JPH05319296A - Motor-driven power steering controller - Google Patents

Abstract

PURPOSE:To improve the safety by using the AC component, besides the DC component of the signal supplied from a torque sensor, in the motor-driven power steering controller for an automobile. CONSTITUTION:The car speed signal outputted by a car speed sensor 10 is received by a control unit 9, and a car speed measuring means 9c measures the car speed, and inputted into a motor current determining means 9e. While, the turning force of a steering wheel 1 is detected by a torque sensor 3, and a steering torque measuring means 9a detects the magnitude and direction of the steering torque and inputted these values into the motor current determining means 9e. Further, a steering torque ac component separating means 9a2 extracts the ac component of the steering torque signal and sends it into the motor current determining means 9e. The motor current determining means 9e compares the car speed and torque with each, prescribed value, and in case of low speed and low torque, and in the case where the large steering is dangerous, the motor current is determined by the output of the steering torque ac component separating means 9a2, while in case of the large torque, the motor current is determined by the output of the steering torque measuring means 9a1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor drive type power steering control device for supplementally energizing a steering device of an automobile by a rotational force of a motor.

[0002]

2. Description of the Related Art Conventionally, this type of device assists the driving force of a motor on a steering shaft by a transmission mechanism such as a gear or a belt via a speed reducer based on a signal from a torque sensor.

[0003]

In the conventional motor drive type power steering control device as described above, the signal from the torque sensor when the torque is not acting causes a drift as if the signal is generated. If a problem occurs, the steering shaft is rotated because an instruction to drive the motor is issued, and there is a problem that the steering shaft moves differently from the driver's will to operate the steering shaft.

The present invention has been made in order to solve the above problems, and the steering shaft is operated by the driver even if the signal when the torque is not acting on the torque sensor causes a drift due to long-term use. It is an object of the present invention to obtain a motor-driven power steering control device with high safety by preventing a movement different from that of the above.

[0005]

According to another aspect of the present invention, there is provided a motor-driven power steering control device, wherein the control means controls an AC component in addition to a DC component of a signal from a torque sensor to control a current to an electric motor. It is intended to be used.

Further, the control means mainly uses the AC component signal of the signal component of the torque sensor which is the base for controlling the motor current when the vehicle runs at a speed higher than the dangerous vehicle speed when the steering wheel is steered largely. Is.

Further, the control means provides a torque discrimination range at low speed running, mainly uses the AC component signal of the signal of the torque sensor at low torque, and directly controls the torque sensor input signal at the time of large torque generation. It was done.

In the motor-driven power steering control device of the present invention, in addition to the input signal from the torque sensor, an AC component of the torque sensor input signal,
Learning control means for correcting the drift of the torque sensor output by the learning control based on the steering rotation angle signal and the vehicle speed signal is provided.

Further, the learning control means compares the input signal from the torque sensor with the AC component output of the torque sensor when the rotation angle of the steering wheel is in the neutral position at a constant vehicle speed and continues for a certain time or longer, whereby the torque is calculated. The determination is made as to whether or not a drift has occurred in the output of the sensor, and the drift of the torque sensor output is corrected by learning.

When the steering angle at the constant vehicle speed and the steering angle is in the neutral position continues for a certain period of time or more, by comparing the input signal from the torque sensor with the AC component output of the torque sensor, the output of the torque sensor drifts. The abnormality detecting means is provided for determining whether or not the abnormality has occurred and detecting an abnormality of the torque sensor.

[0011]

Since the motor drive type power steering control device according to the present invention includes the drift only in the output of the torque sensor, if the AC component of the torque sensor output not including the drift component is used for the current control of the electric motor,
Even if the torque sensor outputs a signal that the torque sensor output is drifting and the torque is not acting, it is offset in a certain direction and the electric motor assists the steering shaft. There is no.

If the steering wheel is steered by a large amount and the vehicle is running at a speed higher than dangerous, the AC component signal is mainly used as the signal of the torque sensor which is the base for controlling the motor current. The electric motor does not assist the steering shaft due to the drift of the torque sensor output.

Further, a torque discrimination range is provided during low speed running, and the AC component signal of the signal of the torque sensor that serves as the base for controlling the motor current is mainly used during low torque, and the torque sensor input is used when large torque is generated. If it is controlled using a signal, similar to the above,
The electric motor does not assist the steering shaft due to the drift of the torque sensor output, and the power assist required by the driver can be obtained when the torque is large.

