Parking assistance method and parking assistance device

Abstract

A processor 10 of a parking assistance device 1: calculates paths R for moving a target vehicle V1, which is an electric vehicle, from a reference location S1 based on the position of the target vehicle V1 to each of a plurality of parking spaces PL; calculates an estimated power consumption value for the target vehicle V1 when moving along each path R on the basis of curvature of one or a plurality of curves included in each path R; on the basis of the estimated power consumption value for each path R, selects, as a target parking space OPL, a parking space PL that can be reached by the path R; and moves the target vehicle V1 to the target parking space OPL.

Description

Parking assistance method and parking assistance apparatus

[0001] The present invention relates to a parking assistance method and a parking assistance apparatus.

[0002] There is known a technique of calculating predicted power consumption of a planned travel route from the current location of an autonomous driving vehicle to a drop-off point, and determining, as a vehicle to be dispatched, an autonomous driving vehicle having a larger predicted remaining power after traveling along the planned travel route (Patent Document 1).

[0003] Japanese Patent Laid-Open No.2022-44235

[0004] In the conventional art, road gradient and congestion information are used to predict predicted power consumption when traveling along a planned travel route. However, since the power consumption of parking control by an electric vehicle is greatly affected by the steering amount of a steering wheel, there is a problem that the conventional method cannot accurately determine the power consumption required for parking control of the electric vehicle.

[0005] A problem to be solved by the present invention is to appropriately evaluate the power consumption required for parking control of an electric vehicle.

[0006] The present invention solves the above problem by: respectively calculating tracks for moving a target vehicle, which is an electric vehicle, from a reference position based on the position of the target vehicle to a plurality of parking spaces; respectively calculating estimated power consumption values when the target vehicle travels along each track according to the curvature of one or more curves included in each track; selecting a target parking space based on the estimated power consumption values; and moving the target vehicle to the target parking space.

[0007] According to the present invention, the power consumption required for parking control of an electric vehicle can be appropriately evaluated.

[0008] FIG. 1 is a block diagram showing the configuration of a parking assistance system. FIG. 2 is a flowchart showing an example of a control procedure for parking assistance. FIG. 3 is a diagram showing an example of a track relative to a parking space. FIG. 4 is a diagram showing an example of candidate tracks in an energy saving mode. FIG. 5 is a diagram showing an example of a reference position proposed in the energy saving mode.

[0009] <First Embodiment> Embodiments of the present invention will be described below with reference to the drawings. Figure 1 is a block diagram showing the configuration of a parking assistance system 100 equipped with a parking assistance device 1. The parking assistance system 100 comprises a parking assistance device 1, a sensor 2, a position detection device 3, a navigation device 4, a vehicle actuator 5, and an input / output device 6. The parking assistance device 1 and each of the above devices are connected by a CAN (Controller Area Network) or other wired / wireless in-vehicle LAN, and exchange information with each other. Each device may be a device mounted on the vehicle, or it may be a portable terminal device that can be brought into the passenger compartment and connected to the in-vehicle LAN.

[0010] Sensor 2 acquires surrounding detection information regarding the parking space, including the target parking position where the target vehicle will park. Sensor 2 includes one or more cameras 21 positioned on the vehicle. Cameras 21 include image sensors equipped with image elements such as CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor), ultrasonic cameras, and infrared cameras, and capture images of the vehicle's surroundings in all directions. Sensor 2 includes a radar device 22 that detects (measures distance) the presence, position, and position changes of objects around the vehicle. The radar device 22 measures the distance and direction to an object by emitting electromagnetic waves toward the object and measuring the reflected waves. The radar device 22 includes laser radar, millimeter-wave radar, LiDAR (light detection and ranging) unit, ultrasonic radar, and sonar. Sensor 2 acquires the position of the parking space. Sensor 2 acquires information regarding the usage status of the parking space (empty / parked), the type of parking space (parallel parking space, tandem parking space), and the type of parking in the parking space (forward parking, reverse parking). Furthermore, sensor 2 can acquire this information from an external information provider via the communication device provided by parking assistance device 1. The information provider may be an external server or a server installed in the parking facility.

[0011] The position detection device 3 receives signals from the GNSS (Global Navigation Satellite System) 31 and detects the position of the target vehicle to be controlled. The position detection device 3 includes an IMU (Inertial Measurement Unit) 32. The IMU 32 is an inertial measurement device that detects three-dimensional inertial motion and detects the relative position information and attitude of the vehicle by measuring the tilt and acceleration of three axes. The position detection device 3 further detects the position of the vehicle using the detection information from the gyro sensor and / or the detection information from the vehicle speed sensor. The position detection device 3 detects the position (current position) of the moving vehicle over time and detects the position at each point in time. The position detection device 3 provides the detection results to the processor 10. The position detection device 3 may also be provided in the navigation device 4, which will be described later.

[0012] The navigation device 4 includes map information 41 and parking information 42. Map information 41 includes location information of parking facilities. Parking information 42 includes location information of predetermined locations such as the entrance to the parking facility and the entrance to each floor. Parking information 42 includes map information that identifies the location of each of the multiple parking spaces provided by the parking facility. Parking information 42 includes information on whether each parking space is available, the configuration of each parking space (parallel, diagonal parallel, tandem, etc.), and the method of parking in each parking space (forward parking, reverse parking, etc.).

[0013] The actuator 5 comprises a steering device 51, a drive device 52, and a braking device 53. The actuator 5, in accordance with parking control commands from the processor 10, causes the target vehicle to travel along a trajectory to a target parking space, either automatically or manually, and parks the target vehicle in the target parking space. The actuator 5 performs operation in accordance with control commands from the processor 10 and / or control commands from the driver's manual operation. The method of parking control by automatic driving is not limited, and methods known at the time of filing can be used.

[0014] The input / output device 6 includes an output function that presents information to the driver and an input function that receives information from the driver. In this embodiment, the input / output device 6 is a touch panel display 61 that displays the presented information on the screen and has a GUI (Graphical User Interface) function that accepts touch input or press input from the driver regarding the presented information. The processor 10 presents the estimated power consumption value for each parking space on the touch panel display 61 and accepts input of a target parking space selection command selected by the driver. The input / output device 6 may consist of a speaker with an output function and a microphone with an input function.

