Control device, program, and control method for electric vehicle

Abstract

A control device (70, 80) of an electric vehicle (10) performs processing for executing drive control on a right-side motor (31) so as to control the rotational speed of a right-side drive wheel (12R) at a right-side command value, and executing drive control on a left-side motor (31) so as to control the rotational speed of a left-side drive wheel (12L) at a left-side command value. The control device calculates the right-side command value and the left-side command value so as to set the rotational speed of the drive wheel located on the outer side with respect to the turning direction of the electric vehicle, among the right-side drive wheel and the left-side drive wheel, higher than a base command value while setting the rotational speed of the drive wheel located on the inner side with respect to the turning direction of the electric vehicle lower than the base command value. The control device acquires the amounts of deviation in the vehicle width direction between guidance lines (200, 201) and the center position of the vehicle body (11), and performs calculation such that the base command value decreases as the acquired deviation amounts increase.

Description

Control device, program, and control method for electric vehicle Cross-Reference to Related Applications

[0001] The present application is based on Japanese Patent Application No. 2025-051285 filed on March 26, 2025, the content of which is incorporated herein by reference.

[0002] The present disclosure relates to a control device, a program, and a control method for an electric vehicle.

[0003] Conventionally, as disclosed, for example, in Patent Document 1, there is known an electric vehicle including a vehicle body, a left drive wheel and a right drive wheel rotatably supported by the vehicle body, and a left motor and a right motor for driving the left and right drive wheels. The electric vehicle travels along a guide line and turns by generating a rotational speed difference between the rotational speed of the left drive wheel and the rotational speed of the right drive wheel.

[0004] A control device for the electric vehicle calculates a right command value that is a command value for the rotational speed of the right drive wheel, and a left command value that is a command value for the rotational speed of the left drive wheel. The control device executes drive control of the right motor to control the rotational speed of the right drive wheel to the right command value, and executes drive control of the left motor to control the rotational speed of the left drive wheel to the left command value.

[0005] Japanese Unexamined Patent Publication No. 2015-207224

[0006] In order to prevent the travel track of the electric vehicle from derailing from a curved guide line, which is a curved guide line, control for reducing the travel speed of the electric vehicle can be executed before the electric vehicle enters the curved line. In this case, for example, there is a concern that the travel time of the electric vehicle from a first point to a second point via the curved line on the guide line becomes longer.

[0007] A main object of the present disclosure is to provide a control device, a program, and a control method for an electric vehicle that can suppress the occurrence of a situation where the travel speed of the electric vehicle is reduced before the electric vehicle enters a curved line.

[0008] This disclosure relates to a control device for an electric vehicle, which is applied to an electric vehicle that travels along a guide line and turns by creating a rotational speed difference between the rotational speed of the left drive wheel and the rotational speed of the right drive wheel, comprising: a vehicle body; a left drive wheel and a right drive wheel rotatably supported with respect to the vehicle body; a left motor for driving the left drive wheel; and a right motor for driving the right drive wheel, wherein the control device performs: a command value calculation process for calculating a right command value which is a command value for the rotational speed of the right drive wheel and a left command value which is a command value for the rotational speed of the left drive wheel; and a process for executing drive control of the right motor to control the rotational speed of the right drive wheel to the right command value and for executing drive control of the left motor to control the rotational speed of the left drive wheel to the left command value.

[0009] The command value calculation process includes: a base value calculation process for calculating a base command value for the rotational speed of the right drive wheel and the left drive wheel; and an individual calculation process for calculating the right command value and the left command value such that the rotational speed of the drive wheel on the inside in the turning direction of the electric vehicle is lower than the base command value, while the rotational speed of the drive wheel on the outside in the turning direction of the electric vehicle is higher than the base command value.

[0010] The right-side command value and left-side command value are calculated as described above in relation to the base command value, which greatly contributes to the electric vehicle's speed, thereby causing the electric vehicle to turn along the curve line.

[0011] In this disclosure, in the base value calculation process, the amount of displacement in the vehicle width direction of the vehicle body between the guide line and the center position of the vehicle body is obtained, and the larger the obtained displacement amount, the smaller the base command value is calculated.

[0012] As a result, when an electric vehicle enters a curve, the base command value is reduced only after a discrepancy begins to occur between the guide line and the center position of the vehicle body. Therefore, it is possible to suppress situations in which the electric vehicle's speed is reduced before it enters a curve.