Further, the motor-driven power steering control device according to the present invention compares the input signal from the torque sensor with the AC component thereof under the condition that the vehicle speed and the steering rotation angle are constant, and A value for correcting the drift of the sensor output can be learned, and the drift can be corrected by this learning value to remove the drift component included in the torque sensor output.

When the steering angle of the steering wheel is in the neutral position at a constant vehicle speed for a certain period of time or longer, the input signal from the torque sensor and its AC component in this state are compared to determine the torque sensor output. Whether or not the output has drifted can be determined, and if the drift has occurred, the drift of the torque sensor output can be corrected by learning.

Further, by comparing the input signal from the torque sensor and the AC component thereof under the above-mentioned constant condition, it can be determined whether or not the output drift of the torque sensor is generated, and if the learning control range is exceeded, the torque is exceeded. It can be determined that the sensor is abnormal.

[0017]

【Example】

Example 1. An embodiment of the present invention will be described below. FIG. 1 is a configuration diagram including a block circuit diagram of a motor-driven power steering control device according to an embodiment of the present invention. In FIG. 1, 1 is a steering wheel which receives a steering torque of a driving vehicle, and 3 is a steering wheel. A torque sensor that outputs a signal in accordance with the rotational force applied to 1; 4a, a first universal joint; 4b, a second universal joint; 2a, a first steering shaft that connects the steering wheel 1 and the torque sensor 3; Reference numeral 2b is a second steering shaft connecting the torque sensor 3 and the first universal joint 4a, and 2c is a third steering shaft connecting the first universal joint 4a and the second universal joint 4b.

Reference numeral 5 is a first pinion shaft connected to the second universal joint 4b, and 6 is a rack having a first rack tooth portion 6a and a second rack tooth portion 6b meshing with the first pinion shaft 5. Shaft, 7a is one tie rod 8a
And one end of the first rack tooth portion 6a are connected to each other, and 7b is another ball joint that connects the other tie rod 8b and the end portion of the second rack tooth portion 6b.

Reference numeral 9 is a control unit, 10 is a vehicle speed sensor for detecting a vehicle speed, 11 is an on-vehicle battery, 12 is a key switch, 13 is a direct current motor having a shunt winding or a magnet field, and the battery 11 controls the control unit 9. It is driven by being supplied with power via. Reference numeral 14 is a worm shaft that is connected to the output shaft of the motor 13 to form a speed reducer, 15 is a worm wheel shaft that is driven by meshing with the worm shaft 14, 17 is connected to the worm wheel shaft 15, and a second rack tooth portion 6b is a second pinion shaft that meshes with 6b.

FIG. 2 shows a block circuit diagram of the control unit 9 shown in FIG. 1, 9a1 being steering torque measuring means for measuring steering torque by input from the torque sensor 3, and 9a2 being input by the torque sensor 3. Steering torque AC component separating means for separating an AC component, and 9c is a vehicle speed measuring means for measuring a vehicle speed by an input from the vehicle speed sensor 10.

The reference numeral 9e designates mainly the torque sensor 3 when the vehicle runs at a speed higher than a dangerous speed when the steering wheel 1 is steered largely.
The AC component signal of the signal is used as a signal for controlling the motor current, and a torque identification range is provided during low speed traveling, and when the torque is low, the AC component signal of the signal of the torque sensor 3 mainly controls the motor current. When a large torque is generated, the input signal from the torque sensor 3 is directly used as a signal for controlling the motor current, and the motor current determining means for determining the motor current, 9f is the output of the motor current determining means 9e. Based on this, the motor current control means controls the motor current.

Next, the operation of the first embodiment will be described with reference to FIGS. First, when starting the engine, when the key switch 12 is turned on, the control unit 9 is connected to the battery 11 to start the operation.

The vehicle speed sensor 10 detects the vehicle speed, and the vehicle speed measuring means 9c which receives the detection signal measures the vehicle speed and outputs the measurement result to the motor current determining means 9e.

On the other hand, the torque sensor 3 to which the torque is transmitted from the steering wheel 1 detects this steering torque, and outputs a signal having a magnitude corresponding to the direction and magnitude of this steering torque to the steering torque measuring means 9a1 and the steering torque AC. It outputs to the component separation means 9a2. The steering torque measuring means 9a1 measures the steering torque and outputs the measurement result to the motor current determining means 9e. Further, the steering torque AC component separating means 9a2 extracts the AC component of the input signal to determine the motor current determining means 9e.
Output to.

