JP2015223875A - Automatic steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic steering device in which a variation of the followability, convergence performance and responsiveness of an actual steering angle resulting from a change of a steering load condition are not generated.SOLUTION: An automatic steering device comprises a motor current control part gain decision part 56 which decides a control gain of a motor current control part 54 from a motor parameter, a motor rotation angle θm and a motor actual current Im. When the motor actual current Im is larger than a prescribed motor actual current Im0, the motor current control part gain decision part 56 acquires first motor rotation angle acceleration αm1 when disturbance torque T being a part of the motor parameter is set zero with respect to the motor actual current Im, also acquires second motor rotation angle acceleration αm2 from the secondary differentiation of the motor rotation angle θm, and when an absolute value of a difference between the first motor rotation angle acceleration αm1 and the second motor rotation angle acceleration αm2 becomes larger than prescribed motor rotation angle acceleration α0, the motor current control part gain decision part 56 increases the control gain of the motor current control part 54.

Description

  The present invention relates to an automatic steering apparatus.

  2. Description of the Related Art Conventionally, in an automatic steering apparatus that steers by controlling the rotation of a steering motor, the motor current is controlled so that the deviation between the target steering angle and the actual steering angle detected by the steering angle detection means is reduced. However, the steering load condition changes depending on the friction coefficient between the tire and the road surface, the vehicle speed, and the like, and there is a problem that the followability and convergence of the actual steering angle vary due to the change.

  Therefore, for example, in the automatic steering device described in Patent Document 1, when the change rate of the actual steering angle is small with respect to the deviation between the target steering angle and the actual steering angle, it is determined that the steering load is large, and the control gain is set. Since it is increased, there is no variation in the followability and convergence of the actual steering angle.

Japanese Patent Application Laid-Open No. 11-078935

  However, in the above method, since the change rate of the actual steering angle is detected and the control gain is changed, the followability, convergence, and responsiveness of the actual steering angle may be delayed.

  An object of the present invention is to provide an automatic steering device that does not cause variations in followability, convergence, and response of an actual steering angle due to changes in steering load conditions.

  In order to solve the above problems, the invention according to claim 1 controls the motor current control unit so that the deviation between the steering angle command and the actual steering angle detected by the actual steering angle detection means is reduced, and the motor In an automatic steering apparatus for controlling rotation of the motor, motor actual current detection means for detecting motor actual current, motor rotation angle detection means for detecting motor rotation angle, motor parameter storage means for storing parameters of the motor, and the motor Motor current control unit gain determining means for determining a motor current control unit gain from the parameters of the motor, the motor rotation angle, and the motor actual current, and the motor current control unit gain determining means is configured such that the motor actual current is a predetermined current. When the value is larger than the value, the rotation of the first motor when the disturbance torque, which is a part of the motor parameters, is set to zero with respect to the actual motor current. In addition to obtaining the acceleration, the rotational angular acceleration of the second motor is obtained from the second derivative of the rotational angle of the motor, and the difference between the rotational angular acceleration of the first motor and the rotational angular acceleration of the second motor is calculated. The gist is to increase the control gain of the motor current control unit when the absolute value becomes larger than a predetermined motor rotation angular acceleration.

  In the automatic steering device according to the present invention, the motor actual current detecting means for detecting the motor actual current, the motor rotation angle detecting means for detecting the motor rotation angle, the motor parameter storage means for storing the motor parameters of the motor, A motor current control unit gain determining unit that determines a control gain of the motor current control unit from the parameter, the motor rotation angle, and the motor actual current, and the motor current control unit gain determining unit determines whether the motor actual current is greater than a predetermined motor actual current. When the motor torque is large, the first motor rotation angular acceleration when the disturbance torque, which is a part of the motor parameter, is set to zero is obtained with respect to the motor actual current, and the second difference is obtained from the second derivative of the motor rotation angle. And the absolute value of the difference between the first motor rotational angular acceleration and the second motor rotational angular acceleration is a predetermined motor rotational angular acceleration. Ri if it becomes large, and configured to increase the control gain of the motor current control unit.

  That is, when the motor actual current is larger than the predetermined motor actual current, it is determined that the motor is rotating at high speed in the normal state. In order to verify this, the first motor rotation angular acceleration when the disturbance torque that is a part of the motor parameter is set to zero is obtained with respect to the motor actual current, and further, from the second derivative of the motor rotation angle. The second motor rotational angular acceleration is obtained, and it is determined whether or not the absolute value of the difference between the first motor rotational angular acceleration and the second motor rotational angular acceleration is greater than a predetermined motor rotational angular acceleration.