[0013] The above-mentioned objectives and other objectives, features and advantages of this disclosure will become clearer from the following detailed description with reference to the attached drawings. The drawings are as follows: Figure 1 is an overall configuration diagram of the autonomous vehicle according to the first embodiment; Figure 2 is a diagram showing the electric drive unit and its surrounding configuration; Figure 3 is a side view of the autonomous vehicle; Figure 4 is a front view of the autonomous vehicle body; Figure 5 is a block diagram of the control processing by the controller; Figure 6 is a flowchart of the control processing by the controller; Figure 7 is a diagram showing the autonomous vehicle traveling along a straight line; Figure 8 is a diagram showing the autonomous vehicle traveling along a curved line; Figure 9 is a diagram showing the autonomous vehicle according to a comparative example traveling along a guide line; Figure 10 is a block diagram of the control processing by the controller according to the second embodiment; Figure 11 is a block diagram of the control processing by the controller according to the third embodiment; and Figure 12 is a flowchart of the control processing by the controller according to the fourth embodiment.

[0014] Multiple embodiments will be described with reference to the drawings. In multiple embodiments, functionally and / or structurally corresponding and / or related parts may be given the same reference numeral, or reference numerals that differ by hundreds or more digits. For corresponding and / or related parts, refer to the descriptions of other embodiments.

[0015] <First Embodiment> Hereinafter, a first embodiment of the control device according to the present disclosure will be described with reference to the drawings. The control device of this embodiment is applied to an automated guided vehicle (AGV) guided by a magnetic tape which is a guide line in a factory or warehouse, etc. The automated guided vehicle is, for example, an unmanned transport vehicle or an unmanned transport robot. The automated guided vehicle may be a manned transport vehicle or a manned transport robot.

[0016] First, the overall configuration of the autonomous vehicle 10 will be explained using Figures 1 to 3.

[0017] The autonomous vehicle 10 comprises a vehicle body 11, a right-side drive wheel 12R, a left-side drive wheel 12L, and a drive unit 20. The upper part of the vehicle body 11 is a mounting section 14 on which transported items can be placed. The right-side drive wheel 12R and the left-side drive wheel 12L are positioned opposite each other in the vehicle width direction of the autonomous vehicle 10. In this embodiment, two sets of the right-side drive wheel 12R and the left-side drive wheel 12L are provided as front and rear wheels.

[0018] The drive unit 20 is a device for rotationally driving each drive wheel 12R, 12L and is housed within the vehicle body 11. The drive unit 20 includes an electric drive device 30 corresponding to each drive wheel 12R, 12L, brakes 60 corresponding to each drive wheel 12R, 12L, a higher-level controller 70, a battery 71, a main switch 73, a brake switch 75, and sensors 77, etc. The main switch 73 and the brake switch 75 are, for example, relays (specifically, mechanical relays). In Figure 1, power lines PL1 and PL2 are shown as solid lines, and signal line SL is shown as a dashed line.

[0019] Each electric drive unit 30 drives the drive shafts 13R and 13L connected to the respective drive wheels 12R and 12L. Each electric drive unit 30 is equipped with an MCU (Motor Control Unit) 58 and a reduction gear 59.

[0020] Each MCU 58 is connected to the battery 71 via a power line PL1. A main switch 73 is provided between the battery 71 and the four MCUs 58 on the power line PL1. The main switch 73 can be switched between ON, which supplies power from the battery 71 to each MCU 58, and OFF, which cuts off the power supply to each MCU 58. When the main switch 73 is ON, each MCU 58 operates by being powered from the battery 71.

[0021] The reduction gear 59 reduces the rotational speed of the motor 31 (see Figure 2) of the MCU 58 and transmits it to the drive shafts 13R and 13L. The reduction gear 59 is, for example, a planetary gear mechanism or a cycloidal gear mechanism.

[0022] The brakes 60 are devices that apply braking force to the drive shafts 13R and 13L. The brakes 60 are connected to the battery 71 by a power line PL2. A brake switch 75 is provided between the battery 71 and each brake 60 in the power line PL2. The brake switch 75 can be switched between ON, which supplies power from the battery 71 to each brake 60, and OFF, which cuts off the power supply to each brake 60. Each brake 60 is powered and driven by the battery 71 when the brake switch 75 is ON. The braking force applied by each brake 60 to each drive shaft 13R and 13L can also be controlled by each MCU 58 or a higher-level controller 70.

[0023] The upper-level controller 70 and each MCU 58 are connected to each other by a signal line SL. The signal line SL is a signal line that conforms to the communication standard of, for example, CAN (Controller Area Network). The upper-level controller 70 includes a processor as hardware, a memory unit, and a communication bus connecting the processor and the memory unit.

[0024] The memory unit includes memory and storage as hardware. Memory is a storage device for storing data used in the controller's processing. Memory provides the processor with a temporary workspace for use when the processor is performing processing. Memory includes, for example, ROM or RAM. Storage is a storage device that stores various programs and data for the processor to read and execute, and is a non-transitory tangible storage medium. Storage includes, for example, HDD or flash memory. The storage stores program information and the like for processing described later.

[0025] For example, program information stored on a non-transitional physical recording medium is installed in the storage unit. The recording medium may be, for example, a USB memory stick, CD-ROM, or DVD. Furthermore, program information transmitted via a communication network, such as OTA (Over The Air), is also installed in the storage unit.

