Vehicle

Abstract

The present application relates to a vehicle. The vehicle of an embodiment of the present application determines a return position on a travel route when the vehicle departs from the travel route and returns to the travel route, and calculates target positions of a first tire and a second tire that can travel on the travel route when the vehicle is at the return position, finds a common center point at which a difference between a distance from a current position of the first tire and a distance from the target position of the first tire and a difference between a distance from a current position of the second tire and a distance from the target position of the second tire are within a prescribed range, and sets a steering angle of each of a plurality of tires in a manner in which a tangent direction of a turning circle of each of the plurality of tires with the common center point as a center and a distance to the common center point as a radius or a direction in which an angle difference from the tangent direction is within a prescribed range is respectively set.

Description

Technical Field

[0001] This invention relates to a vehicle that travels on a pre-set route. Background Technology

[0002] In order to enable complex movements within a site, a vehicle traveling on a pre-set route is configured such that multiple tires are each set with a different steering angle (for example, see Patent Document 1).

[0003] Patent Document 1: Japanese Patent Application Publication No. 2010-20515 Summary of the Invention

[0004] In the event that the aforementioned vehicle deviates from its driving route for some reason, it is desirable to quickly return to the driving route without performing unnecessary actions. This application was made in view of such a situation, and its purpose is to provide a vehicle that can efficiently return to the driving route when it deviates from it.

[0005] One embodiment of this application discloses a vehicle that travels on a pre-set driving route. The vehicle includes: a plurality of tires, including a first tire and a second tire, each capable of being set to a different steering angle; and a processing device that sets the steering angle of each of the plurality of tires. When the vehicle leaves the driving route and returns to it, the processing device determines a return position on the driving route and calculates the target positions of the first tire and the second tire that can travel on the driving route when the vehicle is at the return position. It then finds a common center point where the difference between the distance from the current position of the first tire and the distance from the target position of the first tire is within a specified range, and the difference between the distance from the current position of the second tire and the distance from the target position of the second tire is also within a specified range. The steering angle of each of the plurality of tires is set in a manner that the tangent direction of a turning circle centered on the common center point and with a radius equal to the distance to the common center point, or in a direction whose angle difference with the tangent direction is within a specified range, is used to set the steering angle of each of the plurality of tires.

[0006] Based on the above structure, a vehicle can be provided that can efficiently return to the driving route when it deviates from the driving route. Attached Figure Description

[0007] Figure 1 This is a simplified top view of the vehicle.

[0008] Figure 2 This is a flowchart of the route return procedure.

[0009] Figure 3 This is a diagram illustrating the method for determining the return position.

[0010] Figure 4 This is a diagram illustrating the method for calculating the target location.

[0011] Figure 5 This diagram illustrates the method for calculating the target position when the driving route is a curve.

[0012] Figure 6 This is a diagram illustrating the method for finding the common center point.

[0013] Figure 7 This diagram illustrates how to set the steering angle of each tire. Detailed Implementation

[0014] <Vehicle Overview>

[0015] First, an overview of the vehicle 100 according to the embodiment will be described. Figure 1 This is a simplified top view of vehicle 100. Vehicle 100 travels on a pre-set route. Vehicle 100 can be configured to travel automatically on the route, or it can be configured to travel partially manually (e.g., only acceleration and deceleration are manual while the rest is automatic).

[0016] like Figure 1 As shown, the vehicle 100 includes a body 10, multiple tires 11-14, a tire drive device 15, a positioning system 16, and a processing device 17.

[0017] The vehicle body 10 is configured to transport heavy objects, and in this embodiment, it has an approximately rectangular shape in the top view. When the vehicle 100 travels on a route, the end of the vehicle body 10 along its long side serves as the front end, and it travels along the long side of the vehicle body 10. In this embodiment, the end of the vehicle body 10 on the left side of the paper is the front end, and it travels towards the left of the paper (refer to the arrow). Furthermore, the purpose, shape, and direction of travel of the vehicle body 10 are not limited to the above.

[0018] The multiple tires 11 to 14 include a first tire 11 corresponding to the right front wheel, a second tire 12 corresponding to the left front wheel, a third tire 13 corresponding to the right rear wheel, and a fourth tire 14 corresponding to the left rear wheel. However, the configuration of each tire 11 to 14 is not limited to this. In addition, the number of tires on the vehicle 100 is not limited to four.

