateral force acquisition unit 30. Furthermore, the wheel load estimation device 10 includes an angular acceleration calculation unit 32, a vehicle specification DB (Database) 34, a center of gravity inertia value calculation unit 36, a yaw moment calculation unit 38, a wheel load variation calculation unit 40, and a wheel load estimation unit 42. The front-to-rear acceleration acquisition unit 12, the lateral acceleration acquisition unit 14, the roll rate acquisition unit 16, the pitch rate acquisition unit 18, the yaw rate acquisition unit 20, the load acquisition unit 22, the load position acquisition unit 24, the lifting height acquisition unit 26, the tire front-to-rear force acquisition unit 28, the tire lateral force acquisition unit 30, and the angular acceleration calculation unit 32 constitute the acquisition unit in this disclosure.

[0096] The forward and backward acceleration acquisition unit 12 receives the detection value output from IMU 112 and acquires the acceleration G in the x-axis direction contained in the detection value. x As the center of gravity of the vehicle as a whole, CG all acceleration G at the point xall Similarly, the lateral acceleration acquisition unit 14 receives the detection value output from the IMU 112 and acquires the acceleration G in the y-axis direction contained in the detection value. y As the center of gravity of the vehicle as a whole, CG all Lateral acceleration G at the location yall .

[0097] The roll rate acquisition unit 16 receives the detection value output from the IMU 112 and acquires the angular velocity around the x-axis included in the detection value as the roll rate P. The pitch rate acquisition unit 18 receives the detection value output from the IMU 112 and acquires the angular velocity around the y-axis included in the detection value as the pitch rate Q. The yaw rate acquisition unit 20 receives the detection value output from the IMU 112 and acquires the angular velocity around the z-axis included in the detection value as the yaw rate R.

[0098] The load acquisition unit 22 receives the detection value output from the pressure sensor 114, converts the detection value representing pressure into weight, and thus obtains the weight M of the load 104 loaded on the fork 106. αThe loading position acquisition unit 24 receives the detection value output from the pressure sensor 114 and obtains the position where the maximum detection value is detected on the loading surface of the fork 106 as the position of the load 104 loaded on the fork 106. The lifting height acquisition unit 26 receives the detection value output from the encoder 116, calculates the height of the fork 106 relative to a reference position (e.g., the lowest position) from the rotation angle of the unloading hydraulic motor represented by the detection value, and obtains this height as the lifting height.

[0099] The tire front and rear force acquisition unit 28 receives the detection values ​​output from the operation quantity sensor 118, and inputs the accelerator pedal depress amount, the braking driving force based on the brake pedal depress amount, and the steering angle represented by the detection values ​​into a predefined tire characteristic model to obtain the tire front and rear force FL. Fx FR Fx Similarly, the tire lateral force acquisition unit 30 receives the detection value output from the operation quantity sensor 118, and inputs the accelerator pedal depress amount, braking force based on the brake pedal depress amount, steering angle, vehicle speed, yaw rate, etc., represented by the detection value into predefined tire characteristics to obtain the tire lateral force FL. Fy FR Fy RL Fy RR Fy .

[0100] The angular acceleration calculation unit 32 performs approximate differentiation on the roll angular velocity P, pitch angular velocity Q, and yaw angular velocity obtained from each sampling in the roll angular velocity acquisition unit 16, pitch angular velocity acquisition unit 18, and yaw angular velocity acquisition unit 20, and calculates the roll angular acceleration P for each. · Pitch acceleration Q · and yaw acceleration R · .

[0101] The vehicle specification DB34 stores various data related to the vehicle. Specifically, it stores data including the roll center h. R Weight M β Static load FL of each wheel z0 FR z0 RL z0 RR z0 The shape and weight (m) of each component j The structure includes information about the configuration of each wheel.

[0102] The center of gravity inertia calculation unit 36 ​​calculates the weight M of the load 104 obtained by the loading load acquisition unit 22. α And the weight M of the vehicle stored in vehicle specification DB34 β Add them together and calculate the total weight M of the vehicle, including the cargo of 104, which is 100. allFurthermore, the center of gravity inertia calculation unit 36 ​​calculates the position 104A of the center of gravity of the load based on the information obtained by the loading load acquisition unit 22, the loading position acquisition unit 24, and the lifting height acquisition unit 26. The method for calculating the position 104A of the center of gravity of the load can, for example, be the method described in Japanese Patent Application Publication No. 2020-93741.