[0026] The higher-level controller 70 and each MCU 58 transmit and receive information from each other via the signal line SL. The higher-level controller 70 controls each MCU 58 by inputting commands to each MCU 58 via the signal line SL. The higher-level controller 70 switches the main switch 73 and the brake switch 75 on and off. The higher-level controller 70 keeps the main switch 73 and the brake switch 75 on while the drive unit 20 is operating.

[0027] The sensors 77 include, for example, an abnormal stop button, a collision detection switch, a location information sensor that reads floor position information, and a human presence sensor that detects people. The detection results from the sensors 77 are input to the higher-level controller 70.

[0028] Next, we will explain the electric drive unit 30 and its surrounding configuration using Figure 2. Since each electric drive unit 30 has a similar configuration, we will explain using one electric drive unit 30 as an example.

[0029] The electric drive unit 30 includes a power switch 32, an inverter 34, a current sensor 41, and an angle sensor 42. The electric drive unit 30 also includes a motor 31, a reduction gear 59, and a controller 80. The power switch 32 is, for example, a relay (specifically, for example, a mechanical relay).

[0030] The inverter 34 is connected to the battery 71 via a power switch 32 and a main switch 73. The power switch 32 can be switched between ON, which supplies power from the battery 71 to the inverter 34, and OFF, which cuts off the power.

[0031] The inverter 34 is equipped with upper and lower arm switches corresponding to each phase, and is, for example, a three-phase inverter. The inverter 34 converts the DC power supplied from the battery 71 into AC power and supplies the converted AC power to the armature winding 31a of the motor 31. As a result, the rotor of the motor 31 rotates, and consequently the drive wheels 12R and 12L rotate.

[0032] The current sensor 41 detects the current flowing through the armature winding 31a. The angle sensor 42 detects the rotation angle (electrical angle) of the rotor. The detected values ​​from the current sensor 41 and the angle sensor 42 are input to the controller 80.

[0033] The autonomous vehicle 10 is equipped with a voltage sensor 43 that detects the voltage between the terminals of the battery 71. The value detected by the voltage sensor 43 is input to the controller 80.

[0034] The controller 80 is an ECU that performs various controls on the electric drive unit 30, and comprises a processor 81 as hardware, a storage unit 82, and a communication bus 83 that connects the processor 81 and the storage unit 82.

[0035] The memory unit 82 includes memory and storage as hardware. The memory is a storage device for storing data used in the processing of the controller 80. The memory provides the processor 81 with a temporary workspace for use when the processor 81 performs processing. The memory includes, for example, ROM or RAM. The storage is a storage device that stores various programs and data for the processor 81 to read and execute, and is a non-transitory tangible storage medium. The storage includes, for example, an HDD or flash memory. The storage stores program information and the like for processing described later.

[0036] For example, program information stored on a non-transitional physical recording medium is installed in the storage unit 82. The recording medium is, for example, a USB memory stick, a CD-ROM, or a DVD. Also, for example, program information transmitted via a communication network, such as OTA (Over The Air), is installed in the storage unit 82.

[0037] Incidentally, the electric drive unit 30 may have multiple power switches 32, inverters 34, current sensors 41, and angle sensors 42, rather than just one.

[0038] The controller 80 controls the power switch 32 to turn on or off. Specifically, the controller 80 keeps the power switch 32 on while the electric drive unit 30 is operating. The controller 80 controls the switching of the upper and lower arm switches of the inverter 34 based on commands from the higher-level controller 70 and the detected values ​​of the current sensor 41, angle sensor 42, and voltage sensor 43. More specifically, the controller 80 controls the switching of the inverter 34 so that the rotational speed of the drive wheel corresponding to itself matches the command value of the rotational speed received from the higher-level controller 70.

[0039] In addition to the sensors 77, the autonomous vehicle 10 is equipped with a guide sensor 78 used for controlling the vehicle's movement. The guide sensor 78 will be described below with reference to Figures 1, 3, and 4.

[0040] The autonomous vehicle 10 travels along a guide line (specifically, a magnetic tape) provided on the floor surface on which the drive wheels 12R and 12L roll. The values ​​detected by the guide sensor 78 are used for this travel control. The guide sensor 78 passes through the center position in the vehicle width direction and extends in the vehicle width direction. The guide sensor 78 is located in the vehicle body 11, in the vehicle length direction of the autonomous vehicle 10, in front of the front wheels, the right drive wheel 12R and the left drive wheel 12L. The guide sensor 78 is located in the vehicle body 11, in the portion facing the floor surface in the vertical direction.

