Vehicle seat control device, method, and program

Abstract

To obtain a vehicle seat control device that performs vibration control without phase shift in response to the pitch motion of the vehicle. [Solution] The vehicle seat control device 10 includes: a road surface estimation unit 32 that estimates vertical displacement at each position on the road surface based on the degree of vibration of the front wheels or near the front wheels of the vehicle; a prediction unit 34 that predicts the time when the rear wheels will pass the position that the front wheels have passed, based on the distance between the front and rear wheels of the vehicle and the vehicle speed of the vehicle; a pitch angle estimation unit 36 ​​that estimates the pitch angle of the vehicle when the displacement estimated by the road surface estimation unit is input to the rear wheels, using a vehicle model that shows the characteristics of the vehicle; and a control unit 38 that controls the posture of the vehicle seat so as to cancel the pitch angle estimated by the pitch angle estimation unit at the time predicted by the prediction unit.

Description

[Technical Field]

[0001] This disclosure relates to a vehicle seat control device, a vehicle seat control method, and a vehicle seat control program. [Background technology]

[0002] Vehicle pitch motion is transmitted to occupants as seat pitch motion, causing discomfort. In particular, in the case of trucks, the vehicle's pitch motion differs significantly between when empty and when fully loaded. Also, trucks have a stiffer suspension setting, assuming they will be loaded. Therefore, when the vehicle is empty or lightly loaded, if pitch motion occurs where the rear wheels are jolted upwards around the front wheels, the suspension does not move, and the vehicle's pitch motion is directly transmitted to the seats, causing greater discomfort to occupants.

[0003] Regarding the control of the seat's posture when vehicle pitch motion occurs, a vehicle seat posture control device has been proposed that includes a vehicle state detection means for detecting the vehicle's state, a posture changing means for changing the posture of the vehicle seat, and a control means for controlling the posture changing means based on the vehicle state detected by the vehicle state detection means. This device changes the posture of the vehicle seat in the direction of the vehicle's pitching, and the control means predicts and calculates the pitching angle at predetermined time intervals when the vehicle's speed changes as pitching behavior based on the detection signal from the vehicle state detection means, and controls the posture changing means to cancel out the pitching behavior (Patent Document 1).

[0004] Furthermore, there are trucks equipped with driver's seats that have seat suspension (Non-Patent Document 1). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2007-253883 [Non-patent literature]

[0006] [Non-Patent Document 1] Toyota, Dyna, package options, [online], [search date 2025.01.20], Internet <URL: https: / / toyota.jp / sc_files / media / images / carlineup / dyna / 008_b_005 / spec / spec / dump / dyna_dump_equip.pdf> [Overview of the project] [Problems that the invention aims to solve]

[0007] The technology described in Patent Document 1 predicts pitching behavior based on vehicle conditions detected in real time. However, due to the operating delay of the actuators in the active control system and the time required for control, there is a time delay in the timing of controlling the seat posture relative to the time when the pitching behavior is predicted. In other words, it is difficult to perform vibration control without phase shift using the technology described in Patent Document 1.

[0008] The technology described in Non-Patent Document 1 is a passive system, and therefore suffers from insufficient comfort due to issues such as excessive gain or overshoot at the seatback resonance point relative to the vehicle's pitch motion.

[0009] This disclosure has been made in view of the above points, and aims to provide a vehicle seat control device, method, and program that can perform vibration control without phase shift in response to the pitch motion of a vehicle. [Means for solving the problem]

[0010] A vehicle seat control device according to a first aspect of the present disclosure includes: a road surface estimation unit that estimates vertical displacement at each position on the road surface based on the degree of vibration of the front wheels or near the front wheels of the vehicle; a prediction unit that predicts the time at which the rear wheels will pass the position that the front wheels have passed, based on the distance between the front wheels and the rear wheels of the vehicle and the vehicle speed of the vehicle; a pitch angle estimation unit that estimates the pitch angle of the vehicle when the displacement estimated by the road surface estimation unit is input to the rear wheels, using a vehicle model that represents the characteristics of the vehicle; and a control unit that controls the posture of the vehicle seat so as to cancel the pitch angle estimated by the pitch angle estimation unit at the time predicted by the prediction unit.

