Vehicle control device

Abstract

To provide a vehicle control device that executes a steering control further compatible with the displacement of the neutral point of a steering angle.SOLUTION: In a vehicle control device 1, a neutral point deciding unit of a vehicle control unit 11 decides the neutral point of a steering angle of a steering wheel which causes an automobile to run straight relative to loads on turning wheels that cause the automobile to turn in accordance with the steering angle of the steering wheel of the automobile, and a steering control unit of the vehicle control unit 11 executes a steering control on the automobile on the basis of the neutral point decided by the neutral point deciding unit. Accordingly, a steering control can be executed which is further compatible with the displacement of the neutral point of the steering angle corresponding to the loads on the turning wheels.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vehicle control device. [Background technology]

[0002] Technologies for performing steering control of automobiles have been proposed. For example, Patent Document 1 discloses a device that determines the neutral point of the steering angle of a steering mechanism using the detection value of a yaw rate sensor whose detection characteristics change depending on temperature, detects the value of the steering angle based on the determined neutral point of the steering angle, and applies a steering torque to the steering mechanism so that the value of the steering angle follows a target steering angle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6743719 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the technology for performing steering control of an automobile as described above, the neutral point of the steering angle may shift depending on the driving conditions of the automobile, and there is a demand for a technology for performing steering control that responds to such a shift in the neutral point of the steering angle.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a vehicle control device that executes steering control in response to deviations in the neutral point of the steering angle. [Means for solving the problem]

[0006] The present invention is a vehicle control device that includes a neutral point determination unit that determines the neutral point of the steering wheel angle at which the vehicle moves straight in response to the load on the steering wheels that turns the vehicle in accordance with the steering angle of the steering wheel of the vehicle, and a steering control unit that performs steering control of the vehicle based on the neutral point determined by the neutral point determination unit.

[0007] According to this configuration, the neutral point determination unit determines the neutral point of the steering wheel angle at which the vehicle moves straight in response to the load on the steering wheels that turns the vehicle in accordance with the steering angle of the steering wheel of the vehicle, and the steering control unit executes steering control of the vehicle based on the neutral point determined by the neutral point determination unit, so that steering control can be executed in response to the shift in the neutral point of the steering angle caused by the load on the steering wheels.

[0008] In this case, the vehicle may further include a load detection unit that detects the load on the steering wheels, and the neutral point determination unit may determine the neutral point based on a record of the steering wheel angle at which the vehicle moves straight in response to the load on the steering wheels detected by the load detection unit.

[0009] According to this configuration, the load on the steering wheel is detected by the load detection unit, and the neutral point determination unit determines the neutral point based on the record of the steering wheel angle when the vehicle moves straight in response to the load on the steering wheel detected by the load detection unit, thereby making it possible to more accurately determine the neutral point of the steering angle corresponding to the load on the steering wheel.

[0010] The vehicle may further include a load detection unit that detects the load on the steering wheel, and the neutral point determination unit may determine the neutral point based on the load on the steering wheel detected by the load detection unit and a predetermined relationship between the load on the steering wheel and the neutral point.

[0011] According to this configuration, the load on the steering wheel is detected by the load detection unit, and the neutral point is determined by the neutral point determination unit based on the load on the steering wheel detected by the load detection unit and a predetermined relationship between the load on the steering wheel and the neutral point, so that the neutral point of the steering angle corresponding to the load on the steering wheel can be determined with more responsiveness.

[0012] The vehicle may further include a deceleration detection unit that detects the deceleration of the vehicle, and the neutral point determination unit may determine the neutral point based on the deceleration detected by the deceleration detection unit and a predetermined relationship between the deceleration and the neutral point.

[0013] According to this configuration, the deceleration detection unit detects the deceleration of the vehicle, and the neutral point determination unit determines the neutral point based on the deceleration detected by the deceleration detection unit and a predetermined relationship between the deceleration and the neutral point, so that it is possible to determine the neutral point of the steering angle corresponding to the load on the steering wheels, which fluctuates depending on the deceleration of the vehicle.

[0014] The motor vehicle may also be a commercial vehicle.

