JP2015166211A - electric power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric power steering device excellent in a steering feeling without causing discomfort even in a steered state to any of the left or right in a left-right one-hand steering state.SOLUTION: When determined as a right one-hand operation state by steering state determination means, during left steering, it is necessary to input steering force against gravity compared with right steering time. Thus, during the left steering, a steering feeling can be improved by increasing assist force more than the right steering time. On the other hand, when determined as a left one-hand operation state by the steering state determination means, during the right steering, it is necessary to input the steering force against the gravity compared with the left steering time. Thus, during the right steering, a steering feeling can be improved by increasing assist force more than the left steering time.

Description

  The present invention relates to an electric power steering apparatus.

  Conventionally, in an electric power steering apparatus that assists steering by an electric motor, a target current is generated from a vehicle speed and a steering torque, and an actual current flowing through the electric motor is detected by a current detector. A comfortable steering feeling is obtained by calculating the difference between the target current and the actual current and generating the optimum assist force by performing the known PID control (proportional control, integral control, differential control). Assist control is performed so that

  However, in the conventional electric power steering apparatus, the assist force does not change depending on whether the driver performs the steering operation with both hands or with one hand. Therefore, when the steering wheel is operated with one hand, there is a problem that the assist force is insufficient, the driver's steering burden is increased, and the steering feeling is poor. Therefore, for example, in the electric power steering apparatus described in Patent Document 1, the steering feeling is improved by applying a larger assist force in the one-handed steering state than in the two-handed steering state.

JP 2002-160658 A

  However, in the method as described above, for example, when the right steering in the right one-handed steering state is compared with the left steering, it is necessary to input the steering force against the gravity during the left steering. For this reason, a relatively large steering force is required as compared with the right steering, and the left and right steering forces become unbalanced, which may deteriorate the steering feeling.

  An object of the present invention is to provide an electric power steering apparatus that has a good steering feeling and that does not feel uncomfortable in either the left or right one-handed steering state.

  In order to solve the above problems, the invention according to claim 1 is directed to a steering force assisting device provided to apply an assist force for assisting a steering operation to a steering system by a motor, and a driver performs the steering operation with both hands. Or, an operation state detection means for detecting whether the right hand or the left hand is operated, a steering state determination means for determining a steering state from detection data detected by the operation state detection means, and a steering for detecting a steering torque Torque detection means; vehicle speed detection means for detecting vehicle speed; steering torque detected from the steering torque detection means; target current command value generation means for generating a target current command value from the vehicle speed detected from the vehicle speed detection means; Based on the control state quantity generated by the target current command value generation means, the drive power for the motor that is the drive source of the steering force assisting device An electric power steering apparatus comprising: a control means for controlling the operation of the steering force assisting device by supplying the control means; when the control state is determined to be a right one-hand operation state by the steering state determination means, The gist is to increase the assist force during left steering from during steering, and to increase the assist force during right steering from left steering when the steering state determination means determines that the left hand is one-handed. To do.

  In the electric power steering apparatus according to the present invention, when the steering state determination unit determines that the right one-hand operation state is established, the assist force is increased during left steering than during right steering, and the left hand one-hand operation state is determined by the steering state determination unit. When it is determined that the assist force is increased during the right steering than during the left steering, the assist force is increased.

  That is, when it is determined that the right one-handed operation state is determined by the steering state determination means, it is necessary to input the steering force against the gravity during left steering as compared to during right steering. Therefore, the steering feeling can be improved by increasing the assist force during left steering compared to during right steering. On the other hand, when the left-handed one-hand operation state is determined by the steering state determination means, it is necessary to input the steering force against the gravity during right steering as compared to during left steering. Therefore, the steering feeling can be improved by increasing the assist force during right steering than during left steering.

  The gist of the invention described in claim 2 is that an assist map is provided as means for increasing the assist force.

  By providing the assist map, the assist force can be quickly changed according to the steering state determined by the steering state determination means, so that the steering feeling can be further improved.

  According to the present invention, it is possible to provide an electric power steering apparatus with a good steering feeling that does not give a sense of incongruity in either a left-right one-hand steering state or a left-right steering state.

The schematic block diagram of an electric power steering device (EPS). The whole control block diagram of EPS. The assist map figure of each steering state in this embodiment. The flowchart figure which shows the process sequence of the steering state determination part in this embodiment.