[0011] A vehicle seat control method according to a second aspect of this disclosure is a method in which a computer performs the following actions: estimates the vertical displacement at each position on the road surface based on the degree of vibration of the front wheels or near the front wheels of the vehicle; predicts the time at which the rear wheels will pass the position that the front wheels have passed based on the distance between the front and rear wheels of the vehicle and the vehicle speed of the vehicle; estimates the pitch angle of the vehicle when the estimated displacement is input to the rear wheels using a vehicle model that represents the characteristics of the vehicle; and controls the posture of the vehicle seat at the predicted time so as to cancel the estimated pitch angle.

[0012] A vehicle seat control program according to a third aspect of this disclosure is a program that causes a computer to perform the following actions: estimate the vertical displacement at each position on the road surface based on the degree of vibration of the front wheels or near the front wheels of the vehicle; predict the time at which the rear wheels will pass the position that the front wheels have passed based on the distance between the front and rear wheels of the vehicle and the vehicle speed of the vehicle; estimate the pitch angle of the vehicle when the estimated displacement is input to the rear wheels using a vehicle model that represents the characteristics of the vehicle; and control the posture of the vehicle seat at the predicted time so as to cancel the estimated pitch angle. [Effects of the Invention]

[0013] According to the vehicle seat control device, method, and program according to the present disclosure, vibration control without phase shift can be performed with respect to the pitch motion of the vehicle.

Brief Description of the Drawings

[0014] [Figure 1] It is a schematic configuration diagram of a vehicle seat control system. [Figure 2] It is a block diagram showing the hardware configuration of a vehicle seat control device. [Figure 3] It is a functional block diagram of a vehicle seat control device. [Figure 4] It is a diagram for explaining the estimation of the pitch angle of a vehicle. [Figure 5] It is a diagram showing an example of a vehicle model. [Figure 6] It is a diagram for explaining the estimation of the mass and center of gravity position of a load. [Figure 7] It is a flowchart showing the flow of vehicle seat control processing. [Figure 8] It is a diagram showing another example of a vehicle model.

Embodiments for Carrying Out the Invention

[0015] Hereinafter, an example of an embodiment of the present disclosure will be described while referring to the drawings. In each drawing, the same or equivalent components and parts are given the same reference numerals. Also, the dimensions and ratios in the drawings are exaggerated for the convenience of explanation and may be different from the actual ratios.

[0016] As shown in FIG. 1, the vehicle seat control system 100 according to the present embodiment includes a vehicle seat control device 10, a vehicle speed sensor 52, a front wheel stroke sensor 54, a rear wheel stroke sensor 56, and a seat actuator 58.

[0017] The vehicle speed sensor 52 is, for example, a sensor that detects pulses associated with the rotation of the wheels, and is installed in the transmission to measure the vehicle speed V of the vehicle 80. The front wheel stroke sensor 54 measures the amount of suspension stroke of the front wheels 84. The rear wheel stroke sensor 56 measures the amount of suspension stroke of the rear wheels 86. Each sensor outputs the measured value to the vehicle seat control device 10.

[0018] The seat actuator 58 is a mechanism that changes the posture of the seat 82 of the vehicle 80. Specifically, the seat actuator 58 changes the pitch angle of the seat cushion (seat surface) and the seat back (backrest) based on a control signal from the vehicle seat control device 10.

[0019] The vehicle seat control device 10 generates a control signal to change the posture of the seat 82 based on the measured values ​​output from the vehicle speed sensor 52, the front wheel stroke sensor 54, and the rear wheel stroke sensor 56, and outputs it to the seat actuator 58.

[0020] Figure 2 is a block diagram showing the hardware configuration of the vehicle seat control device 10. As shown in Figure 2, the vehicle seat control device 10 includes a CPU (Central Processing Unit) 12, memory 14, storage device 16, input device 18, output device 20, storage medium reader 22, and communication I / F (Interface) 24. Each component is connected to the others via a bus 26 so as to be able to communicate with each other.