[0019] The tire drive unit 15 rotates and drives each of the tires 11 to 14, and sets the steering angle (the angle of each tire 11 to 14 relative to the vehicle body 10). In this embodiment, the tire drive unit 15 can be set such that the rotational speed and steering angle of each of the tires 11 to 14 are different from each other. Furthermore, the tire drive unit 15 can use an internal combustion engine to rotate and drive each of the tires 11 to 14, or it can use an electric motor to rotate and drive each of the tires 11 to 14. In addition, feedback control is performed on the steering angle of each of the tires 11 to 14 based on the detection results of the steering angle detection sensor.

[0020] The positioning system 16 is a system for determining the current position (here, the center position of the vehicle body 10, but not limited to this) and orientation of the vehicle body 10. In this embodiment, the positioning system 16 has GNSS (Global Navigation Satellite System) receivers at the front and rear portions of the vehicle body 10, enabling it to determine the detailed positions of the front and rear portions of the vehicle body 10. Furthermore, the positioning system 16 calculates the current position and orientation of the vehicle body 10 based on the positions of the front and rear portions. However, the positioning system 16 can also use a camera or other methods to determine the current position and orientation of the vehicle body 10. Alternatively, the positioning system 16 may have only one receiver with two antennas. Furthermore, the positioning system 16 may have only one receiver, calculating (obtaining) the orientation of the vehicle body 10 based on the latest measured position of the vehicle body 10 and the position of the vehicle body 10 a predetermined time prior.

[0021] The processing device 17 includes a processor, volatile memory, non-volatile memory, and I / O interfaces. The processing device 17 is electrically connected to the positioning system 16 and can obtain the current position and orientation of the vehicle body 10 from the positioning system 16. Furthermore, the processing device 17 is electrically connected to the tire drive device 15 and can send control signals to the tire drive device 15 to control the tire drive device 15, setting the rotational speed and steering angle of each tire 11-14.

[0022] In addition, the non-volatile memory of the processing device 17 stores data of the preset driving route of the vehicle 100, and also stores data of the route return program. The processor of the processing device 17 performs calculations using the volatile memory based on the route return program. Based on the results of the calculations in the volatile memory, the processing device 17 sends control signals to the tire drive device 15.

[0023] <Route Return Procedure>

[0024] Next, the route return procedure will be explained. Figure 2This is a flowchart of the route return procedure. The route return procedure is used to return the vehicle 100, which has deviated from the driving route, to the driving route, and is executed during driving on the driving route. Figure 2 The processing shown is performed by the processing device 17.

[0025] If the route return procedure is initiated, the processing device 17 obtains the current position and orientation of the vehicle body 10 (step S1). The current position and orientation of the vehicle body 10 can be obtained from the positioning system 16 described above.

[0026] Next, the processing device 17 calculates the current position of each tire 11 to 14 (step S2). Since the relative position of each tire 11 to 14 with respect to the vehicle body 10 is known, the current position of each tire 11 to 14 can be calculated based on the current position and orientation of the vehicle body 10.

[0027] Next, the processing device 17 determines the speed at which the vehicle 100 returns to the travel route (hereinafter referred to as the "return travel speed") (step S3). The return travel speed is determined not only by the speed of the vehicle 100 during the route travel procedure but also by factors such as the weight of the cargo loaded on the vehicle body 10. For example, if the cargo on the vehicle body 10 is light, the return travel speed can be determined to be a large value. Alternatively, the return travel speed can be constant (in which case step S3 can be omitted).

[0028] Next, the processing device 17 determines the reference distance (step S4). The reference distance is determined based on the return travel speed determined in step S3. In this embodiment, as the return travel speed increases, the reference distance is determined to be a larger value, and as the return travel speed decreases, the reference distance is determined to be a smaller value. However, the relationship between the return travel speed and the reference distance is not limited to the above situation.

[0029] Next, the processing device 17 determines the return position (step S5). In this embodiment, the return position is determined based on the reference distance determined in step S4. Specifically, as... Figure 3 As shown, position B, which is on the driving route R and has moved a reference distance L from the current position A of vehicle 100, is determined as the return position. The return position B is located ahead of the driving direction of the driving route R as observed from vehicle 100.