  When the absolute value of the difference between the first motor rotational angular acceleration and the second motor rotational angular acceleration is greater than a predetermined motor rotational angular acceleration, the tire It is determined that the steering load condition is large based on the coefficient of friction with the road surface, the vehicle speed, and the like, and the control gain of the motor current control unit is increased. By increasing the control gain of the motor current control unit, the motor actual current in the motor current control unit can be increased.

  As a result, it is possible to overcome the increased steering load condition and follow the command steering angle without variation in the followability, convergence, and response of the actual steering angle.

  According to the present invention, it is possible to provide an automatic steering device that does not cause variations in followability, convergence, and response of an actual steering angle due to changes in steering load conditions.

The schematic block diagram of the automatic steering apparatus in this embodiment. The control block diagram of the automatic steering device in this embodiment. The relationship figure of the motor rotational angular acceleration and motor actual current in this embodiment. The flowchart figure which shows the process sequence of the motor current control part gain determination part in this embodiment.

Hereinafter, an embodiment of the present invention embodied in an automatic steering apparatus 1 having a column-type electric power steering apparatus (hereinafter referred to as EPS) will be described with reference to the drawings.
As shown in FIG. 1, the automatic steering apparatus of the present embodiment includes an automatic operation ECU 28 that is a host controller that transmits a steering angle command θp * to the EPS ECU 29 via the in-vehicle network 60 (CAN).

  Next, the EPS of this embodiment will be described. As shown in FIG. 1, in the EPS of the present embodiment, a steering shaft 3 to which a steering 2 is fixed is connected to a rack shaft 5 via a rack and pinion mechanism 4. The rotation of the steering shaft 3 accompanying the steering operation is converted into a reciprocating linear motion of the rack shaft 5 by the rack and pinion mechanism 4.

  The steering shaft 3 of this embodiment is formed by connecting a column shaft 8, an intermediate shaft 9, and a pinion shaft 10. The reciprocating linear motion of the rack shaft 5 accompanying the rotation of the steering shaft 3 is transmitted to a knuckle (not shown) via tie rods 11 connected to both ends of the rack shaft 5, whereby the steered angle of the steered wheels 12. Has been changed.

  The EPS also includes an EPS actuator 24 as a steering force assisting device that applies an assist force for assisting a steering operation to the steering system using the motor 21 as a drive source, and an EPS ECU 29 that controls the operation of the EPS actuator 24. Yes.

  The EPS actuator 24 of the present embodiment is a column type EPS actuator, and the motor 21 that is a drive source thereof is drivingly connected to the column shaft 8 via a speed reduction mechanism 23. The rotation of the motor 21 is decelerated by the speed reduction mechanism 23 and transmitted to the column shaft 8 so that the motor torque is applied to the steering system as an assist force.

  On the other hand, the EPSECU 29 is connected to a vehicle speed sensor 25, a torque sensor 26, a steering angle sensor 27 as actual steering angle detection means, and a motor rotation angle sensor 22 as motor rotation angle detection means. Based on the sensor output signal, the vehicle speed V, steering torque τ, actual steering angle θp, and motor rotation angle θm are detected.

  The torque sensor 26 is a twin resolver type torque sensor. The EPS ECU 29 calculates a steering torque τ based on output signals of a pair of resolvers provided at both ends of a torsion bar (not shown). Further, the EPS ECU 29 calculates a target assist force based on each detected state quantity, and assists the operation of the EPS actuator 24, that is, an assist given to the steering system through the supply of drive power to the motor 21 that is the drive source. Control the power.

Next, an electrical configuration of the automatic steering apparatus according to the present embodiment will be described.
FIG. 2 is a control block diagram of the automatic steering apparatus of the present embodiment. As shown in the figure, the EPS ECU 29 includes a microcomputer 30 that outputs a motor control signal, a drive circuit unit 31 that supplies drive power to the motor 21 that is a drive source of the EPS actuator 24 based on the motor control signal, and And a current sensor 32 which is a motor actual current detecting means for detecting a motor actual current Im supplied to the motor 21.

  The drive circuit unit 31 is a known PWM inverter (not shown) formed by connecting two arms corresponding to each phase in parallel with a pair of switching elements connected in series as a basic unit (arm). The motor control signal output from the microcomputer 30 defines the on-duty ratio of each switching element that constitutes the drive circuit unit 31. A motor control signal is applied to the gate terminal of each switching element, and each switching element is turned on / off in response to the motor control signal, thereby generating motor driving power based on the power supply voltage of the battery 20, and the motor 21. It is configured to output to.

