JP6775894B2 - Parking support device - Google Patents

Description

The present invention relates to a parking support device that assists a driver in parking by using an electric power steering motor.

Conventionally, when parking a vehicle, the steering is automatically steered by using an EPS motor in an electric power steering (hereinafter, electric power steering is referred to as "EPS") device to guide the vehicle to a predetermined parking position. A parking support device that assists the driver in parking has been proposed. In this parking support device, the steering torque of the steering wheel by the driver is detected by the torque sensor, and the auxiliary torque corresponding to the detected steering torque is generated by the EPS motor. However, when it is used for parking support, it is used. Even if the driver does not operate the steering, torque is generated by the EPS motor to steer the steering.

Further, in the above-mentioned parking support device, when the EPS motor becomes unable to rotate due to the steering wheel hitting an obstacle during automatic steering, the maximum current continues to flow in the EPS motor, which causes the motor to overheat. , Even if the steering becomes unsteerable during automatic steering, the upper limit current that can be passed to the EPS motor at that time is set so that the wheels can be steered with the minimum available turning radius while suppressing overheating of the EPS motor. It has been proposed to steer the wheels with the minimum available radius by setting the current value smaller than the value before the steering becomes impossible (Patent Document 1).

Japanese Unexamined Patent Publication No. 2014-136430 (see paragraph 0007-0011)

However, in the above-mentioned Patent Document 1, it is assumed that the steering wheel hits an obstacle during the automatic steering in the unsteerable state during the automatic steering, and the driver steps on the brake during the automatic steering. If the steering becomes impossible due to this, the steering cannot be steered even if the upper limit current that can be passed through the EPS motor is set to a current value smaller than the value before the steering becomes impossible.

In this way, if the driver intentionally steps on the brake during automatic steering, it can be determined that the driver intends to interrupt or stop the automatic steering. Therefore, the current flowing through the EPS motor may be reduced to the extent that it does not overheat. It is not necessary to support parking by automatic steering at the minimum turning radius, and it is not necessary to provide an expensive configuration for continuing the automatic steering at the minimum turning radius described above. In addition, even if the steering wheel hits an obstacle during automatic steering and becomes unsteerable, the motor current flowing through the EPS motor is reduced to the extent that the EPS motor does not overheat, and automatic steering is temporarily interrupted, and then the cause is caused by the obstacle. The automatic steering may be restarted after the unsteerable state is released, and an expensive configuration for continuing the automatic steering at the minimum turning radius is unnecessary.

The present invention controls to reduce the flow current value of the electric power steering motor when the electric power steering motor is in a non-rotatable state for a certain period of time when parking assistance is performed by using the electric power steering motor. The purpose is to prevent overheating of the electric power steering motor with a simple configuration.

In order to achieve the above object, the parking assist device of the present invention comprises a torque sensor that detects the steering torque of the steering of the vehicle, an electric power steering motor that generates an auxiliary torque to be applied to the steering, and the torque sensor. A control means that derives the auxiliary torque according to the detected torque and gives a current command value corresponding to the indicated steering angle that generates the derived auxiliary torque to the electric power steering motor, and the control means that provides the control means when parking is assisted. Parking that outputs a steering angle command value to control the electric power steering motor, outputs the current command value based on the steering angle command value to the electric power steering motor by the control means, and automatically steers the steering. The parking support means is provided with a support means, and the parking support means determines whether or not the state in which the indicated steering angle does not change, which is not necessary for parking assistance, continues for a certain period of time, and if it is determined to continue, the indicated steering angle is reduced in the opposite direction. It is characterized in that the steering angle command value is output to the control means.

According to the present invention, the parking support means determines whether or not the state in which the indicated steering angle, which is not necessary for parking assistance, does not change continues for a certain period of time, and if it is determined to continue, the indicated steering angle to the electric power steering motor is determined. Since the steering angle command value that decreases in the opposite direction is output from the parking support means to the control means, for example, the driver operates the brake during the operation of the parking support, and the indicated steering angle that is not necessary for the parking support does not change. When the condition occurs for a certain period of time, the electric power steering motor can be released from the loaded state by reducing the instruction steering angle to the electric power steering motor in the opposite direction, and the simple configuration prevents the motor from overheating. Can be done.

It is a block diagram of one Embodiment of the parking support device which concerns on this invention. It is a block diagram of a part of FIG. It is operation explanatory drawing of one Embodiment.

An embodiment of the parking support device according to the present invention will be described in detail with reference to FIGS. 1 to 3. FIG. 1 shows the configuration of one embodiment of the parking support device.

As shown in FIG. 1, the parking support device 1 includes an EPS (electric power steering) motor 2, an EPS ECU (Electric Control Unit) 3 having a microcomputer configuration for controlling the EPS motor 2, and a parking support means of the present invention. It is equipped with a parking support ECU 4 having a corresponding microcomputer configuration.