[0015] This configuration is useful in commercial vehicles, where the load on the steering wheel is likely to fluctuate depending on the number of passengers or load, and the neutral point is likely to shift, because it allows steering control to be performed in response to the shift in the neutral point of the steering angle caused by the load on the steering wheel. [Effects of the Invention]

[0016] According to the vehicle control device of the present invention, steering control can be performed in response to a deviation of the neutral point of the steering angle. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a block diagram showing a hardware configuration of a vehicle control device according to an embodiment; [Figure 2] FIG. 2 is a functional block diagram of a vehicle control unit in FIG. 1. [Figure 3] 1 is a diagram illustrating the principle of a ball nut type steering mechanism. [Figure 4] FIG. 1 is a diagram illustrating the principle by which the neutral point of a ball-nut type steering mechanism varies depending on the load on the steering wheel. [Figure 5] 1A is a graph showing a predetermined relationship between the load on the steering wheel and the neutral point, and FIG. 1B is a graph showing a predetermined relationship between the deceleration and the neutral point. [Figure 6] 3 is a flowchart illustrating an operation of the vehicle control device according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] A vehicle control device according to an embodiment of the present invention will be described in detail below with reference to the drawings. The vehicle control device 1 shown in FIG. 1 is mounted on an automobile 100 and assists the driver of the automobile 100 in driving operations using various systems. The automobile 100 is, for example, a large commercial vehicle such as a truck, van, or bus. The following description will focus on the configuration of the vehicle control device 1 of this embodiment, related to LKA (Lane Keeping Assist) control and LDP (Lane Departure Prevention) control, which perform steering control of the automobile 100 so that the automobile 100 does not deviate from the lane in which it is traveling.

[0019] 1, the vehicle control device 1 of this embodiment includes, as components specific to LKA control and LDP control, an LKA / LDP switch 2, a camera 3, a steering angle sensor 6, a torque sensor 7, a steering actuator 8, an ECU-A 9, and an ECU-B 10. The ECU-A 9 and ECU-B 10 configure a vehicle control unit 11. The vehicle control device 1 also includes a speed measurement unit 4, an SAS 5, an ECU-C 12, a load detection unit 13, and a G sensor 17.

[0020] In Figure 1, the double-wire connections between each component represent connections via a Controller Area Network (CAN). The single-wire connections between each component represent connections via electrical wires that directly connect devices one-to-one. The thick double-wire and single-wire connections between each component represent connections specific to LKA control and LDP control.

[0021] The LKA / LDP switch 2 is a switch that accepts an operation by the driver of the automobile 100 to turn on and off the LKA control and LDP control. The camera 3 captures an image of the area ahead of the automobile 100, including the white or yellow lines that demarcate lanes on the road surface. The camera 3 transmits information about the captured image of the area ahead of the automobile 100 to the ECU-A9. As will be described later, the ECU (Electronic Control Unit)-A9 assists the driver of the automobile 100 in driving operations using various systems including the LKA control and LDP control.

[0022] The SAS (Steering Angle Sensor) 5 detects the steering angle input by the driver of the automobile 100 via the steering wheel, and outputs the detected steering angle to the ECU-A 9. The steering angle sensor 6 detects the steering angle input by the driver of the automobile 100 via the steering wheel, and outputs the detected steering angle to the ECU-B 10 and the ECU-A 9. The ECU (Electronic Control Unit)-B 10 executes steering control of the automobile 100.

[0023] The torque sensor 7 detects torque generated by steering the steering wheels of the automobile 100. The torque sensor 7 transmits the detected torque to the ECU-B 10. The steering actuator 8 controls the steering angle of the steering wheels of the automobile 100 in response to a command from the ECU-B 10. The steering angle sensor 6 and the steering actuator 8 are components for implementing the present invention. The SAS 5 is a configuration that has conventionally been included in automobiles. Note that the reason for using two steering angle detection devices, the SAS 5 and the steering angle sensor 6, in this embodiment is to improve self-sufficiency and responsiveness regarding steering assist control.

[0024] The speed measurement unit 4 measures the speed of the automobile 100. The speed measurement unit 4 is, for example, a wheel speed sensor provided on a wheel of the automobile 100 or on an axle that rotates integrally with the wheel, and detects the rotational speed of the wheel as a signal. The speed measurement unit 4 transmits a signal corresponding to the rotational speed of the wheel to the ECU-A9 via the ECU-C12. The ECU (Electronic Control Unit)-C12 transmits an instruction value to a modulator (not shown) based on the stroke of the brake pedal of the automobile 100, which is converted into an electric signal by a brake pedal sensor (not shown). The modulator sends a predetermined air pressure to a chamber based on the instruction value from the ECU-C12, thereby actuating the brakes of the automobile 100.