[0015] The parking assist device 1 performs parking control for a target vehicle that is an electric vehicle. The target vehicle controlled by the parking assist device 1 is an electric vehicle. An electric vehicle is a vehicle that uses electricity for power, and includes hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), battery electric vehicles (BEVs), hydrogen fuel cell electric vehicles (FCEVs), etc. The processor 10 includes a ROM (Read Only Memory) 12 that stores a program for performing parking control, a CPU (Central Processing Unit) 11 that executes the program stored in the ROM 12, and a RAM (Random Access Memory) 13 that functions as an accessible storage device. The processor 10 may be composed of one or more integrated circuits.

[0016] Figure 2 is a flowchart showing the control procedure for parking control. The processor 10 determines whether or not it is a situation in which parking control should be executed (S1). For example, if the processor 10 determines, using the detection information from the sensor 2, that the target vehicle is located within the parking facility, that the target vehicle is located near a parking space, that the target vehicle has stopped near a parking space, or that it has received a parking control execution command input by the driver using the input / output device 6, it determines that it is a situation in which parking control should be executed and proceeds to S2. The processor 10 acquires detection information about the surroundings of the target vehicle using the sensor 2 (S2). The detection information is continuously acquired by the sensor 2 at predetermined intervals. The processor 10 acquires the detection information necessary for executing parking control. Based on the detection information, the processor 10 identifies a parking space that is available among the parking spaces around the target vehicle and is not occupied by another vehicle (empty) (S3). The processor 10 determines a reference position as the starting position for parking control (S4). The reference position is defined based on the position of the target vehicle. The reference position may be the current position of the target vehicle, a position where the target vehicle is expected to pass in the future, a position where the target vehicle stopped to select a parking space, or a position where the target vehicle stopped to begin parking in a parking space. The reference position may be a predefined position designated by the parking assist device 1. When the target vehicle slows down or stops in the parking lot, the processor 10 infers that the driver wishes to use (park) a nearby parking space, and sets the stopping point of the target vehicle as the reference position. The processor 10 calculates one or more trajectories from the reference position based on the position of the target vehicle, which is an electric vehicle, to one or more parking spaces (S5). The trajectory is defined by the coordinate values ​​of each point on which the target vehicle moves. The processor 10 determines that a parking space close to the reference position is likely to be the target parking space, and calculates the trajectory sequentially starting from the parking space closest to the reference position.

[0017] Figure 3 shows an example of the surrounding conditions and trajectory of the target vehicle V1. In the example shown in Figure 3, parking control is performed within a parking facility equipped with multiple parking spaces PL1 to PL12 (hereinafter collectively referred to as PL), where the movable area is restricted by two walls W and pillars L. The target vehicle V1 enters the parking facility along the direction of arrow DR and stops at an arbitrary position. The position information of the target vehicle V1 is detected by the position detection device 3. The processor 10 uses the stopping position of the target vehicle V1 as the reference position S1 for parking control. The reference position S1 is not limited to the stopping position or current position of the target vehicle V1, but may be a predetermined position designated by the processor 10, such as the entrance or gate of the parking facility that the target vehicle V1 passes through. Based on the detection information acquired from the sensor 2, the processor 10 detects the position of an available parking space PL near the reference position S1. In the example shown in Figure 3, the processor 10 assumes that the parking space PL2, which is empty and closest to the reference position S1, is the first target parking space, and calculates one or more trajectories from the reference position S1 to the parking space PL2. Subsequently, it may target the parking space PL3, which is the next closest to the reference position S1, and calculate one or more trajectories from the reference position to the parking space PL2. The processor 10 sequentially calculates the trajectories to each available parking space PL in order of proximity from the reference position S1. The processor 10 may identify the location of each parking space PL based on the detection information from the sensor 2, or it may identify the location of the available parking space PL using parking information 42 obtained from a management system provided by the parking lot, such as a valet parking system.

[0018] As shown in Figure 3, when the target vehicle V1 decelerates or stops at the reference position S1, the processor 10 assumes that the closest available parking space PL2 to the reference position S1 is the target parking space OPL. The processor 10 calculates two trajectories RA and RB (hereinafter collectively referred to as R) when moving the target vehicle V1 to parking space PL2. The number of trajectories R calculated for a single parking space PL is not limited. The calculated trajectory RA includes trajectory RA1 from the reference position S1 to the turning position QA1, trajectory RA2 reversing from position QA1 to position QA2, trajectory RA3 from position QA2 to position QA3, and trajectory RA4 reversing from position QA3 to parking space PL2. The trajectory RB includes trajectory RB1 from the reference position S1 to position QB1, and trajectory RB2 reversing from position QB1 to parking space PL2.

[0019] The proposed order of trajectories RA and RB can be arbitrarily defined. As shown in Figure 3, the first turning point QA1 of trajectory RA is closer to the reference position S1 than the turning point QB1 of trajectory RB. Trajectory RA has 2 turning points, which is more than the 1 turning point of trajectory RB. One may prioritize proposing trajectory RA, which has a smaller movement range from the reference position S1 (the turning point is closer to the reference position S1), or trajectory RB, which has fewer turning points, or trajectory R, ​​which has a lower estimated power consumption. The driver can compare the proposed trajectory R, ​​the surrounding conditions, and the estimated power consumption and select the trajectory R in which to actually park. For example, if there is ample space around the reference position S1 and it is not a problem to move a large distance from the reference position S1 to the turning point, the user can select trajectory R, ​​which has a lower estimated power consumption even if the movement distance is large.

[0020] The processor 10 calculates one or more trajectories R for parking spaces PL3, PL8, PL9, PL11, and PL12. The positions of parking spaces PL3, PL8, PL9, PL11, and PL12 may be obtained by sensor 2 or from the parking management system. The information shown in Figure 3 is displayed on the display 61. In Figure 3, two trajectories R are shown as examples for the available parking space PL2, which is closest to the current position of the target vehicle V1, but one or more trajectories R for parking spaces PL3, PL8, PL9, PL11, and PL12, which are calculated simultaneously or sequentially, can also be displayed on the display 61 simultaneously or sequentially. The processor 10 calculates the trajectories R under predetermined conditions, although it is not particularly limited. The processor 10 calculates the trajectories R to each parking space PL under predetermined conditions, such as the number of turns being less than a predetermined number, the travel distance being less than a predetermined distance, or the time required for parking control being less than a predetermined time. Incidentally, if the energy-saving mode described in the second embodiment is selected, the processor 10 relaxes the predetermined conditions and calculates a trajectory R with a low estimated power consumption even if the travel distance is greater than or equal to a predetermined distance, or the time required for parking control is greater than or equal to a predetermined time.

