Parking assist device for vehicle

The present invention relates to a parking assist device for a vehicle.

Various manufacturers have developed parking assist devices that can automatically move a vehicle to a parking position without a steering operation, an accelerator operation, and a brake operation performed by a driver. Among the parking assist devices, a parking assist device for a vehicle has been known which calculates an optimum path to the parking position, calculates a steering angle for maintaining the optimum path, and performs assisted parking so as to maintain vehicle speed even when there is deceleration caused by the steering angle or deceleration caused by a gradient or a step (for example, see PTL 1).

Patent Literature

PTL 1: JP 2010-076675 A

Technical Problem

With the technique disclosed in PTL 1, however, the own vehicle speed of the vehicle during assisted parking, which has been decelerated due to the steering angle, the obstacle, and the gradient, is measured, and the assisted parking is performed by calculating and correcting a driving force when the vehicle speed is equal to or lower than predetermined speed.

In this case, the driving force is calculated on the basis of a difference between the predetermined speed and the own measured vehicle speed or a change rate of the own vehicle speed, and the own vehicle speed is controlled by reducing the difference from the own vehicle speed or reducing the change rate of the own vehicle speed depending on a change of the driving force, whereby the predetermined speed can be maintained.

However, the own vehicle speed does not change and remains at zero even if the driving force is changed when there is an obstacle in a parking path and a host vehicle stops, and thus, it is difficult to maintain the own vehicle speed of the vehicle. It is possible to overcome the obstacle by extremely slowly raising the driving force even if the own vehicle speed is not known, but it takes some time until the vehicle is parked at a target position or it is difficult to complete the parking.

In addition, when a strong driving force is applied to overcome the obstacle, there is a possibility that the vehicle may overcome the obstacle vigorously so that there is a risk of colliding with any other parked vehicle or the like.

Solution to Problem

In order to solve the above-described problems, a parking assist device for a vehicle of the present invention, for example, calculates a speed command value or/and an engine torque amount command value, obtained by predicting acceleration or deceleration of the vehicle, in advance, on the basis of each height of an obstacle and a step inside a parking path, each distance to the obstacle and step, a gradient of a road surface condition, and a steering angle, and controls speed of the vehicle on the basis of the calculated speed command value or/and engine torque amount command value.

Advantageous Effects of Invention

According to the present invention, it is possible to provide the parking assist device for a vehicle that is capable of parking without decreasing or excessively increasing the speed or causing the vehicle to stop during assisted parking and does not collide with any other parked vehicle or the like by maintaining the own vehicle speed of the vehicle to be constant even immediately after overcoming an obstacle and a step.

FIG. 1 is an ECU configuration diagram of a parking assist device for a vehicle according to a first embodiment of the present invention.

FIG. 2 is a control block diagram illustrating an operation of the parking assist device for a vehicle according to the first embodiment of the present invention.

FIG. 3 is a schematic view illustrating a parking state.

FIG. 4 is a flowchart illustrating the operation of the parking assist device for a vehicle according to the first embodiment of the present invention.

FIG. 5 is a timing chart diagram in a case where there is a step according to the first embodiment of the present invention.

FIG. 6 is a block diagram illustrating an overall configuration of a parking assist device for a vehicle according to a second embodiment of the invention.

Hereinafter, examples of the present invention will be described with reference to the drawings.

First Example

A parking assist device for a vehicle according to a first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is an ECU configuration diagram of the parking assist device for a vehicle according to the embodiment of the present invention. In FIG. 1 , a camera control unit 107 is connected to a front camera 101 , a left camera 102 , a rear camera 103 , a right camera 104 , and a user interface unit 105 via an LVDS. In addition, the camera control unit 107 is connected to the user interface unit 105 , a steering control unit 106 , an engine control unit 108 , and a brake control unit 109 via a CAN.

The front camera 101 is, for example, a camera that images a front side of a vehicle. The left camera 102 is, for example, a camera that images a left side of the vehicle. The rear camera 103 is, for example, a camera that images a rear side of the vehicle. The right camera 104 is, for example, a camera that images a right side of the vehicle.

