Vehicle seat control method and control device

Abstract

To suppress a posture change of an occupant due to the lateral direction acceleration of a vehicle by changing the orientation of a seat back to the yaw direction of the vehicle, and suppress reduction in the comfort due to continuation of pressing against the seat back.SOLUTION: A control method of a vehicle seat comprises the steps of: detecting at least one of the lateral direction acceleration and steering angle of a vehicle (S1, S11); determining whether an absolute value of the lateral direction acceleration is increased or decreased on the basis of at least one of the lateral direction acceleration and steering angle (S3, S13); and turning a seat back Sb such that the component of the lateral direction acceleration in parallel to the front-rear direction of the seat back Sb becomes the component facing forward in a period in which the absolute value of the lateral direction acceleration of the vehicle 1 is increased, and / or turning the seat back Sb such that the component of the lateral direction acceleration in parallel to the front-rear direction of the seat back Sb becomes the component facing backward in a period in which the absolute value of the lateral direction acceleration is decreased (S6, S16).SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a method and a control device for a vehicle seat. [Background technology]

[0002] Patent Document 1 listed below proposes a technology in which the seatback support section is made movable, and part of the inertial acceleration in the vehicle width direction that occurs to the occupant when changing lanes, etc. is decomposed into component force components that press the occupant against the seatback support section, and the component force components are used to suppress the occupant's movement relative to the seat, thereby suppressing occupant swaying and reducing car sickness. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-71370 Summary of the Invention [Problem to be solved by the invention]

[0004] However, according to the technology of Patent Document 1, the occupant is constantly pressed against the seat back while acceleration in the vehicle width direction is occurring, which may make the occupant feel a sense of pressure and reduce comfort. The present invention aims to suppress changes in the posture of occupants due to lateral acceleration of the vehicle by changing the orientation of the seat back in the yaw direction of the vehicle, and to suppress a decrease in comfort due to continued pressure against the seat back. [Means for solving the problem]

[0005] According to one aspect of the present invention, there is provided a control method for a vehicle seat in which at least the seat back can be rotated in the yaw direction of the vehicle, the control method includes detecting at least one of a lateral acceleration and a steering angle of the vehicle, determining whether an absolute value of the lateral acceleration increases or decreases based on the at least one of the lateral acceleration and the steering angle, and rotating the seat back so that a component of the lateral acceleration parallel to the fore-and-aft direction of the seat back becomes a forward component during a period in which the absolute value of the lateral acceleration of the vehicle is increasing, and / or rotating the seat back so that a component of the lateral acceleration parallel to the fore-and-aft direction of the seat back becomes a backward component during a period in which the absolute value of the lateral acceleration is decreasing. [Effects of the Invention]

[0006] According to the present invention, by changing the orientation of the seat back in the yaw direction of the vehicle, it is possible to suppress changes in the posture of the occupant due to the lateral acceleration of the vehicle, and to suppress a decrease in comfort due to the occupant being continuously pressed against the seat back. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic configuration diagram of an example of a vehicle control device according to an embodiment; [Figure 2] FIG. 2 is an explanatory diagram of each direction set in a vehicle. [Figure 3] (a) is a graph showing the time change in the lateral acceleration of the lateral transient motion and the positive acceleration added by the acceleration, (b) is a graph showing the time change in the lateral acceleration of the lateral transient motion and the negative acceleration added by the deceleration, and (c) is the experimental result showing the change in the roll attitude angle of the occupant in cases (a) and (b). [Figure 4] (a) is a graph showing the time change in lateral acceleration of lateral transient motion, (b) is a graph showing the time change in deceleration and acceleration applied by braking and driving the vehicle, and (c) is a graph showing the time change in the roll attitude angle of the occupant. [Figure 5](a) is a graph showing the time variation of the lateral acceleration and lateral jerk of the vehicle body that occurs when changing lanes, and (b) is a graph showing an example of setting the direction of the vertical acceleration component of the seat back. [Figure 6] 3A and 3B are schematic diagrams illustrating the relationship between the motion of the vehicle and the inertial force acting on the occupant. [Figure 7] 1A to 1D are schematic diagrams illustrating the inertial acceleration acting on an occupant due to the lateral acceleration of the vehicle and the vertical acceleration component of the seat back. [Figure 8] (a) is a graph showing the time change in the lateral acceleration and lateral jerk of the vehicle body that occur when changing lanes, (b) is a graph showing an example of setting the direction of the seat back vertical acceleration component, (c) is a graph showing the time change in the steering angle and steering angular velocity, and (d) is a graph of the composite code D that combines the sign of the steering angle and the sign of the steering angular velocity. [Figure 9] 4 is a flowchart of a first example of a method for controlling a vehicle seat according to an embodiment. [Figure 10] 10 is a flowchart of a second example of a method for controlling a vehicle seat according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the drawings are schematic and may differ from the actual product. Furthermore, the embodiments of the present invention shown below are examples of devices and methods for embodying the technical concept of the present invention, and the technical concept of the present invention does not limit the structure, arrangement, etc. of component parts to those described below. The technical concept of the present invention can be modified in various ways within the technical scope defined by the claims.

