JP6822742B2 - 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 electric power steering motor in the electric power steering device is used to automatically steer the steering wheel to guide the vehicle to a predetermined parking position to assist the driver in parking. A support device has been proposed (Patent Document 1).

The electric power steering device detects the steering torque of the steering by the driver with a torque sensor, and the auxiliary torque corresponding to the detected steering torque is applied. The parking support device described above refers to the electric power steering ECU (hereinafter, the electric power steering is referred to as "electric power steering". It is generated by driving the EPS motor by (called EPS), but when it is used for parking assistance, the EPS motor generates torque to steer the steering without the driver operating the steering. .. At this time, the parking support means outputs the target steering angle at the time of parking support to the EPS ECU, and the EPS ECU controls the target steering angle to be the target steering angle.

Japanese Unexamined Patent Publication No. 2014-189168 (see paragraph 0002-0003)

However, in the conventional device, when the power supply voltage supplied to the EPS ECU from the battery mounted on the vehicle drops or the temperature of the EPS motor rises, for example, the power supply voltage of the EPS ECU is higher than the rated operating state. If it also decreases, the EPS motor cannot be driven at the target steering angle output from the parking support means.

Therefore, in the conventional parking support control, when the EPSECU determines that the power supply voltage of the EPSECU is lower than the rated operating state or the temperature of the EPS motor is higher than the predetermined value as described above, the parking support is performed. It is common practice to stop driving the EPS motor even if there is a parking assistance command (output of the target steering angle) from the means, but the driver does not control the parking assistance that should be performed by automatic steering. , There is a problem of feeling uncomfortable.

The present invention determines the target steering angle at the time of parking based on the controllable steering speed at which the EPS motor can be controlled, thereby continuing the parking support by the automatic steering and controlling the parking support that should be originally performed by the automatic steering. The purpose is to prevent the driver from feeling uncomfortable that this is not done.

In order to achieve the above object, the parking assist device of the present invention includes a torque sensor that detects the steering torque of the steering, an electric power steering motor that generates an auxiliary torque to be applied to the steering, and a torque detected by the torque sensor. A control means that derives the auxiliary torque according to the above and gives a current command value to the electric power steering motor so as to generate the derived auxiliary torque, and the control means of the electric power steering motor at the time of parking assistance. The control means includes at least the control means, which outputs a target steering angle and controls the electric power steering motor by the control means based on the target steering angle to automatically steer the steering. The controllable steering speed that can control the electric power steering motor is calculated based on the power supply state of the above, and the calculated controllable steering speed is output to the parking support means, and the parking support means controls the control steering. The target rudder angle at the time of parking assistance is determined by receiving the speed , and the target is a coordinate plane in which one coordinate axis is used as the coordinate axis related to time and another coordinate axis different from the one coordinate axis is used as the coordinate axis related to the target steering angle. The steering angle is switched to a gentle inclination with a small increase per hour at the switching point of the controllable steering speed, and the control means for giving the current command value based on the target steering angle to the electric power steering motor. It is characterized by outputting the rudder angle command value to.

According to the present invention, the controllable steering speed at which the electric power steering motor can be controlled is calculated by the control means and output to the parking support means, and the parking support means receives the controllable steering speed and the target steering angle at the time of parking. Is determined, and the steering angle command value is output to the control means in order to give the current command value based on the target steering angle to the electric power steering motor. Therefore, the electric power steering motor is always parked based on the controllable steering speed that can be controlled. By determining the target rudder angle at the time of support, even if the electric power steering motor cannot be driven by the target rudder angle output from the parking support means, the parking support by automatic steering can be continued, which is originally automatic. It is possible to prevent the driver from feeling a sense of discomfort that the parking assistance that should be steered is not controlled.

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 an operation explanatory view of FIG. It is an operation explanatory view of FIG. It is an operation explanatory view of FIG.

An embodiment of the parking support device according to the present invention will be described in detail with reference to FIGS. 1 to 5. 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 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 corresponding to the target steering angle 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 output. Is taken into the EPS ECU 3, the required motor current is applied to the EPS motor 2 while monitoring the actual drive current of the EPS motor 2, the EPS motor 2 is automatically driven, the steering 6 is steered, and the operation is performed. The vehicle is guided to a predetermined parking position without steering by a person.

At this time, as shown in FIG. 2, in the EPSECU3, since it is known whether or not the power supply voltage in the power supply state of the EPSECU3 by the battery B (see FIG. 1) is lower than, for example, 12V during the rated operation, the power supply voltage is lower than 12V. The controllable steering speed that can control the EPS motor 2 with the current power supply voltage that has also decreased is calculated by the calculation unit 3a, and the calculated controllable steering speed information is transmitted by the communication unit 3b that performs CAN (Control Area Network) communication. It is transmitted to the parking support ECU 4.

On the other hand, when the parking support ECU 4 receives the information on the controllable steering speed from the EPS ECU 3, the calculation unit 4a determines the target steering angle at the time of parking support by calculation based on the controllable steering speed, and sets the determined target steering angle. The steering angle command value is output to the EPS ECU 3 in order to give the based current command value to the EPS motor 2. In this way, the drive control of the EPS motor 2 is performed in real time.