[0021] Figure 3 shows an example of a parallel parking arrangement in a series of parking spaces PL, but the arrangement of parking spaces PL is not limited to this; it may also be a diagonal parallel parking arrangement or a tandem parking arrangement. Furthermore, the parking arrangement in a parking space PL may be forward parking or reverse parking. The arrangement of parking spaces PL and / or the parking arrangement may be stored in the parking information 42 in association with each parking space PL. The processor 10 may read the arrangement of parking spaces PL and / or the parking arrangement from the parking information 42 based on position information, or it may determine the arrangement of parking spaces PL and / or the parking arrangement based on detection information from the sensor 2. The processor 10 calculates the trajectory R to move the target vehicle V1 from the reference position S1 to the target parking space OPL, taking into account the arrangement of parking spaces PL and / or the parking arrangement.

[0022] The processor 10 calculates an estimated power consumption value for each track R when the target vehicle V1, which is an electric vehicle, moves along each track R, based on the curvature of one or more curves included in each track R (S6). The estimated power consumption value in this embodiment is an index value indicating the amount of electricity consumed when the target vehicle V1 moves along the track R, which includes each curve of each curvature, and parks in the target parking space PL. Although not particularly limited, the estimated power consumption value is an estimate of the amount of electricity consumed by the target vehicle when moving to the parking space along a track determined according to the maximum steering angle and wheelbase of each target vehicle. The estimated power consumption value can be calculated based on the curvature of the track curves, or the amount of steering when passing through the track curves. Alternatively, the estimated power consumption value may be based on curvature information and / or steering amount information. The curvature information is the maximum value of the curvature of the curves included in the track R, or the integral value of each curvature of each curve included in the track R. If the maximum value or integral value of the curvature of the curves of the track R is large, the amount of electricity consumed by the target vehicle when parking along the track R will also increase. The larger the maximum curvature of the curves included in track R, or the larger the integral value of each curvature, the higher the estimated power consumption, and the higher the estimated power consumption, the greater the power consumption required to travel along track R. The steering amount information is the maximum steering amount when passing through the curves included in track R, or the integral value of the steering amount when passing through each curve included in track R. If the maximum steering amount or the integral value of the steering amount when passing through the curves of track R is large, the amount of power consumed by the vehicle when parking along track R will also increase. The larger the maximum steering amount or the larger the integral value of each steering amount when passing through the curves included in track R, the higher the estimated power consumption, and the higher the estimated power consumption, the greater the power consumption required to travel along track R. In this embodiment, the estimated power consumption is information indicating the magnitude of the power consumption consumed by parking. The estimated power consumption may be the power consumption consumed by parking itself, information indicating the level or ranking of the power consumption magnitude, or a color or mark (graphic) indicating the level of power consumption magnitude. By calculating estimated power consumption, it is possible to quantitatively determine how much power each parking space / parking track consumes, and to what extent and how energy-efficient each one is.In this embodiment, an estimated power consumption value is calculated based on the curvature of the curve of the track R or the amount of steering when passing through the curve, and a target parking space is selected based on the estimated power consumption value, thereby reducing energy consumption due to parking.

[0023] The track R includes both straight and curved sections. In this embodiment, we focus on the power consumption due to steering in accordance with the curvature of the curved section of the track R and calculate an estimated power consumption. When moving along the curve of the track R, power is consumed according to the steering force that rotates the steering wheel and power according to the steering force that holds the steering wheel in the rotated position. If the curvature of the curve included in the track R is large, the amount of steering required for the target vehicle V1 when moving along that curve will be large. According to the simulation, the proportion of the total power consumption when moving the target vehicle V1 along the parking track R which includes curves and straight sections was the power consumption for traveling along the curved section which requires steering, which was larger than the power consumption for traveling along the straight section which does not require steering. Similarly, according to the simulation, the power consumption for traveling a unit distance along the curved section was larger than the power consumption for traveling a unit distance along the straight section. In addition, according to the simulation, the amount of power consumed when traveling along a curved section with high curvature was larger than the amount of power consumed when traveling along a curved section with low curvature. In this embodiment, we focus on the amount of power consumed by steering the steering mechanism operating in the curved portion of track R, and calculate an estimated power consumption value corresponding to the amount of power consumed for parking control of the electric vehicle based on the curvature of the curved portion where steering is required. The estimated power consumption value is calculated based on the curvature of the curve of track R. The estimated power consumption value is calculated based on the amount of steering when passing through the curve of track R.

[0024] Depending on the track R, there may be multiple curved sections. In this case, it is necessary to consider the power consumption generated in each of the multiple curved sections. Also, a curved section is not composed of only one point, but is composed of multiple consecutive points. For this reason, in this embodiment, one or more of the following can be defined as "the curvature of one or more curves included in each track R": the maximum value of the curvature of the curve included in the track R, the curvature of a representative point such as the starting point of the curve among the points that make up the curve, the integral value of the curvature of the curve included in the track R from the reference position to the parking space, and the integral value of the amount of change in the curvature of the curve included in the track R from the reference position to the parking space. The curvature may also be obtained by adding the calculation results of each method. The object of integration is the curvature at each point set according to the unit distance / unit time of the track R in the curved sections of the track R other than straight lines (where the curvature is not zero). The object of integration may be the curvature at each point where the curvature of the track R changes, or the amount of change in curvature at each point. The object of integration may be the curvature of curves with a predetermined curvature or greater. The processor 10 calculates an estimated power consumption value for each track R when the target vehicle V1 moves along each track R, based on the curvature of the curves included in each track R. The estimated power consumption value may be the maximum value of the curvature of the curves included in the track R, or the integral value of the curvature of each curve included in the track R. If the curvature is high, the estimated power consumption value will be calculated to be high, and if the estimated power consumption value is high, the power consumption used for parking control will be predicted to be high. According to this embodiment, when moving along the track R from the reference position S1 to the parking space PL, an appropriate estimated power consumption value that takes into account the power consumption when moving along the curve can be calculated based on the curvature of each curve included in the track R. Since the estimated power consumption value can be calculated using a geometric calculation method based on curvature, the power consumption of each track R for each parking space PL can be evaluated while suppressing the computational load. Note that the estimated power consumption value is a value that indicates the magnitude of the amount of power consumed when the target vehicle V1 moves along the track R from the reference position to the parking space, and is different from the amount of power actually consumed in parking control itself. The estimated power consumption value is a unique index established by focusing on the amount of power consumed when moving along a curve in parking control.Thus, in this embodiment, the curvature of the track in parking control is considered, and the estimated power consumption is calculated based on the curvature of one or more curves included in the track. The greater the curvature of the track, the higher the estimated power consumption. As a result, when the target vehicle V1 moves along the track R from the reference position S1 to the parking space PL, the estimated power consumption can be calculated easily and with high accuracy based on the curvature of each curve in the track R.