[0021] The storage device 16 stores a vehicle seat control program for executing the vehicle seat control processing described later. The CPU 12 is a central processing unit that executes various programs and controls each component. Specifically, the CPU 12 reads the program from the storage device 16 and executes the program using memory 14 as a workspace. The CPU 12 controls each component and performs various calculations according to the program stored in the storage device 16.

[0022] Memory 14 is composed of RAM (Random Access Memory) and temporarily stores programs and data as a working area. Storage device 16 is composed of ROM (Read Only Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), etc., and stores various programs and data, including the operating system.

[0023] The input device 18 is a device for performing various types of input, such as a keyboard or mouse. The output device 20 is a device for outputting various types of information, such as a display or printer. By using a touch panel display as the output device 20, it may also function as the input device 18.

[0024] The storage medium reader 22 reads data stored on various storage media such as CD (Compact Disc)-ROM, DVD (Digital Versatile Disc)-ROM, Blu-ray disc, and USB (Universal Serial Bus) memory, and writes data to the storage media. The communication I / F 24 is an interface for communication with other devices, and standards such as Ethernet (registered trademark), FDDI, or Wi-Fi (registered trademark) are used.

[0025] Next, the functional configuration of the vehicle seat control device 10 will be described. Figure 3 is a block diagram showing an example of the functional configuration of the vehicle seat control device 10. As shown in Figure 3, the vehicle seat control device 10 includes a road surface estimation unit 32, a prediction unit 34, a pitch angle estimation unit 36, and a control unit 38 as its functional configuration. Each functional configuration is realized when the CPU 12 reads the vehicle seat control program stored in the storage device 16, expands it into the memory 14, and executes it.

[0026] The road surface estimation unit 32 estimates the vertical displacement at each position on the road surface 90 based on the degree of vibration of the front wheels 84 or near the front wheels 84 of the vehicle 80. Specifically, the road surface estimation unit 32 obtains the suspension stroke amount of the front wheels 84 from the front wheel stroke sensor 54. Based on a vibration model including the spring constant and damping coefficient of the suspension of the front wheels 84, and the obtained suspension stroke amount of the front wheels 84, the road surface estimation unit 32 estimates the vertical displacement of the road surface 90 at that position, relative to a plane. By estimating the vertical displacement at each position on the road surface 90, the shape of the road surface 90 surface, such as protrusions that cause vibration to the vehicle 80, is estimated.

[0027] The method for estimating the vertical displacement of the road surface 90 is not limited to the above example. For example, an acceleration sensor may be installed near the front wheel 84 to detect vertical acceleration, and the vertical displacement of the road surface 90 may be estimated by integrating the detected acceleration. Alternatively, if the acceleration sensor is installed on the frame or floor, the vertical displacement of the road surface 90 may be estimated using a vibration model that takes into account the transmission of acceleration from the front wheel 84 to the frame or floor.

[0028] As shown in Figure 4, the prediction unit 34 predicts the time at which the rear wheels 86 will pass the position that the front wheels 84 have just passed, based on the distance between the front wheels 84 and the rear wheels 86 of the vehicle 80 (wheelbase L) and the vehicle speed V of the vehicle 80. Specifically, let t be the time at which the front wheels 84 pass a certain position. At time t, the prediction unit 34 obtains the vehicle speed V from the vehicle speed sensor 52 and predicts the time difference T from the position of the front wheels 84 at time t until the rear wheels 86 pass the position as T = L / V, based on the vehicle speed V and the wheelbase L. The prediction unit 34 also predicts the time at which the rear wheels 86 pass the corresponding position as t + T.

[0029] The pitch angle estimation unit 36 ​​uses a vehicle model that represents the characteristics of the vehicle 80 to estimate the pitch angle of the vehicle 80 when the vertical displacement of the road surface 90 estimated by the road surface estimation unit 32 is input to the rear wheels 86.

[0030] Figure 5 shows an example of a vehicle model. Vis the vehicle mass, m C is the mass of the load, L is the wheelbase, L Ci (i = F for the front wheels, i = R for the rear wheels, and the same applies hereinafter) is the distance from the center of gravity of the load to each wheel, k iS is the stiffness of the suspension, c iS is the damping of the suspension, m iW is the wheel mass, k iT is the stiffness of the tire.