[0041] As shown in FIG. 4, the guide sensor 78 includes a plurality of (for example, 16) magnetic sensors P1 to P16. The magnetic sensors P1 to P16 are horizontally arranged in a direction perpendicular to the straight traveling direction of the automated guided vehicle 10. That is, the magnetic sensors P1 to P16 are arranged in the vehicle width direction. The magnetic sensors P1 to P16 are arranged at equal intervals in order from the right end to the left end of the automated guided vehicle 10. The magnetic sensors P1 to P16 are turned on when the guide line exists directly below themselves, and turned off when the guide line does not exist directly below themselves. That is, the magnetic sensors P1 to P16 detect only the guide line directly below themselves.

[0042] The automated guided vehicle 10 controls the rotational speeds of the drive wheels 12R and 12L of the automated guided vehicle 10 so as to bring the center position of the guide sensor 78 in the vehicle width direction close to the center position of the automated guided vehicle 10 in the vehicle width direction. Thereby, the automated guided vehicle 10 travels along the guide line.

[0043] Next, the calculation processing of the rotational speed command value executed by the host controller 70 will be described. FIG. 5 is a block diagram of this processing.

[0044] A deviation amount calculation unit 90 calculates a deviation amount ΔG between the position Gr of the guide line detected by the guide sensor 78 and the center position Gc of the guide sensor 78 in the vehicle width direction. In the present embodiment, the center position Gc of the guide sensor 78 in the vehicle width direction and the center position of the vehicle body 11 in the vehicle width direction are the same position or equivalent positions. Hereinafter, when the center position of the vehicle body 11 in the vehicle width direction is deviated to the right side relative to the guide line, it is defined as a positive deviation amount ΔG, and when the center position of the vehicle body 11 in the vehicle width direction is deviated to the left side relative to the guide line, it is defined as a negative deviation amount ΔG.

[0045] An absolute value calculation unit 91 calculates an absolute value Gabs of the calculated deviation amount ΔG. Note that the absolute value of the deviation amount ΔG is also referred to as the magnitude of the deviation amount ΔG.

[0046] A base command value calculation unit 93 calculates a base command value NcB (= NB − ΔB) by subtracting the base decrease amount ΔB calculated by a base decrease amount calculation unit 92 from a reference rotational speed NB. The base command value NcB is a command value that serves as a reference for the rotational speeds of a right driving wheel 12R and a left driving wheel 12L. The processing performed by the base decrease amount calculation unit 92 will be described in detail later.

[0047] A correction value calculation unit 94 calculates a correction value ΔN as a manipulated variable for performing feedback control to bring the calculated deviation amount ΔG to 0. In the present embodiment, the feedback control performed by the correction value calculation unit 94 is proportional-integral-derivative control. However, the feedback control is not limited to proportional-integral-derivative control, and may be, for example, proportional-integral control.

[0048] A right command value calculation unit 95 calculates a right command value NR (= NcB + ΔN), which is a command value for the rotational speed of the right driving wheel 12R, by adding the calculated correction value ΔN to the calculated base command value NcB. A left command value calculation unit 96 calculates a left command value NL (= NcB − ΔN), which is a command value for the rotational speed of the left driving wheel 12L, by subtracting the calculated correction value ΔN from the calculated base command value NcB.

[0049] The calculated right command value NR is input to a controller 80 of a right MCU 58R, which is the MCU 58 that drives the right driving wheel 12R. In the right MCU 58R, the controller 80 performs switching control of an inverter 34 so as to control the rotational speed of the right driving wheel 12R to the right command value NR. On the other hand, the calculated left command value NL is input to a controller 80 of a left MCU 58L, which is the MCU 58 that drives the left driving wheel 12L. In the left MCU 58L, the controller 80 performs switching control of an inverter 34 so as to control the rotational speed of the left driving wheel 12L to the left command value NL.

[0050] When the center position of the vehicle body 11 shifts to the right relative to the guidance line, resulting in a positive shift amount ΔG, the rotational speed of the left drive wheel 12L on the inside of the turning direction must be lower than the rotational speed of the right drive wheel 12R on the outside of the turning direction in order to make the automated vehicle 10 turn left. The correction value calculation unit 94 basically calculates a negative correction value ΔN when the shift amount ΔG is a positive value. As a result, the right command value NR becomes relatively higher than the left command value NL. In this case, the correction value ΔN input to the right command value calculation unit 95 corresponds to an "outside correction value" that makes the rotational speed of the right drive wheel 12R on the outside of the turning direction higher than the base command value NcB. The correction value ΔN input to the left command value calculation unit 96 corresponds to an "inside correction value" that makes the rotational speed of the left drive wheel 12L on the inside of the turning direction lower than the base command value NcB.

