JP2016008010A - Electric power steering device and automatic steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric power steering device capable of calmly dealing with a situation during burst of a wheel.SOLUTION: An emergency control section 40 has a function for calculating a yaw rate deviation to be a difference between a target yaw rate and a detected yaw rate detected in a yaw rate detection device, generating steering torque gain when steering torque is equal to or less than a maximum set value, generating air pressure gain when air pressure is equal to or less than a maximum set value, and calculating an auxiliary control signal by multiplying the yaw rate deviation by the steering torque gain and the air pressure gain. A basic control section 50 includes a steering characteristic storage section 51 for storing assist torque in accordance with vehicle speed and the steering torque, and an addition section 52 for adding the auxiliary control signal of the emergency control section 40 to a base steering characteristic stored in the steering characteristic storage section 51 and outputting the added base steering characteristic to a driving device 29.

Description

  The present invention relates to an electric power steering device and an automatic steering device.

  As shown in Patent Document 1, there is an automatic steering device that recognizes a lane of a road with a camera and automatically steers a steered wheel by an electric power steering device in a direction along the lane.

  There is a high possibility that the wheels will burst during driving during automatic steering. Alternatively, there is a considerable possibility that the wheels may burst during traveling during manual steering.

Japanese Patent No. 3677061

  When a wheel bursts, the vehicle flows to the side of the bursted wheel. For this reason, the driver hurries and steers. When performing strong steering in a rush, excessive steering is likely to occur if there is steering assist. When steering is performed weakly and calmly, if there is no steering assist, the vehicle will flow to the bursting wheel side. The present invention has been made to solve the above-described problems, and the object of the present invention is to change the steering assist according to the strength of the steering, to steer too much, and the vehicle flows to the bursted wheel side. Provided is an electric power steering device that prevents the above.

  According to a first aspect of the present invention, there is provided a steering apparatus having one end connected to a steering wheel and the other end connected to a steering wheel, and having a transmission path for transmitting a steering operation of a driver to the steering wheel, and in the middle of the transmission path. A steering torque detecting device for detecting a steering torque, a yaw rate detecting device for detecting the yaw rate of the vehicle, a vehicle speed detecting device for detecting the vehicle speed of the vehicle, and a steering force on the transmission route. And a drive device that amplifies a control signal and supplies a drive current to the motor, and at the time of a steering operation by the driver, the assist torque according to the vehicle speed and the steering torque is obtained. An electric power steering apparatus comprising: a basic control unit that controls the control signal supplied to the drive device; and detects an air pressure of a wheel such as the steering wheel. An air pressure detecting device; and an emergency control unit that issues an auxiliary control signal when the air pressure is equal to or less than a maximum set value and the steering torque is equal to or less than the maximum set value. The emergency control unit includes a target yaw rate and the yaw rate detection A yaw rate deviation that is a difference from the detected yaw rate detected by the device is calculated, and a steering torque gain is generated when the steering torque is less than or equal to the maximum set value, and an air pressure gain is calculated when the air pressure is less than or equal to the maximum set value. And generating the auxiliary control signal by multiplying the yaw rate deviation by the steering torque gain and the air pressure gain, and the basic control unit has the assist torque according to the vehicle speed and the steering torque. A steering characteristic storage unit for storing the auxiliary control of the emergency control unit to the base steering characteristic stored in the steering characteristic storage unit. Adding signals, it is characterized in that an adding section for outputting to the drive unit.

  According to the first aspect, when strong steering is performed at the time of a burst of wheels, there is no auxiliary control signal from the emergency control unit, and the steering operation is performed with the base steering characteristic stored in the steering characteristic storage unit. In the case of strong steering, it is easier to avoid excessive steering if there is no auxiliary control signal. When weak steering is performed during a burst of wheels, there is an auxiliary control signal from the emergency control unit, and the steering operation is performed with the added steering characteristic obtained by adding the auxiliary control signal to the base steering characteristic stored in the steering characteristic storage unit. Do. In the case of weak steering, it is possible to prevent the vehicle from flowing toward the wheel where the vehicle has burst by assisting by the auxiliary control signal.

  According to a second aspect of the present invention, in the first aspect, the emergency control unit calculates a yaw rate PI control value PI-controlled from the target yaw rate and the detected yaw rate, and when the steering torque is equal to or less than a maximum set value. A steering torque gain multiplier for generating the steering torque gain, and a tire air pressure gain multiplier for generating the air pressure gain when the air pressure is equal to or lower than the maximum set value, and the steering torque is included in the yaw rate PI control value. The auxiliary control signal is calculated by multiplying a gain and the air pressure gain.