[0103] In addition, the center of gravity inertia calculation unit 36 ​​calculates the center of gravity CG of the vehicle as a whole 100 based on the position 104A of the center of gravity of the load and the structure of each component stored in the vehicle specification DB34. all The positions of the center of gravity of component j are 102A, 106A, 108A, and 110A. Furthermore, the center of gravity inertia calculation unit 36 ​​calculates the center of gravity CG of the entire vehicle 100 according to equation (5). all The difference (Δx) between position 100A and the positions 102A, 104A, 106A, 108A, and 110A of the center of gravity of component j in each axial direction. j Δy j and Δz j In addition, the center of gravity inertia calculation unit 36 ​​uses the calculated Δxj, Δyj, and Δzj and the weight m of component j stored in vehicle specification DB34. j The inertial tensor J is calculated according to equation (4). all .

[0104] In addition, the center of gravity inertia calculation unit 36 ​​calculates the center of gravity CG of the entire vehicle 100. all Position 100A in the z-axis direction (z all Let h be the value of h. CG .

[0105] Therefore, the center of gravity inertia calculation unit 36 ​​calculates information related to the center of gravity (M). all CG all The differences (Δxj, Δyj, and Δzj) in each axial direction between position 100A and the positions of the center of gravity of component j (102A, 106A, 108A, 110A), the position of the center of gravity of the load (104A), and the positions of the center of gravity of component j (102A, 104A, 106A, 108A, 110A) of each axis of h. CG And calculate the inertial tensor J of the rigid body as the inertial value containing the principal axis of inertia about the center of gravity. all .

[0106] The yaw moment calculation unit 38 is based on the center of gravity CG of the vehicle as a whole, calculated by the center of gravity inertia value calculation unit 36. all Using position 100A and the configuration information of each wheel stored in vehicle specification DB34, the left and right wheels relative to CG are calculated.all y-direction distance t l and t r and the front and rear wheels relative to CG all x-direction distance l f and l r Furthermore, the yaw moment calculation unit 38 uses the calculated t l t r l f l r The front and rear tire forces FL obtained by the front and rear tire force acquisition unit 28 and the lateral tire force acquisition unit 30 Fx FR Fx and tire lateral force FL Fy FR Fy RL Fy RR Fy According to equation (8), the overall center of gravity CG of the vehicle is calculated as 100. all Yaw moment N v .

[0107] The wheel load variation calculation unit 40 calculates h based on the value of the center of gravity inertia calculated by the center of gravity inertia calculation unit 36. CG and the position h of the roll center stored in vehicle specification DB34 R , calculate CG all With the roll center h R The z-direction distance h between them R_CG Furthermore, the wheel load variation calculation unit 40 uses the front and rear acceleration G obtained by the front and rear acceleration acquisition unit 12. xall The lateral acceleration G obtained by the lateral acceleration acquisition unit 14 yall The roll rate P obtained by the roll rate acquisition unit 16, the pitch rate Q obtained by the pitch rate acquisition unit 18, the yaw rate R obtained by the yaw rate acquisition unit 20, and the roll acceleration P calculated by the angular acceleration calculation unit 32. · Pitch acceleration Q · yaw acceleration R · The overall weight M of the vehicle, calculated from the center of gravity inertia value, is 100. all Inertial tensor J all CG all The position h in the z-axis direction CG The calculated CG all With the roll center h R The z-direction distance h between them R_CG And the yaw moment N calculated by the yaw moment calculation unit 38 v Each round relative to CG all Distance t in the x or y direction l t rl f l r The variation ΔFL of the load on each wheel is calculated according to equation (9). z ΔFR z ΔRL z and ΔRR z .

[0108] The wheel load estimation unit 42 calculates the variation ΔFL of each wheel load based on the wheel load variation calculation unit 40. z ΔFR z ΔRL z and ΔRR z The static load FL of each wheel stored in vehicle specification DB34 z0 FR z0 RL z0 and RR z0 The sum of these values ​​is used to estimate the load FL of each wheel. z FR z RL z and RR z Output the estimated result.