[0025] When the target vehicle V1 passes through each curve of each curvature, the steering speed and the amount of change in it change according to the set speed (vehicle speed) set for passing through each curve. When the steering speed and the amount of change in it increase, the power consumption of the target vehicle V1 tends to increase. For this reason, it is necessary to consider not only the curvature but also the power consumption caused by the steering speed and / or the amount of change in steering speed according to the set speed when passing through the curve. In this embodiment, based on the curvature of each curve and the set speed set according to each curvature, an estimated power consumption value is calculated according to the increase in power consumption when the target vehicle V1 moves along each track. The increase in power consumption is the increase in power consumption compared to the power consumption when driving at the reference speed set in the parking control. Specifically, the processor 10 obtains the set speed at each curve set according to each curvature and calculates a correction value according to the increase in power consumption when the target vehicle V1 moves along the track R including each curve at the set speed. Then, the processor 10 adds the calculated correction value to the power consumption estimate based on the curve curvature mentioned above to calculate the final power consumption estimate. The set speed when passing through each curve can be obtained from the parking plan formulated in the parking control. According to this embodiment, in addition to the curvature of the curve included in the trajectory R, ​​the power consumed at a set speed set according to the curvature is also taken into consideration. Therefore, the power consumption based on the steering speed and / or the change in steering speed when passing through the curve at the actual set speed is not ignored and is included in the calculation, and the estimated power consumption when moving along the trajectory R can be calculated with high accuracy.

[0026] The processor 10 calculates the steering amount of the target vehicle V1 as it moves along each curve, based on the curvature of one or more curves included in the trajectory R, ​​and calculates an estimated power consumption for each trajectory R based on the steering amount. The processor 10 calculates the steering amount required to make the target vehicle V1 follow the trajectory R. The processor 10 obtains a predefined set speed in parking control and calculates the steering force and steering hold force corresponding to the steering amount when moving along each curve of the trajectory R at the set speed. Based on the steering force and steering hold force corresponding to the steering amount of the target vehicle V1 as it moves along each curve, the processor 10 calculates an estimated power consumption for each trajectory R based on the steering amount.

[0027] As mentioned above, depending on the trajectory R, ​​there may be multiple curved sections. In this case, it is necessary to consider the power consumption generated in each of the multiple curved sections. Also, a curved section is not composed of only one point, but is composed of multiple consecutive points. For this reason, in this embodiment, the steering amount can be one or more of the following: the maximum value of the steering amount steered to move along the trajectory R, ​​the integral value of the steering amount steered to move along the trajectory R from the reference position to the parking space, and the integral value of the steering change amount steered to move along the trajectory R from the reference position to the parking space. The steering amount may also be obtained by adding the calculation results of each method. The processor 10 may obtain the steering amount from the parking plan formulated in the parking control. The object to be integrated is the steering amount at each point set according to the unit distance / unit time of the trajectory R in the curved section where driving with a steering angle that is not zero is performed. The object to be integrated may be the steering amount at each point where the steering amount changes when driving along the trajectory R, ​​or it may be the steering change amount at each point. The object to be integrated may be a steering amount greater than or equal to a predetermined steering amount. The processor 10 calculates an estimated power consumption value for each track R when the target vehicle V1 moves along each track R based on the steering amount when traveling along each track R. The estimated power consumption value may be the maximum steering amount when passing through a curve included in the track R, or the integral value of each steering amount when passing through each curve included in the track R. If the steering amount is high, the estimated power consumption value will be calculated to be high, and if the estimated power consumption value is high, the power consumption will be predicted to be high. According to this embodiment, the amount of steering operation when moving along a curve is calculated based on the curvature of each curve included in the track R, and an appropriate estimated power consumption value that takes into account the power consumption due to that steering operation can be calculated. Since the estimated power consumption value can be calculated using a geometric calculation method based on curvature, the power consumption of each track R for each parking space PL can be evaluated while suppressing the computational load. Note that the estimated power consumption value is a value that indicates the magnitude of the amount of power consumed in order for the target vehicle V1 to move along the track R from the reference position to the parking space, and is different from the amount of power actually consumed in parking control.Thus, in this embodiment, we focus on the amount of steering input in parking control and calculate the estimated power consumption according to the amount of steering input. The higher the amount of steering input, the higher the estimated power consumption. As a result, when moving along the trajectory R from the reference position S1 to the parking space PL, the estimated power consumption can be calculated with high accuracy using a simple method based on the amount of steering input at each curve of the trajectory R.

[0028] In this embodiment, not only the amount of steering input but also the power consumption resulting from the steering speed and / or the change in steering speed, according to the set speed when passing through a curve, is considered. Based on each curvature and the set speed when passing through the curve of that curvature, the processor 10 calculates the amount of steering input and the steering speed and / or the change in steering speed when the target vehicle V1 moves through each curve at the set speed. Based on the amount of steering input and the steering speed and / or the change in steering speed, the processor 10 calculates an estimated power consumption corresponding to the increase in power consumption when the target vehicle V1 moves along each track R. The increase in power consumption is the increase in power consumption compared to the power consumption when driving at the reference speed set in parking control. Specifically, the processor 10 obtains the set speed at each curve set according to each curvature and calculates a correction value corresponding to the increase in power consumption when the target vehicle V1 moves along the track R including each curve at the set speed, based on the steering speed and / or the change in steering speed when moving through each curve at the set speed. The processor 10 then adds the calculated correction value to the power consumption estimate based on the steering amount described above to calculate the final power consumption estimate. The set speed when passing through each curve and the steering speed and / or change in steering speed when moving through each curve at that set speed can be obtained from the parking plan formulated in the parking control. According to this embodiment, in addition to the steering amount, the steering speed and / or change in steering speed when passing through a curve at a set speed set according to the curvature is taken into consideration, so the power consumption based on the steering speed and / or change in steering speed when passing through a curve at the actual set speed is not ignored and the power consumption estimate when moving along the trajectory R can be calculated with high accuracy.