If the power supply voltage in the power supply state of the EPSECU3 is 12V during the rated operation by the drive control of the EPS motor 2 during parking assistance, for example, the motor current as shown by the one-point chain line in FIG. 3 is EPS. It is possible to pass through the motor 2 and drive and control the EPS motor 2 at the target steering angle from the parking support ECU 4 within a certain rated current range, whereas when the power supply voltage of the EPS ECU 3 drops to, for example, 9V. As shown by the solid line in FIG. 3, the region of the motor current that can flow through the EPS motor 2 moves in the direction in which the horizontal axis (rotational speed) becomes smaller. Therefore, as hatched in FIG. There is a problem that the current that can flow from the EPS ECU 3 becomes insufficient, and the EPS motor 2 cannot be driven and controlled at the target steering angle from the parking support ECU 4 within a certain rated current range.

Therefore, as described above, the EPS ECU 3 calculates the controllable steering speed at which the EPS motor 2 can be controlled by the power supply voltage in the current power supply state by the calculation unit 3a, and the calculated controllable steering speed information is obtained by the parking support ECU 4 When the parking support ECU 4 receives the information on the controllable steering speed from the EPS ECU 3, the calculation unit 4a determines the target steering angle at the time of parking support by calculation based on the controllable steering speed, and the determined target steering angle is determined. The rudder angle command value is output to the EPS ECU 3 in order to give the current command value based on the above to the EPS motor 2. At this time, since the controllable steering speed and the power supply voltage have a certain relationship as shown in FIG. 4, the controllable steering speed is calculated by the calculation of the calculation unit 3a based on the power supply voltage.

Then, the calculated controllable steering speed is transmitted from the EPS ECU 3 to the parking support ECU 4, and the calculation unit 4a of the parking support ECU 4 calculates and determines the target steering angle at the time of parking support based on the received controllable steering speed. A current command value based on the determined target steering angle is output to the EPS ECU 3, and the EPS ECU 3 drives the EPS motor 2 with the motor current based on the target steering angle.

Specifically, as shown in FIG. 5B, when the controllable steering speed is, for example, 360 deg / s or less, the target steering angle is determined and the EPS motor 2 is driven and controlled. When the power supply voltage of the EPSECU 3 drops, the controllable steering speed according to the lowered power supply voltage is calculated by the calculation unit 3a of the EPSECU3, and assuming that the calculated new controllable steering speed is, for example, 270 deg / s or less. Since the target steering angle based on the new controllable steering speed is determined by the calculation unit 4a of the parking support ECU 4, the target steering angle is gentle at the switching point of the controllable steering speed, as shown in FIG. 5A. Switch to a smooth slope. The degree of switching of the target rudder angle at this time may be arbitrary, such as gradually lowering.

Therefore, according to the above-described embodiment, the calculation unit 3a calculates the controllable steering speed at which the EPS motor 2 can be controlled by the power supply voltage which is the current power supply state, and the calculated controllable steering speed information is used as the parking support ECU 4 When the parking support ECU 4 receives the information on the controllable steering speed from the EPS ECU 3, the calculation unit 4a determines the target steering angle at the time of parking assistance by calculation based on the controllable steering speed, and the determined target steering angle is determined. Since the steering angle command value is output to the EPS ECU 3 in order to give the current command value based on the above to the EPS motor 2, the target steering angle at the time of parking assistance is always determined based on the controllable steering speed at which the EPS motor 2 can be controlled. Even if the EPS motor 2 cannot be driven by the target rudder angle output from the parking support ECU 4, parking support by automatic steering can be continued.

As a result, it becomes possible to prevent the driver from feeling uncomfortable that the parking support that should be originally performed by automatic steering is not controlled, and it is possible to realize highly reliable and stable parking support. ..

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, the case where the controllable steering speed is calculated based on the power supply voltage which is the power supply state of the EPS ECU 3 has been described. However, when the temperature of the EPS motor 2 increases, the torque generated decreases and the EPS motor 2 is operated. Since it becomes impossible to drive at the target steering angle output from the parking support ECU 4, the controllable steering speed may be calculated based on the temperature of the EPS motor 2.

Further, the case where the controllable steering speed is calculated by the calculation unit 3a based on the power supply voltage which is the power supply state of the EPSECU 3 has been described, but the calculation unit 3a outputs the steering angular velocity if the steering angle servo control is possible. Alternatively, the rated current may be energized or may be a predetermined current, and a three-dimensional map using the temperature of the EPS motor 2 is maintained to derive a controllable steering speed according to the power supply voltage and the motor temperature. Alternatively, a flag indicating the controllable steering speed or a speed value corresponding to the value of the power supply voltage may be derived.

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

Claims (1)

A torque sensor that detects the steering torque of the steering wheel 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 to the electric power steering motor so as to generate the derived auxiliary torque.
Parking support that outputs the target steering angle of the electric power steering motor at the time of parking support to the control means, controls the electric power steering motor by the control means based on the target steering angle, and automatically steers the steering. With means,
The control means calculates a controllable steering speed that can control the electric power steering motor based on at least the power supply state of the control means, and outputs the calculated controllable steering speed to the parking support means.
The parking support means determines a target steering angle at the time of parking assistance in response to the controllable steering speed, one coordinate axis is set as a coordinate axis related to time, and another coordinate axis different from the one coordinate axis is set as a target steering angle. On the coordinate plane with the coordinate axes, the target steering angle switches to a gentle inclination with a small increase per hour at the switching point of the controllable steering speed, and the current command value based on the target steering angle is used as the above. A parking support device characterized in that a steering angle command value is output to the control means to be given to an electric power steering motor.

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