JP2003081112A - Motor-driven power steering control device and method of controlling the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve steering wheel returnability in a low speed range or during fine steering. SOLUTION: In a steering mechanism in which a steering wheel and a tire are mechanically linked, a motor-driven power steering control device for controlling a motor for generating torque to assist a driver to steer the wheel comprises a road surface reaction torque detector 15S for measuring or calculating road surface reaction torque received by the tire from the road surface, a returning torque compensator 17 for calculating returning torque for returning the steering wheel to a neutral position based on the road surface returning torque, and a motor current determiner 7 for determining current to be provided to the motor at least based on the returning torque calculated by the returning torque compensator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric power steering control device for a vehicle and a control method thereof for generating a torque for assisting a steering torque by a driver by a motor to assist a steering force of a steering system. Is.

[0002]

2. Description of the Related Art FIG. 36 shows, for example, Japanese Unexamined Patent Publication No. 7-1869.
FIG. 1 is a block diagram showing the configuration of a conventional electric power steering control device described in Japanese Patent Publication No. 94, in which reference numeral 1 is a steering torque detector for detecting a steering torque when a driver steers the steering wheel, and 2 is a steering wheel. A steering torque controller that calculates an auxiliary torque signal based on the output of the torque detector 1, 3
Is a damping compensator that calculates a damping compensation signal based on the output of the motor speed detector 5, and 4 is an inertia compensator that calculates an inertia compensation signal based on the output of the motor acceleration detector 6. Reference numeral 7 is a motor current determiner that calculates a target current signal from a target torque that is the sum of the auxiliary torque signal calculated by the first adder 12, the damping compensation signal and the inertia compensation signal, and 8 is the output of the steering torque detector 1. And the output of the motor speed detector 5 are in the same direction, and the determination results are output to the steering torque controller 2, the damping compensator 3 and the inertia compensator 4, respectively.
9 determines the voltage to be applied to the motor 10 based on the error between the target current signal obtained by the second adder 13 and the motor current value detected by the motor current detector 11, and A motor driver that applies a voltage,
In the motor 10, the motor current value responds according to the applied voltage, and an assist torque that is substantially proportional to the motor current value is generated to drive the steering mechanism. A vehicle speed detector 14 detects the vehicle speed and outputs the detected vehicle speed signal to the steering torque controller 2, the damping compensator 3 and the inertia compensator 4.

Next, the operation of the conventional electric power steering controller will be described. When the driver of the automobile steers the steering wheel, the steering torque at that time is measured by the steering torque detector 1 and output to the steering torque controller 2.
The steering torque controller 2 calculates an auxiliary torque signal that is substantially proportional to the output signal of the steering torque detector 1, and drives the motor 10 based on this auxiliary torque signal to assist the steering torque of the driver. This reduces the steering torque by the driver.

At this time, the judging device 8 judges whether or not the output of the steering torque detector 1 and the output of the motor speed detector 5 are the same, and if they are the same, the damping compensator 3 and the inertia compensator. 4 is not operated, the steering torque controller 2 determines the target torque based on the auxiliary torque signal determined according to the output of the steering torque detector 1 and the vehicle speed signal from the vehicle speed detector 14, and the motor current The motor drive current is determined by the determiner 7. If they are not the same, the steering torque controller 2 is not operated, the target torque is determined based on the outputs of the damping compensator 3 and the inertia compensator 4, and the motor drive current is determined by the motor current determiner 7. . At this time, when the vehicle speed is low, the direction of the target torque is the same as the direction of rotation of the motor, and when the vehicle speed is high, the direction of the target torque is opposite to the direction of rotation of the motor.

Therefore, when the driver is turning the steering wheel, the steering torque of the driver is assisted so as to reduce the torque required for steering. Also, when the driver is returning the steering wheel, it assists the steering wheel to return to the origin when the vehicle speed is low, and prevents the steering wheel from trying to return at an excessive rotation speed when the vehicle speed is high. The motor 10 is controlled to.

[0006] In general, a driver steers a vehicle when turning a curved portion or an intersection of a road, and then, when returning to straight running, uses the spontaneous return force of the handle due to the road surface reaction torque of the tire to operate the handle. To put it back. However, since the road surface reaction torque of the tire is weak during minute steering when the vehicle speed is low speed or high speed, the road surface reaction torque may be less than the friction torque in the steering mechanism, and the steering wheel may not return when returning to a straight line. Many. Therefore,
In this case, the driver has to apply torque to the steering wheel to return the steering wheel, which causes a problem that the steering feeling is deteriorated. On the other hand, in the conventional technique, when the vehicle speed is low, it is determined whether the output of the steering torque detector 1 and the output of the motor acceleration detector 6 are the same. By determining the motor drive current so as to rotate the motor 10 in the same direction as above, the steering wheel return property at the low speed is improved.

[0007]

However, in the above-mentioned conventional technique, steering is performed in a range in which the road surface reaction torque of the tire is small, such as when turning at an intersection at low speed or when turning at a curved portion of a loose road at high speed. In such a case, unless the driver applies torque in the direction of returning the handle, the handle stops, and the motor 10 does not rotate. Therefore, the determiner 8 cannot determine whether the output of the steering torque detector 1 and the output of the motor speed detector 5 are the same, so that the motor is rotated in the same direction as the motor rotation direction. However, there is a problem in that the motor drive current cannot be determined and the handle return characteristic cannot be improved. Further, in the above-mentioned conventional technique, when the vehicle is traveling at a high speed, the motor drive current can only be determined so as to rotate the motor in the direction opposite to the motor rotation direction, so that there is a problem that the handle return characteristic cannot be improved. It was

The present invention has been made in order to solve the above-mentioned problems, and the road surface reaction torque of a tire can be reduced when a vehicle crosses an intersection at a low speed or a curved road is bent at a high speed. It is an object of the present invention to provide an electric steering device that allows a driver to return a steering wheel without applying torque in a direction of returning the steering wheel when the steering wheel is steered within a small range.

[0009]

SUMMARY OF THE INVENTION An electric power steering control device according to the present invention controls a motor that generates a torque for assisting a driver in steering in a steering mechanism in which a steering wheel and a tire are mechanically connected. An electric power steering control device for controlling a road surface reaction force torque detector that detects a road surface reaction force torque received by a tire from a road surface, and a neutral steering wheel based on the road surface reaction force torque. A return torque compensator that calculates a return torque for returning to a position and a motor current determiner that determines a current to be supplied to the motor based on at least the return torque calculated by the return torque compensator are provided.

Further, the electric power steering control device according to the present invention includes a steering torque detector for detecting a steering torque by a driver, and a steering torque for calculating a torque for assisting the steering based on the steering torque. And a controller.

Further, in the electric power steering control device according to the present invention, the road surface reaction torque detector is a strain detector and is provided in the steering system from the gear mechanism to the tire.

Further, in the electric power steering control device according to the present invention, the road surface reaction force torque detector calculates the road surface reaction force torque based on the parameters detected by the detectors for detecting various parameters. It is composed of a torque calculator.

In the electric power steering control device according to the present invention, the road surface reaction torque calculator uses the steering torque, the motor acceleration and the motor current as parameters.

The electric power steering controller according to the present invention further comprises a motor current detector for detecting the motor current, and the steering torque is calculated based on the detected motor current.

Further, the electric power steering control device according to the present invention includes a motor current detector for detecting a motor current, a power source voltage detector for detecting a power source voltage connected to the motor, and a PWM signal for driving the motor. To detect P
A WM signal detector is further provided, and the motor acceleration is calculated based on the motor current, the power supply voltage, and the PWM signal.

In the electric power steering control device according to the present invention, the road surface reaction torque calculator uses the steering torque and the motor current as parameters.

Further, in the electric power steering control apparatus according to the present invention, the road surface reaction torque calculator uses the steering torque, the motor acceleration and the motor torque as parameters.

In the electric power steering control device according to the present invention, the road surface reaction torque calculator uses the steering torque, the motor acceleration and the motor current command value as parameters.

Further, in the electric power steering controller according to the present invention, the return torque compensator calculates the return torque based on a value obtained by multiplying the output of the road surface reaction force detector by a predetermined gain, and The maximum value of the return torque is limited by a predetermined limit.

Further, the electric power steering control device according to the present invention further comprises a vehicle speed detector for detecting the speed of the vehicle, and the value of the gain or the limit is adjusted according to the vehicle speed detected by the vehicle speed detector. It is something.

Further, in the electric power steering control device according to the present invention, the return torque compensator has a plurality of gain stages.