Then, the output signal of the steering angle sensor 7 that detects the steering angle due to the steering of the steering 6 and the output signal of the torque sensor 8 that detects the steering torque applied to the steering 6 by the driver are input to the EPS ECU 3, and the torque is torqued. A command current corresponding to the steering torque detected by the sensor 8 is supplied to the EPS motor 2 to drive and control the EPS motor 2 to generate an auxiliary torque for the steering operation of the driver. Here, EPSECU 3 corresponds to the control means in the present invention.

By the way, the torque sensor 8 is a combination of two sensors, a sensor that outputs a torque signal A with respect to a steering torque based on a steering operation by the driver, and a sensor that outputs a torque signal B whose phase is inverted. If the sensors are normal, the added value of the output signals of both sensors whose phases are opposite to each other should always be constant even if the steering torque changes, and the added value of the output signals of both sensors starts from a constant value. If it deviates, it can be determined that one of the sensors has an abnormality. Therefore, it is common to adopt a so-called double system composed of two sensors of the torque sensor 8, which is used for EPS control. The safety of the sensor is guaranteed.

Further, in order to perform parking support using the EPS motor 2 under the control of the parking support ECU 5, for example, when a parking support request is detected by shifting the shift lever to the back gear, as shown in FIG. 3, parking support is performed. A steering angle command value is output from the ECU 4, and based on this steering angle command value, the steering angle and steering angle speed detected by the steering angle sensor 7, and both torque signals A and B from the torque sensor 8 are taken into the EPS ECU 3. While monitoring the actual drive current of the EPS motor 2 by the EPS ECU 3, a required voltage is applied to the EPS motor 2 to energize the motor current, the EPS motor 2 is automatically driven, the steering 6 is steered, and the driver. The vehicle is guided to a predetermined parking position without steering by.

At this time, as shown in FIG. 2, in the EPSECU3, the energization direction of the motor current of the EPSECU3 by the power supply of the battery B (see FIG. 1), that is, the energization direction of the direction of rotating the EPS motor 2 clockwise or counterclockwise. , The current value is determined by the motor current energization state determination unit 3a of the EPS ECU 3, and information on the motor current energization state such as the determined motor current flow direction and the current value is transmitted by CAN (Control Area Network) communication. It is transmitted to the parking support ECU 4 by the unit 3b.

The determination of the motor current energization state by the motor current energization state determination unit 3a of the EPSECU 3 is performed as follows. For example, if the motor current is positively equal to or greater than the first predetermined value, the direction of energization for rotating the EPS motor 2 to the right is determined by the motor current energization state determination unit 3a to be "right energization", and the motor current becomes negative. If it is equal to or less than the second predetermined value, the direction of energization for rotating the EPS motor 2 counterclockwise is determined by the motor current energization state determination unit 3a to be "left energization", and the motor current is positive and negative with the first predetermined value. If it is between the second predetermined value of the above, the EPS motor 2 is in the neutral position and is determined to be "neutral" by the motor current energization state determination unit 3a, and as information on the motor current energization state together with the current value at that time. , It is transmitted from the communication unit 3b to the parking support ECU 4 by CAN communication.

When the parking support ECU 4 receives the information on the motor current energization state from the EPS ECU 3, the instruction rudder angle change determination unit 4a changes the instruction rudder angle to the EPS motor 2 by the EPS ECU 3 at the time of parking support based on the received motor current energization state. It is determined whether or not the state without the rudder continues for a predetermined period of time or longer, and if it is determined that there is a change in the indicated rudder angle, the EPS motor 2 is parked in order to give a current command value based on the indicated rudder angle. The steering angle command value is output from the support ECU 4 to the EPS ECU 3.

In this way, while the drive control of the EPS motor 2 is performed in real time, if it is determined that the indicated steering angle does not change for a certain period of time or more, the following control is performed.

Now, when a parking assistance request is detected, parking assistance control is started, and for example, a motor current of a first predetermined value or more such as rotating the EPS motor 2 to the right at a predetermined instruction steering angle is applied to the EPS motor 2. When energized, the indicated steering angle increases as shown in FIG. 3A, and parking support is provided by automatic steering. At this time, the energization direction of the motor current energized state determined by the motor current energized state determination unit 3a is “right energization” as shown in FIG. 3 (b).

Then, in the state where the EPS motor 2 is "right energized" in this way, if the driver operates the brake, the vehicle stops without changing the indicated steering angle, and the state in which the indicated steering angle does not change for a certain period of time continues. As shown in FIG. 3B, based on the motor current energization state determined by the motor current energization state determination unit 3a, the instruction rudder angle change determination unit 4a of the parking support ECU 4 determines the instruction rudder angle at the time of parking support for a certain period of time. If it is determined that there is no change as described above, as shown in FIG. 6A, the steering angle indicated to the EPS motor 2 is reduced to the left in the opposite direction, and the steering angle is slightly returned to the left. The command value is output from the parking support ECU 4 to the EPS ECU 3, and the EPS ECU 3 outputs a current command value that rotates the EPS motor 2 to the left to return it to "neutral".