[0009] In this specification, "longitudinal acceleration" includes not only the rate of increase in vehicle speed in the forward direction of the vehicle, but also the rate of decrease in that speed (i.e., deceleration). In particular, the sign of acceleration when the vehicle speed increases is positive, and the sign of acceleration when the vehicle speed decreases is negative. Furthermore, "lateral acceleration" is a concept that includes acceleration occurring in one direction in the vehicle width direction (either left or right relative to the forward direction of the vehicle) and acceleration occurring in the other direction (the other of left or right). For convenience of explanation, the sign of "lateral acceleration" is defined as positive when it is to the left relative to the forward direction of the vehicle, and as negative when it is to the right. Similarly, the direction in which the vehicle turns left is defined as the positive direction of the steering angle, and the direction in which the vehicle turns right is defined as the negative direction of the steering angle.

[0010] (composition) 1 is a schematic configuration diagram of an example of a vehicle control device according to an embodiment. A vehicle 1 is equipped with a vehicle control device 10 that controls the driving of the vehicle 1. The driving control by the vehicle control device 10 includes autonomous driving control that automatically drives the vehicle 1 without the involvement of a driver based on the driving environment around the vehicle 1, and driving assistance control that assists the driver in driving the vehicle 1 by controlling at least one of driving, braking, and steering of the vehicle 1. The driving assistance control may be, for example, automatic steering, automatic braking, preceding vehicle following control, constant speed driving control, lane keeping control, merging assistance control, etc.

[0011] The vehicle control device 10 includes an object sensor 11, a vehicle sensor 12, a positioning device 13, a map database (map DB) 14, a communication device 15, a navigation device 16, an actuator 17, a controller 18, and a seat actuator 19. The object sensor 11 includes a plurality of different types of object detection sensors mounted on the vehicle 1, such as a laser radar, a millimeter wave radar, a camera, and a LIDAR (Light Detection and Ranging, Laser Imaging Detection and Ranging) that detect objects around the vehicle 1.

[0012] The vehicle sensor 12 is mounted on the vehicle 1 and detects various information (vehicle signals) obtained from the vehicle 1. For example, the vehicle sensor 12 includes a vehicle speed sensor that detects the vehicle speed of the vehicle 1, a wheel speed sensor that detects the rotational speed of the tires of the vehicle 1, a three-axis acceleration sensor that detects the acceleration and deceleration in three axial directions of the vehicle 1, a yaw rate sensor that detects the yaw angular velocity (yaw rate) of the vehicle body, and a roll rate sensor that detects the roll angular velocity of the vehicle body. The vehicle sensor 12 includes, for example, an accelerator sensor for detecting the accelerator opening degree of the vehicle, a brake sensor for detecting the brake operation amount by the driver, a steering angle sensor for detecting the steering angle of the steered wheels, and a steering angle θ of the steering wheel. s The steering angle sensor detects the steering angle velocity ω of the steering wheel. s This information can also be obtained from the vehicle sensor 12.

[0013] The positioning device 13 includes a Global Navigation System (GNSS) receiver and receives radio waves from multiple navigation satellites to measure the current position of the vehicle 1. The GNSS receiver may be, for example, a Global Positioning System (GPS) receiver. The positioning device 13 may also be, for example, an inertial navigation system. The map database 14 stores road map data. For example, the map database 14 may store high-precision map data suitable as map information for automated driving. The map database 14 may also store map data for navigation. The communication device 15 performs wireless communication with a communication device outside the vehicle 1. The communication method used by the communication device 15 may be, for example, wireless communication using a public mobile phone network, vehicle-to-vehicle communication, road-to-vehicle communication, or satellite communication.

[0014] The navigation device 16 recognizes the current position of the vehicle using the positioning device 13 and obtains map information for the current position from the map database 14. The navigation device 16 sets a driving route to the destination input by the occupant and provides route guidance to the occupant along this driving route. The navigation device 16 also outputs information about the set driving route to the controller 18. During autonomous driving control, the controller 18 automatically drives the vehicle 1 so that the vehicle travels along the driving route set by the navigation device 16.

[0015] The actuator 17 is a device that performs operations to bring the vehicle 1 into a desired motion state in response to a control signal from the controller 18. The actuator 17 mainly includes a drive system actuator that adjusts the acceleration of the vehicle 1 in the longitudinal direction, and a steering system actuator that adjusts the turning motion of the vehicle 1. If the vehicle 1 is equipped with an engine as a driving source, the drive system actuator may include a throttle valve that adjusts the amount of air supplied to the engine (throttle opening), and a friction brake that adjusts the braking force applied to the wheels of the vehicle 1.

[0016] If the vehicle 1 is equipped with a motor as a driving source (if it is a hybrid vehicle or an electric vehicle), the drivetrain actuator may include a power adjustment device (such as an inverter and a converter) that adjusts the power supplied to the motor. In this case, the deceleration function of the drivetrain actuator may be achieved by regenerative driving (regenerative braking) instead of or in addition to a friction brake. On the other hand, the steering actuator may include an assist motor that controls the steering torque in an electric power steering system, or a steering motor that controls the steering torque in a steer-by-wire system.