[0031] The pitch angle estimation unit 36 estimates the mass m of the load in the above vehicle model C and the position of the center of gravity based on the amount of change in the load applied to each of the front wheels 84 and the rear wheels 86 before and after loading the load. The load applied to each wheel is calculated from the stroke amounts of the suspensions of the front wheels 84 and the rear wheels 86 measured by the front wheel stroke sensor 54 and the rear wheel stroke sensor 56, respectively. For example, the pitch angle estimation unit 36 estimates the mass m of the load C and the position of the center of gravity according to FIG. 6 and the following formula. m C = (F FW + F RW ) / g a = F RW / (F FW + F RW )

[0032] F FW is the increment of the front wheel load due to the load, F RW is the increment of the rear wheel load due to the load, g is the gravitational acceleration, and a is the ratio of the distance from the front wheel 84 to the center of gravity of the load to the wheelbase L. Thus, even if the loading and unloading of the load are performed at a relay point or the like and the state (mass and center of gravity position) of the load changes, in the above vehicle model, it is possible to follow the change in the state of the load.

[0033] The pitch angle estimation unit 36 ​​inputs the displacement estimated by the road surface estimation unit 32 to the rear wheel portion of the vehicle model described above, and estimates the pitch angle of the vehicle 80 with respect to the road surface plane and centered on the front wheel 84, as shown in Figure 4. In the example in Figure 4, it is shown that the pitch angle when the rear wheel 86 passes over the road surface protrusion that the front wheel passed over at time t is estimated at time t+T (T=L / V).

[0034] The control unit 38 controls the posture of the seat 82 so as to cancel the pitch angle of the vehicle 80 estimated by the pitch angle estimation unit 36 ​​at the time predicted by the prediction unit 34. Specifically, if the estimated pitch angle of the vehicle 80 is θ, the control unit 38 generates a control signal to rotate the pitch angle of the seat 82 by -θ at the time predicted by the prediction unit 34 and outputs it to the seat actuator 58.

[0035] The control unit 38 may control the seat back of the seat 82, the seat cushion, or both. When controlling the pitch angle of both the seat back and the seat cushion, the effect on the occupant changes depending on the position of the seat 82's center of rotation. For example, if the center of rotation is at the rear end of the seat cushion, the vertical movement of the front end of the seat cushion relative to the vehicle floor associated with controlling the pitch angle of the seat 82 will be greater compared to when the center of rotation is at the front end of the seat cushion. As a result, it becomes difficult to maintain a constant amount of operation on the accelerator pedal and brake pedal.

[0036] Therefore, the amount of rotation of the seat cushion's pitch angle is made smaller than the amount of rotation of the seat back's pitch angle. This effectively suppresses pitch vibrations transmitted from the seat back while further reducing the vertical movement of the front edge of the seat cushion that affects pedal operation. Thus, even if the rotation center of the seat 82 needs to be set behind the seat cushion for design purposes, it becomes possible to improve ride comfort while minimizing the impact on driving operation. In addition, the amount of rotation of the seat cushion's pitch angle may be made adjustable by the occupant. This makes it possible to adjust the amount of rotation of the pitch angle to suit the occupant's preference.

[0037] Next, the operation of the vehicle seat control system 100 will be explained.

[0038] Figure 7 is a flowchart showing the flow of vehicle seat control processing executed by the CPU 12 of the vehicle seat control device 10. The CPU 12 reads the vehicle seat control program from the storage device 16, loads it into memory 14, and executes it. As a result, the CPU 12 functions as one of the various functional configurations of the vehicle seat control device 10, and the vehicle seat control processing shown in Figure 7 is executed. Note that the vehicle seat control processing is an example of the vehicle seat control method of this disclosure.

[0039] First, in step S10, the road surface estimation unit 32 determines whether the ignition switch of the vehicle 80 is turned on or not. If the ignition switch is turned on, the process proceeds to step S12; otherwise, this determination is repeated.