The user interface unit 105 is, for example, an on-board display equipped with a touch panel that combines a parking position and a parking path calculated by the camera control unit 106 with images captured by the front camera 101 , the left camera 102 , the rear camera 103 , and the right camera 104 , and presents the combined images to a driver and receives a parking assistance start instruction from the driver.

Incidentally, the user interface unit 105 receives the image combined by the camera control unit 106 via the LVDS and displays the image, and notifies the camera control unit 106 of the parking assistance start instruction from the driver via the CAN.

The camera control unit 106 is a camera control unit that includes a parking frame recognition unit, a parking frame path calculation unit, a road surface shape recognition unit, an obstacle recognition unit, a steering angle command value calculation unit, a steering/torque command value calculation unit, a steering/torque command value addition unit, and an idling stop determination unit.

Incidentally, the camera control unit 106 calculates a steering angle command value and transmits the steering angle command value to the steering control unit, and calculates a speed command value or/and an engine torque amount command value and transmits the speed command value or/and engine torque amount command value to the engine control unit and brake control unit via the CAN in order to control the parking assist device for a vehicle.

The steering control unit 107 controls steering using the steering angle command value calculated by the camera control unit 106 and performs automatic steering during assisted parking.

The engine control unit 108 controls the engine using the speed command value or/and the engine torque amount command value calculated by the camera control unit 106 , and controls vehicle speed during assisted parking.

The brake control unit 109 controls brake using the speed command value or/and engine torque amount command value calculated by the camera control unit 106 , and controls the brake during assisted parking.

Hereinafter, an operation of a parking assist device 200 for a vehicle according to the first embodiment of the present invention will be described with reference to a block diagram of FIG. 2 . In FIG. 2 , the parking assist device 200 for a vehicle includes front and rear imaging units 201 , left and right imaging units 202 , a parking frame recognition unit 203 , a parking path calculation unit 204 , a road surface shape recognition unit 205 , an obstacle recognition unit 206 , a steering angle command value calculation unit 207 , a speed/torque command value calculation unit 208 , a speed/torque command value addition unit 209 , a steering control unit 210 , a vehicle speed control unit 211 , a brake control unit 212 , an idling stop control unit 213 , and a user interface unit 214 . A feature of the present invention is the parking assist device for a vehicle that includes the speed/torque command value calculation unit 208 , the speed/torque command value addition unit 209 , the road surface shape recognition unit 205 , and the obstacle recognition unit 206 .

The front and rear imaging units 201 are the front camera 101 and the rear camera 103 that image the front and rear sides of the vehicle. The left and right imaging units 202 are the left camera 102 and the right camera 104 that image the left and right sides of the vehicle.

The parking frame recognition unit 203 is a block in the camera control unit 106 and recognizes a parking frame position by analyzing front, rear, left and right images captured by the front and rear imaging units 201 and the left and right imaging units 202 .

The parking path calculation unit 204 is a block in the camera control unit 106 and calculates a parking path to a parking position on the basis of a distance and a direction from a current vehicle stop position to the parking position recognized by the parking frame recognition unit 203 .

FIG. 3 illustrates the parking path to be calculated. The parking path is calculated from 300 that is a parking assistance start position, via 301 with a switching position, to 302 that is a parking assistance end position.

The road surface shape recognition unit 205 is a block in the camera control unit 106 and detects a gradient of a road surface condition in a parking lot. The gradient of the road surface condition may be detected by using an acceleration sensor, or the gradient of the road surface condition may be detected by image analysis of the images captured by the front and rear imaging units 201 and the left and right imaging units 202 .