[0017] The seat actuator 19 is an actuator that rotates the seat back of a vehicle seat provided in the passenger compartment of the vehicle 1 in the yaw direction of the vehicle 1, thereby changing the orientation of the seat back in the fore-and-aft direction. Here, the yaw direction of the vehicle 1 is the direction of rotation about a rotation axis that is perpendicular to the fore-and-aft and lateral directions of the vehicle 1 (hereinafter sometimes referred to as the "vertical direction"). Also, the fore-and-aft direction of the seat back is the direction perpendicular to the front of the seat back. The seat actuator 19 may rotate (pivot) only the seat back relative to the seat cushion of the vehicle seat, or may rotate the seat back and seat cushion together (that is, may rotate the vehicle seat).

[0018] The controller 18 is an electronic control unit (ECU) that controls the driving of the vehicle 1. Furthermore, the controller 18 drives a seat actuator 19 to control the front-to-rear orientation of the seat back of the vehicle seat. The controller 18 includes a processor 18a and peripheral components such as a storage device 18b. The processor 18a may be, for example, a CPU or an MPU.

[0019] The storage device 18b may include a semiconductor storage device, a magnetic storage device, an optical storage device, etc. The storage device 18b may include memories such as a register, a cache memory, and a ROM and a RAM used as a main storage device. The functions of the controller 18 described below are realized by, for example, the processor 18a executing a computer program stored in the storage device 18b. The controller 18 may be formed of dedicated hardware for executing the various information processes described below. For example, the controller 18 may include a functional logic circuit configured in a general-purpose semiconductor integrated circuit. For example, the controller 18 may include a PLD such as an FPGA.

[0020] Next, a method for controlling a vehicle seat of a vehicle 1 by the vehicle control device 10 of the embodiment will be described. For ease of explanation, the directions and angles of the vehicle 1 used in this specification are defined as shown in FIG. 2. Reference character O indicates an occupant riding in the vehicle 1, and reference character S indicates a vehicle seat in which the occupant O sits. The occupant O may be a driver or a passenger. The vehicle seat S includes at least a seat back Sb and a seat cushion Sc.

[0021] The "vertical direction," "front-rear direction," and "lateral direction" are referred to as the ζ-axis direction, the ξ-axis direction, and the η-axis direction, respectively. Furthermore, the angle in the ζ-η plane, with the trunk of occupant O as the axis, from the ζ axis toward the η axis, is expressed as the "roll attitude angle Φ." The angle in the ζ-ξ plane, with the trunk of occupant O as the axis, with the direction from the ζ axis toward the ξ axis, is expressed as the "pitch attitude angle Ψ."

[0022] When the vehicle 1 undergoes a lateral transient movement (hereinafter referred to as "lateral transient movement"), the vehicle control device 10 changes the orientation of the seat back Sb, thereby reducing the body sway of the occupant O caused by the lateral inertial acceleration acting on the occupant O and improving the comfort of the occupant while riding. In this specification, the term "lateral transient motion" refers to motion in which lateral acceleration changes (i.e., motion in which lateral jerk occurs).

[0023] In Patent Document 1, the body of the occupant O is pressed against the seat back Sb by tilting the seat back Sb so that the inertial acceleration acting on the occupant O in accordance with the movement of the vehicle 1 is resolved into force components in directions that press the occupant O against the seat back Sb in the fore-and-aft direction of the trunk of the occupant O. This increases the friction between the seat back Sb and the body of the occupant O, thereby reducing the change in the roll attitude angle Φ of the body of the occupant O relative to the seat back Sb.

[0024] Generally, the comfort of a passenger O while riding in the vehicle can be improved by reducing the body sway of the passenger O in response to the movement of the vehicle 1. For example, car sickness is thought to be caused by a mismatch between the movement perceived by the kinesthetic organs due to the movement of the passenger's body and head and the recognition of movement by the passenger's vision, etc. (Motion Conflict Theory). By pressing the body of the occupant O against the seat back Sb as in Patent Document 1, the change in posture of the occupant O during lateral movement of the vehicle 1 can be suppressed, which is expected to have the effect of reducing car sickness.

[0025] On the other hand, since inertial acceleration also occurs in the fore-and-aft direction of the occupant's body, the occupant is subjected to acceleration in the fore-and-aft direction due to the lateral movement of the vehicle. As a result, the occupant's body is moved not only in the roll direction but also in the pitch direction. In particular, the head is easily moved by the fore-and-aft acceleration. As a result, there is a risk that the effect of reducing car sickness by reducing the change in the roll attitude angle Φ of the occupant O will be offset by the tendency to induce car sickness due to the body and head movement in the pitch direction.

[0026] Figures 3(a) to 3(c) show the simulation results of the maximum amplitude of the roll attitude angle Φ of the occupant O when a small longitudinal acceleration is applied to a vehicle performing a lateral transient motion. Here, as shown in Figures 3(a) and 3(b), a lateral transient motion such as a lane change causes an amplitude of 1.5 [m / s 2 While generating a sinusoidal lateral acceleration of ±0.25 [m / s], the threshold acceleration (hereinafter referred to as "threshold acceleration") that is the threshold for whether or not the occupant O can recognize the vehicle is set. 2 ] is added.

[0027] Generally, the lower limit of acceleration that a human can perceive in the front-to-back direction of the body in a static laboratory environment (hereinafter referred to as the "standard sensory threshold") is approximately 0.05 to 0.1 m / s 2 However, when exposed to external factors such as vibrations in a vehicle driving environment, the threshold acceleration for whether or not the occupant O can recognize the vehicle is approximately 0.2 to 0.3 m / s. 2Even if a longitudinal acceleration of this magnitude is applied, it is difficult for the occupant O to recognize it as acceleration or deceleration.