[0029] The processor 10 calculates the vehicle speed when the target vehicle V1 moves along the curve included in the track R from the reference position S1 to the parking space PL. If the vehicle speed is less than a predetermined speed, the estimated power consumption is calculated to be higher than when the vehicle speed is above the predetermined speed. When the target vehicle V1 moves along the curve at an extremely low speed, it becomes a stationary steering operation, and the power consumption for steering tends to be high. If the amount of movement when moving along the curve at an extremely low speed is large, the estimated power consumption will be higher than when the amount of movement is small. In this embodiment, the amount of movement is the number of times the target vehicle V1 moves along the curve of track R at a speed below a predetermined speed, or the time or distance when moving along the curve of track R at a speed below a predetermined speed. In this embodiment, if the amount of movement when the target vehicle V1 moves along the curve of track R at a speed below a predetermined speed is large, the estimated power consumption is calculated to be higher than when the amount of movement is small. The predetermined speed may be defined as 0.5 km / h. When the steering is operated when the vehicle speed of the target vehicle V1 is at an extremely low speed of 0.5 km / h or less, or when it is stopped, the power consumption tends to increase compared to other cases. In this embodiment, when the vehicle speed is below a predetermined speed while steering along the curve of track R, the estimated power consumption is judged to be higher than in other cases. This allows for the calculation of the estimated power consumption with high accuracy, taking into account the increased power consumption when the vehicle speed is extremely low along each curve of track R.

[0030] The processor 10 counts the number of turns along the trajectory R from the reference position S1 to the parking space PL, and calculates a higher estimated power consumption when there are many turns than when there are few. In parking control at the turning points, the processor 10 decelerates, stops, steers, reverses the direction of travel, starts, and accelerates the target vehicle V1. At the turning points, steering / steering occurs in the extremely low speed range during stopping and starting. All of these operations consume relatively large amounts of power. Therefore, the more turns there are, the higher the power consumption tends to be compared to when there are fewer turns. In this embodiment, the more turns there are, the higher the estimated power consumption is calculated. The number of turns along the trajectory R may be obtained from the planned parking control command. This allows for the calculation of an estimated power consumption with high accuracy, taking into account the increased power consumption at the turning points included in the trajectory R.

[0031] An example of a specific method for calculating the estimated power consumption is described below. [1] First estimated power consumption: The processor 10 calculates the first estimated power consumption by multiplying the curvature of the curves included in the trajectory R by a predefined first estimated torque conversion coefficient. When the target vehicle V1 is made to perform parking control along the trajectory R, ​​the steering is operated by a steering amount corresponding to the curvature of each curve as it moves along each curve of the trajectory R, ​​and power is consumed according to the steering amount. There is a predetermined relationship between the curvature of each curve, the steering amount, and the power consumption. The first estimated torque conversion coefficient is experimentally defined based on the power consumption when the steering is operated by a steering amount corresponding to each curvature as the target vehicle V1 moves along each curve of each curvature, and is stored in the ROM 12. The first estimated torque conversion coefficient may be defined for each set vehicle speed. The first estimated torque conversion coefficient may include a first corrected torque conversion coefficient for calculating a correction value, which is the power consumption (increase) that increases with changes in the set speed. The processor 10 calculates the power consumption at each point on each curve by multiplying each curvature at each point on each curve by a first estimated torque conversion coefficient, and then calculates a first estimated power consumption by integrating these values ​​from the start to the end of the track R. Alternatively, the first estimated power consumption may be calculated by multiplying the maximum curvature or the curvature at the starting point by the first estimated torque conversion coefficient. Alternatively, the first estimated torque conversion coefficient may be defined based on the change in power consumption with respect to the change in curvature, and the first estimated power consumption may be calculated by multiplying the change in curvature by the first estimated torque conversion coefficient. Furthermore, power consumption when moving along a curve with a curvature greater than or equal to a predetermined curvature tends to be greater than power consumption when moving along a curve with a curvature less than the predetermined curvature. The first estimated power consumption may be calculated using only the curves in the track R whose curvature is greater than or equal to the predetermined value. The predetermined value of curvature is not particularly limited, but can be defined according to the turning curvature of each target vehicle V1 calculated based on the vehicle's unique wheelbase and maximum steering angle. It is preferable to calculate the predetermined value of curvature individually, taking into account the vehicle design and performance of each target vehicle V1. For example, if we consider a target vehicle V1 with a minimum turning radius of 5m, the predetermined value of the curvature can be set to 0.11 to 0.14 rad / m, preferably 0.125 rad / m.[2] Second estimated power consumption: The processor 10 calculates a second estimated power consumption by multiplying the steering amount when moving along the curves included in the trajectory R by a predefined second estimated torque conversion coefficient. Similar to the explanation for the first estimated power consumption, when the steering is turned to pass through each curve of each curvature, power is consumed according to the amount of steering. There is a predetermined relationship between the amount of steering and power consumption when traveling along each curve. The second estimated torque conversion coefficient is experimentally defined based on the power consumption when the steering is turned with a steering amount corresponding to each curvature when the target vehicle V1 moves along each curve of each curvature, and is stored in the ROM 12. The second estimated torque conversion coefficient may be defined for each set vehicle speed. The second estimated torque conversion coefficient may include a second corrected torque conversion coefficient for calculating a correction value which is the power consumption (increase) that increases with the change in set speed. The processor 10 obtains the power consumption at each point by multiplying the steering amount when moving at each point on each curve by the second estimated torque conversion coefficient, and calculates a second estimated power consumption by integrating these from the start to the end of the trajectory R. The second estimated power consumption may be calculated by multiplying the maximum steering amount or the curvature of the steering start point by a second estimated torque conversion coefficient. Alternatively, the second estimated torque conversion coefficient may be defined based on the change in power consumption with respect to the steering change, and the second estimated power consumption may be calculated by multiplying the steering change by the second estimated torque conversion coefficient. Furthermore, power consumption when the steering amount is greater than or equal to a predetermined steering amount tends to be greater than power consumption when the steering amount is less than the predetermined steering amount. In this embodiment, the second estimated power consumption is calculated using only the steering amount that is greater than or equal to a predetermined steering amount (for example, 70% or more of the steerable steering amount) among the steering amounts steered to move along the trajectory R. For example, if the steerable steering amount is 500°, the second estimated power consumption may be calculated using only the steering amount of 350° or more, which is 70% of the maximum steering amount. [3] Third estimated power consumption: The processor 10 calculates a third estimated power consumption for when the vehicle V1 moves along the curve at a low speed by multiplying the amount of movement of the vehicle V1 at a speed less than a predetermined speed by a predefined third estimated torque conversion coefficient.The amount of movement when moving along a curve at a speed below a predetermined speed is the number of times the target vehicle V1 moves along the curve of track R at a speed below a predetermined speed, or the time or distance spent moving along the curve of track R at a speed below a predetermined speed. The third estimated torque conversion coefficient is obtained by acquiring the energy consumed when the target vehicle V1 moves along curves of each curvature at a speed below a predetermined speed, is experimentally defined according to the curvature, and is stored in ROM 12. The third estimated torque conversion coefficient may be defined according to the vehicle performance and vehicle specifications (vehicle weight). The processor 10 multiplies the amount of movement when the target vehicle V1 moves along a curve at a speed below a predetermined speed by the third estimated torque conversion coefficient to calculate the third estimated power consumption consumed to steer at extremely low speeds. [4] Fourth estimated power consumption: The processor 10 multiplies the number of turns when moving along track R from the reference position S1 to the parking space PL by a predefined fourth estimated torque conversion coefficient to calculate the fourth estimated power consumption consumed each time a turnaround operation is performed. The fourth estimated torque conversion factor is experimentally defined based on the energy consumption required for the target vehicle V1 to operate forward and backward in a region including a single turning point, and is stored in ROM 12. The fourth estimated torque conversion factor may also be defined according to the vehicle performance. The processor 10 calculates the fourth estimated power consumption value by multiplying the fourth estimated torque conversion factor by the number of turning points when moving along the trajectory R.