[0030] Next, the processing device 17 calculates the target position of the first tire 11 and the target position of the second tire 12 (step S6). For example... Figure 4As shown, the target position B1 of the first tire 11 is the position of the first tire 11 that allows the vehicle 100 to travel on the driving route R when it is in the return position B. Similarly, the target position B2 of the second tire 12 is the position of the second tire 12 that allows the vehicle 100 to travel on the driving route R when it is in the return position B.

[0031] For example, such as Figure 4 As shown, when the driving route R is a straight line, the positions of the first tire 11 and the second tire 12 when the vehicle body 10 is in the return position B and the front-to-back direction of the vehicle body 10 is parallel to the driving route R are respectively set as the target position B1 of the first tire 11 and the target position B2 of the second tire 12.

[0032] Additionally, for example, such as Figure 5 As shown, when the driving route R is a curve, the positions of the first tire 11 and the second tire 12 when the vehicle body 10 is in the return position B and the front-to-back direction of the vehicle body 10 is parallel to the tangent of the driving route R are respectively set as the target position B1 of the first tire 11 and the target position B2 of the second tire 12.

[0033] Next, the processing device 17 determines the common center point (step S7). For example... Figure 6 As shown, the common center point X is the point where the distance from the current position A1 of the first tire 11 is the same as the distance from the target position B1 of the first tire 11, and the difference between the distance from the current position A2 of the second tire 12 and the distance from the target position B2 of the second tire 12 is the same. That is, the common center point X is the intersection of the perpendicular bisector of the line connecting the current position A1 and the target position B1 of the first tire 11, and the perpendicular bisector of the line connecting the current position A2 and the target position B2 of the second tire 12.

[0034] Next, the processing device 17 sets the steering angle of each tire 11-14 (step S8). Specifically, as follows: Figure 7 As shown, if it is the first tire 11, the steering angle of the first tire 11 is set such that the first tire 11 is tangent to a turning circle C1 with the common center point X obtained in step S7 as the center and the distance from the current position A1 of the first tire 11 to the common center point X as the radius. Similarly, for the tires 12 to 14 other than the first tire 11, the steering angle of each tire 12 to 14 is also set such that each tire 12 to 14 is tangent to a turning circle C2 to C4 with the common center point X as the center and the distance from the current position A2 to A4 of each tire 12 to 14 to the common center point X as the radius.

[0035] Next, the processing device 17 rotates the vehicle 100 toward the driving route, driving each of the tires 11-14 (step S9). The processing device 17 can rotate each of the tires 11-14 at the same rotational speed, or it can rotate each of the tires 11-14 at different rotational speeds depending on the distance from the current position of each tire 11-14 to the target position. For example, the tire with a longer distance from the current position to the target position is rotated at a faster rotational speed than the tire with a shorter distance.

[0036] After step S9, the process returns to step S1, and steps S1 to S9 are repeated before the vehicle 100 returns to the driving route. That is, during the period before the vehicle 100, which has deviated from the driving route, returns to the driving route, the processing device 17 continuously updates the return position (step S5), thereby continuously updating the steering angle settings of each tire 11 to 14 (step S8). Alternatively, steps S1 to S8 can be performed while rotating and driving each tire 11 to 14 (i.e., during the execution of step S9). Thus, as the vehicle 100 approaches the driving route, the steering angle is corrected so that each tire 11 to 14 is oriented in the direction along the driving route. As a result, if the vehicle 100 reaches the return position, the vehicle 100 can immediately travel on the driving route.

[0037] However, steps S1 to S9 can be skipped, and the temporarily set steering angles of each tire 11 to 14 can be maintained until the vehicle 100 returns to the driving route. In this case, after the vehicle 100 reaches the return position, the vehicle 100 can immediately travel on the driving route by adjusting the steering angle so that each tire 11 to 14 is oriented towards the direction of travel of the driving route. That is, the vehicle 100 can quickly return to the driving route.

[0038] Furthermore, in the aforementioned route return procedure, although the common center point is defined as the point where the distance from the current position of the first tire 11 is the same as the distance from the target position of the first tire 11, and the difference between the distance from the current position of the second tire 12 and the distance from the target position of the second tire 12 is the same (step S7), the common center point can also be determined by considering the slippage of each tire 11 to 14. That is, the common center point can also be defined as the point where the difference between the distance from the current position of the first tire 11 and the distance from the target position of the first tire 11 is within a specified range, and the difference between the distance from the current position of the second tire 12 and the distance from the target position of the second tire 12 is within a specified range.