[0109] Figure 6 This is a block diagram showing the hardware configuration of the wheel load estimation device 10 according to the first embodiment. Figure 6 As shown, the wheel load estimation device 10 includes a CPU (Central Processing Unit) 52, a memory 54, a storage device 56, an input device 58, an output device 60, a storage medium reading device 62, and a communication I / F (Interface) 64. All components are communicatively connected to each other via a bus 66.

[0110] The storage device 56 stores a wheel load estimation program for performing wheel load estimation processing. The CPU 52 is a central processing unit that executes various programs or controls various components. That is, the CPU 52 reads the program from the storage device 56 and uses the memory 54 as the working area to execute the program. The CPU 52 performs control and various arithmetic processing of the aforementioned components according to the program stored in the storage device 56.

[0111] The memory 54 consists of RAM (Random Access Memory), which serves as temporary storage for programs and data in the working area. The storage device 56 consists of ROM (Read Only Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), etc., which store various programs including the operating system, as well as various data.

[0112] Input device 58 is, for example, a keyboard, mouse, or other device used for various input operations. Output device 60 is, for example, a monitor, printer, or other device used for outputting various information. A touch panel monitor can also be used as an output device 60, thus enabling it to function as an input device 58. Storage medium reading device 62 performs tasks such as reading data from various storage media, including CD (Compact Disc)-ROM, DVD (Digital Versatile Disc)-ROM, Blu-ray discs, and USB (Universal Serial Bus) memory, and writing data to the storage media.

[0113] Communication I / F64 is an interface used to communicate with other devices, such as using standards like Ethernet (registered trademark), FDDI, and Wi-Fi (registered trademark).

[0114] Next, the operation of the wheel load estimation device 10 in the first embodiment will be explained. When the forklift starts moving, the wheel load estimation device 10 will execute... Figure 7 The wheel load estimation process is shown.

[0115] In step S10, the load acquisition unit 22 acquires the weight M of the load 104 loaded on the fork 106 from the detection value of the pressure sensor 114. α The loading position acquisition unit 24 obtains the position of the load 104 from the detection value of the pressure sensor 114, and the lifting height acquisition unit 26 obtains the lifting height from the detection value of the encoder 116.

[0116] Next, in step S12, the center of gravity inertia calculation unit 36 ​​calculates the weight M of the entire vehicle 100 based on the information obtained in step S10 and the information stored in the vehicle specification DB34. all and center of gravity CG all The inertial tensor J is calculated from position 100A and the positions of the centroids of constituent part j (102A, 104A, 106A, 108A, 110A) according to equation (4). all .

[0117] Next, in step S14, the tire front and rear force acquisition unit 28 and the tire lateral force acquisition unit 30 acquire the tire front and rear force FL based on the detection value of the operation quantity sensor 118 and the predefined tire characteristic model. Fx FR Fx and tire lateral force FL Fy FR Fy RL Fy RR Fy .

[0118] Next, in step S16, the forward and backward acceleration acquisition unit 12, the lateral acceleration acquisition unit 14, the roll rate acquisition unit 16, the pitch rate acquisition unit 18, and the yaw rate acquisition unit 20 each acquire the forward and backward acceleration G from the detection value of IMU112. xall Lateral acceleration G yall The yaw rate is P, the pitch rate is Q, and the roll rate is R.

[0119] Next, in step S18, the angular acceleration calculation unit 32 performs approximate differentiation on the roll angular velocity P, pitch angular velocity Q, and yaw angular velocity R obtained in step S16, and calculates the roll angular acceleration P respectively. · Pitch acceleration Q · and yaw acceleration R · .

[0120] Next, in step S20, the yaw moment calculation unit 38 calculates the yaw moment relative to CG for each of the left and right wheels. all y-direction distance t l and t r and the front and rear wheels relative to CG all x-direction distance l f and l r Furthermore, the yaw moment calculation unit 38 uses the calculated t l t r l f l r And the tire front and rear forces FL obtained in step S14 above. Fx FR Fx and tire lateral force FL Fy FR Fy RL Fy RR Fy The yaw moment N is calculated according to equation (8). v .

[0121] Next, in step S22, the wheel load variation calculation unit 40 uses the G obtained or calculated in steps S12 to S20 above. xall G yall P, Q, R, P · Q · R · M all J all h CG h R_CG N v t l t r l f l rThe variation ΔFL of the load on each wheel is calculated according to equation (9). z ΔFR z ΔRL z and ΔRR z .