[0051] On the other hand, if the center position of the vehicle body 11 shifts to the left relative to the guide line, resulting in a negative shift amount ΔG, then in order to make the automated vehicle 10 turn right, the rotational speed of the right drive wheel 12R on the inside of the turning direction must be lower than the rotational speed of the left drive wheel 12L on the outside of the turning direction. When the shift amount ΔG is negative, the correction value calculation unit 94 basically calculates a positive correction value ΔN. As a result, the left command value NL becomes relatively higher than the right command value NR. In this case, the correction value ΔN input to the left command value calculation unit 96 corresponds to an "outside correction value" that makes the rotational speed of the left drive wheel 12L on the outside of the turning direction higher than the base command value NcB. Also, the correction value ΔN input to the right command value calculation unit 95 corresponds to an "inside correction value" that makes the rotational speed of the right drive wheel 12R on the inside of the turning direction lower than the base command value NcB.

[0052] Next, the processing of the base drop amount calculation unit 92, which is a characteristic configuration of this embodiment, will be described. The base drop amount calculation unit 92 acquires the absolute value Gabs of the calculated deviation amount and calculates the base drop amount ΔB as an manipulated variable for feedback control to set the acquired absolute value Gabs to 0. In this case, the larger the acquired absolute value Gabs, the larger the base drop amount ΔB will basically be. As a result, the larger the absolute value Gabs, the smaller the base command value NcB becomes. The above-described calculation method for the base drop amount ΔB is intended to suppress the occurrence of a situation in which the driving speed of the autonomous vehicle 10 is reduced before the autonomous vehicle 10 enters the curved guide line, which is a curved guide line.

[0053] In this embodiment, the feedback control in the base reduction amount calculation unit 92 is proportional-integral-derivative control. However, the feedback control is not limited to proportional-integral-derivative control; for example, it may be proportional-integral control.

[0054] Figure 6 is a flowchart showing the driving control processing procedure of the autonomous vehicle 10, which is executed by the upper-level controller 70 and the controllers 80 of the right-side MCU 58R and left-side MCU 58L.

[0055] In step S10, the upper controller 70 calculates the displacement amount ΔG in the displacement amount calculation unit 90.

[0056] In step S11, the upper controller 70 calculates the absolute value Gabs of the calculated deviation amount ΔG in the absolute value calculation unit 91.

[0057] In step S12, the upper controller 70 calculates a correction value ΔN in the correction value calculation unit 94 based on the calculated deviation amount ΔG.

[0058] In step S13, the upper controller 70 calculates the base reduction amount ΔB in the base reduction amount calculation unit 92 based on the calculated absolute value Gabs.

[0059] In step S14, the upper controller 70 calculates the base command value NcB in the base command value calculation unit 93 based on the calculated base reduction amount ΔB and the reference rotational speed NB. Note that the processing in steps S13 and S14 corresponds to the "base value calculation processing".

[0060] In step S15, the upper-level controller 70 calculates the right-side command value NR based on the calculated base command value NcB and correction value ΔN in the right-side command value calculation unit 95, and inputs the calculated right-side command value NR to the controller 80 of each right-side MCU 58R. The upper-level controller 70 also calculates the left-side command value NL based on the calculated base command value NcB and correction value ΔN in the left-side command value calculation unit 96, and inputs the calculated left-side command value NL to the controller 80 of each left-side MCU 58L. Note that the processing in steps S12 and S15 corresponds to "individual calculation processing".

[0061] In step S16, the controller 80 of each right-side MCU 58R controls the switching of the inverter 34 to control the rotational speed of the right-side drive wheel 12R to the right-side command value NR. Similarly, the controller 80 of each left-side MCU 58L controls the switching of the inverter 34 to control the rotational speed of the left-side drive wheel 12L to the left-side command value NL.

[0062] Next, the effects of this embodiment will be explained using Figures 7 and 8. Figures 7 and 8 show the situation in which the autonomous vehicle 10 travels along a straight guide line, the straight line 200, and then enters the curved line 201.

[0063] As shown in Figure 7, when the autonomous vehicle 10 travels along the straight line 200, the correction value ΔN becomes 0, and the right command value NR and the left command value NL become the same value. As a result, in the example shown in Figure 7, the right command value NR and the left command value NL become the same value, and the autonomous vehicle 10 travels at a speed of 0.5 m / s.

[0064] Subsequently, the part of the autonomous vehicle 10's body 11 to which the guide sensor 78 is mounted enters the curve line 201. In this case, as the autonomous vehicle 10 moves, the amount of deviation ΔG increases, so a correction value ΔN is calculated to make the autonomous vehicle 10 turn left. As a result, as shown in Figure 8, the autonomous vehicle 10 can travel along the curve line 201.

[0065] Furthermore, a discrepancy occurs between the curve line 201 and the center position of the vehicle body 11, and the base command value NcB is reduced. As a result, the centrifugal force acting on the transported goods when the autonomous vehicle 10 turns can be reduced. This makes it possible to suppress situations in which the transported goods shift from their proper loading position in the loading section 14, such as when the transported goods are heavy, causing the load to collapse.