  The EPS ECU 29 is connected to a motor rotation angle sensor 22 for detecting the motor rotation angle θm of the motor 21. The microcomputer 30 drives based on the motor actual current Im and the motor rotation angle θm detected based on the output signals of these sensors, and the steering torque τ, the vehicle speed V, and the actual steering angle θp. A motor control signal is output to the circuit unit 31.

  Each control block shown below is realized by a computer program executed by the microcomputer 30. The microcomputer 30 detects each state quantity at a predetermined sampling period, and generates a motor control signal by executing each arithmetic processing shown in the following control blocks at every predetermined period.

  As shown in FIG. 2, the microcomputer 30 includes an automatic driving steering angle processing unit 35 and a motor current generation unit 36 that generates a motor control signal for controlling the drive circuit unit 31.

  The automatic driving steering angle processing unit 35 receives the steering angle command θp * transmitted from the automatic driving ECU 28 via the in-vehicle network 60 (CAN), and takes in the actual steering angle θp detected by the steering angle sensor 27. . Then, the automatic driving steering angle processing unit 35 subtracts the steering angle command θp * and the actual steering angle θp by the subtractor 41 to generate a steering angle deviation Δθp.

  Further, the automatic driving steering angle processing unit 35 performs PID control on the steering angle deviation Δθp by the position control unit 40, generates a motor current command Im1 * at the time of automatic driving, and generates a motor current command Im1 * at the time of automatic driving at the subsequent motor. Input to the current generator 36.

  The motor current generation unit 36 includes a torque / motor current command value map 50, a manual intervention determination unit 51, a motor command current switching unit 52, a motor current control unit 54 having variable PID control, a PWM output unit 55, The motor current control unit gain determination unit 56 is a motor current control unit gain determination unit, the motor parameter storage unit 57 is a motor parameter storage unit, and the motor current control unit gain storage unit 58 is configured.

  The torque / motor current command value map 50 receives the steering torque τ and the vehicle speed V and generates a manual intervention motor current command Im2 *. The torque / motor current command value map 50 is configured to determine a larger manual intervention motor current command Im2 * as the vehicle speed V is smaller for the same steering torque τ.

  The manual intervention determination unit 51 determines whether or not the driver has performed steering intervention during automatic steering. That is, when a steering torque τ greater than a predetermined value is detected for a predetermined time or more, it is determined that the driver has intervened during automatic steering, and a manual intervention flag FLGma is output to the motor command current switching unit 52.

  The motor command current switching unit 52 switches the motor current command Im1 * during automatic operation and the motor current command Im2 * during manual intervention according to the determination of the manual intervention determination unit 51. That is, when the manual intervention determination unit 51 determines that manual intervention is not performed, the motor command current switching unit contacts 52a and 52c are connected, and the motor current command Im1 * during automatic operation is output as the motor current command Im *. . On the other hand, when the manual intervention determination unit 51 determines that manual intervention is performed, the motor command current switching unit contacts 52b and 52c are connected and the manual intervention motor current command Im2 * is output as the motor current command Im *. .

  The motor current control unit 54 performs variable PID (proportional + integral + derivative) control on the motor current deviation ΔIm output from the subtractor 53 and outputs a motor voltage command V *. The variable PID control gain is input from the motor current control unit gain determination unit 56 (details will be described later).

  The PWM output unit 55 converts the motor voltage command V * output from the motor current control unit 54 into a motor control signal and outputs it to the drive circuit unit 31. The drive circuit unit 31 controls the rotation of the motor.

  The motor current control unit gain determination unit 56 reads the motor parameter K (torque constant) and the motor parameter J (motor inertia) stored in the motor parameter storage unit 57, and calculates the first motor rotation angular acceleration αm1. The motor current control unit gain determination unit 56 calculates the second motor rotation angular acceleration αm2 by second-order differentiation of the motor rotation angle θm detected from the motor rotation angle sensor 22.

  Then, the motor current control unit gain determination unit 56 determines whether the motor current control unit gain storage unit 58 stores the motor current control unit according to the difference between the first motor rotation angular acceleration αm1 and the second motor rotation angular acceleration αm2. The high gain Gm or the normal gain Gn of the motor current control unit is read, and the variable PID control gain of the motor current control unit 54 is changed.

Next, the relationship between the motor rotation angular acceleration and the motor actual current in this embodiment will be described with reference to FIG.
The horizontal axis in FIG. 3 is the actual motor current, and the vertical axis is the motor rotation angular acceleration.
Here, each parameter of the motor is defined as follows.
K: torque constant, J: motor inertia, T: disturbance torque, acceleration α = K * Im / J−T / J (1)
The straight line L1 (thin line) in FIG. 3 represents the motor rotation angular acceleration line when the disturbance torque is zero in the equation (1), and the straight line L2 (thick line) represents the motor rotation angular acceleration line when the disturbance torque is present. .