[0028] In contrast, there is a clear difference in the body movement of occupant O, as shown in Figure 3(c), with a negative longitudinal acceleration (-0.25 m / s 2 ]) is added, the positive forward / backward acceleration (0.25 [m / s 2 ]) is added, the roll attitude angle Φ of the occupant O is significantly reduced. This effect is thought to be due to an increase or decrease in friction caused by a change in the pressing load of the occupant O against the seat back Sb. From these results, it can be seen that there exists an acceleration range in which the change in posture of the occupant O can be reduced by acceleration or deceleration in the longitudinal direction without causing discomfort or inducing car sickness.

[0029] Therefore, the inventors of the present invention used an inverted pendulum-type occupant model to simulate changes in the roll attitude angle Φ of the occupant O when a threshold acceleration (±0.025 G) in the longitudinal direction is applied when the vehicle 1 performs a lateral transient motion. Figures 4(a) to 4(c) show simulation results of the maximum amplitude of the roll attitude angle Φ of the occupant O when the roll direction attitude change stiffness of the occupant O is increased or decreased by a threshold acceleration (±0.025 G) in the longitudinal direction when the vehicle 1 performs a predetermined lateral transient motion (lane change). In this lane change, after a certain time (in this case, 4 seconds), vehicle 1 moves to the adjacent lane (the amount of lateral movement is specified) and returns to straight-ahead driving.The driving intention is set so that the vehicle speed is the same at the initial speed and the end point, and then optimization calculations are performed, and the optimal solution is calculated both with and without adding a threshold acceleration.

[0030] When changing lanes, two transient movements occur in which the direction of lateral acceleration reverses: in the phase in which the vehicle's longitudinal direction is directed toward an adjacent lane (hereinafter referred to as "movement phase I"), and in the phase in which the vehicle's longitudinal direction is returned to its original position (hereinafter referred to as "return phase II"). For each transient movement, it was found that the change in the roll attitude angle Φ of the body of occupant O was minimized when vehicle 1 was decelerated in the section in which the absolute value of acceleration increased, and when vehicle 1 was accelerated in the section in which the absolute value of acceleration decreased. The simulation results showed that the change in roll attitude angle Φ of occupant O was reduced by approximately 17% compared to when no longitudinal acceleration was applied to vehicle 1.

[0031] In the present invention, instead of applying such a threshold acceleration in the fore-and-aft direction, the seat back Sb is rotated, and the inertial acceleration applied to the occupant O due to the lateral movement of the vehicle 1 is vector-decomposed into a component parallel to the fore-and-aft direction of the seat back Sb and a component perpendicular to the fore-and-aft direction of the seat back Sb, thereby generating an acceleration in the fore-and-aft direction of the trunk of the occupant O's body (i.e., the fore-and-aft direction of the seat back Sb). If the acceleration in the front-rear direction of the seat back Sb is generated in the same manner as the acceleration in FIG. 4(b), it is possible to obtain the same effect as the simulation result in FIG. 4(c). In the following description, the component parallel to the fore-and-aft direction of the seat back Sb generated from the inertial acceleration applied to the occupant O due to the lateral movement of the vehicle 1 by changing the orientation of the seat back Sb may be referred to as the "seat back vertical acceleration component."

[0032] An example of setting the seatback vertical acceleration component will be described with reference to Figures 5(a) and 5(b). Figure 5(a) is a graph showing the time change in the lateral acceleration and lateral jerk of the vehicle body that occur when vehicle 1 changes lanes, and Figure 5(b) is a graph showing an example of setting the direction of the seatback vertical acceleration component. Whether the absolute value of the lateral acceleration is increasing or decreasing can be determined by the sign of the product of the lateral acceleration and the lateral jerk (first-order derivative of the lateral acceleration). For this purpose, for example, the controller 18 may acquire the lateral acceleration detected by the three-axis acceleration sensor of the vehicle sensor 12 and calculate the lateral jerk by differentiating the lateral acceleration. Then, the direction of the seatback vertical acceleration component may be set based on the sign function Sgn [lateral acceleration × lateral jerk]. The sign function Sgn[x] is a function such that Sgn[x] = +1 when variable x > 0, Sgn[x] = 0 when variable x = 0, and Sgn[x] = -1 when variable x < 0. Specifically, when the value of the sign function Sgn [lateral acceleration × lateral jerk] is "1," the absolute value of the lateral acceleration increases, so the direction of the seatback vertical acceleration component is set to the deceleration direction (i.e., forward).On the other hand, when the value of the sign function Sgn [lateral acceleration × lateral jerk] is "-1," the absolute value of the lateral acceleration decreases, so the direction of the seatback vertical acceleration component is set to the acceleration direction (i.e., backward).

[0033] In the examples of Figures 5(a) and 5(b), the lane change of vehicle 1 includes a first phase I-1 in which the signs of both the lateral acceleration and the lateral jerk are positive, a second phase I-2 in which the sign of the lateral acceleration is positive and the sign of the lateral jerk is negative, a third phase II-1 in which the signs of both the lateral acceleration and the lateral jerk are negative, and a fourth phase II-2 in which the sign of the lateral acceleration is negative and the sign of the lateral jerk is positive. Therefore, the direction of the seat back vertical acceleration component is set to the deceleration direction in the first phase I-1 and the third phase II-1, and the direction of the seat back vertical acceleration component is set to the acceleration direction in the second phase I-2 and the fourth phase II-2.