Further, the control method of the electric power steering control device according to the present invention controls the motor for generating the torque for assisting the steering of the driver in the steering mechanism in which the steering wheel and the tire are mechanically connected. And a step of measuring or calculating a road surface reaction torque received by the tire from the road surface, and a return torque for returning the steering wheel to the neutral position based on the road surface reaction torque. And a step of determining a current to be supplied to the motor based on at least the return torque.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In the following description, the same parts as those in the conventional example are designated by the same reference numerals and the description thereof will be omitted. Further, the present invention can solve the problems of the conventional technology only with the software of the microcomputer, and the hardware of the control device is the same as that of the conventional technology, so that the description thereof will be omitted.

Embodiment 1. FIG. 1 is a block diagram showing a configuration of an electric power steering control device according to a first embodiment of the present invention. In FIG. 1, reference numeral 15 is a front wheel steering angle, that is, a road surface on which a steering wheel is to be returned to an origin. A road surface reaction force torque detector which is a road surface reaction force torque detecting means for detecting the reaction force torque, and 16 is based on the road surface reaction force torque signal detected by the road surface reaction force torque detector 15.
A notch torque controller that outputs a notch assisting torque signal for generating a torque to the motor 10 in a direction opposite to the detected road reaction torque, and 17 is a handle for the motor 10 based on the road reaction torque signal. A return torque compensator that outputs a handle return assist torque signal for generating a torque in the direction of returning to the origin. In the first embodiment, the cut torque controller 16 and the return torque compensator 17 are detected. It serves as road surface reaction torque addition control means for controlling the torque of the motor 10 based on the road surface reaction torque. The road reaction torque detector 15 includes, for example, a strain measuring means such as a load cell or a strain gauge arranged on one side or both sides of the front wheel side of the rack that connects the front wheel and the steering shaft. the road surface reaction torque T _{the react} detect a compressive force that acts on the rack as a distortion amount of the rack, in the compression force calculated from the distortion amount, by multiplying the offset X _offset of the rotational center of the rack and the tire Road reaction torque T
detect _react .

3 is a damping compensator for calculating a damping compensation signal based on the motor speed signal detected by the motor speed detector 5, and 4 is an inertia compensation signal based on the motor acceleration signal detected by the motor acceleration detector 6. An inertia compensator for calculation, 7 calculates a target current signal from the target torque which is the sum of the cutting assist torque signal, the steering wheel return assist torque signal, the damping compensation signal and the inertia compensation signal calculated by the first adder 12. The motor current determiner 9 determines the voltage to be applied to the motor 10 based on the error between the target current signal obtained by the second adder 13 and the motor current signal detected by the motor current detector 11. At the same time, a motor driver for applying the above voltage to the motor 10,
The motor 10 responds to the motor current value according to the applied voltage, and generates a torque that is substantially proportional to the motor current value to drive the steering mechanism. A vehicle speed detector 14 detects the vehicle speed and outputs the detected vehicle speed signal to the cut torque controller 16, the return torque compensator 17, the damping compensator 3 and the inertia compensator 4.

Next, the operation of the electric power steering control device having the above structure will be described with reference to the flowchart of FIG. Note that the difference from the conventional technique is the algorithm surrounded by the alternate long and short dash line in the block diagram of FIG. 1 up to the calculation of the target current. Control, or general control such as open loop control based on the target current and the motor speed signal is performed. The control method may be implemented by either digital control or analog control. The following description will be limited to the algorithm for calculating the target current. First, in step S101, the road surface reaction force torque signal detected by the road surface reaction force torque detector 15 is read and stored in the memory.
Next, in step S102, the motor speed signal detected by the motor speed detector 5 is read and stored in the memory. In step S103, in the motor acceleration detector 6,
The motor speed signal is differentiated to obtain the motor acceleration signal, which is stored in the memory. In step S104,
In the cutting torque controller 16, a map operation is performed on the road surface reaction force torque signal, and a cutting assist torque signal is obtained and stored in a memory. At this time, the cutting assist torque signal is applied to the motor 1 in the direction opposite to the road surface reaction torque.
The above map is set so that 0 generates torque.
Next, in step S105, the return torque compensator 17 performs map calculation on the road surface reaction force torque signal,
The steering wheel return assist torque signal is obtained and stored in the memory. Here, the steering wheel returning assist torque signal is for avoiding the phenomenon that the steering wheel does not automatically return to the origin when the road reaction torque is smaller than the friction torque in the steering mechanism. The frictional torque value in the mechanism is set to an upper limit, and is limited by a limiter. Within the limiter range, the road surface reaction force torque signal is multiplied by a proportional gain. Next, step S106.
Then, the damping compensator 3 multiplies the motor speed signal by the proportional gain to obtain the damping compensation signal and stores it in the memory. In step S107, the inertia compensator 4 multiplies the motor acceleration signal by the proportional gain to obtain the inertia compensation signal. Obtained and stored in memory. Next, in step S108, the first
By the adder 12 of step S104 to S10 described above.
The target torque is calculated by adding the cutting assist torque signal, the steering wheel return assist torque signal, the damping compensation signal and the inertia compensation signal obtained in step 7, and the target torque is stored in the memory. Then, in step S109, the motor current determiner 7
Thus, the target torque obtained in step S108 is multiplied by the gain to obtain the target current, which is stored in the memory.
The gain at this time is set to the reciprocal of the torque constant converted into the steering shaft of the motor 10.

The control parameters such as the gain of the cut torque controller 16, the return torque compensator 17, the damping compensator 3, and the inertia compensator 4 are set according to the vehicle speed signal from the vehicle speed detector 14. . At this time, the gain of the damping compensator 3 and the inertia compensator 4 may be set to 0 for a vehicle in which damping of the steering mechanism itself is strong or a vehicle in which a motor having a small moment of inertia equivalent to the steering axis is mounted. Therefore, in this case, the motor speed detector 5, the motor acceleration detector 6, the damping controller 3 and the inertia compensator 4 are unnecessary. Further, as the motor speed detector 5 used in the first embodiment, for example, a motor speed sensor such as a tacho generator may be used, or the motor speed is detected by making a difference between the pulse outputs of the rotary encoder. Alternatively, the motor speed may be detected from the counter electromotive voltage obtained by subtracting the product of the current value applied to the motor and the coil resistance value from the voltage applied to the motor.

Generally, a driver of an automobile often releases the hand after turning the steering wheel and returns the steering wheel to the center by the self-restoring force due to the reaction torque of the road surface, thereby reducing the steering effort. Further, in the conventional electric power steering apparatus, the returning characteristic of the steering wheel is poor due to the friction torque of the motor 10 and the gear. That is, when only the steering torque signal is detected and the target torque is determined, if the hand is released after the steering wheel is turned, the steering torque signal becomes 0, so that the steering wheel return torque cannot be generated. Further, when the target torque is determined based on the motor rotation signal in addition to the steering torque signal and the rotation of the motor 10 is stopped, the motor 10 cannot generate the torque for returning the steering wheel. . On the other hand, the electric power steering apparatus according to the first embodiment is provided with the road surface reaction force torque detector 15, and detects the road surface reaction force torque substantially proportional to the angle of the steering wheel even if the road surface reaction force torque detector 15 is released. A notch torque controller 1 that outputs a force torque signal and is a road surface reaction force torque addition control means.
6 and the return torque compensator 17 are provided to control the torque of the motor 10 by calculating the cutting assist torque signal and the steering wheel return assist torque signal according to the road surface reaction force torque signal. The motor 10 can output torque in the steering wheel returning direction even after the steering wheel is released, and the steering wheel can be surely returned to the center.

In the first embodiment, map calculation is performed in steps S104 and S105 of FIG.
In Steps S106 and S107, the calculation is performed by multiplying the gain, but each step may be configured to be multiplied by the gain or may be configured to be the map calculation. Further, steps S104 and S105 are combined to prepare one map in which the cutting assist torque signal and the steering wheel return assist torque signal are combined, and the cutting assist torque signal and the steering wheel return assist torque signal are combined with the road surface reaction force torque signal. The map calculation may be performed as the road surface reaction torque addition control signal corresponding to the sum of

Embodiment 2. FIG. 4 is a block diagram showing a configuration of an electric power steering control device according to a second embodiment of the present invention. In FIG. 4, reference numeral 1 denotes a steering torque detector which is steering torque detecting means for detecting steering torque,
Reference numeral 2 is a steering torque controller which is a steering assist control means for calculating a steering assist torque signal based on a steering torque signal which is an output of the steering torque detector 1, and 15 is a road surface which is intended to return the steering angle of the front wheels to the origin. A road surface reaction force torque detector for detecting a reaction torque, 17 is a motor 10 based on a road surface reaction force torque signal output from the road surface reaction force torque detector.
Is a return torque compensator that outputs a handle return assist torque signal for generating a torque in the direction of returning the handle to the origin. In the second embodiment, the return torque compensator 17 is the road surface reaction force torque addition control means. Make up. Further, 3 is a damping compensator, 4 is an inertia compensator, 5 is a motor speed detector, 6 is a motor acceleration detector, 7 is a motor current determiner, 9 is a motor driver, 10 is a motor, 11 is a motor current detection. , 12 is a first adder, 13 is a second adder, and 14 is a vehicle speed detector.