[0066] On the other hand, Figure 9 shows a comparative example. The comparative example's higher-level controller 70 does not include an absolute value calculation unit 91, a base reduction amount calculation unit 92, and a base command value calculation unit 93. In the comparative example's higher-level controller 70, the reference rotational speed NB is input to the right command value calculation unit 95 and the left command value calculation unit 96.

[0067] In the comparative example, when the autonomous vehicle 10 travels along a straight line 200 preceding a curved line 201, the higher-level controller 70 receives a deceleration command from a device 210 (for example, an RFID tag) installed near the straight line 200. As a result, the higher-level controller 70 reduces the reference rotational speed NB before the autonomous vehicle 10 enters the curved line 201. In this case, the autonomous vehicle 10's travel speed on the subsequent straight line 200 and curved line 201 decreases.

[0068] According to the embodiment described above, before the autonomous vehicle 10 enters the curve line 201, it is possible to suppress the occurrence of the transported goods shifting from the appropriate loading position without reducing the travel speed of the autonomous vehicle 10. Furthermore, according to this embodiment, it is possible to construct a control algorithm that does not require transmission information from a device 210 such as the RFID tag for deceleration instructions shown in Figure 9.

[0069] <Modified Example of the First Embodiment> The correction value calculated by the correction value calculation unit 94 may be a value (coefficient) that is multiplied by the base command value NcB in the right command value calculation unit 95 and the left command value calculation unit 96. Specifically, the correction value calculation unit 94 calculates a right correction value kr that is multiplied by the base command value NcB in the right command value calculation unit 95, and a left correction value kl that is multiplied by the base command value NcB in the left command value calculation unit 96.

[0070] If the center position of the vehicle body 11 shifts to the right relative to the guidance line, and the amount of shift ΔG becomes a positive value, the automated driving vehicle 10 needs to turn left. In this case, the correction value calculation unit 94 calculates a right-side correction value kr that is greater than 1, and a left-side correction value kl that is less than 1. As a result, the right-side command value NR (=kr × NcB) becomes relatively higher than the left-side command value NL (=kl × NcB).

[0071] On the other hand, if the center position of the vehicle body 11 shifts to the left relative to the guidance line, and the amount of shift ΔG becomes a negative value, the automated vehicle 10 needs to turn to the right. In this case, the correction value calculation unit 94 calculates a right-side correction value kr that is less than 1, and a left-side correction value kl that is greater than 1. As a result, the left-side command value NL becomes relatively higher than the right-side command value NR. The right-side correction value kr and the left-side correction value kl should be calculated such that the magnitude of the shift amount from 1 for the right-side correction value kr and the magnitude of the shift amount from 1 for the left-side correction value kl are the same.

[0072] <Second Embodiment> The second embodiment will be described below, focusing on the differences from the first embodiment, with reference to the drawings. In this embodiment, as shown in Figure 10, map information is used in the base reduction amount calculation unit 92 and the correction value calculation unit 94 instead of feedback control.

[0073] The correction value calculation unit 94 calculates the correction value ΔN based on the acquired displacement amount ΔG and the correction value ΔN, as well as the map information to which the displacement amount ΔG and the correction value ΔN are linked. The base reduction amount calculation unit 92 calculates the base reduction amount ΔB based on the acquired absolute value Gabs, as well as the map information to which the absolute value Gabs, as well as the base reduction amount ΔB, are linked. The map information used by the base reduction amount calculation unit 92 and the correction value calculation unit 94 is stored, for example, in the storage unit 82.

[0074] In configurations that utilize map information, the time required to calculate the appropriate base reduction amount ΔB corresponding to the absolute value Gabs can be reduced compared to cases where feedback control is used.

[0075] <Modification of the second embodiment> The information used in the base reduction amount calculation unit 92 and the correction value calculation unit 94 is not limited to map information, but may also be mathematical formula information.

[0076] <Third Embodiment> The third embodiment will now be described, focusing on the differences from the first embodiment, with reference to the drawings. In this embodiment, as shown in Figure 11, the upper controller 70 includes a limiting unit 97.

[0077] When either the calculated right-side command value NR or the left-side command value NL reaches the upper limit value LimH, the limiting unit 97 instructs the base reduction amount calculation unit 92 to increase the base reduction amount ΔB. This makes it possible to reduce both the right-side command value NR and the left-side command value NL while maintaining the difference between them. In this case, the influence of this reduction on the turning direction of the autonomous vehicle 10 can be suppressed.

[0078] On the other hand, if either the calculated right-side command value NR or the left-side command value NL reaches the lower limit LimL (<LimH), the limiting unit 97 instructs the base reduction amount calculation unit 92 to reduce the base reduction amount ΔB. This allows the difference between the right-side command value NR and the left-side command value NL to be maintained while increasing both values. In this case, the influence of this increase on the turning direction of the autonomous vehicle 10 can be suppressed.