[0122] Next, in step S24, the wheel load estimation unit 42 calculates the variation ΔFL of each wheel load in step S22 above. z ΔFR z ΔRL z and ΔRR z The static load FL of each wheel stored in vehicle specification DB34 z0 FR z0 RL z0 RR z0 The sum of these values ​​is used to estimate the load on each wheel, and the estimated result is output. Then, the process returns to step S10, and steps S10 to S24 are repeatedly executed during forklift operation. The estimated wheel loads are used for forklift anti-tipping and other controls.

[0123] As explained above, the wheel load estimation device according to the first embodiment estimates the load on each wheel by setting the principal axis of inertia and the product of inertia in accordance with the loading state of the load, thereby enabling accurate estimation of wheel loads. Furthermore, wheel loads can be estimated using only a small sensor such as an IMU, eliminating the need for load measurements using general strain gauges, load cells, etc. Therefore, wheel loads can be estimated without reducing the rigidity of the fork section, thus avoiding the risk of rigidity reduction.

[0124] Furthermore, according to the wheel load estimation device of the first embodiment, by utilizing the fact that the sum of the variations in the loads of each wheel is zero, not only the loads of each wheel can be calculated, but also the yaw moment can be calculated. The estimated yaw moment can be used for torque vectorization control.

[0125] <Second Implementation>

[0126] Next, the second embodiment will be described. First, the principle of the second embodiment will be explained. In the second embodiment, the load on each wheel of a three-wheeled forklift with two front wheels and one rear wheel will be described. Furthermore, the preconditions are the same as in the first embodiment.

[0127] In the case of a 3-wheeled forklift, the rear wheels are positioned at the center of the rear axle. Therefore, considering that they do not contribute to roll behavior but only to pitch behavior, equation (9) in the first embodiment is rewritten as equation (18) below.

[0128] [Mathematical Expression 14]

[0129]

[0130] Furthermore, when equations (10) and (12) in the first embodiment are rewritten in the same way as described above, they become equations (19) and (20) as described below.

[0131] [Mathematical Expression 15]

[0132]

[0133]

[0134] As described above, in the case of a 3-wheeled forklift, the load on each wheel can be estimated in the same way as in the case of a 4-wheeled forklift described in the first embodiment.

[0135] Next, the configuration of the wheel load estimation device of the second embodiment will be described. Furthermore, in the wheel load estimation device of the second embodiment, for configurations identical to those of the wheel load estimation device 10 of the first embodiment, the same reference numerals will be used, and detailed descriptions will be omitted.

[0136] like Figure 8 As shown, the wheel load estimation device 210 of the second embodiment is connected to the IMU 112, the pressure sensor 114, and the encoder 116. The wheel load estimation device 210 is installed at any position on the vehicle (forklift).

[0137] like Figure 9 As shown, the wheel load estimation device 210 functionally includes a front-to-rear acceleration acquisition unit 12, a lateral acceleration acquisition unit 14, a roll rate acquisition unit 16, a pitch rate acquisition unit 18, and a yaw rate acquisition unit 20. Additionally, the wheel load estimation device 210 includes a load acquisition unit 22, a load position acquisition unit 24, and a lifting height acquisition unit 26. Furthermore, the wheel load estimation device 210 includes an angular acceleration calculation unit 32, a vehicle specification DB 34, a center of gravity inertia value calculation unit 236, a wheel load variation calculation unit 240, and a wheel load estimation unit 242.

[0138] The center of gravity inertia calculation unit 236 is the same as the center of gravity inertia calculation unit 36 ​​in the first embodiment, and calculates the weight M of the vehicle as a whole 100 including the load 104. all Inertial tensor J all And the vehicle's overall center of gravity CG all The position h in the z-axis direction CG Furthermore, the center of gravity inertia value calculation part 236 is based on the overall center of gravity CG of the vehicle (100). all Using position 100A and the configuration information of each wheel stored in vehicle specification DB34, the front left and right wheels relative to CG are calculated. all y-direction distance t l and tr and the front and rear wheels relative to CG all x-direction distance l f and l r That is, the center of gravity inertia calculation unit 236 calculates information related to the center of gravity (M). all CG all The differences (Δxj, Δyj, and Δzj) in each axial direction between position 100A and the positions of the center of gravity of component j (102A, 106A, 108A, 110A), the position of the center of gravity of the load (104A), and the positions of the center of gravity of component j (102A, 104A, 106A, 108A, 110A) of each axis of h. CG The front left and right wheels are relative to CG. all y-direction distance t l and t r and the front and rear wheels relative to CG all x-direction distance l f and l r And calculate the inertial tensor J of the rigid body as the inertial value containing the principal axis of inertia about the center of gravity. all .