Next, the operation of the electric power steering control device according to the second embodiment will be described with reference to the flowchart of FIG. Note that, in the following, similar to the above-described first embodiment, the description will be limited to the algorithm up to the calculation of the target current. First, in step S201, the road surface reaction torque signal detected by the road surface reaction torque detector 15 is read and stored in the memory. Next, step S202.
Then, the steering torque signal detected by the steering torque detector 1 is read and stored in the memory. In step S203, the motor speed signal detected by the motor speed detector 5 is read and stored in the memory. In step S204, the motor acceleration detector 6 differentiates the motor speed signal to obtain the motor acceleration signal, which is stored in the memory. Next, in steps S205 to S206, in the steering torque controller 2, in order to improve the frequency characteristic of the steering torque signal, the steering torque signal is passed through a phase compensator configured on the S / W of the microcomputer to perform phase compensation. A map calculation is performed on the phase-compensated steering torque signal, and a steering assist torque signal is obtained and stored in a memory. Next, step S20.
In step 7, the return torque compensator 17 performs map calculation on the road surface reaction force torque signal to obtain a steering wheel return assist torque signal and stores it in the memory. Step S20
In step 8, the damping compensator 3 multiplies the motor speed signal by a proportional gain to obtain a damping compensation signal, which is stored in the memory. In step S209, the inertia compensator 4
An inertia compensation signal is obtained by multiplying the motor acceleration signal by a proportional gain and stored in a memory. Next, the process proceeds to step S210, and the first adder 12 causes each of the steps S20.
The target torque is calculated by adding the steering assist torque signal, the steering wheel return assist torque signal, the damping compensation signal and the inertia compensation signal obtained in 6 to S209, and this is stored in the memory. After that, in step S211, the motor current determiner 7 multiplies the target torque obtained in step S211 by the gain to obtain the target current, which is stored in the memory. The gain at this time is set to the reciprocal of the torque constant converted into the steering shaft of the motor 10.

In the second embodiment, as in the first embodiment, the control parameters of the steering torque controller 2, the return torque compensator 17, the damping compensator 3, and the inertia compensator 4 are the vehicle speed. It is changed according to the output of the detector 14. At this time, for a vehicle in which damping of the steering mechanism itself is strong or a vehicle in which a motor having a small moment of inertia equivalent to the steering axis is mounted, each gain of the damping compensator 3 and the inertia compensator 4 may be set to 0. In this case, , The motor speed detector 5, the motor acceleration detector 6, the damping controller 3, and the inertia compensator 4 are unnecessary. Also,
The steering torque controller 2 may be configured to obtain the steering assist torque signal based on the steering torque signal and its differential value.

As described above, in the second embodiment, when the driver holds the steering wheel and steers, the steering assist torque signal for assisting the steering is generated based on the steering torque signal, and When the steering wheel is released, the steering wheel return assist torque signal for returning the steering wheel to the origin can be generated based on the road surface reaction force torque signal. It is possible to output, and the handle can be surely returned to the center. That is, when the driver holds the steering wheel, the conventional control algorithm is diverted as it is, and a control algorithm for returning the steering wheel to the origin when newly released is added.
The handle return characteristic can be improved.

In the second embodiment, map calculation is performed in steps S206 and S207 of FIG. 5, and calculation is performed by multiplying the gain in steps S208 and S209. Alternatively, the map calculation may be performed. In the second embodiment, the phase compensator for improving the frequency characteristic of the steering torque signal is constructed on the S / W of the microcomputer. However, the frequency characteristic of the steering torque signal is previously confirmed by the analog phase compensator. After the improvement, the configuration may be such that A / D conversion is performed and the signal is taken into the microcomputer. In that case, step S205 is unnecessary.

Embodiment 3. In the second embodiment, the road surface reaction torque is directly detected by using the road surface reaction torque detector 15 provided with a strain measuring device such as a load cell. As shown in FIG. 6, a low-pass filter is provided in place of the road surface reaction torque detector 15, and a steering torque signal output from the steering torque detector 1 and a motor acceleration signal output from the motor acceleration detector 6 and a motor are provided. The road surface reaction force torque signal is calculated and output from the motor current value output from the current detector 11,
Road reaction torque detector 1 configured on S / W of microcomputer
The electric power steering control device is configured using 5S. As a result, the road surface reaction torque detector 1
Since 5 can be omitted and wiring associated therewith can be eliminated, the electric power steering control device can be downsized. The details of the calculation of the road reaction torque signal by the road reaction torque detector 15S will be described later.

The operation of the electric power steering controller of the third embodiment will be described with reference to the flowchart of FIG. First, in step S301, the steering torque signal detected by the steering torque detector 1 is read and stored in the memory. Next, in step S302, the motor speed signal detected by the motor speed detector 5 is read and stored in the memory. In step S303, the motor acceleration detector 6 differentiates the motor speed signal to obtain the motor acceleration signal and stores it in the memory.
At 04, the motor current signal is read and stored in the memory. Next, in steps S305 to S306, the road surface reaction force torque detector 15S performs the following calculation to obtain a road surface reaction force torque signal. First, in step S305, the steady reaction force signal T ′ is calculated by the following equation (1) using the steering torque signal T _sens , the motor acceleration signal dω corresponding to the steering shaft rotational acceleration, and the motor current signal _{Imtr.
Get rea_est} . _{T'rea_est} = T _sens + K _t · I _mtr −J · dω (1) K _t : Motor torque constant (converted to steering shaft) J: Moment of inertia of steering mechanism Next, in step S306, the low-pass filter provided torque detector 15S, together with obtaining a road surface reaction force torque signal T _{Rea_est} performs primary filter operation, as shown in the following equation (2), the road surface reaction torque signal _{T rea} _est Is stored in memory. _{dT rea_est / dt = -T rea_est /} T 1 + T 'rea_est / T 1 ‥‥‥‥ (2) where, T ₁ is a time constant of the primary filter, corner frequency f _c = 1 / (2π・ T ₁ ) is set to be between 0.05 and 1.0 Hz.

Next, in steps S307 to S308,
In the steering torque controller 2, the steering torque signal is passed through a phase compensator to be phase-compensated, a map operation is performed on the phase-compensated steering torque signal, and a steering assist torque signal is obtained and stored in a memory. In step S309, the return torque compensator 17 causes the road surface reaction force torque signal T
_A steering wheel return assist torque signal is obtained by map calculation for _{rea_est} , and this is stored in the memory, and step S3
In step 10, the damping compensator 3 multiplies the motor speed signal by a proportional gain to obtain a damping compensation signal, which is stored in a memory. Is stored in the memory. Next, the process proceeds to step S312, and the first adder 12 performs the above steps S30.
The target torque is obtained by adding the steering assist torque signal, the steering wheel return assist torque signal, the damping compensation signal and the inertia compensation signal obtained in 8 to S311, and the target torque is stored in the memory. After that, in step S313, the motor current determiner 7 multiplies the target torque obtained in step S312 by the gain to obtain the target current, which is stored in the memory. The gain at this time is set to the reciprocal of the torque constant converted into the steering shaft of the motor 10. The above steps S301 to S313 are repeated.