[0079] Furthermore, the configuration of the third embodiment may be applied to the second embodiment.

[0080] <Fourth Embodiment> The fourth embodiment will be described below, focusing on the differences from the first to third embodiments, with reference to the drawings. In this embodiment, the calculation process for the correction value ΔN and base reduction amount ΔB based on map information is switched based on the absolute value Gabs of the displacement amount ΔG, and the calculation process for the correction value ΔN and base reduction amount ΔB based on feedback control is switched.

[0081] Figure 12 is a flowchart showing the driving control processing procedure for the autonomous vehicle 10, which is executed by the upper-level controller 70 and the controllers 80 of the right-side MCU 58R and left-side MCU 58L. In Figure 12, the same step numbers are used for processes that are the same as those shown in Figure 6 for convenience.

[0082] After the completion of the process in step S11, in step S20, the higher-level controller 70 determines whether the calculated absolute value Gabs is greater than the threshold Gth.

[0083] If the upper-level controller 70 determines that the absolute value Gabs is less than or equal to the threshold Gth, it performs calculation processing based on feedback control in steps S21 and S22. Specifically, in step S21, the upper-level controller 70 calculates the correction value ΔN in the correction value calculation unit 94 shown in Figure 5. In the subsequent step S22, the upper-level controller 70 calculates the base reduction amount ΔB in the base reduction amount calculation unit 92 shown in Figure 5.

[0084] On the other hand, if the upper-level controller 70 determines in step S20 that the absolute value Gabs is greater than the threshold Gth, it performs calculation processing based on the map information in steps S23 and S24. Specifically, in step S23, the upper-level controller 70 calculates the correction value ΔN in the correction value calculation unit 94 of Figure 10. In the subsequent step S24, the upper-level controller 70 calculates the base reduction amount ΔB in the base reduction amount calculation unit 92 of Figure 10. Note that the information used in steps S23 and S24 may be mathematical formula information instead of map information.

[0085] After completing the processing in step S22 or S24, the higher-level controller 70 proceeds to step S14 and calculates the base command value NcB based on the base drop amount ΔB calculated in step S22 or S24 and the reference rotational speed NB. Note that the processing in steps S22 and S14 corresponds to the "first base value calculation processing," and the processing in steps S23 and S14 corresponds to the "second base value calculation processing."

[0086] In the subsequent step S15, the upper-level controller 70 calculates the right-side command value NR in the right-side command value calculation unit 95 based on the calculated base command value NcB and the correction value ΔN calculated in step S21 or S23. The upper-level controller 70 also calculates the left-side command value NL in the left-side command value calculation unit 96 based on the calculated base command value NcB and the correction value ΔN calculated in step S21 or S23. The processing in steps S21 and S15 corresponds to the "first individual calculation process," and the processing in steps S23 and S15 corresponds to the "second individual calculation process."

[0087] For example, if the deviation amount ΔG becomes large and the autonomous vehicle 10 is likely to derail from the guidance line, a positive determination is made in step S20. In this case, the base drop amount ΔB and the correction value ΔN can be quickly calculated based on the map information, so the derailment of the autonomous vehicle 10 can be effectively prevented.

[0088] <Other Embodiments> The above embodiments may be modified and implemented as follows.

[0089] In each of the above embodiments, the upper-level controller 70 calculates the left command value NL and the right command value NR. However, the invention is not limited to this, for example, the controller 80 of the left MCU 58L may calculate the left command value NL, and the controller 80 of the right MCU 58R may calculate the right command value NR.

[0090] In an autonomous vehicle, either the pair of front wheels or the pair of rear wheels may be driven wheels. Furthermore, an autonomous vehicle is not limited to four wheels; for example, it may be a two-wheeled electric vehicle or an electric vehicle with five or more wheels.

[0091] In this disclosure or claims, the term "processor" means one or more hardware processors configured to execute processing defined by computer program code (i.e., one or more instructions of a computer program) contained in a computer program by reading the computer program code each time. In other words, a "processor" is a hardware device that executes one or more programmed processes. Therefore, computer program code can also be said to be software that can define the processing of the processor according to its content. A "processor" can be a general-purpose or specific-purpose processor, and may be, but is not limited to, a CPU, microprocessor, GPU, and DFP (Data Flow Processor).

[0092] In this disclosure or claims, the term “memory” means one or more hardware memories that are non-transitional tangible recording media configured to record computer program code and / or data in a manner accessible from a processor. “Memory” can be implemented by memory technology such as SRAM, SDRAM, non-volatile / flash type memory, or other types of memory. The computer program code that constitutes the program is recorded in memory and executed by a processor, thereby enabling the processor to perform the various functions described above.