[0139] The wheel load variation calculation unit 240 calculates CG in the same way as the wheel load variation calculation unit 40 in the first embodiment. all With the roll center h R The z-direction distance h between them R_CG Furthermore, the wheel load variation calculation unit 240 uses the forward and backward acceleration G. xall Lateral acceleration G yall , P roll rate, Q pitch rate, R yaw rate, P roll acceleration · Pitch acceleration Q · yaw acceleration R · The overall weight of the vehicle is 100 M. all Inertial tensor J all CG all The position h in the z-axis direction CG The calculated CG all With the roll center h R The z-direction distance h between them R_CG and each round relative to CG all Distance t in the x or y direction l t r l f l r The variation ΔFL of the load on each wheel is calculated according to equation (20). z ΔFR z and ΔR z And the overall 100% CG of the vehicle's center of gravity.all Yaw moment N v .

[0140] The wheel load estimation unit 242 calculates the variation ΔFL of each wheel load based on the variation of wheel load calculated by the wheel load variation calculation unit 240. z ΔFR z and ΔR z The static load FL of each wheel stored in vehicle specification DB34 z0 FR z0 and R z0 The sum of these values ​​is used to estimate the load FL of each wheel. z FR z and R z Furthermore, the wheel load estimation unit 242 outputs the estimated wheel loads and the yaw moment N calculated by the wheel load variation calculation unit 240. v As a presumption.

[0141] The hardware configuration of the wheel load estimation device 210 in the second embodiment is the same as... Figure 6 The hardware configuration of the wheel load estimation device 10 of the first embodiment shown is the same, so the description is omitted.

[0142] Next, the operation of the wheel load estimation device 210 in the second embodiment will be explained. When the forklift starts moving, the wheel load estimation device 210 will execute... Figure 10 The wheel load estimation process is shown. Furthermore, in the wheel load estimation process of the second embodiment, for processes identical to those in the first embodiment, the same step numbers are used, and detailed descriptions are omitted.

[0143] After step S10, in the next step S212, the center of gravity inertia calculation unit 236 calculates the weight M of the entire vehicle 100 including the load 104. all Inertial tensor J all CG of the vehicle's overall center of gravity (100). all The position h in the z-axis direction CG The front left and right wheels are relative to CG. all y-direction distance t l and t r and the front and rear wheels relative to CG all x-direction distance l f and l r .

[0144] Next, after steps S16 and S18, in the next step S222, the wheel load variation calculation unit 240 uses the G obtained or calculated in the above steps S212 to S18. xall G yall P, Q, R, P ·Q · R · M all J all h CG h R_CG t l t r l f l r The variation ΔFL of the load on each wheel is calculated according to equation (20). z ΔFR z and ΔR z and yaw moment N v .

[0145] Next, in step S224, the wheel load estimation unit 242 calculates the variation ΔFL of each wheel load in step S222 above. z ΔFR z and ΔR z With static load FL z0 FR z0 and R z0 The sum of these values ​​is used to estimate the load on each wheel, and then compared with the yaw moment N calculated in step S222 above. v Together, they are output as an estimated result. Then, the processing returns to step S10, and the processing of steps S10 to S224 is repeatedly executed during forklift operation. The estimated wheel load output is used for forklift anti-tipping control, just like in the first embodiment, and the output yaw moment is used for torque vectoring control, etc.

[0146] As explained above, the wheel load estimation device according to the second embodiment can also achieve the same effect as the first embodiment for a three-wheeled forklift.

[0147] Furthermore, in the second embodiment, similar to the first embodiment, a tire front and rear force acquisition unit 28, a tire lateral force acquisition unit 30, and a yaw moment calculation unit 38 can be provided to calculate the yaw moment. In this case, using formula (18), the variation in load of each wheel can be calculated. In addition, in the first embodiment, similar to the second embodiment, the tire front and rear force acquisition unit 28, the tire lateral force acquisition unit 30, and the yaw moment calculation unit 38 can be omitted. In the wheel load variation calculation unit 40, under the constraint of formula (11) where the sum of the variation in the load of each wheel is 0, formula (12) is used to calculate the yaw moment together with the variation in load of each wheel.