Next, the reason why the road reaction torque can be detected by the above equations (1) and (2) will be described. The equation of motion of the steering mechanism is the following equation (3).
It is represented by. J · dω _s / dt = T _hdl + T _mtr −T _fric −T _react ... (3) dω _s / dt: Steering shaft rotational acceleration T _hdl : Steering torque T _mtr : Motor output torque (converted to steering shaft) T _fric : Friction torque T _react in the steering mechanism: Road surface reaction force torque (converted to steering axis) Solving the above equation (3) for the road surface reaction force torque T _react gives the following equation (4). T _react = T _hdl + T _mtr −J · dω _s / dt −T _fric (4) Therefore, by using each value of the steering torque, the motor output torque, the steering shaft rotational acceleration, and the friction torque in the steering mechanism. , The road surface reaction torque T _{re act} can be obtained. The steering torque T _hdl, it is possible to use a steering torque signal T _sens, as the motor output torque T _mtr, torque constant K in the motor current signal I _mtr
A value multiplied by _t can be used. Further, the motor acceleration signal dω can be used as the steering shaft rotation acceleration (dω _s / dt). Therefore, the road surface reaction force torque excluding the influence of the friction torque T _fric in the steering mechanism can be detected by the above equation (1). On the other hand, the friction torque T _fric acts as a relay for the rotation speed of the steering mechanism. Further, it is widely known that a relay can be equivalently represented by a gain and a phase by an equivalent linearization method in control engineering. Therefore,
The road surface reaction force torque signal T _{rea_est} can be obtained by adjusting the gain and phase of the steady reaction force signal T ′ _{rea_est} detected by the above equation (1) by the primary filter of the above equation (2). . That is, a filter is used as the most general method for adjusting the gain and the phase. The gain and phase can be adjusted by the filter in the frequency region above the break frequency, and if the break frequency is set in the range of 0.5 to 1 times the frequency to be adjusted, the gain will be about 1 to 0.5.
The doubling and phase can be adjusted in the range of approximately 0 to -20 deg, and the influence of the friction torque can be canceled in most cases. The steering frequency that is generally used in automobiles is in the range of 0.1 to 1 Hz, and the corner frequency is set to 0.5 to 1 times the steering frequency, that is, approximately 0.05 to 1 Hz. If this is done, the effect of friction torque can be canceled. The specific break frequency is
The steering frequency is set to be the most effective control based on the detected road surface reaction torque signal.

The structure for detecting this manner, in the third embodiment, the road surface reaction torque signal T _{Rea_est,} the steering torque signal T _sens a motor acceleration signal dω and (steering shaft rotational acceleration) and the motor current signal I _mtr By providing the road surface reaction force torque detector 15S, the road surface reaction force torque detector 15 and wiring associated therewith are not required, and the cost of the electric power steering control device can be reduced.

In the third embodiment, the steering torque signal T input to the road surface reaction torque detector 15S is used.
_Although the signal before phase compensation is used as _sens , when the phase compensator for improving the frequency characteristic of the steering torque detector 1 is configured by analog, the signal after phase compensation is used as the steering torque signal T _sens. May be. Further, the phase compensator for improving the frequency characteristic of the steering torque signal may be configured on the S / W of the microcomputer. It may be configured to be incorporated in a microcomputer. In that case, the step S307 is unnecessary.

In the above example, in step S305,
From the steering torque signal T _sens , the motor acceleration signal dω (steering shaft rotational acceleration), and the motor current signal _Imtr ,
Using equation (1) shown below, the steady reaction force signal T '
_{Although rea_est} is obtained, it is suitable for electric power steering control devices that have a small motor inertia torque relative to the road surface reaction torque detection value, such as an electric power steering control device equipped with a small motor or brushless motor. On the other hand, the motor inertia torque term (−J · dω) may be ignored. Further, for the electric power steering control device in which the motor torque converted into the steering shaft in the steering range where the road surface reaction torque addition control is required is smaller than the road surface reaction torque detection value, the steering shaft The converted motor torque term may be ignored. _{T 'rea_est = T sens + K} t · I mtr -J · dω ‥‥‥‥ (1) K t: torque constant of the motor (steering shaft conversion) J: When this moment of inertia of the steering mechanism, and the motor inertia torque term, Since at least one of the motor torque terms converted into the steering axis can be ignored, the calculation load of the microcomputer can be reduced because the calculation is unnecessary.

Fourth Embodiment In the third embodiment, the motor output torque is obtained from a value obtained by multiplying the output I _mtr of the motor current detector 11 by the steering shaft-converted motor torque constant K _t . However, the electric power steering control of the fourth embodiment is performed. As shown in FIG. 8, the apparatus is provided with a motor torque detector 20 for detecting a motor output torque, which is provided with a strain measuring means such as a load cell, and directly detects the torque of the output shaft of the motor 10. Configured,
By directly detecting the torque of the output shaft of the motor 10, the detection accuracy of the motor output torque can be improved, and since the output _Imtr of the motor current detector 11 is not used, the influence of noise on the motor current signal can be reduced. Since it is not received, the road surface reaction torque can be accurately detected.

Next, the operation of the electric power steering controller of the fourth embodiment will be described with reference to the flowchart of FIG. The steps from reading the steering torque signal (step S301a) to calculating the motor acceleration signal dω (step S303a) are the same as steps S301 to S303 in the flowchart shown in FIG. In step S304a, the output of the motor torque detector 20 converted into the steering shaft is set to A
/ D conversion is performed and read, and is stored in the memory as the motor torque signal T _m . Next, in step S305a, using the steering torque signal T _sens , the motor acceleration signal dω corresponding to the steering shaft rotation angular velocity, and the motor torque signal T _m , the steady reaction force signal _{T'rea_est is calculated} by the following equation (5). To get T ′ _{rea_est} = T _sens + T _m −J · dω (5) In step S306a, the steady reaction force signal T ′ _{rea_est} obtained by the above equation (5) is used to show the third embodiment. The road surface reaction force torque signal T _{rea_est} is obtained by performing the primary filter operation of the equation (2), and the road surface reaction force torque signal T _{rea_est} is stored in the memory. The following steps S307a to S3
13a is step S307 in FIG. 7 of the third embodiment.
Since it is the same as that from step S313 to step S313, the description is omitted. . As described above, in the fourth embodiment, the motor output torque T _m is directly detected from the output of the motor torque detector 20, so that the motor torque detection accuracy is high and the electric power steering is not affected by the motor current signal noise. It becomes possible to realize the control device.

Embodiment 5. In the third embodiment, the motor output torque is obtained from a value obtained by multiplying the output I _mtr of the motor current detector 11 by the motor torque constant K _t converted into the steering shaft. steering control apparatus, as shown in FIG. 10, instead of the output I _mtr of the motor current detector 11, with a motor current control target value I _t is the output of the motor current determiner 7, the motor output torque It is configured to detect,
The motor current control target value I _t is a value stored in the memory is calculated in step S313 of the flowchart shown in FIG 7. That is, the third embodiment
At step repeats the processing routine to S301～S313, motor current control target value by using the output I _mtr of the motor current detector 11 detected in step S304 I _t
Look, but so as to control the motor 10, in the fifth embodiment, as described later, it is sought after once the motor current control target value I _t, rather than the I _mtr detected in step S304, using motor current control target value I _t is a motor control current, since in order to detect the motor output torque, it is possible to improve the detection accuracy of the motor output torque. Further, since it is not affected by the noise of the motor current signal, the road surface reaction torque can be detected accurately.

Next, the operation of the electric power steering control system according to the fifth embodiment will be described. First, FIG.
Flow through, and is then stored in the memory in search of the motor current control target value I _t, and proceeds to the processing routine shown in the flowchart of FIG. 11, in step S301b, reads the steering torque signal detected by the steering torque detector 1 Store in memory. Next, in step S302b, the motor speed signal detected by the motor speed detector 5 is read and stored in the memory. In step S303b, the motor acceleration detector 6 differentiates the motor speed signal to obtain the motor acceleration signal and stores it in the memory. In the processing routine of FIG. 11, step S30 of FIG.
Without reading the motor current signal I _mtr performed in step 4,
In step S305b, the steering torque signal T _sens and the motor acceleration signal d corresponding to the steering shaft rotation angular velocity d
Using ω and the motor current control target signal I _t calculated in the previous cycle of this processing routine and stored in the memory,
The steady reaction force signal _{T'rea_est} is obtained from the following equation (6). 'In _{rea_est = T sens + K t ·} I t -J · dω ‥‥‥‥ (6) Step S306b, the constant reaction force signal T obtained by the above formula (7)' T with _{Rea_est,} the above embodiment 3 The road surface reaction force torque signal T _{rea — est} is obtained by performing the first-order filter calculation of the equation (2) shown in (3) and stored in the memory. The following steps S307b to S313b are the same as in FIG.
Since it is the same as steps S307 to S313 of No. 1, description thereof will be omitted. . Thus, in the fifth embodiment, instead of the motor current signal I _mtr, using a motor current control target signal I _t is the output of the motor current determiner 7, so as to detect the output shaft torque of the motor Therefore, it is possible to realize an electric power steering control device that has high motor torque detection accuracy and is not affected by motor current signal noise.

