JP2017177943A - Automatic steering system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic steering system capable of reducing discomfort that a driver receives at the time of override control.SOLUTION: An automatic steering system comprises: a torque sensor for detecting an input torque to a steering wheel; an electric power steering device; an automatic steering instruction device for calculating and outputting an instruction steering angle for a vehicle to travel along a front road; and a steering control part for outputting a steering angle control current to a motor provided with the electric power steering device according to the instruction steering angle, and executing feedback control to cause an actual steering angle to follow the instruction steering angle. After detecting that the input torque reaches or exceeds a predetermined first threshold, the steering control part temporarily stops the execution of the feedback control, and fixes the steering angle control current to a value obtained at the time when the input torque reaches or exceeds the predetermined first threshold.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an automatic steering apparatus for a vehicle.

  For example, as disclosed in Japanese Patent Application Laid-Open No. 2005-343184, an automatic steering apparatus that automatically recognizes the shape of a road on which the vehicle is traveling and automatically steers the vehicle is known. Further, in an automatic steering device for a vehicle, as disclosed in Japanese Patent Application Laid-Open No. 2005-343184, it is determined whether or not a steering wheel is operated (override operation) by a driver during execution of automatic steering. When it is determined that it has been performed, a technique is known in which automatic steering is stopped to give priority to a driver's operation.

JP 2005-343184 A

  When the driver performs an override operation during execution of automatic steering by the automatic steering device, the driver steers the operation force temporarily opposite to the automatic steering until the automatic steering device determines an input of the override operation. Need to enter on the wheel. Then, after the automatic steering device determines the input of the override operation, the automatic steering stops, so the repulsive force felt for the operation of the steering wheel suddenly disappears for the driver, and it feels heavy until then. I feel uncomfortable that the operation of the steering wheel suddenly became lighter.

  The present invention solves the above-described problems, and an object of the present invention is to provide an automatic steering device that can reduce a sense of discomfort experienced by a driver when an override operation is performed.

  An automatic steering device according to one aspect of the present invention recognizes the shape of a road on which a torque sensor, an electric power steering device, and a vehicle are running to detect input torque to a steering wheel by a driver, and follows the shape of the road. An automatic steering instruction device that calculates an instruction steering angle that is information of a steering angle necessary for the vehicle to travel and outputs the calculated instruction steering angle to the electric power steering device, and the electric power steering device according to the instruction steering angle. A steering control unit that outputs a steering angle control current to a motor and executes feedback control for causing an actual steering angle to follow the commanded steering angle, wherein the steering control unit executes the feedback control After detecting that the input torque is equal to or greater than a predetermined first threshold value, wherein the input torque is less than the predetermined first threshold value. During a period until it is detected that the value is less than the predetermined second threshold, the execution of the feedback control is temporarily stopped, and the steering angle control current is set to be equal to or greater than the predetermined first threshold. It is fixed to the value at the time of detecting that it became.

  ADVANTAGE OF THE INVENTION According to this invention, the automatic steering apparatus which can reduce the discomfort which a driver | operator receives at the time of execution of override operation can be provided.

It is a block diagram which shows the structure of an automatic steering apparatus. It is a block diagram for demonstrating control of an electric power steering apparatus. It is a block diagram for demonstrating control of an electric power steering apparatus.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the drawings used for the following description, the scale of each component is made different in order to make each component recognizable on the drawing. It is not limited only to the quantity of the component described in (1), the shape of the component, the ratio of the size of the component, and the relative positional relationship of each component.

  An automatic steering apparatus 1 according to this embodiment shown in FIG. 1 is an apparatus that performs steering during an automatic driving operation of a vehicle. The automatic steering device 1 includes an electric power steering device (hereinafter referred to as EPS) 10 having a mechanism for changing the steering angle of the vehicle, and an automatic steering instruction device 2 that gives a steering instruction to the EPS 10 during an automatic driving operation. Prepare.

  The rotation of the steering wheel 9 by the input of the driver of the vehicle is converted into the rotation of the steered wheels 20 in the steered direction via the steered mechanism 15 provided in the EPS 10. In the present embodiment, as an example, the steering mechanism unit 15 has a rack and pinion mechanism. The pinion shaft 15 a provided with the pinion gear of the rack and pinion mechanism of the steering mechanism portion 15 is connected to the steering wheel 9 via a universal joint or the like, and the pinion shaft 15 a rotates together with the steering wheel 9.

  The EPS 10 includes a motor 14 that is an electric actuator, and applies an operation force applied to the steering wheel 9 by the driver by applying torque output from the motor 14 to the pinion shaft 15a in accordance with an input to the steering wheel 9 by the driver. A so-called power assist operation is performed. Further, the EPS 10 rotates the pinion shaft 15a by the motor 14 in response to an instruction output from the automatic steering instruction device 2 independently of an input to the steering wheel 9 by the driver during an automatic driving operation of the vehicle. The steered wheels 20 are rotated in the steered direction. Since the mechanical configuration of the EPS 10 is known, a detailed description thereof will be omitted.