Hereinafter, an embodiment of the present invention embodied in 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, in the EPS 1 of the present embodiment, a steering shaft 3 to which a steering wheel 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 the knuckle (not shown) via the tie rods 11 connected to both ends of the rack shaft 5, thereby turning the steered wheels 12. The corner is changed.

  The EPS 1 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 ECU 27 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 ECU 27 includes a vehicle speed sensor 25 (vehicle speed detection means), a torque sensor 26 (steering torque detection means), a motor rotation angle sensor 22, and the steering wheel 2. (Operation state detection means) is connected, and the ECU 27 detects the vehicle speed V, the steering torque τ, the motor rotation angle θm, and the pressure sensor output signal PS based on the output signals of these sensors.

  The torque sensor 26 is a twin resolver type torque sensor. The ECU 27 calculates a steering torque τ based on output signals from a pair of resolvers provided at both ends of a torsion bar (not shown). Further, the ECU 27 calculates a target assist force based on each of the detected state quantities, and assists the operation of the EPS actuator 24 through the supply of drive power to the motor 21 that is the drive source, that is, the assist that is given to the steering system. Control the power.

Next, an electrical configuration in the EPS 1 of the present embodiment will be described.
FIG. 2 is an overall control block diagram of the EPS 1 of the present embodiment. As shown in the figure, the ECU 27 is a microcomputer 29 (control means) that outputs a motor control signal, and a drive circuit that supplies drive power to the motor 21 that is the drive source of the EPS actuator 24 based on the motor control signal. 40, and an actual current value detection sensor 30 (actual current value detection means) for detecting the actual current value Im supplied to the motor 21.

  The drive circuit 40 is a known PWM inverter (not shown) in which two or more arms corresponding to each phase are connected in parallel with a pair of switching elements connected in series as a basic unit (arm). Further, the motor control signal output from the microcomputer 29 defines the on-duty ratio of each switching element that constitutes the drive circuit 40. A motor control signal is applied to the gate terminal of each switching element, and in response to the motor control signal, each switching element is turned on / off to generate motor driving power based on the power supply voltage of the battery 28, and the motor 21. It is configured to output to.

  A motor rotation angle sensor 22 for detecting the motor rotation angle θm of the motor 21 is connected to the ECU 27. The microcomputer 29 outputs a motor control signal to the drive circuit 40 based on the actual current value Im, the motor rotation angle θm, the steering torque τ, and the vehicle speed V detected based on the output signals of these sensors. To do.

  Each control block shown below is realized by a computer program executed by the microcomputer 29. The microcomputer 29 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 every predetermined period.

  As shown in FIG. 2, the microcomputer 29 includes a steering state determination unit 31 (steering state determination unit) that determines a steering state, and a current command value generation unit 32 that generates a current command value for controlling the motor 21 (target current command). Value generating means) and a motor control signal generating unit 44 for generating a motor control signal for controlling the drive circuit 40.

  The steering state determination unit 31 receives an ignition signal IG that is output when an ignition switch (not shown) is turned on, and a pressure sensor output signal PS that is detection data detected by the pressure sensor 20. Here, the pressure-sensitive sensor 20 is a sensor that detects whether the driver is performing a steering operation with both hands, a right hand, or a left hand. Based on the ignition signal IG and the pressure-sensitive sensor output signal PS, the steering state determination unit 31 uses the assist map 1 (33), assist map 2 (34), and assist map set in the current command value generation unit 32. 3 (35), an assist map 1 selection signal AMS1, an assist map 2 selection signal AMS2, and an assist map 3 selection signal AMS3 are generated.

  The current command value generation unit 32 includes a steering torque τ detected by the torque sensor 26, a vehicle speed V detected by the vehicle speed sensor 25, an assist map 1 selection signal AMS1 generated by the steering state determination unit 31, and an assist map. The 2 selection signal AMS2 and the assist map 3 selection signal AMS3 are input.

  The current command value generation unit 32 is a control state amount of the assist torque based on the steering torque τ, the vehicle speed V, the assist map 1 selection signal AMS1, the assist map 2 selection signal AMS2, and the assist map 3 selection signal AMS3. The current command value I * is determined from the assist map 1 (33), the assist map 2 (34), and the assist map 3 (35).

The assist map will be described based on the assist map diagram of each steering state in the present embodiment of FIG.
In the assist map diagram, the horizontal axis represents the steering torque τ, the vertical axis represents the current command value I *, and in the case of the same steering torque, the smaller the vehicle speed V, the larger the current command value I * is determined. .