The motor current determining means 9e compares the vehicle speed measurement signal with a predetermined vehicle speed threshold value. When it is determined from the comparison result that the vehicle is traveling at low speed, the motor current determining means 9e
Compares the steering torque measurement signal with a preset torque discrimination range, and when it determines that the torque is low, determines the motor current based on the output signal of the steering torque AC component separating means 9a2, and When it is determined that the large torque is generated, the motor current is determined based on the output signal of the steering torque measuring means 9a1.

Further, when the motor current determining means 9e determines from the comparison result of the vehicle speed measurement signal and the predetermined vehicle speed threshold value that the steering wheel 1 is steered by a large amount, it is judged that the vehicle is traveling at a speed higher than the dangerous vehicle speed. The steering torque AC component separating means 9
The motor current is determined based on the output signal of a2.

Then, the motor current control means 9f controls the current of the DC motor 13 based on the output signal of the motor current determination means 9e according to the determined magnitude of the motor current. The rotating force of the DC motor 13 is equivalent to the worm shaft 14
Is transmitted to the worm wheel shaft 15 and further transmitted from the second pinion shaft 17 to the rack tooth portion 6b of the rack shaft 6 for power assist.

As described above, the torque sensor 3 serving as a base for controlling the motor current during low speed running and low torque.
If the AC component of the output signal of the torque sensor 3 is mainly used, and the AC component of the output signal of the torque sensor 3 is mainly used when the steering wheel 1 is steered by a large amount and the vehicle travels at a speed higher than the dangerous vehicle speed. Even if the torque sensor 3 outputs a signal as if the torque is acting even though the output of No. 3 drifts to the whole and the torque is not acting, it is offset in a certain direction, and the drift component causes the DC motor 13 Does not assist the steering shaft.

Example 2. FIG. 3 is a configuration diagram including a block diagram of a motor drive type power steering control device according to the present invention. In FIG.
The steering angle sensor detects the steering angle of the control unit 9 and has the same configuration as that of the first embodiment except for the configuration of the control unit 9.

FIG. 4 shows the control unit 9 shown in FIG.
9a1, 9a2, 9c, 9f showing a block circuit diagram of
Has the same function as that described in the first embodiment, the description thereof is omitted, and 9b is a steering angle measuring means for measuring the steering angle of the steering wheel based on the output of the steering angle sensor 18, and 9d.
Indicates that the signal from the steering angle measuring means 9b is at the steering wheel neutral position and the signal from the vehicle speed measuring means 9c is a constant vehicle speed. When this state continues for a certain time or longer, the steering torque measuring means 9a1 and the steering torque AC component are The output signals of the separating means 9a2 are compared, and if a drift occurs in the output of the torque sensor 3, learning is performed to correct the drift of the output of the steering torque measuring means 9a1 and to correct the output of the torque sensor 3. It is steering torque sensor abnormality detecting means for detecting that the torque sensor 3 is abnormal when the amount of drift exceeds a certain value, and gives an output corrected by the learning control to the motor current determining means 9g. Reference numeral 9g is a motor current determining means for determining the motor current to a value corresponding to a value obtained by correcting the steering torque measurement value of the steering torque measuring means 9a1.

Next, the operation of the second embodiment will be described with reference to FIGS. The steering torque sensor abnormality detecting means 9d inputs a vehicle speed measurement signal from the vehicle speed sensor 10 via the vehicle speed measuring means 9c, inputs a steering angle measurement signal from the steering angle sensor 18 via the steering angle measuring means 9b, and The steering torque measurement signal and the steering torque AC component separation signal are input from the torque sensor 3 through the steering torque measuring means 9a1 and the steering torque AC component separation means 9a2, respectively.

The steering torque sensor abnormality detecting means 9d monitors the steering angle measurement signal and the vehicle speed measurement signal to determine whether the steering wheel 1 is in the neutral position and the vehicle speed is constant for a certain period of time or longer. to decide. If it is determined that the steering torque sensor abnormality detection means 9d has continued for a certain period of time or more, the steering torque sensor abnormality detection means 9d compares the steering torque measurement signal and the steering torque AC component separation signal, and, for example, determines the difference between the two, and determines the predetermined learning control range. If the learning control range is exceeded, it is determined that the output of the torque sensor 3 is abnormal and the power assist is stopped. If it is within the learning control range, it is determined to be normal.

When it is judged to be normal, the steering torque sensor abnormality detecting means 9d learns and corrects the drift amount because the difference between the steering torque measurement signal and the steering torque AC component separation signal is the drift amount. This learning is performed every time the above condition is satisfied, in which the steering angle is kept at the neutral position at the constant vehicle speed for a predetermined time or longer.