  The automatic steering instruction device 2 includes an external environment recognition device 3 for recognizing the external environment around the vehicle, a navigation device 4 for recognizing the shape of the road on which the vehicle is traveling, and the vehicle traveling speed, longitudinal acceleration, yaw rate, etc. A vehicle behavior detection device 5 for detecting the behavior of the vehicle is provided.

  The external environment recognition device 3 recognizes the shape of the traveling road ahead of the vehicle and the presence of an object existing on and around the traveling road based on information from a sensor that recognizes the external environment of the vehicle. The external environment recognition device 3 includes, for example, a stereo camera that keeps the front of the vehicle in the field of view, and performs known image processing and the like on the image captured by the stereo camera, thereby existing in the shape of the road ahead and the traveling direction. Recognize the position and movement of objects.

  The navigation device 4 includes a positioning device that detects the current position (latitude, longitude) of the vehicle using at least one of a satellite positioning system, an inertial navigation device, and road-to-vehicle communication, a map information storage unit that stores map information, Is provided. The map information includes information indicating the shape of the road such as the curvature of the road, the gradient of the longitudinal section, and the state of intersection with another road. The navigation device 4 recognizes the shape of the road ahead of the vehicle based on the current position of the vehicle detected by the positioning device and the map information stored in the map information storage unit.

  The automatic steering instruction device 2 is based on information such as the shape of the road recognized by the external environment recognition device 3 and the navigation device 4, information on the current behavior of the vehicle, and information on the vehicle motion model. Is calculated for the steering angle θc, which is the angle of the pinion shaft 8a necessary for traveling along the road that is currently traveling, and is output to the EPS 10. Since an automatic steering instruction device using an external environment recognition device such as a stereo camera is known, a detailed description of the configuration is omitted.

  The EPS 10 includes a steering mechanism unit 15, a steering control unit 11, an input torque sensor 12, a pinion shaft angle sensor 13, and a motor 14. The steered mechanism unit 15 has a mechanism that converts a force that rotates the pinion shaft 15a into a force that rotates the steered wheels 20 in the steered direction. A steering mechanism using a rack and pinion mechanism as in this embodiment is a known technique.

  The steering control unit 11 is composed of a computer having a CPU, ROM, RAM, input / output device and the like connected to a bus, and controls the operation of the EPS 10 based on a predetermined program.

  The input torque sensor 12 detects an input torque Tm that is a torque input to the pinion shaft 15a by the driver via the steering wheel 9. The pinion shaft angle sensor 13 detects the rotation angle θ of the pinion shaft 15a.

  The motor 14 is an electric motor that outputs a motor output torque To that is a torque for rotating the pinion shaft 15a around the axis. That is, the input torque Tm input from the driver via the steering wheel 9 and the motor torque To input from the motor 14 are input to the pinion shaft 15a.

  FIG. 2 is a block diagram of the steering control during the automatic driving operation of the EPS 10. As shown in FIG. 2, information on the commanded steering angle θc calculated by the automatic steering commanding device 2 is input to the EPS 10.

  During the automatic driving operation of the vehicle, the steering control unit 11 of the EPS 10 changes the steering angle control current Is applied to the motor 14 with the commanded steering angle θc as a target value, thereby controlling the angle θ of the pinion shaft 15a as a control amount. The feedback control is performed to follow the command steering angle θc.

  As shown in FIG. 3, the steering control unit 11 of the present embodiment includes a PID control unit 11 a that calculates a steering angle control current Is by using general PID control as a feedback control method. The PID control unit 11a can change the values of the proportional gain Kp, the differential gain Kd, and the integral gain Ki for the steering angle control and the steering angular speed control.

  Further, the steering control unit 11 of the EPS 10 calculates the assist current Ia to be given to the motor 14 so that the input torque Tm and the pinion shaft angle θ have a predetermined relationship, and assists the driver in inputting to the steering wheel 9. Execute power assist operation. The steering control unit 11 can change the value of the power assist gain, which is a gain when calculating the assist current value Ia from the input torque Tm.

  As described above, the command current Ic input to the motor 14 during the automatic operation is a value obtained by adding the assist current Ia to the steering angle control current Is. The motor 14 outputs a motor torque To corresponding to the command current Ic.

  If the driver is not applying force to the steering wheel 9, the steering angle control current Is output from the PID control unit 11a and the command current Ic input to the motor 14 are equal. Further, when the driver applies the input torque Tm to the steering wheel 9 during the automatic driving operation, the input torque Tm and the assist current Ia act on the EPS 10 as disturbances. Further, the road surface reaction torque Tr generated with the movement of the steered wheels 20 with respect to the road surface is also input to the pinion shaft 15a.