  The motor current control unit gain determination unit 56 calculates the first motor rotational angular acceleration αm1 by setting the disturbance torque T in the equation (1) to zero when the motor actual current Im becomes equal to or greater than the predetermined motor actual current Im0. The second motor rotation angular acceleration αm2 is obtained from the second derivative of the motor rotation angle θm.

  When the absolute value of the difference between the first motor rotational angular acceleration αm1 and the second motor rotational angular acceleration αm2 is larger than the predetermined motor rotational angular acceleration α0, the friction coefficient between the tire and the road surface, the vehicle speed, etc. Therefore, it is determined that the steering load condition is large, and the control gain of the motor current control unit 54 is increased. As a result, it is possible to overcome the increased steering load condition and follow the command steering angle without variation in the followability, convergence, and response of the actual steering angle.

Next, a processing procedure of the motor current control unit gain determination unit 56 by the microcomputer 30 of the present embodiment will be described with reference to FIG.
First, the microcomputer 30 reads the motor actual current Im (step S101). Next, the microcomputer 30 determines whether or not the motor actual current Im is equal to or greater than a predetermined motor actual current Im0 (step S102).

  If the motor actual current Im is equal to or greater than the predetermined motor actual current Im0 (step S102: YES), the microcomputer 30 reads the motor parameter K (torque constant) and the motor parameter J (motor inertia) (step S103). ).

  Next, the microcomputer 30 calculates the first motor rotation angular acceleration αm1 (step S104). Further, the microcomputer 30 calculates the second motor rotation angular acceleration αm2 (step S105).

  Then, the microcomputer 30 determines whether or not the absolute value of the difference between the first motor rotational angular acceleration αm1 and the second motor rotational angular acceleration αm2 is equal to or greater than a predetermined motor rotational angular acceleration α0 (step S106).

  When the absolute value of the difference between the first motor rotational angular acceleration αm1 and the second motor rotational angular acceleration αm2 is equal to or greater than a predetermined motor rotational angular acceleration α0 (step S106: YES), the microcomputer 30 The high gain Gm of the motor current control unit is read from the motor current control unit gain storage unit 58 (step S107), and is output to the motor current control unit 54 (variable PID control) (step S108), and the process ends.

  On the other hand, the microcomputer 30 determines that the motor actual current Im is smaller than the predetermined motor actual current Im0 (step S102: NO), or the difference between the first motor rotation angular acceleration αm1 and the second motor rotation angular acceleration αm2. Is smaller than the predetermined motor rotation angular acceleration α0 (step S106: NO), the normal gain Gn of the motor current control unit is read from the motor current control unit gain storage unit 58 (step S109). The current is output to the current controller 54 (variable PID control) (step S108), and the process is terminated.

Next, the operation and effect of the automatic steering apparatus of the present embodiment configured as described above will be described.
A current sensor 32 for detecting a motor actual current Im of the motor 21; a motor rotation angle sensor 22 for detecting a motor rotation angle θm of the motor 21; a motor parameter storage unit 57 for storing the motor parameters of the motor 21; A motor current control unit gain determination unit 56 for determining a control gain of the motor current control unit 54 from the motor rotation angle θm and the motor actual current Im. The motor current control unit gain determination unit 56 has a predetermined motor actual current Im When the motor actual current Im0 is larger than the motor actual current Im0, the first motor rotation angular acceleration αm1 when the disturbance torque T, which is a part of the motor parameter, is set to zero is obtained with respect to the motor actual current Im. The second motor rotation angular acceleration αm2 is obtained from the second derivative of the angle θm, and the first motor rotation angular acceleration αm1 and the second motor rotation angular acceleration αm1 are calculated. If the absolute value of the difference between the motor rotation angular acceleration αm2 is larger than the predetermined motor rotational angular acceleration α0 was configured to increase the control gain of the motor current control unit 54.

  With this configuration, when the motor actual current Im is larger than the predetermined motor actual current Im0, it is determined that the motor 21 is rotating at high speed in the normal state. In order to verify this, the first motor rotation angular acceleration αm1 when the disturbance torque T, which is part of the parameters of the motor 21, is set to zero with respect to the motor actual current Im, and the motor rotation angle θm is further obtained. The second motor rotational angular acceleration αm2 is obtained from the second derivative of the above, and the absolute value of the difference between the first motor rotational angular acceleration αm1 and the second motor rotational angular acceleration αm2 is greater than the predetermined motor rotational angular acceleration α0. It is determined whether or not.