  When the assist map 1 selection signal AMS1 is output from the steering state determination unit 31, the assist map 1 selection AND gate 36 is activated and the assist map 1 (33) is selected. The assist map 1 (33) outputs a minimum current command value I * for the same steering torque τ as compared to the assist map 2 (34) and the assist map 3 (35).

  When the assist map 2 selection signal AMS2 is output from the steering state determination unit 31, the assist map 2 selection AND gate 37 is activated, and the assist map 2 (34) is selected. The assist map 2 (34) outputs an intermediate current command value I * for the same steering torque τ compared to the assist map 1 (33) and the assist map 3 (35).

  When the assist map 3 selection signal AMS3 is output from the steering state determination unit 31, the assist map 3 selection AND gate 38 is activated and the assist map 3 (35) is selected. The assist map 3 (35) outputs the maximum current command value I * with respect to the same steering torque τ compared to the assist map 1 (33) and the assist map 2 (34).

  The motor control signal generator 44 receives the current command value I * from the current command value generator 32 and the actual current value Im detected from the actual current value detection sensor 30. The motor control signal generation unit 44 generates a current deviation value ΔI as a result of subtraction through the subtractor 39J from the input current command value I * and the actual current value Im.

  Furthermore, the motor control signal generation unit 44 inputs the current deviation value ΔI generated by the subtractor 39J to the subsequent current control unit 39. The current control unit 39 controls and calculates the input current deviation value ΔI by known proportional, integral, and differential control, and generates a motor control signal. The motor control signal generated by the motor control signal generation unit 44 is input to the drive circuit 40 and supplies drive power for driving the motor 21.

Next, the processing procedure of the steering state determination unit by the microcomputer 29 of the present embodiment will be described based on the flowchart of FIG.
First, the microcomputer 29 determines whether or not the ignition signal IG is on (step S100). If the microcomputer 29 determines that the ignition signal IG is on (step S100: YES), the microcomputer 29 reads the pressure sensor output signal PS (step S101). On the other hand, if the microcomputer 29 determines that the ignition signal IG is not on (step S100: NO), the microcomputer 29 returns to step S100 and waits until the ignition signal IG is turned on.

  Next, the microcomputer 29 determines whether one-handed steering is performed (step S102). The microcomputer 29 determines that one-handed steering is performed when the pressure-sensitive sensor output signal PS is output only from the left or right half of the steering wheel. If the microcomputer 29 determines that the steering is one-handed (step S102: YES), the microcomputer 29 determines whether the steering is right-handed (step S103). The microcomputer 29 determines right-hand steering when the pressure-sensitive sensor output signal PS is output only from the right half region of the steering wheel. Further, when the microcomputer 29 determines that the steering is right hand steering (step S103: YES), the microcomputer 29 determines whether the steering is right steering (step S104).

  If the microcomputer 29 determines that the steering wheel is steered right (step S104: YES), the microcomputer 29 outputs an assist map 1 selection signal AMS1 (step S105) and ends the process.

  On the other hand, if the microcomputer 29 determines that steering is not right steering (step S104: NO), it determines whether steering left steering (step S106). If the microcomputer 29 determines that the steering wheel is left steered (step S106: YES), the microcomputer 29 outputs an assist map 3 selection signal AMS3 (step S107) and ends the process.

  Furthermore, if the microcomputer 29 determines that the steering is not left steering (step S106: NO), the microcomputer 29 determines that the steering wheel is in a steered state, outputs an assist map 2 selection signal AMS2 (step S108), and performs processing. Finish.

  If the microcomputer 29 determines that the steering is not right-handed (step S103: NO), the microcomputer 29 determines whether the steering is left-handed (step S109). If the microcomputer 29 determines that the steering wheel is steered to the left (step S109: YES), the microcomputer 29 outputs an assist map 1 selection signal AMS1 (step S110) and ends the process.

On the other hand, if the microcomputer 29 determines that the steering is not left steering (step S109: NO), the microcomputer 29 determines whether steering is right steering (step S111). And
If it is determined that the steering wheel is steered right (step S111: YES), an assist map 3 selection signal AMS3 is output (step S112), and the process is terminated.

  If the microcomputer 29 determines that the steering is not right steering (step S111: NO), the microcomputer 29 determines that the steering wheel is in a steered state, outputs an assist map 2 selection signal AMS2 (step S113), and performs processing. Finish.