Sixth Embodiment In the third embodiment, the operation
Steering torque signal T output from the steering torque detector 1 _sens
By using the road reaction torque T_{rea_est}Detected, but the real
In the sixth embodiment, the output of the steering torque detector 1 is the motor current.
Using the fact that it is approximately proportional to the output of the detector 11,
The output of the motor current detector 11 and the motor acceleration.
From the motor acceleration signal dω output from the detector 6,
Surface reaction force torque T_{rea_est}Configured to detect
This allows you to save memory and
The configuration of the program and its arithmetic processing can be simplified.

Next, the operation of the electric power steering controller of the sixth embodiment will be described with reference to the flowchart of FIG. First, in step S304c, the motor current signal I _mtr is read and stored in the memory. Next, in step S305c, using the motor current signal I _mtr , the steady reaction force signal T ′ is calculated by the following equation (7).
_{Get rea_est} . _{T'rea_est} = K _it · I _mtr + K _t · I _mtr −J · dω (7) K _it ; conversion constant from motor current signal to steering torque signal equivalent value, that is, output of steering torque detector 1 Is approximately proportional to the output of the motor current detector 11, the steering torque signal T
Instead of _sens, it calculates a steady reaction force signal _T 'rea_est using proportional term K _it · I _mtr. In step S306c, using the steady reaction force signal _{T'rea_est} obtained by the above equation (7),
The road surface reaction force torque signal T _{rea_est} is obtained by performing the primary filter operation of the equation (2) shown in the third embodiment, and the road surface reaction force torque signal T _{rea_est} is stored in the memory. Since the following steps S307c to S313c are the same as steps S307 to S313 in FIG. 7 of the third embodiment, the description thereof will be omitted. .

As described above, in the sixth embodiment, the fact that the output of the steering torque detector 1 is approximately proportional to the output of the motor current detector 11 is used and the output of the steering torque detector 1 is not used. Since the force torque can be detected, the memory can be saved, and the configuration of the arithmetic processing program and its arithmetic processing can be simplified. For an electric power steering control device in which the motor inertia torque is smaller than the road surface reaction force torque detection value, such as an electric power steering control device equipped with a small motor or a brushless motor, the motor inertia Torque term (-J · dω)
_{Is negligible} , the road surface reaction torque _{Trea_est} can be detected only from the output of the motor current detector 11.

Embodiment 7. In the third embodiment, the motor speed is detected by using the motor speed detector 5 that detects the rotation speed of the motor 10 from the sensor output such as the motor rotation angle sensor or the motor rotation angular velocity sensor. Then, as shown in FIG. 14, the motor current signal I _mtr from the motor current detector 11, the power supply voltage value from the power supply voltage detector (not shown) of the motor drive 9 and the PWM signal which is the output of the motor drive 9 The electric power steering control device is configured using the motor speed detector 5S configured on the S / W of the microcomputer, which detects the motor rotation angular velocity ω from the target value of the motor applied voltage calculated from the duty ratio signal of in which the, the road surface reaction torque T _{Rea_est} from the output signal dω obtained by differentiating operation the motor rotation angular speed ω and the steering torque signal T _sens and the motor current signal I _mtr In which was to so that. This eliminates the need for sensors such as a motor rotation angle sensor and a motor rotation angular velocity sensor when detecting the rotation angular acceleration dω of the motor, thus reducing the cost of the electric power steering control device.

Next, the operation of the electric power steering controller of the seventh embodiment will be described with reference to the flowchart of FIG. First, in step S301d,
The steering torque signal detected by the steering torque detector 1 is read and stored in the memory. Next, in step S302d,
The motor current signal is read and stored in the memory. In step S303d, the output signal _Vb from the power supply voltage detector is A / D converted, the duty ratio command value X _duty which is the output signal of the motor driver 9 is read from the memory, and this duty ratio command value X _duty and the above The value obtained by multiplying the output signal V _b from the power supply voltage detector and the value obtained by multiplying the motor armature resistance R _m by the motor current signal I _mtr are subtracted from each other to obtain the rotational angular velocity ω. The formula for calculating the rotational angular velocity ω is shown below. ω = X _duty · V _b −R _m · I _mtr / K _b (8) K _b ; Back electromotive force constant Next, in step S304d, the rotational angular velocity ω is differentiated to calculate the motor acceleration signal dω. To get Since the following steps S305d to S313d are the same as steps S306 to S313 of FIG. 7 of the third embodiment, description thereof will be omitted.

Embodiment 8. In the third embodiment, the road surface reaction torque signal T _{Rea_est,} the steering torque signal T _{s ens}
16 and the motor acceleration signal dω and the motor current signal I _mtr are detected, and the steering torque controller 2 directly calculates the auxiliary torque signal from the steering torque detector 1. As described above, instead of the steering torque controller 2, the road surface reaction force torque signal T from the road surface reaction force torque detector 15S equipped with a low pass filter is obtained.
_Based on _{rea_est} , the motor 10 is provided with a notch torque controller 16S that calculates and outputs a notch torque signal for generating a torque in the direction opposite to the road surface reaction torque. Even when the inexpensive steering torque detector 1 having a large noise component due to engine vibration or the like is used in the output value, the steering torque can be accurately detected.

Next, the operation of the electric power steering controller of the eighth embodiment will be described with reference to the flowchart of FIG. The road surface reaction force torque signal T is read from the reading of the steering torque signal (step S401).
_{Until rea_est} is calculated (step S406), steps S301 to S3 of the flowchart shown in FIG. 7 are performed.
The description is omitted because it is the same as 06. Step S4
At 07, the cut torque controller 16S calculates the road surface reaction force torque signal T calculated at step S406.
_A map operation is performed on _{rea_est} to obtain a cutting assist torque signal, which is stored in the memory. At this time, the cutting assist torque signal sets the above map so that the motor 10 generates torque in the direction opposite to the road surface reaction force. Next, in step S408, the return torque compensator 17 performs map calculation on the road surface reaction force torque signal T _{rea — est} to _obtain the steering wheel return assist torque signal and stores it in the memory. In step S409, the damping compensator 3 multiplies the motor speed signal by a proportional gain to obtain a damping compensation signal, which is stored in the memory. In step S410, the inertia compensator 4 is used.
Thus, the inertial compensation signal is obtained by multiplying the motor acceleration signal by the proportional gain and stored in the memory. Next, step S41
In step 1, the first adder 12 adds the cutting assist torque signal, the steering wheel return assist torque signal, the damping compensation signal and the inertia compensation signal obtained in steps S407 to S410 to obtain the target torque. This is stored in memory. Then, in step S412, the motor current determiner 7 multiplies the target torque obtained in step S411 by the gain to obtain the target current, which is stored in the memory.

Ninth Embodiment The ninth embodiment is the road surface reaction torque detector 15 used in the third to eighth embodiments.
The invention is related to S, and the other portions may have the configuration of any of the block diagrams of the above-described third to 84th embodiments. Hereinafter, the operation of the electric power steering control device according to the ninth embodiment will be described with reference to FIG. 6 (block diagram of the third embodiment) and the flowchart of FIG. 18. First, in step S501, the steering torque signal detected by the steering torque detector 1 is read and stored in the memory. Next, in step S502, the motor speed signal detected by the motor speed detector 5 is read and stored in the memory. In step S503, the motor acceleration detector 6 differentiates the motor speed signal to obtain the motor acceleration signal and stores it in the memory. In step S504, the motor current signal is read and stored in the memory.

Steps S505 to S508 show the operation of the road surface reaction torque detector 15S. First, in step S505, it is determined whether or not the absolute value of the steering torque signal is equal to or larger than a predetermined threshold value. At this time, the threshold value is set in advance so as to be a value near the sum of the torque required to hold the steering wheel when traveling straight ahead and the measurement offset of the steering torque detector 1.
The value is stored in the ROM. If it is determined in step S505 that the absolute value of the steering torque signal is greater than or equal to the threshold value, the process proceeds to step S507 as it is, and if it is determined that the absolute value is less than the threshold value, the process proceeds to step S506 and the road surface reaction torque After replacing the steering torque signal T _sens used for the calculation in the detector 15S with 0, step S5
Proceed to 07. Hereinafter, step S30 of the above-mentioned Embodiment 3
Similar to 5 to S313, in steps S507 to S511, the steering torque signal T _sens and the motor acceleration signal dω
And the motor current signal I _mtr from the road surface reaction force torque signal T
_{rea_est} is calculated, and the steering assist torque signal and the steering wheel return assist torque signal are obtained from the signal _obtained by phase-compensating the road surface reaction force torque signal _{Trea_est} . Then, step S51
2 to S515, a damping compensation signal and an inertia compensation signal are obtained, the sum of the steering assist torque signal, the steering wheel return assist torque signal, the damping compensation signal and the inertia compensation signal is obtained as a target torque, and this target torque is multiplied by a gain. Find the target current. Above, steps S501 to S51
The operations up to 5 are repeated. The steering torque signal T _sens
When is replaced with 0, the value of the road surface reaction force torque signal T _{rea_est} obtained in step S508 is T _{rea_est} ≈
Therefore, when the absolute value of the steering torque signal is less than the threshold value, the road surface reaction torque is determined not to act and control is performed.