  Next, the operation of the override determination process during the automatic driving operation of the automatic steering device 1 having the above-described configuration will be described.

  Overriding means that the driver operates the steering wheel 9 during the automatic driving operation of the vehicle. The overriding is performed, for example, when the driver tries to drive the vehicle on a route different from the traveling route of the automatic driving operation. The override determination process is a process for temporarily stopping the automatic driving operation and switching to the manual driving by the driver when the operation of the steering wheel 9 by the driver is detected.

  Schematically, the steering control unit 11 of the automatic steering device 1 according to the present embodiment allows the driver when the input torque Tm detected by the input torque sensor 12 is equal to or greater than a first threshold value Tth1 that is a predetermined value. It is determined that an override operation has been performed. Further, after determining that the driver has performed an override operation, the steering control unit 11 has the second threshold value Tth2 in which the input torque Tm detected by the input torque sensor 12 is a predetermined value lower than the first threshold value Tth1. When it becomes less than, it is determined that the override operation by the driver is finished.

  The steering control unit 11 temporarily stops the feedback control of the steering by the automatic steering device 1 during the period when it is determined that the override operation by the driver is being performed.

  In more detail, in the override determination process, the steering control unit 11 determines that the integral gain Kia of the steering angle control in the PID control unit 11a when the input torque Tm is equal to or greater than the third threshold Tth3 that is lower than the first threshold Tth1. Then, the value of the integral gain Kiv of the rudder angular velocity control is fixed to a predetermined value lower than the value used in the automatic driving operation performed up to now. The case where the input torque Tm is equal to or higher than the third threshold value Tth3 lower than the first threshold value Tth1 is a time point immediately after the driver starts the override operation.

  When the driver inputs the input torque Tm during the automatic driving operation, the input torque Tm is determined by the automatic steering device 1 until the steering control unit 11 determines that the input torque Tm is equal to or greater than the first threshold value Tth1 and has been overridden. This is a disturbance to steering feedback control.

  Accordingly, during a period in which the input torque Tm is equal to or greater than the third threshold Tth3 and less than the first threshold Tth1 immediately after the driver starts the override operation, the steering control unit 11 applies torque to the motor 14 that cancels the input torque Tm. In order to generate it, the value of the steering angle control current Is is increased.

  In the present embodiment, at the time when it is detected that the input torque Tm is less than the first threshold Tth1 but starts to increase beyond the third threshold Tth3, the steering gain control integral gain Kia and the steering angular speed control integral gain Kiv. Is fixed to a value lower than the value that has been used in the automatic driving operation until then, the amount of increase in the steering angle control current that the steering control unit 11 increases in response to the increase in the input torque Tm is reduced. .

  Therefore, in the automatic steering device 1 of the present embodiment, the driver receives from the steering wheel 9 in a period after the driver starts the override operation and until the input torque Tm reaches the first threshold value Tth1. The increasing speed of the repulsive force can be reduced. For this reason, in the automatic steering apparatus 1 of this embodiment, the uncomfortable feeling resulting from the repulsive force which a driver | operator receives from the steering wheel 9 at the time of override operation can be reduced.

  Further, when the input torque Tm becomes equal to or greater than the first threshold value Tth1, the steering control unit 11 fixes the steering angle control current Is to the value at that time, and temporarily performs the steering feedback control by the automatic steering device 1. To stop.

  When the feedback control of the steering by the automatic steering device 1 is temporarily stopped, the steering of the vehicle follows only the operation of the steering wheel 9 by the driver. At this time, the steering angle control current Is is fixed to a value at the time when it is detected that the input torque Tm is equal to or greater than the first threshold value Tth1.

  As described above, when the driver inputs the input torque Tm to perform the override operation, the steering control unit 11 sets the value of the steering angle control current Is in order to cause the motor 14 to generate a torque that cancels the input torque Tm. increase. The automatic steering apparatus 1 of the present embodiment maintains the steering angle control current Is increased to cancel the input torque Tm of the override operation even after determining that the override operation has been input.

  As described above, in the automatic steering device 1 according to the present embodiment, even after the driver performs the override operation and stops the steering feedback control, the generation of torque repelling the override operation is maintained without stopping. Therefore, in the automatic steering device 1 of the present embodiment, the repulsive force that the driver receives from the steering wheel 9 disappears instantaneously by stopping the steering feedback control by the automatic steering device 1 during the override operation. It is possible to reduce a sense of discomfort.

  As described above, the steering control unit 11 temporarily stops the steering feedback control by the automatic steering device 1 until it is detected that the input torque Tm is less than the predetermined second threshold value Tth2.