[0025] The load detection unit 13 detects the load on the steering wheel of the automobile 100. The load detection unit 13 is, for example, a load cell arranged in a suspension of the steering wheel of the automobile 100, and detects the load applied to the suspension of the steering wheel of the automobile 100. Note that the load detection unit 13 may indirectly detect the load on the steering wheel of the automobile 100 by detecting the load applied to the cargo bed, drive wheels, etc. of the automobile 100. The load detection unit 13 may also indirectly detect the load on the steering wheel of the automobile 100 by estimating the mass of the automobile 100 based on the output of the power source of the automobile 100 and the acceleration of the automobile 100 detected by the G sensor 17.

[0026] The G sensor (deceleration detection unit) 17 detects the deceleration of the automobile 100. The G sensor 17 detects the forward and lateral acceleration of the automobile 100 in addition to the deceleration of the automobile 100. The deceleration detection unit may indirectly detect the deceleration of the automobile 100 by estimating the deceleration of the automobile 100 from the amount of brake operation of the automobile 100. In addition, the vehicle control device 1 is equipped with a yaw rate sensor 18. The yaw rate sensor 18 detects the yaw rate of the automobile 100.

[0027] Each of the ECUs, ECU-A9, ECU-B10, and ECU-C12, is an electronic control unit having a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), and HDD (Hard Disk Drive), etc. Each ECU loads a program stored in the ROM into the RAM and executes it with the CPU, thereby controlling each part described below.

[0028] Below, an outline of the functions of the vehicle control unit 11, which is composed of the ECU-A9 and ECU-B10, will be explained. As shown in Fig. 2, the vehicle control unit 11 has, as functional blocks executed by its functions, a neutral point determination unit 21 and a steering control unit 22. The neutral point determination unit 21 determines a neutral point of the steering wheel angle at which the automobile 100 moves straight, in response to a load on the steering wheels that turns the automobile 100 in accordance with the steering angle of the steering wheel of the automobile 100. The steering control unit 22 executes steering control of the automobile 100 based on the neutral point determined by the neutral point determination unit 21.

[0029] The operation of the vehicle control device 1 of this embodiment will be described in detail below. The logic described below is calculated by the ECU-A9. The ECU-A9 instructs the ECU-B10 on the steering angle and steering speed. The ECU-B10 sends a command signal to the steering actuator 8 to steer the automobile 100.

[0030] First, with reference to Figures 3 and 4, we will explain why the neutral point of the steering angle of the steering wheel 31 is shifted due to the load on the steering wheels 40. The neutral point of the steering angle of the steering wheel 31 refers to the steering angle (rotation angle) of the steering wheel 31 at which the automobile 100 moves straight. The steering wheel 31 is an annular part that changes the angle of the steering wheels 40 of the automobile 100 according to the steering angle, thereby turning the automobile 100. The steering wheels 40 are, for example, the front wheels of the automobile 100, and change their angle relative to the longitudinal direction of the automobile 100 according to the steering angle of the steering wheel 31, thereby turning the automobile 100.

[0031] As shown in Figure 3, in a ball-nut type steering mechanism that is often used in large commercial vehicles such as trucks, vans, and buses, rotation of a steering wheel 31 rotates a worm shaft 32, which shares a common rotation axis with the steering wheel 31. The worm shaft 32 has a thread groove on its outer circumferential surface. The outer circumferential surface of the worm shaft 32 is surrounded by an annular nut 33. The nut 33 has a thread groove on its inner circumferential surface that corresponds to the thread groove on the outer circumferential surface of the worm shaft 32. The thread groove on the outer circumferential surface of the worm shaft 32 and the thread groove on the inner circumferential surface of the nut 33 mesh with each other via a plurality of balls 34.

[0032] When the worm shaft 32 rotates in accordance with the rotation of the steering wheel 31, the nut 33 moves in a direction parallel to the rotation axis of the worm shaft 32. The nut 33 has a rack 35 on its outer circumferential surface. A select shaft 36, having a pinion 37 provided on its outer circumferential surface, is disposed near the rack 35. The rack 35 and the pinion 37 mesh with each other. When the nut 33 moves in a direction parallel to the rotation axis of the worm shaft 32 in accordance with the rotation of the steering wheel 31, the select shaft 36 is rotated via the rack 35 and pinion 37, which mesh with each other.

[0033] One end of a pitman arm 38 is connected to the select shaft 36. One end of a drag link 39 is connected to the other end of the pitman arm 38. The other end of the drag link 39 is connected to a steering wheel 40. When the select shaft 36 rotates in accordance with the rotation of the steering wheel 31, the angle of the steering wheel 40 is changed via the pitman arm 38 and the drag link 39. In the ball nut type steering mechanism, the steering wheel 40 turns the automobile 100 in accordance with the steering angle of the steering wheel 31 of the automobile 100 as described above.