[0034] 6 is a schematic diagram illustrating the relationship between the motion of the vehicle 1 during a lane change and the inertial acceleration acting on the occupant O. Here, the case where the vehicle 1 changes lanes to the left lane will be explained as an example. When changing lanes to the right lane, the explanation of the symbols will be reversed. In the movement phase I, a turning force in the positive direction is applied to move the vehicle 1 from the current driving lane to the adjacent lane to which the vehicle is to change lanes (steering angle θ sAs a result, a lateral acceleration Ay to the left is generated in the vehicle 1, and an inertial acceleration Ai to the right acts on the occupant O. In the movement phase I, the steering angle θ s from 0 to the maximum steering angle θ smax The first phase I-1 increases to the steering angle θ s is the maximum steering angle θ smax The absolute value of the lateral acceleration Ay increases in the first phase I-1, and decreases in the second phase I-2.

[0035] On the other hand, in the return phase II, a turning force in the negative direction is applied to the vehicle 1 in the adjacent lane to which the vehicle has been changed to return to its original direction (the steering angle θs becomes negative). As a result, a lateral acceleration Ay to the right is generated in the vehicle 1, and an inertial acceleration Ai to the left acts on the occupant O. In the return phase II, the steering angle θ s is 0 to the minimum steering angle θ smin Phase II-1, in which the steering angle is reduced to θ s is the minimum steering angle θ smin The absolute value of the lateral acceleration Ay increases in the third phase II-1, and decreases in the fourth phase II-2.

[0036] 7(a) to 7(d) show examples of setting the orientation of the seat back Sb in the first phase I-1, the second phase I-2, the third phase II-1, and the fourth phase II-2, respectively. By tilting the back of the seat back Sb in the longitudinal direction relative to the longitudinal direction of the vehicle body, the lateral (vehicle width direction) inertial acceleration Ai acting on the occupant O is decomposed into a seat back vertical acceleration component A1 (i.e., a component parallel to the longitudinal direction of the seat back Sb) and a component A2 perpendicular to the longitudinal direction of the seat back Sb.

[0037] In the first phase I-1 and the third phase II-1, the seat back Sb is rotated so that the direction of the seat back vertical acceleration component A1 is in the deceleration direction (i.e., forward direction) as shown in Figures 7(a) and 7(c). To this end, the controller 18 sets the orientation of the seat back Sb so that the direction perpendicular to the front surface of the seat back Sb (i.e., the direction of the seat back vertical acceleration component A1) is inclined in the opposite direction to the steering direction with respect to the forward direction of the vehicle body. For example, in the first phase I-1 (FIG. 7(a)), the steering is to the left, so the orientation of the seat back Sb is set so that the direction perpendicular to the front of the seat back Sb is tilted to the right with respect to the forward direction of the vehicle body. In the third phase II-1 (FIG. 7(c)), the steering is to the right, so the orientation of the seat back Sb is set so that the direction perpendicular to the front of the seat back Sb is tilted to the left with respect to the forward direction of the vehicle body.

[0038] In the second phase I-2 and the fourth phase II-2, the seat back Sb is rotated so that the direction of the seat back vertical acceleration component A1 is the acceleration direction (i.e., backward direction) as shown in Figures 7(b) and 7(d). To this end, the controller 18 sets the orientation of the seat back Sb so that the direction perpendicular to the front surface of the seat back Sb is inclined toward the steering direction with respect to the forward direction of the vehicle body. For example, in the second phase I-2 (FIG. 7(b)), the steering is to the left, so the orientation of the seat back Sb is set so that the direction perpendicular to the front of the seat back Sb is tilted to the left with respect to the forward direction of the vehicle body. In the fourth phase II-2 (FIG. 7(d)), the steering is to the right, so the orientation of the seat back Sb is set so that the direction perpendicular to the front of the seat back Sb is tilted to the right with respect to the forward direction of the vehicle body.

[0039] The inclination angle α of the seat back Sb, which is inclined from the direction perpendicular to the front surface of the vehicle body, is set to, for example, a value at which the seat back vertical acceleration component A1 generated by inclining the seat back Sb exceeds a threshold acceleration (approximately 0.2 to approximately 0.3 [m / s 2 ]) You can set it to the following: For example, the maximum lateral inertial acceleration that occurs during a normal lane change is set to 1.5 m / s 2 ] and set the engine braking acceleration / deceleration rate that is thought to be least uncomfortable for occupant O to 0.25 [m / s 2 ], it is estimated to be 0.25 [m / s 2 The tilt angle α that generates the seat back vertical acceleration component A1 of [amount] is approximately 9.6 [deg].

[0040] 8(a) to 8(d), a second example of a method for setting the direction of the seat back vertical acceleration component will be described. Here, instead of the lateral acceleration and lateral jerk, the steering angle θ s and steering angular velocity ω s The direction of the seat back vertical acceleration component is set based on the Steering angle θ s and steering angular velocity ω s In electronically controlled steering systems, lateral jerk can be obtained using sensor signals that are almost always provided as standard. On the other hand, lateral jerk can be obtained by differentiating the lateral acceleration sensor signal, but noise components increase during the calculation process, which can easily reduce accuracy.