  According to the second aspect, when strong steering is performed at the time of the burst of the wheel, there is no auxiliary control signal from the emergency control unit, and the steering operation is performed with the base steering characteristic stored in the steering characteristic storage unit. In the case of strong steering, it is easier to avoid excessive steering if there is no auxiliary control signal. When weak steering is performed during a burst of wheels, there is an auxiliary control signal from the emergency control unit, and the steering operation is performed with the added steering characteristic obtained by adding the auxiliary control signal to the base steering characteristic stored in the steering characteristic storage unit. Do. In the case of weak steering, it is possible to prevent the vehicle from flowing toward the wheel where the vehicle has burst by assisting by the auxiliary control signal. Furthermore, since the yaw rate is PI-controlled, it becomes easier to follow the target yaw rate than a simple yaw rate deviation.

  A third aspect is the first or second aspect, wherein the target yaw rate is zero.

  According to the third aspect, since it is not necessary to calculate the target yaw rate, the control becomes easy.

  A fourth aspect of the present invention is an automatic steering apparatus to which the electric power steering apparatus according to any one of the first to third aspects is applied.

  According to the fourth aspect, it is possible to provide an optimum automatic steering device when switching from automatic steering to steering operation.

  According to the present invention, when strong steering is performed during a burst of wheels, there is no auxiliary control signal from the emergency control unit, and the steering operation is performed with the base steering characteristic stored in the steering characteristic storage unit. In the case of strong steering, it is easier to avoid excessive steering if there is no auxiliary control signal. When weak steering is performed during a burst of wheels, there is an auxiliary control signal from the emergency control unit, and the steering operation is performed with the added steering characteristic obtained by adding the auxiliary control signal to the base steering characteristic stored in the steering characteristic storage unit. Do. In the case of weak steering, it is possible to prevent the vehicle from flowing toward the wheel where the vehicle has burst by assisting by the auxiliary control signal.

1 is a schematic configuration diagram of an electric power steering apparatus according to an embodiment of the present invention. The control block diagram of the electric power steering device concerning one Embodiment of this invention.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, a column type electric power steering apparatus 1 includes a column mechanism 2 having a steering wheel 90 rotationally connected to one end, and an intermediate shaft 3 having one end rotationally connected to the other end of the column mechanism 2. A rack and pinion mechanism 4 having one end rotationally connected to the other end of the intermediate shaft 3 and an ECU 30 for controlling a motor 21 (to be described later) of the column mechanism 2 are provided. A steering wheel 13 is connected to the other end of the rack and pinion mechanism 4 via a tie rod 12 and a knuckle (not shown).

  As shown in FIG. 1, the column mechanism 2 includes a steering shaft 5 in which a steering wheel 90 is rotationally connected to one end and an intermediate shaft 3 is rotationally connected to the other end, and a steering torque provided in the middle of the steering shaft 5. Detecting device 26, worm wheel 24 provided in the middle of steering shaft 5, worm 23 meshing with worm wheel 24, motor 21 having worm 23 attached to one end of the output shaft, and rotation of the output shaft of motor 21 A steering angle detection device 22 that indirectly detects the steering angle of the steering wheel 13 and a drive device 29 that supplies a drive current to the motor 21 are provided. The worm wheel 24 and the worm 23 constitute a reduction mechanism that reduces the rotation of the output shaft of the motor 21.

  The rack and pinion mechanism 4 includes a pinion shaft 10 whose one end is rotationally connected to the other end of the intermediate shaft 3, and a rack shaft 11 that meshes with the pinion shaft 10. A pinion is formed on the pinion shaft 10, and a rack that meshes with the pinion is formed on the rack shaft 11. Thus, the rotation of the pinion shaft 10 is converted into the reciprocating linear motion of the rack shaft 11.

  As shown in FIG. 2, the ECU 30 includes a basic control unit 50 that controls a control signal supplied to the drive device 29 so that an assist torque corresponding to the vehicle speed and the steering torque can be obtained during the steering operation of the driver, An emergency control unit 40 that issues an auxiliary control signal when the steering torque is equal to or less than the maximum set value and the steering torque is equal to or less than the maximum set value, and a gate circuit 54 that switches between the two control signals depending on the situation.

  The steering apparatus described in the claims refers to the steering shaft 5 of the column mechanism 2 and the rack and pinion mechanism 4 in the above-described embodiment. The transmission path described in the claims indicates the steering shaft 5, the intermediate shaft 3, the pinion shaft 10, and the rack shaft 11 in the above-described embodiment.