[0040] In step S12, the pitch angle estimation unit 36 ​​reads from a predetermined memory unit the loads of the front wheels 84 and rear wheels 86 before loading, which have been calculated from the stroke amount of the front wheels 84 measured in advance by the front wheel stroke sensor 54 and the stroke amount of the rear wheels 86 measured by the rear wheel stroke sensor 56, and stored in the memory unit.

[0041] Next, in step S14, the pitch angle estimation unit 36 ​​obtains the stroke amount of the front wheel 84 measured by the front wheel stroke sensor 54 after loading the cargo, and the stroke amount of the rear wheel 86 measured by the rear wheel stroke sensor 56, and calculates the loads of the front wheel 84 and rear wheel 86 after loading the cargo. Then, the pitch angle estimation unit 36 ​​calculates the increment F of the front wheel load due to the cargo from the difference between the load obtained in step S12 and the load calculated in this step. FW , and the increase in rear wheel load due to the load F RW The pitch angle estimation unit 36 ​​calculates the load increment F. FW F RW The mass and center of gravity of the cargo are estimated using the gravitational acceleration g.

[0042] Next, in step S16, the road surface estimation unit 32 obtains the suspension stroke amount of the front wheel 84 measured at time t by the front wheel stroke sensor 54. Next, in step S18, the road surface estimation unit 32 estimates the vertical displacement of the road surface 90 relative to the plane at the position of the front wheel 84 at time t, based on a vibration model including the spring constant and damping coefficient of the suspension of the front wheel 84, and the obtained suspension stroke amount of the front wheel 84.

[0043] Next, in step S20, the prediction unit 34 obtains the vehicle speed V from the vehicle speed sensor 52 at time t, and predicts the time difference T from the time t until the rear wheels 86 pass over the position of the front wheels 84 as T = L / V, based on the vehicle speed V and the wheelbase L.

[0044] Next, in step S22, the pitch angle estimation unit 36 ​​inputs the vertical displacement of the road surface estimated in step S18 to the rear wheel portion of the vehicle model, which reflects the mass and center of gravity of the load estimated in step S14, and estimates the pitch angle θ of the vehicle 80 at time t+T, with the road surface plane as the reference and the front wheel 84 as the center.

[0045] Next, in step S24, the control unit 38 generates a control signal to rotate the pitch angle of the seat 82 by -θ at time t+T and outputs it to the seat actuator 58.

[0046] Next, in step S26, the road surface estimation unit 32 determines whether the ignition switch of the vehicle 80 has been turned off. If the ignition switch is not turned off, the process returns to step S12; if it is turned off, the vehicle seat control process ends.

[0047] As described above, according to the vehicle seat control system of this embodiment, the vehicle seat control device estimates the vertical displacement at each position on the road surface based on the degree of vibration of the vehicle's front wheels or near the front wheels. The vehicle seat control device also predicts the time when the rear wheels will pass the position previously passed by the front wheels, based on the distance between the front and rear wheels of the vehicle and the vehicle speed. Furthermore, the vehicle seat control device estimates the pitch angle of the vehicle when the estimated vertical displacement of the road surface is input to the rear wheels, using a vehicle model that represents the characteristics of the vehicle. Then, the vehicle seat control device controls the posture of the vehicle's seat to cancel out the estimated pitch angle at the predicted time. This enables vibration control without phase shift in response to the pitch motion of the vehicle.

[0048] According to the above vehicle seat control processing, constant corrections are made for load changes such as loading and unloading of cargo, so phase shifts can be eliminated with high precision.

[0049] In the above embodiment, the vehicle seat control device may further include a correction unit that measures the actual pitch angle of the vehicle using a gyro sensor or the like, and corrects the vehicle model based on the difference between the pitch angle estimated by the pitch angle estimation unit and the actually measured pitch angle. This makes it possible to estimate the pitch angle of the vehicle at time t+T more accurately.

[0050] Furthermore, although the vehicle model used in the above embodiment assumes a configuration in which the cabin is fixed to the chassis, this disclosure can also be applied to vehicles equipped with a vibration-reducing suspension (cab suspension) between the chassis and the cabin. In this case, for example, a vehicle model like the one shown in Figure 8 may be applied. Cab The mass of the cabin section, k CS The rigidity of the cab suspension, c CS This is the damping of the cab suspension.