[0148] Furthermore, while the above embodiments describe obtaining the lifting height from the rotation angle of the unloading hydraulic motor detected by the encoder 116, this is not a limitation. For example, a wire can be provided on the fork, and the change in the length of the wire during unloading can be measured to obtain the lifting height. Additionally, other values ​​obtained by each acquiring unit are not limited to those obtained through the methods described in the above embodiments; other methods can also be used.

[0149] Furthermore, while the above embodiments describe the case where the wheel load estimation device is mounted on a forklift, it is not limited to this and can also be configured as an external device. In this case, a communication unit can be installed on the forklift to transmit the detection values ​​of the IMU 112, pressure sensor 114, encoder 116, and operation quantity sensor 118 to the wheel load estimation device. The wheel load estimation device, configured as an external device, receives various information transmitted from the forklift's communication unit and estimates the wheel load through the same processing as in the above embodiments.

[0150] Furthermore, while the above embodiments describe a forklift as the vehicle, the present invention can also be applied to vehicles that carry loads in various states, such as trucks.

[0151] Here, Figure 11 The image shows an example of the estimated wheel load when using a 3-wheeled forklift to make a forward right turn. Figure 11 In this study, the estimated values ​​of the wheel loads derived from equation (20) are compared with the actual measured values ​​of the wheel loads. For example... Figure 11 As shown, the estimated value of the wheel load is roughly consistent with the measured value, thus the wheel load can be estimated with good accuracy.

[0152] In addition, the results confirm the effect of the change in inertia value caused by the increase in height. Figure 12 The load on each wheel was estimated based on formula (20) when the load was 800 kg, the lifting height was 1.5 m, and the three-wheeled forklift was driven by reverse braking. Figure 12 (A) sets the inertia tensor J by setting the actual lifting height to 0.2m. all In this situation, Figure 12 (B) is set to 1.5m, the same as the actual lifting height, to define the inertia tensor J. all The situation. For example... Figure 12 As shown, J is at a lifting height of 0.2m. all When estimating the wheel load, the estimation error is large. On the other hand, when J is set to the same lifting height as the actual 1.5m... allWhen estimating wheel load, the estimation error is small. This demonstrates the effectiveness of changing the inertia value in accordance with the lifting height.

[0153] Next, with Figure 13 To explain in relation to Figure 12 A comparison of the estimated wheel loads under the same driving conditions, based on whether or not the inertia product is considered. Figure 13 (A) represents the case without an inertial product term. Figure 13 (B) is the case with an inertial product term. In either case, the inertial tensor J all The calculated lift height was set to 1.5m, and only the effect of the inertia product term setting was compared. Figure 13 As shown, by setting the inertia product term, the estimation error of wheel load can be reduced. Furthermore, even without the inertia product term, the wheel load can be estimated with good accuracy to a certain extent; therefore, the inertia product is not necessarily required in this invention. Moreover, in the embodiments described above, without considering the inertia product, as long as the inertia tensor J... all The off-diagonal terms can be set to 0.

[0154] Furthermore, the load estimation process, in which the CPU reads and executes the software (program) in the above embodiments, can also be performed by various processors other than the CPU. Examples of processors in this case include dedicated circuits, such as PLDs (Programmable Logic Devices) with circuit configurations that can be changed after manufacturing (e.g., FPGAs) and ASICs (Application Specific Integrated Circuits) specifically designed to perform particular processes. Additionally, the load estimation process can be performed by one of these various processors, or by a combination of two or more processors of the same or different types (e.g., multiple FPGAs, or a combination of a CPU and an FPGA). More specifically, the hardware structure of these various processors is a circuit composed of circuit elements such as semiconductor components.

[0155] Furthermore, while the above embodiments describe a method where the wheel load estimation program is pre-stored (installed) on a storage device, this is not a limitation. The program may also be provided in the form of storage media such as CD-ROM, DVD-ROM, Blu-ray disc, or USB memory. Alternatively, the program may be provided as a downloadable device via a network.