[0032] The first to fourth estimated torque conversion coefficients and the first / second corrected torque conversion coefficients described above are predefined according to the vehicle performance and stored in ROM 12. The estimated power consumption may be calculated by adding the third and / or fourth estimated power consumption to the first or second estimated power consumption. The processor 10 may define a coefficient k3 (1 > k3 ≥ 0) for the third estimated power consumption and calculate the estimated power consumption by adding the value obtained by multiplying the third estimated power consumption by the coefficient k3 to the first or second estimated power consumption. The processor 10 may define a coefficient k4 (1 > k4 ≥ 0) for the fourth estimated power consumption and calculate the estimated power consumption by adding the value obtained by multiplying the fourth estimated power consumption by the coefficient k4 to the first or second estimated power consumption. The coefficient k3 defined for the third estimated power consumption is set such that the first or second estimated power consumption is larger when the amount of movement of the target vehicle V1 moving along the curve of track R at a speed below a predetermined speed is large than when those values ​​are low. The coefficient k4 defined for the fourth power consumption estimate is set so that the first or second power consumption estimate is larger when the number of turns along the trajectory R is high compared to when the number of turns is low. Both the third and fourth power consumption estimates can be reflected in the first or second power consumption estimate. By assigning weights to the coefficient k3 or coefficient k4, the third and fourth power consumption estimates can be reflected in the first or second power consumption estimate according to the arbitrary weights. This makes it possible to calculate power consumption estimates based on the curvature of each curve included in the parking control trajectory R, ​​as well as power consumption estimates that take into account power consumption when moving slowly along curves and power consumption when making turns.

[0033] Once the estimated power consumption is calculated (S6), the process proceeds to S7. The processor 10 selects a trajectory R based on the estimated power consumption calculated for each trajectory R, ​​and selects the parking space reachable by that trajectory R as the target parking space OPL (S7). The processor 10 selects the trajectory R with the lowest calculated estimated power consumption and selects the target parking space OPL reachable by that trajectory R. The processor 10 calculates the trajectory R to the selected target parking space OPL (S8), and uses the actuator 5 to move the target vehicle V1 to the target parking space OPL (S9). The method for moving the target vehicle V1 from its current position to the target parking space OPL can be any method known at the time of filing. The parking control in this embodiment includes a parking guide mode that presents a parking method to the driver and assists the driver in parking by manual driving, a parking assistance mode that automatically controls only the steering operation while the driver operates the accelerator / brake, and an automatic parking mode that automatically controls the steering and accelerator / brake. The parking control of this embodiment includes systems in which only steering control is performed automatically, systems in which only accelerator drive control and brake braking control are performed automatically, and systems in which both steering control, accelerator drive control, and brake braking control are performed automatically. The driver's operational burden is reduced by performing at least steering or accelerator / brake steering automatically.

[0034] According to this embodiment, the estimated power consumption for parking control is appropriately calculated, and the trajectory R is selected based on the estimated power consumption, thereby suppressing power consumption for parking control. This suppresses the reduction in the driving range that the target vehicle V1 can travel after exiting the parking space. Furthermore, in the case of a target vehicle V1 equipped with a configuration that compensates for power shortages by generating power by means such as an engine, the generation of noise associated with engine operation can be suppressed. Incidentally, when parking control is performed automatically under the control of the parking assist device 1 without requiring the driver to steer the steering wheel, the steering speed may be 800 (rad / sec) or more. When driving (parking) is performed at such a high steering speed, the power consumption increases, reducing the amount of power stored in the battery. When parking control is performed by automatic steering control, it is particularly preferable to consider the amount of power consumption due to parking control and to perform parking control that reduces power consumption. In this embodiment, at least when steering is performed by automatic control, the trajectory R and target parking space with low power consumption can be selected based on the estimated power consumption calculated from the curvature of the curves included in each trajectory R. Therefore, it is possible to reduce power consumption in automatic parking control systems, which tend to consume more power.