In general, a cant is provided on the road so that the vicinity of the center of the road is high and the vicinity of the road is low in order to allow rainwater to flow to the shoulder side. Therefore, when going straight on the road, it is necessary to hold the steering wheel with a slight torque. Further, the steering torque detector 1 that detects the steering torque is often slightly offset due to voltage drift or the like. Therefore, if the steering torque detection signal is used as it is, the road surface reaction force torque detector 15S does not have a road surface reaction force torque detection value of 0 even when the vehicle is straight ahead. When calculating, the driver may feel unnecessary torque even when going straight. On the other hand, in the ninth embodiment, when it is determined that the absolute value of the steering torque signal is less than the predetermined threshold value, the steering torque signal T used for the calculation in the road surface reaction torque detector 15 is calculated. _By replacing _sens with 0 and calculating the steady reaction force signal _{T'rea_est} of the equation (1) shown in the above-mentioned Embodiment 3, the detection value of the road surface reaction force torque detector 15S is substantially 0. In addition, the threshold at this time is set to a value near the sum of the torque required to hold the steering wheel when traveling straight ahead and the measured offset of the steering torque detector.So, solve the above problems. You can

In the ninth embodiment, if it is determined in step S505 that the absolute value of the steering torque signal is less than the threshold value, the steering wheel used for the calculation in the road surface reaction torque detector 15S. Torque signal T _sens is 0
Therefore, the road surface reaction force torque detector 1
As for the relationship between the steering torque signal that is an input to 5S and the steering torque signal used for the calculation in the road surface reaction torque detector 15S, discontinuity occurs as shown in FIG.
As shown in, it may be set so that there are no discontinuities.
That is, when it is determined in step S505 that the absolute value of the steering torque signal is greater than or equal to the threshold value, the steering torque signal T
_After subtracting the above threshold value from _sens , step S507
The discontinuity point may be eliminated by proceeding to step.

Embodiment 10. In the ninth embodiment,
After determining whether or not the absolute value of the steering torque signal is greater than or equal to a predetermined threshold value, the steady reaction force signal T ′ _{rea_est} and the road surface reaction force torque signal T _{rea_est} are calculated. As shown in the flow chart, the steady reaction force signal T '
_After the calculation of _{rea_est} (step S605) and the calculation of the road surface reaction force torque signal T _{rea_est} (step S606), it is determined whether the absolute value of the steering torque signal is equal to or more than a predetermined threshold value (step S607). Also, the same effect as that of the ninth embodiment can be obtained. However, in the tenth embodiment, when it is determined in step S607 that the absolute value of the steering torque signal is less than the threshold value, in step S608, the road surface reaction force torque signal T
_{After setting rea_est} to 0, the steering wheel return assist torque signal is obtained (step S611).

Eleventh Embodiment Embodiments 9 and 10 above
Then, when it is determined that the absolute value of the input steering torque signal is less than the predetermined threshold value by the road surface reaction torque detector 15S configured on the S / W of the microcomputer, the road surface reaction torque detector is detected. The steering torque signal T _sens or the road surface reaction force torque signal T _{rea_est} used for the calculation within 15S is _set to 0.
As an example, the steering wheel return assist torque signal is obtained. However, also in the road surface reaction force torque detector 15 used in the first and second embodiments, a threshold value is set for the road surface reaction force torque signal and the road surface reaction force torque signal is set. Is less than or equal to the above threshold value, the road surface reaction force torque signal T _{rea_est} is _set to 0, and then the cutting assist torque signal and the steering wheel return assist torque signal are calculated, and the threshold value at this time is set to the road surface reaction force torque during straight _traveling. By setting the value near the offset of the detector output, as in Embodiments 9 and 10, it is possible to eliminate the generation of unnecessary torque when traveling straight, so that the steering performance can be improved.

Next, the operation of the electric power steering control device having the above configuration will be described with reference to the flowchart of FIG. First, in step S701, the road surface reaction force torque signal detected by the road surface reaction force torque detector 15 is read and stored in the memory. Next, step S702.
Then, the motor speed signal detected by the motor speed detector 5 is read and stored in the memory. In step S703, the motor acceleration detector 6 differentiates the motor speed signal to obtain a motor acceleration signal, which is stored in the memory. Next, in step S704, it is determined whether the absolute value of the road surface reaction force torque signal is greater than or equal to the above-described predetermined threshold value. When it is determined that the absolute value of the road surface reaction force torque signal is equal to or greater than the threshold value, the process directly proceeds to step S706,
If it is determined that it is less than the threshold value, step S70.
5, the road surface reaction force torque signal _{Trea_est} is _set to 0, and then the process proceeds to step S706. In step S706,
The cut torque controller 16 calculates a map for the road reaction torque signal to obtain a cut assist torque signal, and in step S1707, the return torque compensator 17 calculates a map for the road reaction torque signal. ,
Obtain the steering wheel return assist torque signal. Next, in step S708, the damping compensator 3 multiplies the motor speed signal by a proportional gain to obtain a damping compensation signal and stores it in a memory. In step S709, the inertia compensator 4 multiplies the motor acceleration signal by the proportional gain. Then, the inertia compensation signal is obtained and stored in the memory. Next, the process proceeds to step S710, and the first adder 12 causes each of the steps S70.
6 to S709, the cutting assist torque signal,
A target torque is obtained by adding the steering wheel return assist torque signal, the damping compensation signal and the inertia compensation signal, and this is stored in the memory. After that, in step S711, the motor current determiner 7 multiplies the target torque obtained in step S711 by the gain to obtain the target current, which is stored in the memory.

Twelfth Embodiment In the twelfth embodiment, the time constant of the low-pass filter provided in the road surface reaction force torque detector 15S according to the third to eighth embodiments is changed according to the vehicle speed. Regardless, it is possible to improve the returnability of the handle to the origin.
Hereinafter, FIG. 6 (Embodiment 3) will be described for Embodiment 12.
Block diagram of FIG. 23) and the flowchart of FIG. 23. First, in step S801, the steering torque signal detected by the steering torque detector 1 is read and stored in the memory. Next, in step S802, the motor speed detector 5
The motor speed signal detected at is read and stored in the memory. In step S803, the motor acceleration detector 6 differentiates the motor speed signal to obtain the motor acceleration signal and stores it in the memory. Step S8
At 04, the motor current signal is read and stored in the memory. Next, in step S805, the vehicle speed signal is read and stored in the memory. In step S806, it is determined whether the absolute value of the steering torque signal is greater than or equal to the threshold value. The threshold value at this time is set in advance so as to be near the sum of the torque required to hold the steering wheel when straight ahead and the measured offset of the steering torque detector 1, and the value is stored in the ROM. If it is determined in step S806 that the absolute value of the steering torque signal is equal to or greater than the threshold value, the process proceeds to step S808 as it is, and if it is determined that the absolute value is less than the threshold value, step S808 is performed.
Proceeding to 807, the steering torque signal T _sens used for calculation in the road surface reaction torque detector 15S is replaced with 0, and then proceeding to step S808.

In step S808, the third embodiment described above is performed.
Similarly to, the steady reaction force signal _{T'rea_est} is calculated by the equation (1). _{T'rea_est} = T _sens + K _t · I _mtr −J · dω (1) K _t : Motor torque constant (converted to steering shaft) J: Inertia moment of steering mechanism In step S809, for example, as shown in FIG. As shown,
From the map defined for the vehicle speed signal, the formula (2)
The time constant T ₁ of the first-order filter is read and step S8
In step 10, using the time constant read in step S809, the primary filter calculation of the above equation (2) is performed to obtain the road surface reaction force torque signal T _{rea — est} and store it in the memory. _{dT rea_est / dt = -T rea_est /} T 1 + T 'rea_est / T 1 ‥‥‥‥ (2)

After that, step S3 of the above-mentioned third embodiment
As in steps 07 to S313, the steering torque signal is phase-compensated in step S811, and then in step S812, map calculation is performed on the phase-compensated steering torque signal.
A steering assist torque signal is obtained, and further, step S813-
In S817, the road surface reaction torque signal _T rea_es _t
A map calculation is performed for the steering wheel return assist torque signal, a damping compensation signal and an inertia compensation signal are obtained, and the sum of the steering assist torque signal, the steering wheel return assistance torque signal, the damping compensation signal, and the inertia compensation signal is obtained and the target is obtained. The target current is calculated by multiplying the target torque by a gain. Above, the operations of steps S801 to S817 are repeated.