  As shown in FIG. 1, the automatic steering device determines the position of the lane on the side of the vehicle based on the image from the electric power steering device 1, the video camera 61 (FIG. 2) attached to the bonnet, and the video camera 61. An inferred image processing circuit 62 (FIG. 2), an automatic steering control unit 60 for controlling a control signal supplied to the drive device 29 so that the vehicle can travel along the lane, and a changeover switch 63 (FIG. 2) for switching to automatic steering. 2).

  The electric power steering device 1 is attached to a vehicle. The vehicle includes a vehicle speed detection device 25 that detects a vehicle speed, a yaw rate detection device (not shown) that detects a yaw rate, a steering wheel 90, and a steering wheel 13. Each steered wheel 13 includes an air pressure detection device 27 that detects air pressure. Similarly, the wheels other than the steering wheel 13 are provided with an air pressure detecting device 27 for detecting the air pressure.

  A target yaw rate calculated based on the steering angle and the vehicle speed, a detected yaw rate from the yaw rate detection device, a lane distance from the image processing circuit 62, and a vehicle speed signal from the vehicle speed detection device 25 are input to the automatic steering control unit 60. It has come to be.

  As shown in FIG. 2, the basic control unit 50 receives a steering torque from the steering torque detection device 26 and a vehicle speed signal from the vehicle speed detection device 25.

  A target yaw rate calculated based on the steering angle and the vehicle speed and a detected yaw rate signal from the yaw rate detection device are input to a feedback control unit 41 described later of the emergency control unit 40.

  A steering torque signal from the steering torque detection device 26 is input to a steering torque gain multiplication unit 42 described later of the emergency control unit 40.

  An air pressure signal from the air pressure detecting device 27 is input to a tire air pressure gain multiplying unit 43 described later of the emergency control unit 40.

  The gate circuit 54 includes a steering torque signal from the steering torque detection device 26, a control signal from the automatic steering control unit 60, a control signal from an added steering characteristic storage unit 53, which will be described later, of the basic control unit 50, and A switching signal from the changeover switch 63 is input. If there is a steering torque signal from the steering torque detection device 26, the control signal from the added steering characteristic storage unit 53 is transmitted to the drive device 29, and there is no steering torque signal from the steering torque detection device 26, and the changeover switch 63 is sent. If the automatic steering is selected, the gate circuit 54 has a function of transmitting the control signal of the automatic steering control unit 60 to the drive device 29.

  The basic control unit 50 stores a steering characteristic storage unit 51 that stores an assist torque according to the vehicle speed and steering torque, and adds an auxiliary control signal of the emergency control unit 40 to the base steering characteristic stored in the steering characteristic storage unit 51. And a post-addition steering characteristic storage unit 53 that stores the post-addition steering characteristic added by the addition unit 52 and outputs a control signal to the drive device 29.

  The steering characteristic storage unit 51 stores the relationship between the steering torque and the assist torque for each vehicle speed. A characteristic representing the relationship between the steering torque, the assist torque, and the vehicle speed is referred to as a base steering characteristic. When the steering torque increases, the assist torque tends to increase, and when the vehicle speed increases, the assist torque tends to decrease. The assist torque in this case refers to assist torque that is assisted by the motor 21.

  The post-addition steering characteristic storage unit 53 stores the relationship between the steering torque and the assist torque after adding the auxiliary control signal to the base steering characteristic stored in the steering characteristic storage unit 51 for each vehicle speed. When the steering torque increases, the assist torque tends to increase. When the vehicle speed increases, the assist torque tends to increase. The assist torque in this case refers to assist torque that is assisted by the motor 21. It becomes easier to return the vehicle flowing to the side of the burst wheel by the amount of addition of the auxiliary control signal.

  The emergency control unit 40 includes a feedback control unit 41 that performs PI control based on the target yaw rate and the detected yaw rate, a steering torque gain multiplication unit 42 that generates a torque gain when the steering torque is equal to or less than a maximum setting value, and a maximum air pressure. And a tire air pressure gain multiplier 43 that generates an air pressure gain when it is equal to or less than a set value.

  More specifically, the steering torque gain multiplication unit 42 generates a steering torque gain of zero when it is greater than or equal to the maximum set value, and generates a steering torque gain that gradually increases from zero from the maximum set value or less to the minimum set value, It has a function of generating a steering torque gain of 1 when it is below the minimum set value.

  More specifically, the tire pressure gain multiplication unit 43 generates a tire pressure gain of zero when it is equal to or greater than the maximum set value, and generates a tire pressure gain that gradually increases from zero from the maximum set value or less to the minimum set value, It has a function to generate a tire pressure gain of 1 when it is below the minimum set value.

  Next, the operation of the electric power steering apparatus 1 will be described based on the above-described configuration.