[0041] In the transient vehicle motion in the linear region assumed in this specification (i.e., the region in which the tire lateral force can be approximated as linearly proportional to the tire slip angle), the shape of the waveform of the lateral acceleration and the steering angle θ s The waveform shapes of the lateral jerk and steering angular velocity ω are almost the same. s Therefore, instead of the lateral acceleration and the lateral jerk, the steering angle θ s and steering angular velocity ω s is available.

[0042] FIG. 8(a) is a graph showing the time variation of the lateral acceleration and lateral jerk of the vehicle body that occurs when the vehicle 1 changes lanes, FIG. 8(b) is a graph showing an example of setting the direction of the vertical acceleration component of the seat back, and FIG. 8(c) is a graph showing the time variation of the steering angle θ s and steering angular velocity ω s8(d) is a graph of a composite code D obtained by combining the sign of the steering angle and the sign of the steering angular velocity. As well as the lateral acceleration and lateral jerk, the steering angle θ s and steering angular velocity ω s It is possible to determine whether the absolute value of the lateral acceleration is increasing or decreasing based on the sign of

[0043] For example, the controller 18 detects the steering angle θ s and steering angle θ s By differentiating the steering angular velocity ω s Then, the composite code D=-Sgn[θ s ×ω s ], it may be determined whether the absolute value of the lateral acceleration is increasing or decreasing, and the direction of the seat back vertical acceleration component may be set. Specifically, when the value of the composite code D is "-1," it is determined that the absolute value of the lateral acceleration increases, and the direction of the seatback vertical acceleration component is set to the deceleration direction (i.e., forward direction). Conversely, when the value of the composite code D is "1," it is determined that the absolute value of the lateral acceleration decreases, and the direction of the seatback vertical acceleration component is set to the acceleration direction (i.e., backward direction).

[0044] In the above-described example of setting the seat back vertical acceleration component, the seat back Sb is rotated so that the seat back vertical acceleration component becomes a forward component, and then the seat back Sb is rotated so that the seat back vertical acceleration component becomes a backward component. However, it is not necessary to perform both rotations that result in the seat back vertical acceleration component becoming a forward component and a backward component. In other words, if the seat back Sb is rotated so that the seat back vertical acceleration component becomes a forward component during the period when the absolute value of the lateral acceleration is increasing, or if the seat back Sb is rotated so that the seat back vertical acceleration component becomes a backward component during the period when the absolute value of the lateral acceleration is decreasing, it can be expected that the change in the roll attitude angle Φ of the occupant O will be reduced.

[0045] (operation) FIG. 9 is a flowchart of a first example of a method for controlling a vehicle seat according to the embodiment. In step S1, the three-axis acceleration sensor of the vehicle sensor 12 detects the lateral acceleration of the vehicle 1. In step S2, the controller 18 calculates the lateral jerk by differentiating the lateral acceleration. In step S3, the controller 18 calculates a sign function Sgn [lateral acceleration × lateral jerk] of the product of the lateral acceleration and the lateral jerk, and sets the direction of the seat back vertical acceleration component based on the value of the calculated sign function Sgn [lateral acceleration × lateral jerk]. The controller 18 generates a command signal (hereinafter sometimes referred to as a "seat back rotation command signal") to rotate the seat back Sb by a predetermined tilt angle α so as to generate a seat back vertical acceleration component in the set direction.

[0046] In step S4, the controller 18 performs high-pass filtering on the seat back rotation command signal. The high-pass filtering eliminates steady-state motion of the vehicle 1, and corrects the seat back rotation command signal so that it has a value only during transient motion. In step S5, the controller 18 applies low-pass filtering to the seat back rotation command signal after the high-pass filtering, thereby reducing the influence of the rotation of the seat back Sb by the seat actuator 19 on the occupant's kinesthetic perception. In step S6, the controller 18 outputs the low-pass filtered seat back rotation command signal to the seat actuator 19, and tilts the front-to-rear direction of the back of the seat back Sb relative to the front-to-rear direction of the vehicle body so that the direction of the seat back vertical acceleration component becomes the direction set in step S3. Then, the process ends.

[0047] FIG. 10 is a flowchart of a second example of the method for controlling a vehicle seat according to the embodiment. In step S11, the controller 18 detects that the steering angle sensor of the vehicle sensor 12 detects the steering angle θ of the steering wheel. s Detect. In step S12, the controller 18 calculates the steering angular velocity ω s The steering angle velocity signal is acquired from the vehicle sensor 12. The controller 18 controls the steering angle θ s By differentiating the steering angular velocity ω s may be calculated. In step S13, the controller 18 calculates the composite code D=-Sgn[θ s ×ω s ] and sets the direction of the seat back vertical acceleration component based on the composite code D. The controller 18 generates a seat back rotation command signal so as to generate a seat back vertical acceleration component in the set direction. The processing in steps S14 to S16 is the same as the processing in steps S4 to S6 described with reference to FIG.