[0051] Furthermore, a parent-child spring with nonlinear stiffness may be applied to the vehicle suspension in the above embodiment. With a parent-child spring, when the vehicle is unloaded, only the lower leaf spring deflects, resulting in a low spring constant. When the load is heavy, both the upper and lower leaf springs deflect, resulting in a high spring constant. When a parent-child spring is applied, the suspension is less likely to bottom out even when a heavy load is placed on it, and the sprung mass does not change abruptly. In this case, the spring constant that changes with the load mass should be set in the vehicle model. As a result, even when a suspension with nonlinear stiffness is applied, the pitch angle of the vehicle can be estimated with accuracy, and the seat posture can be controlled appropriately.

[0052] Furthermore, the program processing flow described in the above embodiment is just one example, and unnecessary steps may be deleted, new steps added, or the processing order rearranged, as long as it does not deviate from the main purpose.

[0053] Furthermore, the vehicle seat control processing, which the CPU reads and executes in the above embodiment, may also be executed by various processors other than the CPU. Examples of such processors include PLDs (Programmable Logic Devices) such as FPGAs (Field-Programmable Gate Arrays) whose circuit configuration can be changed after manufacturing, and dedicated electrical circuits that are processors with circuit configurations specifically designed to execute specific processing, such as ASICs (Application Specific Integrated Circuits). The vehicle seat control processing may also be executed by one of these various processors, or by a combination of two or more processors of the same or different types (for example, multiple FPGAs, and a combination of a CPU and an FPGA). More specifically, the hardware structure of these various processors is an electrical circuit that combines circuit elements such as semiconductor elements.

[0054] Furthermore, the vehicle seat control processing in the above embodiment may be performed by one or more ECUs (Electronic Control Units).

[0055] Furthermore, while the above embodiments describe a configuration in which the vehicle seat control program is pre-stored (installed) in a storage device, the invention is not limited to this configuration. The program may be provided in a form recorded on a recording medium such as a CD-ROM, DVD-ROM (Digital Versatile Disc Read Only Memory), or USB (Universal Serial Bus) memory. Alternatively, the program may be provided in a form that can be downloaded from an external device via a network.

[0056] The following additional information is disclosed.

[0057] (Additional note 1) A road surface estimation unit estimates the vertical displacement at each position on the road surface based on the degree of vibration of the vehicle's front wheels or near the front wheels, A prediction unit predicts the time at which the rear wheels will pass the position previously passed by the front wheels, based on the distance between the front and rear wheels of the vehicle and the vehicle speed of the vehicle. A pitch angle estimation unit estimates the pitch angle of the vehicle when the displacement estimated by the road surface estimation unit is input to the rear wheel, using a vehicle model that shows the characteristics of the vehicle. A control unit controls the posture of the vehicle's seat so as to cancel the pitch angle estimated by the pitch angle estimation unit at the time predicted by the prediction unit, Vehicle seat control device including

[0058] (Additional note 2) The vehicle seat control device according to Appendix 1, wherein the road surface estimation unit estimates the displacement based on the suspension stroke of the front wheel or the vertical acceleration.

[0059] (Additional note 3) The vehicle model includes the spring constants of the suspensions of the front and rear wheels, the mass of the load, and the position of the center of gravity. The pitch angle estimation unit estimates the mass and center of gravity of the cargo based on the amount of change in the load on the front wheel and the rear wheel before and after loading the cargo. A vehicle seat control device as described in Appendix 1 or Appendix 2.

[0060] (Additional note 4) A vehicle seat control device according to any one of the appendices 1 to 3, further comprising a correction unit that corrects the vehicle model based on the difference between the pitch angle estimated by the pitch angle estimation unit and the pitch angle actually measured.

[0061] (Additional note 5) The vehicle seat control device according to Appendix 3, which sets the spring constant, which changes with the mass of the load, to the vehicle model when the suspension has nonlinear stiffness.

[0062] (Additional note 6) The vehicle seat control device according to any one of Appendix 1 to Appendix 5, wherein the control unit controls at least one of the seat back and the seat cushion of the seat.