[0156] Explanation of reference numerals in the attached figures

[0157] 10 and 210 wheel load estimation device

[0158] 12. Forward and backward acceleration acquisition part

[0159] 14 Lateral acceleration acquisition section

[0160] 16. Roll angular velocity acquisition unit

[0161] 18. Pitch angular velocity acquisition section

[0162] 20. Yaw rate acquisition section

[0163] 22 Load Acquisition Section

[0164] 24 Loading position acquisition unit

[0165] 26. Increase height to obtain department

[0166] 28. Tire front and rear force acquisition unit

[0167] 30 Tire lateral force acquisition unit

[0168] 32 Angular acceleration calculation part

[0169] 34 Vehicle Specifications (DB)

[0170] 36, 236 Calculation of center of gravity inertia value

[0171] 38. Calculation of yaw moment

[0172] Calculation of load variation for wheels 40 and 240

[0173] 42, 242 Wheel Load Estimation Section

[0174] 44 Communication I / F

[0175] 52 CPU

[0176] 54 Memory

[0177] 56 Storage devices

[0178] 58 Input Devices

[0179] 60 Output device

[0180] 62 Storage medium reading device

[0181] 66 bus

[0182] 100 vehicles as a whole

[0183] 102 Car body

[0184] 104 Loadings

[0185] 106 forks

[0186] 108 Outer Masts

[0187] 110 Inner Mast

[0188] 114 Pressure Sensor

[0189] 116 Encoder

[0190] 118 Operational quantity sensor.

Claims

1. A wheel load estimation device, characterized in that, Include: The acquisition unit acquires the angular velocity, angular acceleration, forward and backward acceleration (as the direction of travel of the rigid body), lateral acceleration (as the width direction of the rigid body), weight of the element, and position of the element including its height of a rigid body containing elements that impart a change to the center of gravity, about three axes. The center of gravity inertia calculation unit calculates information about the rigid body related to the center of gravity, and calculates the inertia value of the rigid body including the principal axis of inertia around the center of gravity. The wheel load variation calculation unit calculates the variation of the wheel load acting on each of the plurality of wheels supporting the rigid body, based on the angular velocity, angular acceleration, and acceleration in the longitudinal and lateral directions obtained by the acquisition unit, and the information related to the center of gravity of the rigid body and the inertia value calculated by the center of gravity inertia value calculation unit. The wheel load estimation unit estimates the wheel load based on the wheel load variation calculated by the wheel load variation calculation unit and the static load acting on each wheel.

2. The wheel load estimation device according to claim 1, wherein, The center of gravity inertia calculation unit calculates the center of gravity position of the rigid body containing the element and the respective positions of the constituent parts based on the weight and position of the element obtained by the acquisition unit and the structure of each of the multiple constituent parts constituting the rigid body. The inertia value is calculated using the difference between the center of gravity position of the rigid body containing the element and the center of gravity position of each constituent part.

3. The wheel load estimation device according to claim 1 or claim 2, wherein, The center of gravity inertia value calculation unit calculates the inertia value that further includes the inertia product.

4. The wheel load estimation device according to any one of claims 1 to 3, wherein, The acquiring unit acquires the lateral force and the front-rear force acting on the wheel. The wheel load variation calculation unit further uses the yaw moment of the rigid body around the center of gravity, calculated based on the lateral force and the front-rear force obtained by the acquisition unit, to calculate the variation in the wheel load.

5. The wheel load estimation device according to any one of claims 1 to 3, wherein, The wheel load variation calculation unit calculates the yaw moment of the rigid body around the center of gravity together with the variation of the wheel load, under the constraint that the sum of the variation of the wheel load of each of the plurality of wheels is 0.

6. The wheel load estimation device according to any one of claims 1 to 5, wherein, The rigid body is the vehicle, and the element that causes the center of gravity to shift is the cargo loaded on the vehicle.

7. The wheel load estimation device according to claim 6, wherein, The vehicle is a forklift, and the load is mounted on forks that can move up and down.

8. The wheel load estimation device according to any one of claims 1 to 7, wherein, The information related to the center of gravity of the rigid body includes the vertical distance between the center of gravity of the rigid body and the tilt center of the rigid body, the lateral position of the center of gravity of the rigid body, and the lateral distance between each of the plurality of wheels and the center of gravity of the rigid body.

9. A wheel load estimation procedure, characterized in that, This is used to enable the computer to function as a component of the wheel load estimation device according to any one of claims 1 to 8.

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