[0035] Alternatively, as shown in the processing of SUB in Figure 2, power consumption estimates may be presented, and parking control may be performed according to the driver's selection. After calculating the power consumption estimates (S6), the processor 10 presents information on the power consumption estimates for each trajectory R on the display 61 (S11). Preferably, the power consumption estimates for each trajectory R are displayed in association with each parking space PL. The power consumption estimate information includes the amount of electricity consumed for steering operation when parking on each trajectory R (kWh), a level indicating the relative height of the power consumption estimate, or a level indicating the contribution to energy-saving operation. Based on the presented power consumption estimates, the driver can determine the amount of power saving for each trajectory R and select one trajectory R from an energy-saving perspective. The processor 10 displays the power consumption estimate information E2 when moving along the trajectory R to the parking space PL2 in association with the display position of the available parking space PL2. As an example, as shown in Figure 3, information E3, E8, E9, E11, and E12 (hereinafter also referred to as information E) may be displayed at each of the display positions of the available parking spaces PL3, PL8, PL9, PL11, and PL12. Information E3, E8, E9, E11, and E12 may also be displayed in callout display areas corresponding to each of the display positions of the parking spaces PL3, PL8, PL9, PL11, and PL12. As representative values ​​of the estimated power consumption of each parking space PL, the minimum, maximum, or average value of the estimated power consumption of the trajectory R leading to each parking space PL may be presented as information E. In information E2, E3, E8, E9, E11, and E12, the estimated power consumption is shown in correspondence with the trajectory R. The estimated power consumption of each trajectory R is displayed in a different color, different font, or different symbol so as to be identifiable. Each trajectory R is displayed in a different color, different thickness, or different form (dashed line, double line). The processor 10 highlights parking space PLs with low estimated power consumption more than parking space PLs with high estimated power consumption. For example, parking space PLs with low estimated power consumption may be shown with an advancing color and / or a thick border, while parking space PLs with high estimated power consumption may be shown with a receding color and / or a thin border. If multiple trajectories R are calculated for each parking space PL, the processor 10 highlights the trajectory R with the low estimated power consumption more than the trajectory R with the high estimated power consumption.Once a target parking space OPL is selected, the processor 10 may display estimated power consumption values ​​for multiple trajectories R leading to that target parking space OPL and accept the selection of a trajectory R. This allows the target vehicle V1 to be moved along a low-power trajectory R to a parking space PL with a low power consumption estimate, thereby executing parking control.

[0036] The processor 10 receives a selection command from the driver to select a parking space PL and a trajectory R (S12). Then, it moves the target vehicle V1, which is the target of control, to the selected target parking space OPL along the selected trajectory R (S9). In this way, by presenting the estimated power consumption of each trajectory R on the display 61 in association with the parking space PL, the driver can compare and consider the degree of power consumption reduction according to the estimated power consumption and the convenience of parking (such as the distance to the turning point). By receiving the driver's selection command based on the estimated power consumption, parking control can be performed with the power consumption desired by the driver. Steps S11 and S12 can be skipped.

[0037] <Second Embodiment> In this embodiment, an energy-saving mode is proposed that performs parking control with even lower power consumption. The basic processing is the same, so all of the description of the first embodiment is incorporated here. This embodiment includes a normal mode and an energy-saving mode. The processor 10 presents an energy-saving mode selection switch on the display 61 using a GUI, and when the switch is touched or pressed by the driver, it supports parking control with further reduced power consumption. The second estimated power consumption of the second trajectory of the second parking control proposed in the energy-saving mode is lower than the first estimated power consumption of the first trajectory of the first parking control proposed in the normal mode. In other words, the second amount of energy consumed in the second parking control is lower than the first amount of energy consumed in the first parking control. The first and second estimated power consumption values ​​are calculated under a predefined standard parking environment. The standard parking environment is defined based on the width of the path that the target vehicle V1 can move and the width of the turning space (length and width). In the normal mode, a first trajectory is calculated that satisfies predetermined conditions such as the travel distance being less than a predetermined distance or the time required for parking control being less than a predetermined time. On the other hand, in energy-saving mode, even if the above predetermined conditions are not met, a second trajectory with a lower estimated power consumption is calculated. In energy-saving mode, even if the parking distance or time exceeds the predetermined conditions, parking control is performed with priority given to reducing power consumption.

[0038] Figure 4 shows the trajectory RC calculated in energy-saving mode. Referring to Figure 2, when parking control is performed (YES in S1), if energy-saving mode is selected, the processor 10 acquires detection information using sensor 2 (S2). Based on the detection information, the processor 10 detects available parking spaces PL2, PL3, PL8, PL9, PL11, and PL12 (S3), and determines the first reference position S1 based on the position of the target vehicle V1 (S4). The processor 10 calculates multiple trajectories R from the reference position S1 to each parking space PL2 (S5). Trajectories RA and RB are the trajectories R calculated in normal mode (see Figure 3). In energy-saving mode, in addition to the trajectories RA and RB calculated in normal mode, the processor calculates a trajectory RC where the turning point is relatively farther from the reference position S1 than trajectories RA and RB. As shown in Figure 4, the second distance (distance along the Y direction in the figure) between the turning point QC1 of orbit RC and the reference position S1 along the direction of travel DR, calculated in energy-saving mode, is longer than the first distance (distance along the Y direction in the figure) between the turning point QB1 of orbit RB and the reference position S1, calculated in normal mode. The predetermined distance under the predetermined conditions mentioned above is set to be greater than or equal to the first distance and less than the second distance. Orbit RC, where the turning point QC1 is greater than or equal to the predetermined distance from the reference position S1, is not considered a candidate for orbit R in normal mode, but is considered a candidate for orbit R in energy-saving mode. When energy-saving mode is selected, the processor 10 calculates three orbits RA, RB, and RC as candidates for orbit R and their respective estimated power consumption values ​​(S6), as shown in Figure 4, and presents them on the display 61 (S11). By obtaining a user selection command (S12) to select a track R and target parking space PL with reduced power consumption from a range of options including tracks RA, RB, and RC, the target vehicle V1 can be moved to the target parking space using power-saving parking control (S9).

[0039] Furthermore, in order to calculate a trajectory R with a lower estimated power consumption, a second reference position S2 may be set by changing the lateral position of the first reference position S1. The processor 10 calculates the proposed reference position of the proposed trajectory that reduces the estimated power consumption of the trajectory R leading to the parking space PL as the second reference position and presents it on the display 61. As shown in Figure 5, the target vehicle V1 enters the parking lot and moves along the arrow DR at the first reference position S1. The lateral position (position in the vehicle width direction) of the target vehicle V1 is approximately the center of the parking lot's roadway. As the target vehicle V1 moves along the arrow DR, the processor 10 detects the available parking spaces PL8, PL9, PL11, and PL12 and sets the parking space PL8 closest to the target vehicle V1 as the target parking space OPL. The processor 10 calculates the proposed reference position, which is the starting point of the proposed trajectory RD that reduces the estimated power consumption of the trajectory R leading to the target parking space OPL (PL8), as the second reference position S2 and presents it on the display 61 of the input / output device 6.