The obstacle recognition unit 206 is a block in the camera control unit 106 and detects whether there is an obstacle and a step in the parking path calculated by the parking path calculation unit 204 . When the obstacle and step are detected, each height of the obstacle and step and each distance to the obstacle and step are calculated by image analysis of the images captured by the front and rear imaging units 201 and the left and right imaging units 202 . In addition, the height of a wheel stopper that is in a coin-operated parking lot is stipulated, and thus, height data of obstacles held in advance may be used when the wheel stopper of the coin-operated parking lot is detected or when the coin-operated parking lot is known on the basis of map data.

The steering angle command value calculation unit 207 is a block in the camera control unit 106 and calculates a steering angle command value, in advance, on the basis of the parking path calculated by the parking path calculation unit 204 .

The speed/torque command value calculation unit 208 is a block in the camera control unit 106 and calculates a speed command value or/and an engine torque amount command value, obtained by predicting acceleration or deceleration of the vehicle in advance, preliminarily before starting assisted parking on the basis of presence or absence of the obstacle and step, each height of the obstacle and step, and each distance to the obstacle and step detected by the obstacle recognition unit 206 , the gradient of the road surface condition in the parking lot detected by the road surface shape recognition unit 205 , the steering angle command value calculated by the steering angle command value calculation unit 207 , and the parking path calculated by the parking path calculation unit 204 .

When the obstacle is detected, the speed command value or/and engine torque amount command value to be calculated are set to be high as compared to a case where no obstacle is detected.

In addition, the speed command value or/and engine torque amount command value are set on the basis of a gradient of the road surface shape. For example, the speed command value or/and engine torque amount command value are set to be high when the road surface shape of the parking lot is an uphill road, the speed command value or/and engine torque amount command value are set to be low when the road surface shape of the parking lot is a downhill road, or parking is performed in an idling stop state when the idling stop determination unit 213 determines that it is possible to move to a target position even in an engine stop state.

Incidentally, when the weight of the vehicle is m [kg], the height of the obstacle is h [m], the gravity acceleration is g [m/s 2 ], and the time is t [s], a speed command value v [m/s] and an engine torque amount command value F [N] to be calculated are calculated on the basis of the following calculation formulas.

v [ m/s ]=(2* g*h ) 1/2   (Formula 1.1)

F [ N ]= m *(2 *g*h ) 1/2 /Δt   (Formula 1.2)

The speed/torque command value addition unit 209 is a block in the camera control unit 106 and adds the speed command value or/and the engine torque amount command value calculated by the speed/torque command value calculation unit 208 .

The steering control unit 210 is a block in the steering control unit 107 , and controls steering using the steering angle calculated in advance by the steering angle command value calculation unit 207 , thereby performing automatic steering according to the parking path.

The vehicle speed control unit 211 is a block in the engine control unit 108 , and controls vehicle speed on the basis of the speed command value or/and engine torque amount command value calculated in advance by the speed/torque amount command value addition unit 209 , thereby automatically controlling vehicle speed according to the parking path.

The brake control unit 212 is a block in the brake control unit 109 , and controls brake on the basis of the speed command value or/and the engine torque amount command value calculated in advance by the speed/torque amount command value addition unit 209 , thereby controlling brake according to the parking path.

The idling stop determination unit 213 is a block in the camera control unit 106 and determines whether the idling stop is possible on the basis of the speed command value or/and the engine torque amount command value calculated in advance by the speed/torque amount command value addition unit 209 .

The user interface unit 214 is, for example, an on-board display equipped with a touch panel that combines the parking position recognized by the parking frame recognition unit 203 and the parking path calculated by the parking path calculation unit 204 with the images captured by the front and rear imaging units 201 and the left and right imaging units 202 , presents the combined images to the driver, and receives a parking assistance start instruction from the driver.

Hereinafter, the operation of the parking assist device 200 for a vehicle according to the first embodiment of the present invention will be described according to a flowchart of FIG. 4 .

First, when the driver activates the parking assist device 200 in order to start the assisted parking, the front and rear imaging units 201 and the left and right imaging units 202 image the front, rear, left, and right sides of the vehicle (step S 401 ).