  As shown in FIG. 1, when the driver rotates the steering wheel 90, the rotation is transmitted to the pinion shaft 10 via the steering shaft 5 and the intermediate shaft 3, and the rotation is reciprocated by the rack shaft 11 by the pinion and the rack. Converted into movement. The reciprocating linear motion of the rack shaft 11 is transmitted to the steering wheel 13 through the tie rod 12 and a knuckle (not shown), and the direction of the steering wheel 13 is changed.

  If there is resistance when the direction of the steering wheel 13 is changed, the steering torque is detected by the steering torque detection device 26, a control signal is transmitted from the ECU 30 to the drive device 29, and the drive current corresponding to the control signal is changed to the motor 21. The rotation of the output shaft of the motor 21 is transmitted to the steering shaft 5 via the worm 23 and the worm wheel 24. Thus, the steering assist of the motor 21 is given to the steering shaft 5.

  Next, control of each part of the ECU 30 will be described.

  As shown in FIG. 2, the vehicle speed of the vehicle speed detection device 25 is input to the basic control unit 50 of the ECU 30 in addition to the steering torque of the steering torque detection device 26. The steering characteristic storage unit 51 of the basic control unit 50 stores base steering characteristics representing the relationship between the steering torque and the assist torque for each vehicle speed. When the auxiliary control signal is not input to the adding unit 52, the base steering characteristic of the steering characteristic storage unit 51 is stored in the post-addition steering characteristic storage unit 53 as the post-addition steering characteristic as it is. When the steering torque of the steering torque detection device 26 and the vehicle speed of the vehicle speed detection device 25 are input, the steering torque and the assist torque corresponding to the vehicle speed are controlled from the added steering characteristic storage unit 53 to the drive device 29 via the gate circuit 54. Output as a signal. With the steering assist of the motor 21, the steering torque of the steering torque detector 26 is reduced. That is, the direction of the steering wheel 13 can be changed by the assist torque of the motor 21 and the steering torque of the steering wheel 90.

  The target yaw rate calculated based on the steering angle and the vehicle speed and the detected yaw rate of the yaw rate detecting device are input to the feedback control unit 41 of the emergency control unit 40. The feedback control unit 41 performs PI control. That is, not only the deviation between the target yaw rate and the detected yaw rate, but also proportional control according to this deviation and integral control according to the accumulated deviation, and a control signal is output.

  The steering torque of the steering torque detector 26 is input to the steering torque gain multiplier 42 of the emergency controller 40. The tire pressure gain multiplication unit 43 of the emergency control unit 40 receives an air pressure signal from the air pressure detection device 27. When the steering torque gain is 1 and the air pressure gain is 1, the control signal from the feedback control unit 41 is directly input to the adding unit 52 as an auxiliary control signal, and the auxiliary control signal is added to the base steering characteristic of the steering characteristic storage unit 51. The added steering characteristic obtained by increasing the assist torque by the amount t is stored in the added steering characteristic storage unit 53.

  When the steering torque gain is 1, the steering torque is less than the minimum set value and the steering is weak. When the steering torque gain is 0, the steering torque is equal to or greater than the maximum set value, and the steering is strong. When the air pressure gain is 1, the air pressure is below the minimum set value, for example, when the steered wheels 13 burst. When the air pressure gain is 0, the air pressure is equal to or greater than the maximum set value, and there is air pressure necessary for traveling. When either the steering torque gain or the air pressure gain is 0, the auxiliary control signal is 0, and the base steering characteristic in the steering characteristic storage unit 51 is stored in the post-addition steering characteristic storage unit 53 as the post-addition steering characteristic. For example, when the steering torque gain is 0.6 and the air pressure gain is 0.4, an auxiliary control signal obtained by multiplying the control signal of the feedback control unit 41 by 0.24 is input to the addition unit 52.

  Next, automatic steering control will be described.

  As shown in FIG. 1, the image signal from the video camera 61 is transmitted to the image processing circuit 62, and the position of the lane on the side of the vehicle is estimated by the image processing circuit 62 based on the image signal. The electric power steering device 1 is steered so that the vehicle can travel along the lane while keeping the distance between the vehicle and the lane constant by the automatic steering control unit 60. When performing automatic steering, the changeover switch 63 shown in FIG. 2 is turned on and the steering wheel 90 is not operated. Then, the control signal of the automatic steering control unit 60 is transmitted to the drive device 29 via the gate circuit 54. When the steering torque of the steering torque detection device 26 is input to the gate circuit 54 by operating the steering wheel 90, the control signal of the automatic steering control unit 60 is cut off, and the control signal of the added steering characteristic storage unit 53 is changed to the drive device. 29.