[0040] As shown in Figure 5, the lateral position b of the second reference position S2, which is along the X-axis direction in the figure and approximately perpendicular to the direction of travel DR (Y-axis direction in the figure) of the target vehicle V1, is different from the lateral position a of the first reference position S1. The lateral position b of the second reference position S2 is shifted by a distance d in the -x direction in the figure from the lateral position a of the first reference position S1. The lateral position is the position along the width direction of the target vehicle V1 (X-coordinate value in the figure). When moving from the proposed second reference position S2 to the parking space PL8 along the track RD, the target vehicle V1 moves from the second reference position S2 to point QD1, makes a U-turn, and moves from point QD1 to the parking space PL8. According to the track RD, the target vehicle V1 can move to the target parking space PL8 in a single U-turn. On the other hand, suppose the target vehicle V1 moves forward along the direction of travel DR from the first reference position S1 while maintaining lateral position a, and moves to the first reference position S1', where the vertical position c in the Y-axis direction is common with the second reference position S2. To move from the first reference position S1' to parking space PL8, the target vehicle V1 must move from the first reference position S1' to point QE1, reverse to point QE2, reverse at point QE2 to move forward to point QE3, reverse at point QE3 to move to parking space PL8. Thus, the curvature of the proposed trajectory RD curve (maximum value, integral value, integral value of change, etc.) and / or the steering amount (maximum value, integral value, integral value of change, etc.) when passing through the curve of the proposed trajectory RD when moving from the second reference position S2 to parking space PL8 is lower than those when moving along trajectory RE from the first reference position S1' to parking space PL8. Also, the number of reversals for trajectory RD is lower than that for trajectory RE. The estimated power consumption of trajectory RD leading to parking space PL8 is lower than the estimated power consumption of trajectory RE leading to parking space PL8.

[0041] In this embodiment, the reference position, which is the starting point of the parking control, is changed, and an alternative proposed trajectory R with reduced power consumption is calculated. By starting the parking control from the proposed reference position with a changed lateral position, the power consumption of the parking control can be reduced. Furthermore, by changing the lateral position of the target vehicle V1, parking control can be performed on a trajectory RD with a lower estimated power consumption than when the target vehicle V1 maintains its lateral position when it enters the parking lot (moves straight). By presenting the first reference positions S1 and S1' and the second reference position S2, which has a different lateral position, on the display 61, the target vehicle V1 can be guided to the second reference position S2. In addition, by presenting the guidance path PR from the first reference position S1 to the second reference position S2, the target vehicle V1 can be moved along the guidance path PR. If the target vehicle V1 can be moved to the second reference position S2, the target vehicle V1 can be moved to the target parking space OPL (PL8) along the proposed trajectory RD with a lower estimated power consumption, starting from the second reference position S2.

[0042] 100...Parking assist system, 1...Parking assist device, 10...Processor, 11...CPU, 12...ROM, 13...RAM, 2...Sensor, 21...Camera, 22...Radar device, 4...Navigation device, 41...Map information, 42...Parking information, 5...Actuator, 51...Steering device, 52...Drive device, 53...Braking device, 6...Input / output device, 61...Display

Claims

1. A parking assistance method used in a processor to assist in parking control of a target vehicle which is an electric vehicle, wherein the processor calculates trajectories for moving the target vehicle from a reference position based on the position of the target vehicle to a plurality of parking spaces, calculates estimated power consumption values ​​for when the target vehicle moves along each trajectory according to the curvature of one or more curves included in each trajectory, selects a parking space reached by the trajectory as a target parking space based on the estimated power consumption values, and moves the target vehicle to the selected target parking space.

2. The parking assistance method according to claim 1, wherein the processor calculates the estimated power consumption when the target vehicle moves along each of the tracks, based on the curvature of the curve and a set speed set according to the curvature.

3. The parking assistance method according to claim 1 or 2, wherein the processor calculates the amount of steering input of the target vehicle when the target vehicle moves along one or more curves included in the trajectory, based on the curvature of the curves included in the trajectory, and calculates the estimated power consumption when the target vehicle moves along each trajectory based on the amount of steering input.

4. The parking assistance method according to claim 3, wherein the processor calculates the amount of steering, the steering speed and / or the amount of change in steering speed when the target vehicle moves along the curve, based on the curvature, and calculates the estimated power consumption when the target vehicle moves along each of the tracks based on the amount of steering and the steering speed and / or the amount of change in steering speed.

5. The parking assistance method according to any one of claims 1 to 4, wherein the processor calculates the vehicle speed when the target vehicle moves along one or more curves included in the trajectory, and calculates a higher estimated power consumption value when the vehicle speed is less than a predetermined vehicle speed than when the vehicle speed is equal to or greater than the predetermined vehicle speed.

6. The parking assistance method according to any one of claims 1 to 5, wherein the processor counts the number of times the trajectory is reversed, and calculates a higher estimated power consumption value when the number of reversals is large than when the number of reversals is small.

7. The parking assistance method according to any one of claims 1 to 6, wherein the processor presents the estimated power consumption value to an input / output device in association with the parking space, obtains input of a selection command from the driver to select one of the parking spaces and the trajectory, sets the selected parking space as the target parking space, and moves the target vehicle to the target parking space along the selected trajectory.

8. The parking assistance method according to any one of claims 1 to 7, wherein the processor calculates a proposed reference position for a proposed trajectory that reduces the estimated power consumption when parking on the trajectory from the reference position to the target parking space, and presents the proposed reference position to an input / output device.

9. A parking assist device equipped with a processor that assists in parking control of a target vehicle which is an electric vehicle, wherein the processor calculates a trajectory for moving the target vehicle from a reference position based on the position of the target vehicle to a plurality of parking spaces, calculates an estimated power consumption value for when the target vehicle moves along each trajectory according to the curvature of one or more curves included in each trajectory, selects a parking space reached by the trajectory as a target parking space based on the estimated power consumption value, and moves the target vehicle to the selected target parking space.

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