Next, the parking frame recognition unit 203 recognizes the parking frame by analyzing front, rear, left and right images captured by the front and rear imaging units 201 and the left and right imaging units 202 (step S 402 ).

Next, the parking path calculation unit 204 calculates the parking path to the parking position on the basis of the distance and direction from the current vehicle stop position to the parking position recognized by the parking position recognition unit 203 (step S 403 ).

Next, the obstacle recognition unit 206 recognizes whether an obstacle and a step are present or absent in the parking path calculated by the parking path calculation unit 204 , and calculates each height of the obstacle and step and each distance to the obstacle and step in the case of presence. (step S 404 ).

Next, the road surface shape recognition unit 205 detects the gradient of the road surface condition in the parking lot (step S 405 ).

Next, the steering angle command value calculation unit 207 calculates the steering angle command value in advance on the basis of the parking path calculated by the parking path calculation unit 204 (step S 406 ).

Next, the speed/torque command value calculation unit 208 calculates a speed command value or/and an engine torque amount command value, obtained by predicting acceleration or deceleration of the vehicle in advance, preliminarily before starting assisted parking on the basis of presence or absence of the obstacle and step, each height of the obstacle and step, and each distance to the obstacle and step detected by the obstacle recognition unit 206 , the gradient of the road surface condition in the parking lot detected by the road surface shape recognition unit 205 , the steering angle command value calculated by the steering angle command value calculation unit 207 , and the parking path calculated by the parking path calculation unit 204 . After that, the speed/torque command value addition unit 209 adds the speed command value or/and engine torque amount command value calculated by the speed/torque command value calculation unit 208 (step S 407 ).

Next, the user interface unit 214 combines the parking position recognized by the parking frame recognition unit 203 and the parking path calculated by the parking path calculation unit 204 with the images captured by the front and rear imaging units 201 and the left and right imaging units 202 , and presents the combined images to the driver (step S 408 ).

Next, upon receiving the parking assistance start instruction from the driver, the user interface unit 214 instructs the parking assist device for a vehicle to start controlling steering and vehicle speed (step S 409 ).

Next, the steering control unit 210 , the vehicle speed control unit 211 , and the brake control unit 212 control steering using the steering angle calculated in advance by the steering angle command value calculation unit 107 , and control vehicle speed and brake on the basis of the speed command value or/and engine torque amount command value calculated in advance by the speed/torque amount command value calculation unit 108 (step S 410 ).

Next, when the vehicle has stopped during the assisted parking due to the step or the like that the vehicle hardly overcomes, the vehicle speed control unit 211 notifies the user interface unit 214 that the vehicle has stopped and the user interface unit 214 displays this notification to the driver. Then, the user interface unit 214 waits for the parking assistance start instruction from the driver, and confirms an intention of the driver regarding whether to overcome the step or the like (step S 411 ).

Next, upon receiving the parking assistance start instruction from the user interface unit 214 , the vehicle speed control unit 211 increases the speed command value or/and engine torque amount (step S 412 ).

Next, the host vehicle is moved to the target position and the vehicle is stopped (step S 413 ).

Hereinafter, a parking state according to the first embodiment of the present invention will be described with reference to a schematic view of FIG. 3 .

The vehicle advances from the parking assistance start position 300 to the switching position 301 , and is reversed to the parking assistance end position 302 , and then, the assisted parking is ended.

Steps S 401 to S 409 are sequentially executed at the parking assistance start position 300 , the assisted parking is started after setting the switching position 301 as the target position, and steps S 410 to S 412 are repeatedly executed to cause the vehicle to advance to the switching position 301 . Next, steps S 401 to S 408 are sequentially executed at the switching position 301 , the parking assistance end position 302 is set as the target position, then, steps S 410 to S 412 are repeatedly executed to cause the vehicle to be reversed to the parking assistance end position 302 , and the assisted parking is ended.

Hereinafter, a timing chart in a case where there is a step according to the first embodiment of the present invention will be described with reference to FIG. 5 . P 0 is a parking assistance start position, P 1 is a switching position, and P 2 is a parking assistance end position. In addition, it is assumed that there is a step between P 1 and P 2 in this timing chart.