[0039] Similarly, in the above route return procedure, the steering angle of each tire 11 to 14 is set in the direction of the tangent of the turning circle centered on the common center point and with the distance from each tire 11 to 14 to the common center point as the radius (step S8). However, the steering angle of each tire 11 to 14 can also be set in the direction where the angle difference with the tangent of the turning circle centered on the common center point and with the distance from each tire 11 to 14 to the common center point as the radius is within a specified range.

[0040] Furthermore, in the aforementioned route return procedure, the common center point is calculated based on the current positions of the first tire 11 and the second tire 12, and the target position (step S7). Figure 6 However, the common center point can also be determined based on the current position and target position of three or more tires.

[0041] <Effects, etc.>

[0042] As described above, the vehicle of this embodiment is a vehicle that travels on a pre-set driving route and has multiple tires, including a first tire and a second tire, which can be set to different steering angles; and a processing device that sets the steering angles of the multiple tires respectively. When the vehicle leaves the driving route and returns to the driving route, the processing device determines the return position on the driving route and calculates the target positions of the first tire and the second tire that the vehicle can travel on the driving route when it is at the return position. It finds a common center point where the difference between the distance from the current position of the first tire and the distance from the target position of the first tire is within a specified range, and the difference between the distance from the current position of the second tire and the distance from the target position of the second tire is within a specified range. The processing device sets the steering angles of the multiple tires respectively in a manner that the tangent direction of a turning circle centered on the common center point and with a radius equal to the distance to the common center point is within a specified range.

[0043] In this way, the vehicle of this embodiment can quickly position each tire in a position that allows it to travel on the driving route, thus enabling it to return to the driving route efficiently.

[0044] Furthermore, in the vehicle of this embodiment, when the processing device determines the return position, it determines the reference distance based on the vehicle's speed when returning to the driving route, and determines the return position by using the distance from the vehicle's current position to the return position as the reference distance.

[0045] Therefore, the vehicle according to this embodiment can appropriately determine the return position based on the driving speed.

[0046] Furthermore, in the vehicle of this embodiment, the processing device continuously updates the return position during the period before the vehicle returns to the driving route after deviating from it, thereby enabling continuous updating of the steering angle settings of the plurality of tires.

[0047] Therefore, according to this embodiment, as the vehicle approaches the driving route, the steering angle is corrected so that each tire is oriented in the direction along the driving route. As a result, the vehicle can immediately travel on the driving route once the return position is reached.

[0048] Explanation of reference numerals in the attached figures

[0049] 10…car body

[0050] 11…First Tire

[0051] 12…Second tire

[0052] 13…Third tire

[0053] 14… Fourth tire

[0054] 15… Tire drive unit

[0055] 16… Positioning System

[0056] 17…processing device

[0057] 100… vehicles.

Claims

1. A vehicle that travels on a pre-set route, comprising: Multiple tires, including a first tire corresponding to the right front wheel and a second tire corresponding to the left front wheel, can be set to different steering angles; and The processing device sets the steering angle of each of the aforementioned tires. The above-mentioned processing device When the vehicle leaves the aforementioned driving route and returns to the aforementioned driving route, the return position on the aforementioned driving route is determined, and the target positions of the first tire and the second tire that can travel on the aforementioned driving route when the vehicle is at the aforementioned return position are calculated. Find the common center point where the difference between the distance from the current position of the first tire and the distance from the target position of the first tire is within a specified range, and the difference between the distance from the current position of the second tire and the distance from the target position of the second tire is within a specified range. The steering angles of the multiple tires are set in a manner that the tangent direction of the turning circle centered on the common center point and with the distance to the common center point as the radius, or the direction in which the angle difference with the tangent direction is within a specified range, for each of the multiple tires.

2. The vehicle according to claim 1, wherein, When determining the return position, the processing device determines the reference distance based on the vehicle's speed when returning to the driving route, and determines the return position by using the distance from the vehicle's current position to the return position as the reference distance.

3. The vehicle according to claim 1 or 2, wherein, The aforementioned processing device continuously updates the return position during the period before the vehicle, which has deviated from the aforementioned driving route, returns to the aforementioned driving route, thereby continuously updating the steering angle settings of the aforementioned multiple tires.

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