  The operation when the wheels burst during automatic steering or when the wheels burst during manual steering will be described.

  When the wheel bursts, the vehicle flows to the side of the bursted wheel. When the driver rushes and performs strong steering of the steering wheel 90, there is no auxiliary control signal from the emergency control unit 40, and the steering operation is performed with the base steering characteristic stored in the steering characteristic storage unit 51. In the case of strong steering, it is easier to avoid excessive steering if there is no auxiliary control signal.

  When the wheel bursts, the vehicle flows to the side of the bursted wheel. When the driver quietly steers the steering wheel 90, there is an auxiliary control signal from the emergency control unit 40, and after adding the auxiliary control signal to the base steering characteristic stored in the steering characteristic storage unit 51 Steering is performed with the steering characteristics. In the case of weak steering, assisting by the auxiliary control signal can prevent the vehicle from flowing toward the bursting wheel side, so that the steering operation can be performed calmly without rushing, and vehicle control failure can be avoided.

  The present invention is not limited to these embodiments, and can of course be implemented in various modes without departing from the gist of the present invention.

  The above-described embodiment uses the post-addition steering characteristic storage unit 53 that stores the post-addition steering characteristic, and inputs a control signal from the post-addition steering characteristic storage unit 53 to the drive device 29. As another embodiment, the control signal from the adder 52 may be input to the drive device 29 without using the post-addition steering characteristic storage unit 53.

  In the above-described embodiment, the target yaw rate is calculated from the steering angle and the vehicle speed, and the vehicle is controlled to be the target yaw rate. As another embodiment, the target yaw rate may be zero. Although the vehicle is in a straight state, the control is facilitated as much as the target yaw rate is not calculated.

3: Intermediate shaft (transmission path), 4: Rack and pinion mechanism (steering device), 5: Steering shaft (steering device, transmission path), 10: Pinion shaft (transmission path), 11: Rack shaft (transmission path) , 21: motor, 22: steering angle detection device, 25: vehicle speed detection device, 26: steering torque detection device, 27: air pressure detection device, 29: drive device, 40: emergency control unit, 50: basic control unit, 51: Steering characteristic storage unit, 52: addition unit, 53: steering characteristic storage unit after addition, 54: gate circuit

Claims (4)

One end is connected to a steering wheel, the other end is connected to a steering wheel, and a steering device having a transmission path for transmitting a driver's steering operation to the steering wheel;
A steering torque detecting device provided in the middle of the transmission path for detecting steering torque;
A yaw rate detection device for detecting the yaw rate of the vehicle;
A vehicle speed detection device for detecting the vehicle speed of the vehicle;
A motor that is provided in the middle of the transmission path and applies a steering force to the transmission path;
A driving device for amplifying a control signal and supplying a driving current to the motor;
In an electric power steering device comprising a basic control unit for controlling the control signal supplied to the drive device so that an assist torque corresponding to the vehicle speed and the steering torque is obtained during a steering operation of the driver,
An air pressure detecting device for detecting air pressure of a wheel such as the steering wheel;
An emergency control unit that issues an auxiliary control signal when the air pressure is less than or equal to a maximum set value and the steering torque is less than or equal to a maximum set value;
The emergency control unit calculates a yaw rate deviation that is a difference between a target yaw rate and a detected yaw rate detected by the yaw rate detection device, and generates a steering torque gain when the steering torque is equal to or less than a maximum set value. A function of calculating an auxiliary control signal by generating an air pressure gain when an air pressure is less than or equal to the maximum set value, and multiplying the yaw rate deviation by the steering torque gain and the air pressure gain;
The basic control unit includes a steering characteristic storage unit that stores the assist torque according to the vehicle speed and the steering torque, and the auxiliary control signal of the emergency control unit is stored in a base steering characteristic that is stored in the steering characteristic storage unit. An electric power steering apparatus comprising: an adding unit that adds and outputs to the driving device. The emergency control unit calculates a yaw rate PI control value PI-controlled from the target yaw rate and the detected yaw rate, and a steering torque that generates the steering torque gain when the steering torque is equal to or less than a maximum set value. A gain multiplying unit and a tire air pressure gain multiplying unit that generates the air pressure gain when the air pressure is less than or equal to the maximum set value, and multiplying the yaw rate PI control value by the steering torque gain and the air pressure gain. The electric power steering apparatus according to claim 1, wherein the auxiliary control signal is calculated. The electric power steering apparatus according to claim 1 or 2, wherein the target yaw rate is zero. An automatic steering apparatus to which the electric power steering apparatus according to any one of claims 1 to 3 is applied.

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