  That is, the steering control unit 11 determines that the override operation by the driver has ended when the input torque Tm becomes less than the predetermined second threshold value Tth2 after determining that the override operation has been performed by the driver. The steering feedback control by the automatic steering device 1 is resumed.

  When the feedback control of steering by the automatic steering device 1 is resumed, the steering control unit 11 releases the fixed values of the steering angle control current Is, the integral gain Kia of the steering angle control, and the integral gain Kiv of the steering angular speed control. .

  As described above, the automatic steering apparatus 1 according to the present embodiment has detected that the input torque Tm has become equal to or greater than the predetermined first threshold value Tth1 when the automatic steering feedback control is executed. In addition, during the period until it is detected that the input torque Tm is less than the predetermined second threshold value Tth2 lower than the predetermined first threshold value Tth1, the execution of the feedback control is temporarily stopped and output to the motor 14 The steering angle control current Is is fixed to a value at the time when it is detected that the input torque Tm is equal to or greater than a predetermined first threshold value.

  According to the automatic steering apparatus 1 of the present embodiment having such a configuration, when the driver performs an override operation, the repulsive force felt for the operation of the steering wheel 9 suddenly disappears and is heavy until then. The uncomfortable feeling that the operation of the steering wheel 9 felt lightened suddenly can be reduced.

  Further, the automatic steering device 1 of the present embodiment controls the steering angle using PID control, and detects that the input torque Tm is equal to or higher than a predetermined third threshold Tth lower than the first threshold Tth1. In addition, the value of the integral gain in the PID control is fixed to a predetermined value lower than the value at the time when it is detected that the input torque Tm is equal to or greater than the third threshold value Tth3.

  According to the automatic steering apparatus 1 of the present embodiment having such a configuration, when the driver performs an override operation, the amount of increase in the repulsive force that is felt in response to the operation of the steering wheel 9 can be reduced.

  In addition to the configuration described above, the steering control unit 11 of the present embodiment has an input torque Tm that is greater than or equal to the first threshold Tth1 or greater than or equal to the third threshold Tth3 when the steering feedback control is performed by the automatic steering device 1. When it is detected that the power assist gain is detected, the power assist gain for calculating the assist current value Ia of the power assist operation by the EPS 10 may be increased.

  As described above, in the automatic steering device 1, by detecting that the driver has started the override operation (when Tm ≧ Tth3 is detected), the power assist gain is made larger than the value during normal driving, When performing the override operation, it is possible to realize a reduction in the feeling of sensation felt at the beginning of the movement of the steering wheel 9 and a reduction in the increase in the operation force due to the fixed steering angle control current Is.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification. An automatic steering apparatus that includes such a change is also applicable. Moreover, it is included in the technical scope of the present invention.

1 Automatic steering device,
2 automatic steering instruction device,
3 External environment recognition device,
4 navigation devices,
5 Vehicle behavior detection device,
9 Steering wheel,
10 Electric power steering system (EPS)
11 Steering control unit,
11a PID controller,
12 Input torque sensor,
13 Pinion shaft angle sensor,
14 motor,
15 steering mechanism,
15a pinion shaft,
20 steered wheels.

Claims (3)

A torque sensor that detects the input torque to the steering wheel by the driver,
Electric power steering device,
An automatic steering instruction device for recognizing the shape of a road on which the vehicle is traveling, calculating and outputting an instruction steering angle that is information on a steering angle necessary for the vehicle to travel along the shape of the road; and A steering control unit that outputs a steering angle control current to a motor included in the electric power steering device according to a commanded steering angle, and executes feedback control that causes an actual steering angle to follow the commanded steering angle;
An automatic steering device comprising:
The steering control unit detects that the input torque is equal to or higher than a predetermined first threshold value when the feedback control is executed, and is a predetermined value that is lower than the predetermined first threshold value. During the period until it is detected that the value is less than the second threshold, the execution of the feedback control is temporarily stopped, and the steering torque control current is equal to or greater than the predetermined first threshold. The automatic steering device is characterized in that the value is fixed to the value at the time of detection. The feedback control is PID control,
When the steering control unit detects that the input torque is equal to or higher than a predetermined third threshold value lower than the first threshold value during execution of the feedback control, the steering control unit sets an integral gain value in the PID control. The automatic steering apparatus according to claim 1, wherein the automatic steering apparatus is fixed to a predetermined value lower than a value at the time of detecting that the input torque is equal to or greater than the third threshold value. When the steering control unit detects that the input torque is greater than or equal to the first threshold or greater than or equal to the third threshold during execution of the feedback control, the gain of the power assist operation by the electric power steering device The automatic steering device according to claim 1, wherein the automatic steering device is increased.

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