[0048] (Variation) When the vehicle 1 undergoes a lateral transient motion, the controller 18 may rotate the seat back Sb as described above and may also apply a small longitudinal acceleration to the vehicle 1. This allows a synergistic effect to be exerted between the effect of reducing the posture change of the occupant O caused by rotating the orientation of the seat back Sb in the yaw direction of the vehicle 1 during a lateral transient motion and the effect of reducing the posture change of the occupant O caused by applying a longitudinal acceleration to the vehicle 1.

[0049] Specifically, the controller 18 sets the basic longitudinal acceleration Ab to be generated in the vehicle 1 according to the amount of accelerator pedal operation by the driver or the required driving force set by autonomous driving control or driving assistance control. The basic longitudinal acceleration Ab corresponds to a target value of acceleration (a target value according to the required driving force) for realizing intended translational motion of the vehicle 1 according to the driving scene.

[0050] Next, the controller 18 calculates the longitudinal acceleration (hereinafter referred to as the "corrected longitudinal acceleration Ac") to be applied in order to suppress a change in the posture of the occupant O. For example, the controller 18 may set the corrected longitudinal acceleration Ac based on the following equation (1) or (2). Ac=-Sgn[lateral acceleration×lateral jerk]×|a|…(1) Ac=-Sgn[θ s ×ω s ]×|a|…(1) Here, |a| is a predetermined set acceleration amount.

[0051] That is, the controller 18 decelerates the vehicle 1 when the seat back Sb is rotated so that the seat back vertical acceleration component (the lateral acceleration component parallel to the fore-and-aft direction of the seat back Sb) becomes a forward component, and accelerates the vehicle 1 when the seat back Sb is rotated so that the seat back vertical acceleration component becomes a backward component. It is preferable to set the time for applying the negative corrective longitudinal acceleration Ac and the time for applying the positive corrective longitudinal acceleration Ac to be approximately the same length, so that the average speed change becomes approximately zero and the intended vehicle motion is not impaired.

[0052] The controller 18 calculates the target longitudinal acceleration At by adding the corrected longitudinal acceleration Ac to the basic longitudinal acceleration Ab. The controller 18 calculates the operation amount of the actuator 17 so that the actual longitudinal acceleration of the vehicle 1 approaches the target longitudinal acceleration At, and controls the actuator 17 based on the operation amount. More specifically, the controller 18 controls the throttle opening, motor output, or friction brake so as to satisfy the target longitudinal acceleration At.

[0053] In particular, if the vehicle 1 is an electric vehicle, the controller 18 operates the power regulation device to apply a positive torque to the motor when increasing the magnitude of the target longitudinal acceleration At (accelerating the vehicle 1). On the other hand, when decreasing the magnitude of the target longitudinal acceleration At (decelerating the vehicle 1), the controller 18 operates the power regulation device to apply a negative torque to the motor, or increases the braking force of the friction brake, or performs both of these operations.

[0054] (Effects of the embodiment) (1) The controller 18 controls a vehicle seat S in which at least the seat back Sb is rotatable in the yaw direction of the vehicle 1. The vehicle sensor 12 detects at least one of the lateral acceleration and the steering angle of the vehicle 1, determines whether the absolute value of the lateral acceleration increases or decreases based on at least one of the lateral acceleration and the steering angle, and rotates the seat back Sb so that the component of the lateral acceleration parallel to the fore-and-aft direction of the seat back Sb becomes a forward component during a period in which the absolute value of the lateral acceleration of the vehicle 1 is increasing, and / or rotates the seat back Sb so that the component of the lateral acceleration parallel to the fore-and-aft direction of the seat back Sb becomes a backward component during a period in which the absolute value of the lateral acceleration is decreasing.

[0055] This allows the orientation of the seat back Sb to be controlled in accordance with the sections in which the lateral acceleration due to vehicle movement increases and decreases, thereby vector-decomposing the lateral inertial acceleration acting on the body of the occupant O into a component parallel to the fore-and-aft direction of the seat back Sb (seat back vertical acceleration component) and a vertical component, and using the seat back vertical acceleration component, it is possible to suppress transient changes in the body posture of the occupant O seated in the vehicle seat S.

[0056] In particular, the direction of the inertial acceleration acting on the body of the occupant O in the fore-and-aft direction of the seat back Sb changes between the section where the lateral acceleration increases and the section where it decreases, thereby suppressing a decrease in comfort caused by the body being continuously pressed against the seat back Sb. Furthermore, in the first half of the lateral transient motion in which the absolute value of the lateral acceleration increases, the seatback vertical acceleration component becomes a forward component, so the body surface pressure of the occupant O on the seatback Sb can be reduced. This reduces the constraint on the body movement from the seatback Sb, and reduces the forced movement of the occupant O to follow the vehicle body roll movement, resulting in suppression of changes in the occupant posture.

[0057] Furthermore, in the latter half of the lateral transient motion where the absolute value of the lateral acceleration decreases, the seatback vertical acceleration component becomes a backward component, so the body surface pressure of the occupant O on the seatback Sb can be increased. This increases the restraint on the body movement from the seatback Sb, making it easier for the body movement of the occupant O, which moves with a delay relative to the vehicle body roll movement, to follow the seat, and as a result, changes in the posture of the occupant O can be suppressed.