  When the absolute value of the difference between the first motor rotational angular acceleration αm1 and the second motor rotational angular acceleration αm2 is larger than the predetermined motor rotational angular acceleration α0, the motor actual current Im is large. First, it is determined that the steering load condition is large based on the friction coefficient between the tire and the road surface, the vehicle speed, and the like, and the control gain of the motor current control unit 54 is increased. By increasing the control gain of the motor current control unit 54, the motor actual current Im in the motor current control unit 54 can be increased.

  As a result, it is possible to overcome the increased steering load condition and follow the command steering angle without variation in the followability, convergence, and response of the actual steering angle.

In addition, you may change this embodiment as follows.
In the present embodiment, the second motor rotation angular acceleration αm2 is obtained from the second derivative of the motor rotation angle θm. However, the present invention is not limited to this, and the second motor rotation angular acceleration αm2 may be detected by an acceleration sensor.

In the present embodiment, the present invention is embodied in the column assist EPS, but the present invention may be applied to a rack assist EPS or a pinion assist EPS.

In the present embodiment, the present invention is embodied as a DC motor as the motor 21 that is the drive source of the EPS actuator 24. However, the present invention may be a three-phase brushless DC motor, an induction motor, and a stepping motor.

1: automatic steering device, 2: steering, 3: steering shaft,
4: rack and pinion mechanism, 5: rack shaft, 8: column shaft,
9: Intermediate shaft, 10: Pinion shaft, 11: Tie rod, 12: Steered wheel, 20: Battery, 21: Motor,
22: Motor rotation angle sensor (motor rotation angle detection means), 23: Deceleration mechanism,
24: EPS actuator, 25: Vehicle speed sensor, 26: Torque sensor,
27: Steering angle sensor (actual steering angle detecting means), 28: Automatic operation ECU,
29: EPSECU, 30: microcomputer, 31: drive circuit unit,
32: Current sensor (motor actual current detection means), 35: Automatic driving steering angle processing unit,
36: Motor current generation unit, 40: Position control unit (PID control), 41, 53: Subtractor,
50: Torque / motor current command value map, 51: Manual intervention determination unit,
52: Motor command current switching unit, 52a, 52b, 52c: Motor command current switching unit contacts,
54: Motor current control unit (variable PID control), 55: PWM output unit,
56: Motor current control unit gain determination unit (motor current control unit gain determination means),
57: Motor parameter storage unit (motor parameter storage means),
58: Motor current control unit gain storage unit, 60: In-vehicle network (CAN),
V: vehicle speed, τ: steering torque, θm: motor rotation angle,
Im1 *: Motor current command during automatic operation, Im2 *: Motor current command during manual intervention,
Im *: motor current command, Im: actual motor current, ΔIm: motor current deviation,
Im0: predetermined motor actual current, V *: motor voltage command,
θp *: steering angle command, θp: actual steering angle, Δθp: steering angle deviation,
αm1: first motor rotational angular acceleration, αm2: second motor rotational angular acceleration,
α0: predetermined motor rotation angular acceleration,
K: Motor parameter (torque constant), J: Motor parameter (motor inertia),
T: Disturbance torque,
Gm: High gain of the motor current control unit, Gn: Normal gain of the motor current control unit,
FLGma: manual intervention flag,
L1: motor rotation angular acceleration straight line with zero disturbance torque,
L2: Motor rotation angular acceleration straight line with disturbance torque

Claims (1)

In the automatic steering device that controls the motor current control unit and controls the rotation of the motor so as to reduce the deviation between the steering angle command and the actual steering angle detected by the actual steering angle detection means,
Motor actual current detecting means for detecting motor actual current;
Motor rotation angle detection means for detecting the motor rotation angle;
Motor parameter storage means for storing parameters of the motor;
A motor current control unit gain determining means for determining a motor current control unit gain from the motor parameters, the motor rotation angle, and the motor actual current;
When the motor actual current is larger than a predetermined current value, the motor current control unit gain determining unit is configured to set a disturbance torque that is a part of the motor parameter to zero with respect to the motor actual current. The rotation angular acceleration of the first motor is obtained, and further, the rotation angular acceleration of the second motor is obtained from the second derivative of the motor rotation angle, and the rotation angular acceleration of the first motor and the second motor are obtained. If the absolute value of the difference in rotational angular acceleration of the motor is greater than a predetermined motor rotational angular acceleration, increasing the control gain of the motor current control unit,
An automatic steering device characterized by this.

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