  Further, when the microcomputer 29 determines that the one-handed steering is not performed (step S102: NO), the microcomputer 29 determines whether the two-handed steering is performed (step S114). The microcomputer 29 determines that both hands are steered when the pressure sensor output signal PS is output from both the left and right areas of the steering wheel. If the microcomputer 29 determines that the steering is two-handed (step S114: YES), the microcomputer 29 outputs an assist map 2 selection signal AMS2 (step S115) and ends the process.

  On the other hand, if the microcomputer 29 determines that the steering is not two-handed (step S114: NO), the microcomputer 29 determines that the steering wheel is in the released state, outputs the assist map 2 selection signal AMS2 (step S116), and ends the process.

Next, the operation and effect of the EPS 1 of the present embodiment configured as described above will be described.
When the steering state determination unit 31 (steering state determination unit) determines that the operation state is the right one-handed operation state, the assist force is increased during left steering as compared with right steering, and the steering state determination unit 31 (steering state determination unit) When it is determined that the left-handed one-hand operation state is set, the assist force is increased during right steering than during left steering.

  That is, when the steering state determination unit 31 (steering state determination unit) determines that the right one-hand operation state is set, it is necessary to input the steering force against the gravity at the time of left steering compared to the time of right steering. . Therefore, the steering feeling can be improved by increasing the assist force during left steering compared to during right steering. On the other hand, when the left-handed one-hand operation state is determined by the steering state determination unit 31 (steering state determination unit), it is necessary to input the steering force against the gravity at the time of right steering as compared with the case of left steering. . Therefore, the steering feeling can be improved by increasing the assist force during right steering than during left steering.

The assist map 1 (33), the assist map 2 (34), and the assist map 3 (35) are provided as means for increasing the assist force.
By providing the assist map 1 (33), the assist map 2 (34), and the assist map 3 (35), promptly according to the steering state determined by the steering state determination unit 31 (steering state determination means). Since the assist force can be changed, the steering feeling can be further improved.

In addition, you may change this embodiment as follows.
In the present embodiment, there are three types of assist maps. However, the present invention is not limited to this, and the assist force may be calculated by the determination of the steering state determination unit.

In the present embodiment, the assist map 2 (34) is an intermediate value between the assist map 1 (33) and the assist map 3 (35). However, the present invention is not limited to this, and the assist map 2 (34) It may be configured to generate a current command value I * larger than the assist map 3 (35).

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.

1: Electric power steering device (EPS), 2: Steering wheel,
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: pressure sensor (operation state detecting means),
21: Motor, 22: Motor rotation angle sensor,
23: Deceleration mechanism, 24: EPS actuator (steering force assist device),
25: vehicle speed sensor (vehicle speed detection means), 26: torque sensor (steering torque detection means), 27: ECU, 28: battery, 29: microcomputer (control means),
30: Actual current value detection sensor (actual current value detection means),
31: Steering state determination unit (steering state determination means),
32: Current command value generation unit (target current command value generation means),
33: Assist map 1, 34: Assist map 2, 35: Assist map 3,
36: Assist map 1 selection AND gate,
37: Assist map 2 selection AND gate,
38: Assist map 3 selection AND gate,
39: current control unit, 39J: subtractor, 40: drive circuit, 44: motor control signal generation unit,
V: vehicle speed, τ: steering torque, θm: motor rotation angle,
IG: ignition signal, PS: pressure sensor output signal,
I *: current command value, Im: actual current value, ΔI: current deviation value,
AMS1: Assist map 1 selection signal, AMS2: Assist map 2 selection signal,
AMS3: Assist map 3 selection signal

Claims (2)

A steering force assisting device provided to apply an assisting force to assist the steering operation to the steering system by the motor;
Operation state detection means for detecting whether the driver is performing the steering operation in both hands, right hand, or left hand; and
Steering state determination means for determining a steering state from detection data detected by the operation state detection means;
Steering torque detection means for detecting steering torque;
Vehicle speed detection means for detecting the vehicle speed;
Target current command value generating means for generating a target current command value from the steering torque detected from the steering torque detecting means and the vehicle speed detected from the vehicle speed detecting means;
Control for controlling the operation of the steering force assisting device by supplying drive power to a motor that is a drive source of the steering force assisting device based on the control state quantity generated by the target current command value generating means. An electric power steering apparatus comprising:
The control means increases the assist force during left steering rather than during right steering when the steering state determination means determines that the one-hand operation state is right hand, and determines that the left hand one-hand operation state is due to the steering state determination means. The assist force is increased at the time of right steering than at the time of left steering,
An electric power steering device. The electric power steering apparatus according to claim 1,
Providing an assist map as means for increasing the assist force;
An electric power steering device.

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