After that, as shown in FIG. 3B, when the motor current energization state determination unit 3a determines that the EPS motor 2 has changed from "right energization" to "neutral", the instruction rudder to the EPS motor 2 is at that point. The control to reduce the angle to the left is stopped, and the steering angle command value that gives a constant current command value that keeps the EPS motor 2 in the "neutral" state is output from the parking support ECU 4 to the EPS ECU 3, and is shown in FIG. As shown, the indicated rudder angle is kept constant, and the EPS motor 2 is released from the loaded state.

By the way, when the brake operation by the driver is released, it is necessary to restart the parking support by the automatic steering. In this case, the control after detecting the above-mentioned parking support request is restarted. , The EPS motor 2 that has returned to "neutral" is controlled to the right energized state again, and the current command value based on the steering angle command value required for parking is output from the EPSECU 3 to the EPS motor 2 to provide parking support by automatic steering. It will be resumed.

In this way, when the driver steps on the brake during parking assistance and the state in which the indicated steering angle at the time of parking assistance does not change, which is determined based on the motor current energization state, continues for a predetermined fixed period of time, parking assistance is provided. Since the ECU 4 outputs a steering angle command value to the EPS ECU 3 that reduces the instruction steering angle to the EPS motor 2 in the opposite direction to the left, EPS is reduced by reducing the instruction steering angle to the EPS motor 2 in the opposite direction. The motor 2 is released from the loaded state to prevent the EPS motor 2 from overheating.

Even if the indicated steering angle does not change for a certain period of time while the motor current is energized to rotate the EPS motor 2 to the left, the parking support ECU 4 sets the indicated steering angle to the EPS motor 2. A steering angle command value that decreases to the right in the opposite direction is output to the EPSECU 3.

Therefore, according to the above-described embodiment, when the motor current energization information from the parking support hand ECU 4 and the EPS ECU 3 is received, the parking support ECU 4 determines whether or not the state in which the indicated steering angle does not change continues for a certain period of time and stops. When it is determined that the parking assist is in effect, a steering angle command value for reducing the instruction steering angle to the EPS motor 2 in the opposite direction is output from the parking support ECU 4 to the EPS ECU 3, so that the driver can operate the brake during the parking support operation, for example. When the state in which the instruction steering angle that is not necessary for parking assistance does not change continues for a certain period of time, the EPS motor 2 is released from the loaded state by reducing the instruction steering angle to the EPS motor 2 in the opposite direction. It is possible to prevent the EPS motor 2 from overheating with a simple configuration.

The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention.

For example, in the above-described embodiment, in the motor current energized state, if the motor current is positive, the direction of energization for rotating the EPS motor 2 clockwise is "right energization", and if the motor current is negative, the EPS motor 2 is rotated counterclockwise. The energization direction is determined as "left energization" and "neutral" in the meantime, but these "right energization", "left energization", and "neutral" may be held by flags and determined.

Further, in the above-described embodiment, in the motor current right energization state, if the motor current is positively equal to or more than the first predetermined value, "right energization" is performed, and if the motor current is negatively equal to or less than the second predetermined value, "left". An example of determining "neutral" if the value is between the first positive value and the second negative value of "energization" is shown, but "right energization", "left energization", and "neutral" The determination method is not limited to this.

Further, in the above-described embodiment, the EPS motor 2 by the EPSECU 3 at the time of parking support is based on the received motor current energization state by the instruction steering angle change determination unit 4a of the parking support ECU 4 based on the information of the motor current energization state from the EPSECU 3. Although the case of determining whether or not the state in which the rudder angle does not change continues for a predetermined period of time or longer has been described, the vehicle has stopped for a certain period of time or longer based on the vehicle speed detected by the vehicle speed sensor and the steering state. You may decide whether or not.

1 ... Parking support device 2 ... Electric power steering (EPS) motor 3 ... Electric power steering (EPS) ECU (control means)
4 ... Parking support ECU (parking support means)

Claims (1)

A torque sensor that detects the steering torque of the vehicle's steering and
An electric power steering motor that generates auxiliary torque applied to the steering, and
A control means that derives the auxiliary torque according to the torque detected by the torque sensor and gives a current command value corresponding to the indicated steering angle that generates the derived auxiliary torque to the electric power steering motor.
The control means outputs a steering angle command value for controlling the electric power steering motor at the time of parking assistance, and the control means outputs the current command value based on the steering angle command value to the electric power steering motor. It is equipped with a parking support means that automatically steers the steering.
The parking support means determines whether or not the state in which the indicated steering angle does not change, which is not necessary for parking assistance, continues for a certain period of time, and if it is determined to continue, the steering angle command value such that the indicated steering angle is reduced in the opposite direction is set. A parking support device characterized by outputting to the control means.

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