[0063] (Additional note 7) The vehicle seat control device according to Appendix 6, wherein when the control unit controls both the seat back and the seat cushion, the control unit controls the amount of rotation of the pitch angle of the seat cushion to be smaller than the amount of rotation of the pitch angle of the seat cushion as the center of rotation of the pitch angle of the seat is closer to the rear end of the seat. [Explanation of symbols]

[0064] 100 Vehicle seat control systems 10. Vehicle seat control device 12 CPU 14 memory 16 Storage device 18 Input device 20 Output device 22 Storage medium reader 24 Communication I / F 26 bus 32 Road surface estimation section 34 Prediction Section 36 Pitch angle estimation unit 38 Control Unit 52 Vehicle speed sensor 54 Front wheel stroke sensor 56 Rear wheel stroke sensor 58 Seat Actuator 80 vehicles 82 seats 84 Front Wheel 86 Rear Wheel 90 Road surface

Claims

1. A road surface estimation unit estimates the vertical displacement at each position on the road surface based on the degree of vibration of the vehicle's front wheels or near the front wheels, A prediction unit predicts the time at which the rear wheels will pass the position previously passed by the front wheels, based on the distance between the front and rear wheels of the vehicle and the vehicle speed of the vehicle. A pitch angle estimation unit estimates the pitch angle of the vehicle when the displacement estimated by the road surface estimation unit is input to the rear wheel, using a vehicle model that shows the characteristics of the vehicle. A control unit controls the posture of the vehicle's seat so as to cancel the pitch angle estimated by the pitch angle estimation unit at the time predicted by the prediction unit, Vehicle seat control device including

2. The vehicle seat control device according to claim 1, wherein the road surface estimation unit estimates the displacement based on the suspension stroke of the front wheel or the vertical acceleration.

3. The vehicle model includes the spring constants of the suspensions of the front and rear wheels, the mass of the load, and the position of the center of gravity. The pitch angle estimation unit estimates the mass and center of gravity of the cargo based on the amount of change in the load on the front wheel and the rear wheel before and after loading the cargo. A vehicle seat control device according to claim 1 or claim 2.

4. The vehicle seat control device according to claim 1 or claim 2, further comprising a correction unit that corrects the vehicle model based on the difference between the pitch angle estimated by the pitch angle estimation unit and the pitch angle actually measured.

5. The vehicle seat control device according to claim 3, wherein the suspension has nonlinear stiffness, and the spring constant, which changes depending on the mass of the load, is set in the vehicle model.

6. The vehicle seat control device according to claim 1 or 2, wherein the control unit controls at least one of the seat back and the seat cushion of the seat.

7. The vehicle seat control device according to claim 6, wherein when the control unit controls both the seat back and the seat cushion, the control unit controls the amount of rotation of the pitch angle of the seat cushion to be smaller than the amount of rotation of the pitch angle of the seat cushion as the center of rotation of the pitch angle of the seat is closer to the rear end of the seat.

8. Based on the degree of vibration of the vehicle's front wheels or near the front wheels, the vertical displacement at each point on the road surface is estimated. Based on the distance between the front and rear wheels of the vehicle and the vehicle speed, the time at which the rear wheels will pass the position previously passed by the front wheels is predicted. Using a vehicle model that shows the characteristics of the vehicle, the pitch angle of the vehicle is estimated when the estimated displacement is input to the rear wheel. The vehicle's seat posture is controlled to cancel out the estimated pitch angle at the predicted time. A vehicle seat control method in which a computer performs the following actions.

9. Based on the degree of vibration of the vehicle's front wheels or near the front wheels, the vertical displacement at each point on the road surface is estimated. Based on the distance between the front and rear wheels of the vehicle and the vehicle speed, the time at which the rear wheels will pass the position previously passed by the front wheels is predicted. Using a vehicle model that shows the characteristics of the vehicle, the pitch angle of the vehicle is estimated when the estimated displacement is input to the rear wheel. The vehicle's seat posture is controlled to cancel out the estimated pitch angle at the predicted time. A vehicle seat control program that causes a computer to perform a specific action.

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