The parking frame is recognized and the parking path is calculated at a point in time of P 1 at which the vehicle is stopped. Then, the speed command value or/and engine torque amount command value are calculated in advance on the basis of the parking path, the road surface shape, each height of the obstacle and step, and each distance to the obstacle and step. Meanwhile, there is the step in this case, and thus, the vehicle speed is controlled by setting the speed command value or/and engine torque amount command value to be high as compared to a case where there is no step. In addition, since the speed command value or/and engine torque amount command value are set to be high, the vehicle speed during the assisted parking also increases.

As described above, the speed command value or/and engine torque amount command value, obtained by predicting the acceleration or deceleration of the vehicle in advance on the basis of each height of the obstacle and step in the parking path, each distance to the obstacle and step, the gradient of the road surface condition, and the steering angle are calculated according to the above-described configuration. Then, it is possible to provide the parking assist device for a vehicle that controls the vehicle speed on the basis of the calculated speed command value or/and engine torque amount command value without decreasing or excessively increasing the speed or causing the vehicle to stop during assisted parking.

Second Example

Hereinafter, a parking assist device for a vehicle according to a second embodiment of the present invention will be described with reference to the drawings.

FIG. 6 is a block diagram illustrating the overall configuration of the parking assist device 200 for a vehicle according to the embodiment of the present invention. A different configuration from the first embodiment is that a lean fuel control unit 614 is further provided. The same content as that of the first embodiment will not be described.

The lean fuel 614 controls implementation of a lean fuel (lean burn).

The assisted parking in the second example is performed such that the own vehicle speed of the vehicle is controlled while applying a brake by a brake control unit 612 to make the own vehicle speed of the vehicle constant using a speed command value or/and an engine torque amount command value obtained by adding a certain amount to a speed command value or/and an engine torque amount command value calculated by a speed/torque command value calculation unit 608 in order to overcome an obstacle and a step. Then, the brake is controlled by the brake control unit 612 such that the vehicle speed is constant even immediately after overcoming the obstacle and step using each distance to the obstacle and step detected by an obstacle recognition unit 605 and a movement distance of the vehicle during the assisted parking.

In addition, fuel consumption deteriorates since the speed command value or/and engine torque amount command value added with the certain amount are used during the assisted parking. Thus, it is preferable to use the lean fuel (lean burn) by the lean fuel unit 614 during assisted parking.

As described above, it is possible to provide the parking assist device for a vehicle that maintains the own vehicle speed of the vehicle to be constant even immediately after overcoming the obstacle and step and does not collide with any other parked vehicle or the like according to the above-described configuration.

In addition, it is possible to maintain the fuel consumption by using the lean fuel during the assisted parking although the fuel consumption would normally deteriorate since the speed command value or/and engine torque amount command value added with the certain amount are used during the assisted parking.

101 front camera

102 left camera

103 right camera

104 rear camera

105 user interface unit

106 camera control unit

107 steering control unit

108 engine control unit

109 brake control unit

200 parking assist device for vehicle

201 front and rear imaging units

202 left and right imaging units

203 parking frame recognition unit

204 parking path calculation unit

205 road surface shape recognition unit

206 obstacle recognition unit

207 steering angle command value calculation unit

208 speed/torque command value calculation unit

209 speed/torque command value addition unit

210 steering control unit

211 vehicle speed control unit

212 brake control unit

213 idling stop determination unit

214 user interface unit

600 parking assist device for vehicle

601 front and rear imaging units

602 left and right imaging units

603 parking frame recognition unit

604 parking path calculation unit

605 road surface shape recognition unit

606 obstacle recognition unit

607 steering angle command value calculation unit

608 speed/torque command value calculation unit

609 speed/torque command value addition unit

610 steering control unit

611 vehicle speed control unit

612 brake control unit

613 idling stop determination unit

614 user interface unit

615 lean fuel unit