The motor current determining means 9g determines the motor current to a value corresponding to the true steering torque based on the drift-corrected steering torque measurement signal. The motor current control means 9f controls the motor current of the DC motor 13 based on the output of the motor current determination means 9g. The torque of the DC motor 13 acts as an assist for power steering.

Although the above learning conditions are assumed to continue for a certain time or longer when the steering angle of the steering wheel is in the neutral position at a constant vehicle speed, other constant conditions may be used, for example, a constant vehicle speed or higher may be used instead of the constant vehicle speed.

[0036]

As described above, according to the present invention, the AC component in addition to the DC component of the torque sensor signal is used for controlling the motor current. Even if you drift
Since the control of the motor current is performed based on the state where no torque is applied to the steering wheel, the steering wheel does not behave differently from the driver's intention.

Further, since the AC component of the torque sensor output is mainly used for controlling the motor current when traveling at a vehicle speed that is dangerous for traveling when the steering wheel is steered by a large amount, in addition to the above-mentioned effect, safety is ensured. Power steering with high performance.

Further, since only the AC component of the torque sensor output is used for the control at the time of low torque, the steering wheel does not behave differently from the driver's intention as described above, and
Since the input signal of the torque sensor is used as it is when a large torque is generated, it is possible to assist the steering wheel required by the driver, resulting in highly safe power steering.

Further, according to the present invention, the learning, correction and abnormality determination of the torque sensor drift are performed by comparing the torque sensor output with the AC component thereof under the condition that the vehicle speed and the steering rotation angle are constant. Since it is configured as described above, even if the signal of the torque sensor drifts due to long-term use, the output of the torque sensor is corrected, and if it is further deviated, an abnormality determination is made.
Power steering with high safety.

[Brief description of drawings]

FIG. 1 is a configuration diagram including a block configuration of a motor drive type power steering control device according to an embodiment of the present invention.

FIG. 2 is a block circuit diagram of a control unit and the like shown in FIG.

FIG. 3 is a configuration diagram including a block configuration of a motor drive type power steering control device according to another embodiment of the present invention.

FIG. 4 is a block circuit diagram of a control unit and the like shown in FIG.

[Explanation of symbols]

 1 Handle 3 Torque Sensor 5 First Pinion Shaft 6 Rack Shaft 6a First Rack Tooth 6b Second Rack Tooth 9 Control Unit 10 Vehicle Speed Sensor 11 Battery 12 Key Switch 13 DC Motor 14 Worm Shaft 15 Worm Wheel Shaft 17 Second pinion shaft 18 Steering angle sensor

Claims (6)

[Claims] 1. A motor-driven power steering system in which a control means controls a current to an electric motor according to a twisting torque of a steering shaft detected by a torque sensor, and the electric motor assists the steering wheel in a steering direction. In the control device, the control means uses an AC component in addition to the DC component of the signal from the torque sensor for control, and is a motor-driven power steering control device. 2. The control means mainly uses the AC component signal of the signal of the torque sensor for controlling the motor current for control when the vehicle is traveling at a vehicle speed that is dangerous for traveling when the steering wheel is steered largely. The motor-driven power steering control device according to claim 1, wherein 3. The control means mainly provides an AC component signal of a signal of the torque sensor, which serves as a base for controlling a motor current when a low torque is provided and a torque identification range is provided at a low torque, for a large torque. The motor-driven power steering control device according to claim 1, wherein when generated, the input signal from the torque sensor is directly used for control. 4. A motor-driven power steering control in which the control means controls the current to the electric motor according to the twisting torque of the steering wheel detected by the torque sensor, and the electric motor assists the steering wheel in the steering direction. In the device, in addition to the input signal from the torque sensor, an AC component of the input signal from the torque sensor, an input signal from the steering angle sensor that detects the rotation angle of the steering, and an input signal from the vehicle speed sensor that detects the vehicle speed A motor-driven power steering control device comprising learning control means for correcting the drift of the torque sensor output based on learning control. 5. The learning control means compares the input signal from the torque sensor and the AC component output of the torque sensor when the rotation angle of the steering wheel is in the neutral position at a constant vehicle speed and continues for a certain time or more. Determines whether or not there is a drift in the output of the torque sensor,
The motor-driven power steering control device according to claim 4, wherein drift of the torque sensor output is corrected by learning. 6. When the rotation angle of the steering wheel is in the neutral position at a constant vehicle speed and continues for a certain period of time or more, the input signal from the torque sensor and the AC component output of the torque sensor are compared to determine the torque sensor output. The motor-driven power steering control device according to claim 4, further comprising an abnormality detection unit that determines whether or not the output has drifted and detects an abnormality of the torque sensor.