[0034] 4, the steering wheel 40 suspended by the suspension of the automobile 100 moves up and down due to fluctuations in the load on the steering wheel 40 caused by fluctuations in the number of occupants, cargo weight, and deceleration of the automobile 100. When the steering wheel 40 moves up and down, the fore-and-aft position of the drag link 39 also moves. When the drag link 39 moves fore and aft, the position of the pitman arm 38 also moves.

[0035] When the position of the pitman arm 38 is moved, the steering wheel 31 is also rotated via the select shaft 36, pinion 37, rack 35, nut 33, and worm shown in Figure 3. In other words, even if the angle of the steering wheels 40 relative to the longitudinal direction of the automobile 100 is maintained at an angle that causes the automobile 100 to travel straight, fluctuations in the load on the steering wheels 40 cause the steering wheel 31 to rotate, and the neutral point of the steering angle of the steering wheel 31 shifts.

[0036] Therefore, in this embodiment, the neutral point determination unit 21 determines a neutral point of the steering angle of the steering wheel 31 at which the automobile 100 moves straight in response to the load on the steering wheels 40 that causes the automobile 100 to turn in accordance with the steering angle of the steering wheel 31 of the automobile 100. More specifically, the neutral point determination unit 21 determines the neutral point based on a record of the steering angle of the steering wheel 31 at which the automobile 100 moves straight in response to the load on the steering wheels 40 detected by the load detection unit 13.

[0037] That is, for example, while the automobile 100 is traveling, the neutral point determination unit 21 associates and records the value of the load on the steered wheels 40 detected by the load detection unit 13 with the steering angle of the steering wheel 31 at which the automobile 100 moves straight. The neutral point determination unit 21 determines the steering angle of the steering wheel 31 at which the automobile 100 moves straight, stored in association with the value of the load on the steered wheels 40, as the neutral point.

[0038] Furthermore, the neutral point determination unit 21 determines the neutral point based on the load on the steered wheels 40 detected by the load detection unit 13 and a predetermined relationship between the load on the steered wheels 40 and the neutral point. For example, the neutral point determination unit 21 stores a predetermined relationship between the load on the steered wheels 40 and the neutral point as shown in Fig. 5(a). The neutral point determination unit 21 determines the neutral point based on the load on the steered wheels 40 detected by the load detection unit 13, while referring to the predetermined relationship between the load on the steered wheels 40 and the neutral point as shown in Fig. 5(a).

[0039] Furthermore, the neutral point determination unit 21 determines the neutral point based on the deceleration detected by the G sensor 17 and a predetermined relationship between the deceleration and the neutral point. For example, the predetermined relationship between the deceleration and the neutral point as shown in Fig. 5(b) is recorded in the neutral point determination unit 21. The neutral point determination unit 21 determines the neutral point for the deceleration detected by the G sensor 17 while referring to the predetermined relationship between the deceleration and the neutral point as shown in Fig. 5(b).

[0040] An example of the operation of the vehicle control device 1 of this embodiment while the automobile 100 is traveling will be described below. As shown in Fig. 6, when the LKA / LDP switch 2 is on, the load detection unit 13 detects the load on the steered wheels 40 (S1). The G sensor 17 detects the deceleration of the automobile (S2). The neutral point determination unit 21 determines the neutral point of the steering angle of the steering wheel 31 at which the automobile 100 moves straight in response to the load on the steered wheels 40 (S3).

[0041] At this time, the neutral point determination unit 21 determines the neutral point based on the record of the steering angle of the steering wheel 31 at which the automobile 100 moves straight in response to the load on the steered wheels 40 detected by the load detection unit 13. Furthermore, the neutral point determination unit 21 determines the neutral point with reference to a predetermined relationship between the load on the steered wheels 40 and the neutral point as shown in Fig. 5(a) with respect to the load on the steered wheels 40 detected by the load detection unit 13. Furthermore, the neutral point determination unit 21 determines the neutral point with reference to a predetermined relationship between the deceleration and the neutral point as shown in Fig. 5(b) with respect to the deceleration detected by the G sensor 17.

[0042] The steering control unit 22 executes steering control of the automobile 100 based on the neutral point determined by the neutral point determination unit 21 (S4). In this manner, steering control corresponding to the deviation of the neutral point of the steering angle is executed.

[0043] According to this embodiment, the neutral point determination unit 21 determines the neutral point of the steering angle of the steering wheel 31 at which the automobile 100 moves straight in response to the load on the steering wheels 40 that causes the automobile 100 to turn in accordance with the steering angle of the steering wheel 31 of the automobile 100, and the steering control unit 22 executes steering control of the automobile 100 based on the neutral point determined by the neutral point determination unit 21, so that steering control can be executed in response to the shift in the neutral point of the steering angle caused by the load on the steering wheels 40.