The frequency band in which the driver of the automobile steers varies depending on the vehicle speed. Generally, at low speed, fast steering is performed.
At high speeds, slow steering is often performed to prevent the vehicle behavior from becoming unstable. In addition, this filter was introduced to express the friction torque of the steering mechanism in terms of equivalent gain and phase, and the optimum filter time constant originally differs depending on the steering frequency. The accuracy of the road surface reaction force torque signal with respect to the actual road surface reaction force torque can be improved by setting the time constant large and setting the time constant small for fast high-frequency steering. In addition, if the road surface reaction force torque signal has higher accuracy, the steering wheel return assist torque signal will correspond to the actual road surface reaction force when steering such as a lane change. Can be given to. On the other hand, the road surface reaction force torque signal T _{rea — est} when the driver releases the steering wheel _gradually decreases as this time constant becomes longer, so that the steering wheel return assist torque signal is also output for a long time. Therefore, if it takes a long time to return the handle to the origin, such as when the handle is largely released at an intersection or the like and then released, the larger the time constant, the better the handle return property. Further, generally, the vehicle speed at which the steering wheel is turned largely at an intersection or the like is generally limited to a low speed, and in a vehicle speed range higher than this, a relatively small steering wheel operation such as a lane change is performed. Therefore, as shown in FIG. 24, the time constant T ₁ of the first-order filter of the above equation (2) increases as the vehicle speed increases until the upper limit speed when a general driver turns the steering wheel largely at an intersection or the like. If the vehicle speed is set to a lower value and the time constant is set to increase as the vehicle speed increases, the steering wheel will return to the origin of the steering wheel when the steering wheel is released after a large turn at a low speed. It is possible to satisfy all of the returnability and the good steering feeling at medium and high speeds and the returnability to the origin of the steering wheel when the steering wheel is turned small and then released.

Further, as shown in FIG. 25, the time constant T ₁ may be set so that the time constant becomes constant up to the upper limit speed when a general driver turns the steering wheel largely at an intersection or the like. Alternatively, when the steering mechanism has a small friction such as a vehicle with a relatively small amount of friction of the steering mechanism, and the steering feeling is to be improved, the time constant T ₁ is shown in FIG. 26, for example. Thus, it may be set so as to increase as the vehicle speed increases in accordance with the general steering frequency with respect to the vehicle speed.

As described above, in the twelfth embodiment, the time constant of the filter in the road surface reaction torque detector 15S, which is equivalent to the friction of the steering mechanism, is changed according to the vehicle speed. Therefore, when returning to the origin of the steering wheel when the steering wheel is released after a large turn at a low speed, good steering feeling at middle and high speeds and the steering wheel when releasing the steering wheel after a small turn is released. It is possible to satisfy all of the returnability to the origin.

Thirteenth Embodiment The thirteenth embodiment is an invention relating to the operation when the steering wheel return assist torque signal is calculated with respect to the road surface reaction force torque signal in the return torque compensator 17, and the other portions are the same as those of the above respective embodiments. Any of the block diagrams of the forms 1 to 11 may be adopted. Here, the thirteenth embodiment will be described based on the flowchart shown in FIG. First, in step S901, the steering torque signal detected by the steering torque detector 1 is read and stored in the memory. Next, in step S902, the motor speed signal detected by the motor speed detector 5 is read and stored in the memory. Step S90
In 3, the motor acceleration detector 6 differentiates the motor speed signal to obtain the motor acceleration signal and stores it in the memory. In step S904, the motor current signal is read and stored in the memory. Next, step S9
At 05, the vehicle speed signal is read and stored in the memory. In step S906, it is determined whether the absolute value of the steering torque signal is greater than or equal to the threshold value. The threshold value at this time is set in advance so as to be a value near the sum of the torque required to hold the steering wheel when traveling straight ahead and the measured offset of the steering torque detector 1, and the value is stored in the ROM. If it is determined in step S906 that the absolute value of the steering torque signal is greater than or equal to the threshold value, the process proceeds to step S908, and if it is determined to be less than the threshold value, the process proceeds to step S907.
After replacing the steering torque signal T _sens used for the calculation in the road surface reaction torque detector 15S with 0, step S908.
After calculating the steady reaction force signal _{T'rea_est} , the road surface reaction force torque signal _{Trea_est} is obtained by filtering the above _{T'rea_est} in step S909. Next, in step S910, the steering torque signal is phase-compensated, and in step S911, the steering assist torque signal is obtained by map calculation with respect to the phase-compensated steering torque signal.

Steps S912 to S913 show the operation of the return torque compensator 17 according to the ninth embodiment. First, in step S912, the above step S90.
The gain and limiter determined for the vehicle speed signal read in 5 are read. Next, in step S913, a steering wheel return assist torque signal is obtained by map calculation with respect to the road surface reaction force torque signal T _{rea — est} and stored in the memory. The map at this time is assumed to correspond to the gain and limiter read in step S912, for example, as shown in FIG. Then, steps S914 to S91.
In step 7, the damping compensation signal and the inertia compensation signal are obtained, the sum of the steering assist torque signal, the steering wheel return assist torque signal, the damping compensation signal and the inertia compensation signal is obtained as the target torque, and this target torque is multiplied by the gain to obtain the target current. Ask for. Above, the operations of steps S901 to S917 are repeated.

Generally, the road reaction torque is a function of the vehicle speed,
The lower the speed becomes, the smaller the road surface reaction torque for the same steering angle becomes, and the returning property of the steering wheel to the origin deteriorates. Further, in the extremely low speed region during parking, since the vehicle is often moved with the steering wheel turned off and straightness is not required, the returnability of the steering wheel to the origin is not important. Therefore, in the extremely low speed region, the steering wheel return assist torque signal is reduced, and when the vehicle speed exceeds a predetermined speed, the steering wheel return assist torque signal becomes larger as the vehicle speed becomes lower.
It is necessary to determine the gain and limiter in 7. In the thirteenth embodiment, in step S912, the gain and the limiter in the return torque compensator 17 are set as shown in FIGS.
As shown in, the gain and the limiter are set to be maximum near the upper limit of the parking speed performed by a general driver. In the vehicle speed range below the upper limit of parking speed,
The steering wheel return assist torque signal may be set to 0 by setting the gain and limiter to 0, or the steering wheel return assist torque signal may be set to 0 by setting the gain and limiter to 0 even in a high speed region where the return property of the steering wheel to the origin is sufficiently high. It may be.

As described above, in the thirteenth embodiment, in the return torque compensator 17, the gain and the limiter at the time of calculating the steering wheel return assist torque signal from the road surface reaction force torque signal are set to the parking speed of a general driver. Since the gain and limiter are maximized near the upper limit,
It is possible to improve the returnability of the steering wheel to the origin regardless of the vehicle speed without deteriorating the operability during parking.

In the thirteenth embodiment, an example in which both the gain and the limiter are changed at the same time has been shown, but the same effect can be expected by changing only one of them and keeping the other constant. Further, in the above example, the limiter limits the maximum value of the steering wheel return assist torque signal, but as shown in FIGS. May be gradually increased or decreased.

Fourteenth Embodiment In the thirteenth embodiment, the gain setting is shown for one step gain, but as shown in FIG. 33, the return setting to the origin of the steering wheel is further improved by setting the gain setting in a plurality of steps. be able to. For example, when driving at high speed, when the steering wheel is turned too much, the running stability is lost and the vehicle spins, which may lead to a serious accident. Therefore, it is important to prevent the steering wheel from being over-turned when traveling at high speed. When the steering wheel is turned too much, the steering torque becomes heavy, so that it is difficult to turn the steering wheel too much, and thus the effect of preventing the steering too much is increased. FIG. 33 shows a map when the steering wheel return assist torque signal is calculated with respect to the road surface reaction force torque signal, and the gain of the first stage in a region where the road surface reaction force torque signal is small is set to a good origin of the steering wheel. Aiming at recoverability, set a small gain according to the vehicle speed. In contrast,
The gain of the second stage in the region where the road surface reaction torque signal is large is set to a large gain, and the more the steering wheel is cut, the larger the road surface reaction torque signal becomes, so that the steering torque becomes heavier. . Further, as in the ninth embodiment, the gain of the first stage is set so that the gain becomes maximum near the upper limit value of the parking speed performed by a general driver, as shown in FIG. 34, and the gain of the second stage is set. As shown in FIG. 35, is set to 0 outside the high speed region, and the gain is set to increase as the speed increases.