[0058] (2) The controller 18 may rotate the seat back Sb so that the component of the lateral acceleration parallel to the fore-and-aft direction of the seat back Sb becomes a forward component during a period in which the absolute value of the lateral acceleration is increasing, and then rotate the seat back Sb so that the component of the lateral acceleration parallel to the fore-and-aft direction of the seat back Sb becomes a backward component during a period in which the absolute value of the lateral acceleration is decreasing. This causes the direction of the inertial acceleration acting on the body of the occupant O in the fore-and-aft direction of the seat back Sb to change between sections where the lateral acceleration increases and sections where it decreases, thereby preventing a decrease in comfort due to the body being continuously pressed against the seat back Sb.

[0059] (3) The controller 18 may calculate the lateral jerk based on the lateral acceleration, and determine that the absolute value of the lateral acceleration increases when the sign of the product obtained by multiplying the lateral acceleration and the lateral jerk is positive, and determine that the absolute value of the lateral acceleration decreases when the sign of the product is negative. This allows the orientation of the seat back Sb to be determined to suppress changes in the posture of the occupant O.

[0060] (4) The controller 18 may detect the steering angle of the vehicle 1, calculate the steering angular velocity based on the steering angle, and determine that the absolute value of the lateral acceleration increases if the sign of the product obtained by multiplying the steering angle and the steering angular velocity is positive, and determine that the absolute value of the lateral acceleration decreases if the sign of the product is negative. This allows the orientation of the seat back Sb to be determined to suppress changes in the posture of the occupant O.

[0061] (5) The controller 18 may decelerate the vehicle 1 when the seat back Sb is rotated so that the component of the lateral acceleration parallel to the fore-and-aft direction of the seat back Sb becomes a forward component, and may accelerate the vehicle 1 when the seat back Sb is rotated so that the component of the lateral acceleration parallel to the fore-and-aft direction of the seat back Sb becomes a backward component. This allows for a synergistic effect of reducing the posture change of the occupant O that occurs when the seat back Sb is rotated in the yaw direction of the vehicle 1 during lateral transient movement, and a synergistic effect of reducing the posture change of the occupant O that occurs when longitudinal acceleration is applied to the vehicle 1. [Explanation of symbols]

[0062] 1...vehicle, 10...vehicle control device, 11...object sensor, 12...vehicle sensor, 13...positioning device, 14...map database, 15...communication device, 16...navigation device, 17...actuator, 18...controller, 18a...processor, 18b...storage device, 19...seat actuator, O...occupant, S...vehicle seat, Sb...seat back, Sc...seat cushion

Claims

1. A method for controlling a vehicle seat in which at least a seat back is rotatable in a yaw direction of the vehicle, comprising: Detecting at least one of a lateral acceleration and a steering angle of the vehicle; determining whether the absolute value of the lateral acceleration increases or decreases based on at least one of the lateral acceleration and the steering angle; During a period in which the absolute value of the lateral acceleration of the vehicle is increasing, the seat back is rotated so that a component of the lateral acceleration parallel to the front-rear direction of the seat back becomes a forward component, and during a period in which the absolute value of the lateral acceleration is decreasing, the seat back is rotated so that the component of the lateral acceleration parallel to the front-rear direction of the seat back becomes a backward component. A control method comprising:

2. 2. The control method according to claim 1, wherein, during a period in which the absolute value of the lateral acceleration is increasing, the seat back is rotated so that the component of the lateral acceleration parallel to the fore-and-aft direction of the seat back becomes a forward component, and then, during a period in which the absolute value of the lateral acceleration is decreasing, the seat back is rotated so that the component of the lateral acceleration parallel to the fore-and-aft direction of the seat back becomes a backward component.

3. calculating a lateral jerk based on the lateral acceleration; 3. The control method according to claim 1, wherein the absolute value of the lateral acceleration is determined to increase when the sign of the product obtained by multiplying the lateral acceleration and the lateral jerk is positive, and the absolute value of the lateral acceleration is determined to decrease when the sign of the product is negative.

4. Calculating a steering angular velocity based on the steering angle; determining that the absolute value of the lateral acceleration increases when the sign of the product obtained by multiplying the steering angle and the steering angular velocity is positive, and determining that the absolute value of the lateral acceleration decreases when the sign of the product is negative; 3. The control method according to claim 1 or 2.

5. decelerating the vehicle when the seat back is rotated so that a component of the lateral acceleration parallel to a front-rear direction of the seat back becomes a forward component; accelerating the vehicle when the seat back is rotated so that a component of the lateral acceleration parallel to the front-rear direction of the seat back becomes a rearward component; 5. The control method according to claim 1, wherein the control method is a control method for controlling a power supply.

6. A control device for a vehicle seat in which at least a seat back is rotatable in a yaw direction of the vehicle, a sensor for detecting at least one of a lateral acceleration and a steering angle of the vehicle; a controller that determines whether an absolute value of the lateral acceleration of the vehicle is increasing or decreasing based on at least one of the lateral acceleration or the steering angle, and rotates the seat back so that a component of the lateral acceleration parallel to the fore-and-aft direction of the seat back becomes a forward component during a period when the absolute value of the lateral acceleration of the vehicle is increasing, and rotates the seat back so that a component of the lateral acceleration parallel to the fore-and-aft direction of the seat back becomes a backward component during a period when the absolute value of the lateral acceleration is decreasing.

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