[0044] Furthermore, according to this embodiment, the load on the steering wheel 40 is detected by the load detection unit 13, and the neutral point is determined by the neutral point determination unit 21 based on the record of the steering angle of the steering wheel 31 when the automobile 100 moves straight in response to the load on the steering wheel 40 detected by the load detection unit 13, so that the neutral point of the steering angle corresponding to the load on the steering wheel 40 can be determined more accurately.

[0045] Furthermore, according to this embodiment, the load on the steered wheel 40 is detected by the load detection unit 13, and the neutral point is determined by the neutral point determination unit 21 based on the load on the steered wheel 40 detected by the load detection unit 13 and a predetermined relationship between the load on the steered wheel 40 and the neutral point, so that the neutral point of the steering angle corresponding to the load on the steered wheel 40 can be determined with more responsiveness.

[0046] Furthermore, according to this embodiment, the deceleration of the automobile 100 is detected by the G sensor 17, and the neutral point is determined by the neutral point determination unit 21 based on the deceleration detected by the G sensor 17 and a predetermined relationship between the deceleration and the neutral point, so that it is possible to determine the neutral point of the steering angle corresponding to the load on the steered wheels 40, which fluctuates depending on the deceleration of the automobile 100.

[0047] Furthermore, according to this embodiment, the load on the steering wheel 40 is likely to fluctuate depending on the number of passengers or load, and the neutral point is likely to shift, making it useful in commercial vehicles, since it is possible to perform steering control that corresponds to the shift in the neutral point of the steering angle corresponding to the load on the steering wheel 40.

[0048] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and can be embodied in various forms. [Explanation of symbols]

[0049] 1...vehicle control device, 2...LKA / LDP switch, 3...camera, 4...speed measurement unit, 5...SAS, 6...steering angle sensor, 7...torque sensor, 8...steering actuator, 9...ECU-A, 10...ECU-B, 11...vehicle control unit, 12...ECU-C, 13...load detection unit, 17...G sensor (deceleration detection unit), 18...yaw rate sensor, 21...neutral point determination unit, 22...steering control unit, 31...steering wheel, 32...worm shaft, 33...nut, 34...ball, 35...rack, 36...select shaft, 37...pinion, 38...pitman arm, 39...drag link, 40...steering wheel, 100...automobile

Claims

1. A vehicle control device for controlling an automobile equipped with a steering mechanism in which the steering wheel is rotated by fluctuations in the load on the steering wheels, a neutral point determination unit that determines a neutral point of the steering angle of the steering wheel at which the vehicle moves straight in response to a load on a steering wheel that turns the vehicle in accordance with the steering angle of the steering wheel of the vehicle; a steering control unit that executes steering control of the vehicle based on the neutral point determined by the neutral point determination unit; a load detection unit that detects the load on the steering wheel, The neutral point determination unit determines the neutral point based on a record of the steering angle of the steering wheel when the vehicle travels straight in response to the load on the steered wheels detected by a load detection unit.

2. A vehicle control device for controlling an automobile equipped with a steering mechanism in which the steering wheel is rotated by a change in load on the steering wheel, a neutral point determination unit that determines a neutral point of the steering angle of the steering wheel at which the vehicle moves straight in response to a load on a steering wheel that turns the vehicle in accordance with the steering angle of the steering wheel of the vehicle; a steering control unit that executes steering control of the vehicle based on the neutral point determined by the neutral point determination unit; a load detection unit that detects the load on the steering wheel, The neutral point determination unit determines the neutral point based on the load on the steered wheel detected by a load detection unit and a predetermined relationship between the load on the steered wheel and the neutral point.

3. A vehicle control device for controlling an automobile equipped with a steering mechanism in which the steering wheel is rotated by fluctuations in the load on the steering wheel, a neutral point determination unit that determines a neutral point of the steering angle of the steering wheel at which the vehicle moves straight in response to a load on a steering wheel that turns the vehicle in accordance with the steering angle of the steering wheel of the vehicle; a steering control unit that executes steering control of the vehicle based on the neutral point determined by the neutral point determination unit; a deceleration detection unit that detects the deceleration of the vehicle, The vehicle control device, wherein the neutral point determination unit determines the neutral point based on the deceleration detected by the deceleration detection unit and a predetermined relationship between the deceleration and the neutral point.

4. The vehicle control device according to any one of claims 1 to 3, wherein the automobile is a commercial vehicle.

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