As described above, in the fourteenth embodiment, the gain of the first stage in the region where the road reaction torque signal is small is set to a small gain according to the vehicle speed, and in the region where the road reaction torque signal is large. The gain of the second stage of is set to a large gain, so when high speed driving, normal steering is performed, good return to the origin of the steering wheel is achieved, and if the steering wheel is turned too much, As the vehicle is cut, the road surface reaction force torque signal rapidly increases, so that the steering torque becomes heavy and it is possible to prevent the steering wheel from being overcut. In the fourteenth embodiment, only the gain is changed, but the limiter may be set to be larger as the speed becomes higher.

[0073]

As described above, according to the electric power steering controller of the present invention, the return torque for returning the steering wheel to the neutral position is calculated based on the road surface reaction torque. The handle return characteristic can be improved. Further, according to the control method of the electric power steering control device of the present invention, the returning torque for returning the steering wheel to the neutral position is calculated based on the road surface reaction torque, so that the steering wheel returning performance is improved. You can

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an electric power steering control device according to a first embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the electric power steering controller according to the first embodiment of the present invention.

FIG. 3 is a diagram showing characteristics of a return torque compensator.

FIG. 4 is a block diagram showing a configuration of an electric power steering control device according to a second embodiment.

FIG. 5 is a flowchart for explaining the operation of the electric power steering control device according to the second embodiment.

FIG. 6 is a block diagram showing a configuration of an electric power steering control device according to a third embodiment.

FIG. 7 is a flowchart for explaining the operation of the electric power steering control device according to the third embodiment.

FIG. 8 is a block diagram showing a configuration of an electric power steering control device according to a fourth embodiment.

FIG. 9 is a flowchart illustrating an operation of the electric power steering control device according to the fourth embodiment.

FIG. 10 is a block diagram showing a configuration of an electric power steering control device according to a fifth embodiment.

FIG. 11 is a flowchart illustrating an operation of the electric power steering control device according to the fifth embodiment.

FIG. 12 is a block diagram showing a configuration of an electric power steering control device according to a sixth embodiment.

FIG. 13 is a flowchart illustrating an operation of the electric power steering control device according to the sixth embodiment.

FIG. 14 is a block diagram showing a configuration of an electric power steering control device according to a seventh embodiment.

FIG. 15 is a flowchart illustrating an operation of the electric power steering control device according to the seventh embodiment.

FIG. 16 is a block diagram showing the configuration of an electric power steering control device according to the eighth embodiment.

FIG. 17 is a flowchart illustrating an operation of the electric power steering control device according to the eighth embodiment.

FIG. 18 is a flowchart for explaining the operation of the electric power steering control device according to the ninth embodiment.

FIG. 19 is a diagram showing a dead zone characteristic of a road surface reaction torque detector.

FIG. 20 is a diagram showing a dead zone characteristic of another road surface reaction torque detector.

FIG. 21 is a flowchart for explaining the operation of the electric power steering control device according to the tenth embodiment.

FIG. 22 is a flowchart for explaining the operation of the electric power steering control device according to the eleventh embodiment.

FIG. 23 is a flowchart for explaining the operation of the electric power steering control device according to the twelfth embodiment.

FIG. 24 is a diagram showing a relationship between a vehicle time and a time constant of a filter of a road surface reaction torque detector.

FIG. 25 is a diagram showing a relationship between a vehicle speed and a time constant of another road surface reaction torque detector filter.

FIG. 26 is a diagram showing a relationship between a vehicle speed and a time constant of a filter of another road surface reaction torque detector.

FIG. 27 is a flowchart for explaining the operation of the electric power steering control device according to the thirteenth embodiment.

FIG. 28 is a diagram showing characteristics of a return torque compensator.

FIG. 29 is a diagram showing a gain characteristic of the return torque compensator.

FIG. 30 is a diagram showing a limiter characteristic of the return torque compensator.

FIG. 31 is a diagram showing characteristics of another return torque compensator.

FIG. 32 is a diagram showing characteristics of another return torque compensator.

FIG. 33 is a diagram showing characteristics of another return torque compensator.

FIG. 34 is a diagram showing a first-stage gain characteristic of the return torque compensator.

FIG. 35 is a diagram showing a second stage gain characteristic of the return torque compensator.

FIG. 36 is a block diagram showing a configuration of a conventional electric power steering control device.

[Explanation of symbols]

1 steering torque detector, 2 steering torque controller, 3 damping compensator, 4 inertia compensator, 5,5S motor speed detector, 6 motor acceleration detector, 7 motor current determiner, 8 judger, 9 motor driver 10 motors,
11 Motor Current Detector, 12 First Adder, 13
Second adder, 14 Vehicle speed detector, 15, 15S Road surface reaction torque detector, 16, 16S Cutting torque controller, 17 Return torque compensator, 20 Motor torque detector.

Continued front page    (72) Inventor Ryoji Nishiyama             2-3 2-3 Marunouchi, Chiyoda-ku, Tokyo             Inside Ryo Electric Co., Ltd. (72) Inventor Takayuki Kifu             2-3 2-3 Marunouchi, Chiyoda-ku, Tokyo             Inside Ryo Electric Co., Ltd. (72) Inventor Shunichi Wada             2-3 2-3 Marunouchi, Chiyoda-ku, Tokyo             Inside Ryo Electric Co., Ltd. F term (reference) 3D032 CC05 DA15 DA23 DA63 DA64                       DA82 DC08 DC12 DC17 DC33                       DD01 DD10 EB12 EC23 EC29                       GG01

Claims (14)

[Claims] 1. An electric power steering control device for controlling a motor that generates torque for assisting steering of a driver in a steering mechanism in which a steering wheel and a tire are mechanically connected, wherein the tire is a road surface. A road surface reaction torque detector that detects by measuring or calculating the road surface reaction torque received from, and a return torque compensator that calculates the return torque for returning the steering wheel to the neutral position based on this road surface reaction torque, An electric power steering controller comprising a motor current determiner that determines a current supplied to a motor based on at least a return torque calculated by a return torque compensator. 2. A steering torque detector for detecting a steering torque by a driver, and a steering torque controller for calculating a torque for assisting the steering based on the steering torque. The electric power steering control device according to claim 1. 3. The electric power steering control device according to claim 1, wherein the road surface reaction torque detector is a strain detector and is provided in a steering system from the gear mechanism to the tire. 4. The road surface reaction force torque detector is configured by a road surface reaction force torque calculator that calculates a road surface reaction force torque based on parameters detected by a detector that detects various parameters. The electric power steering control device according to claim 1. 5. The electric power steering control device according to claim 4, wherein the road surface reaction torque calculator uses steering torque, motor acceleration and motor current as parameters. 6. A motor current detector for detecting a motor current is further provided, and the steering torque is calculated on the basis of the detected motor current.
The electric power steering control device described. 7. A motor current detector for detecting a motor current, a power supply voltage detector for detecting a power supply voltage connected to the motor, and a PWM for detecting a PWM signal for driving the motor.
6. The electric power steering control device according to claim 5, further comprising a signal detector, wherein the motor acceleration is calculated based on the motor current, the power supply voltage and the PWM signal. 8. The electric power steering control device according to claim 4, wherein the road surface reaction torque calculator uses the steering torque and the motor current as parameters. 9. The electric power steering control device according to claim 4, wherein the road surface reaction torque calculator uses steering torque, motor acceleration and motor torque as parameters. 10. The electric power steering control device according to claim 4, wherein the road surface reaction torque calculator uses the steering torque, the motor acceleration, and the motor current command value as parameters. 11. The return torque compensator calculates a return torque based on a value obtained by multiplying an output of the road surface reaction force detector by a predetermined gain, and limits the maximum value of the return torque by a predetermined limit. The electric power steering control device according to claim 1, wherein: 12. The electric motor according to claim 11, further comprising a vehicle speed detector for detecting the speed of the vehicle, wherein the gain or limit value is adjusted according to the vehicle speed detected by the vehicle speed detector. Power steering control device. 13. The electric power steering control device according to claim 11, wherein the return torque compensator has a plurality of gain stages. 14. A control method of an electric power steering control device for controlling a motor that generates a torque for assisting steering of a driver in a steering mechanism, wherein a steering wheel and a tire are mechanically connected to each other. Measuring or calculating the road reaction torque that the tire receives from the road, and calculating the return torque for returning the steering wheel to the neutral position based on this road reaction torque; supplying to the motor at least based on the return torque A control method for an electric power steering control device, comprising the step of determining a current.