[0093] In this disclosure or claims, the term “circuit” refers to one or more logic circuits as hardware, configured to perform specific processing defined by a pre-designed circuit configuration. In other words (and, in contrast to “processor”), “circuit” in this disclosure or claims refers to a hardware device that performs specific processing based on a circuit configuration, rather than processing defined by software such as the computer program code described above. For example, “circuit” may include custom ICs such as ASICs (Application Specific Integrated Circuits) and FPGAs (Field Programmable Gate Arrays) designed with Hardware Description Language (HDL). That is, “circuit” in this disclosure or claims includes all hardware circuits except for the processors described above that perform processing by reading computer program code.

[0094] In this disclosure or claims, the expression "at least one of the circuit and processor" should be interpreted as disjunctive (logical OR) and not as "at least one circuit and at least one processor." Therefore, in this disclosure or claims, "at least one of the circuit and processor causes the device to perform functions" includes cases where the circuit alone causes the device to perform all functions. Also, "at least one of the circuit and processor causes the device to perform functions" includes cases where the processor alone causes the device to perform all functions. Furthermore, "at least one of the circuit and processor causes the device to perform functions" includes cases where the circuit causes the device to perform some functions and the processor causes the device to perform the remaining functions. In the last example, for example, if the device performs functions A to C, functions A and B may be implemented by the circuit, and the remaining function C may be implemented by the processor.

[0095] This disclosure is described in accordance with the embodiments, but it is understood that this disclosure is not limited to such embodiments or structures. This disclosure also includes various modifications and variations within the equivalence. In addition, various combinations and forms, as well as other combinations and forms that include only one, more, or fewer of those elements, fall within the scope and concept of this disclosure.

Claims

1. A control device (70, 80) for an electric vehicle (10) that is applied to an electric vehicle (10) which comprises a vehicle body (11), a left drive wheel (12L) and a right drive wheel (12R) rotatably supported with respect to the vehicle body, a left motor (31) for driving the left drive wheel, and a right motor (31) for driving the right drive wheel, and which travels along guide lines (200, 201) and turns by creating a rotational speed difference between the rotational speed of the left drive wheel and the rotational speed of the right drive wheel, performs a command value calculation process to calculate a right command value which is a command value for the rotational speed of the right drive wheel and a left command value which is a command value for the rotational speed of the left drive wheel, and performs a drive control of the right motor to control the rotational speed of the right drive wheel to the right command value, and performs a drive control of the left motor to control the rotational speed of the left drive wheel to the left command value, wherein the command value calculation process is A control device for an electric vehicle, comprising: a base value calculation process for calculating a base command value for the rotational speed of the right drive wheel and the left drive wheel; and an individual calculation process for calculating the right command value and the left command value such that the rotational speed of the drive wheel on the inside in the turning direction of the electric vehicle is lower than the base command value, while the rotational speed of the drive wheel on the outside in the turning direction of the electric vehicle is higher than the base command value, wherein in the base value calculation process, the amount of deviation of the vehicle body in the vehicle width direction between the guide line and the center position of the vehicle body is obtained, and the larger the obtained amount of deviation, the smaller the base command value is calculated.

2. The control device for an electric vehicle according to claim 1, wherein in the base value calculation process, the base command value is calculated based on map information or mathematical formula information that links the amount of deviation and the amount of decrease of the base command value, and the acquired amount of deviation.

3. In the individual calculation process, an inner correction value is calculated to lower the rotational speed of the inner drive wheel in the turning direction of the electric vehicle compared to the base command value, based on map information or formula information linked to the amount of deviation and the inner correction value, and the acquired amount of deviation; an outer correction value is calculated to raise the rotational speed of the outer drive wheel in the turning direction of the electric vehicle compared to the base command value, based on map information or formula information linked to the amount of deviation and the outer correction value, and the acquired amount of deviation; a command value corresponding to the inner drive wheel in the turning direction, based on the base command value and the inner correction value, based on the right command value and the left command value; and a command value corresponding to the outer drive wheel in the turning direction, based on the base command value and the outer correction value, is calculated.

4. The control device for an electric vehicle according to claim 1, wherein in the base value calculation process, the amount of decrease of the base command value is calculated as an operandi for feedback control to reduce the acquired deviation amount to zero, and the base command value is calculated based on the calculated amount of decrease and the reference rotational speeds of the right drive wheel and the left drive wheel.

5. The control device for an electric vehicle according to claim 4, wherein in the individual calculation process, an inner correction value is calculated to lower the rotational speed of the inner drive wheel in the turning direction of the electric vehicle to a lower value than the base command value, and an outer correction value is calculated to raise the rotational speed of the outer drive wheel in the turning direction of the electric vehicle to a higher value than the base command value, among the right drive wheel and the left drive wheel, as an operand for feedback control to set the acquired deviation amount to 0; a command value corresponding to the inner drive wheel in the turning direction among the right command value and the left command value is calculated based on the base command value and the inner correction value; and a command value corresponding to the outer drive wheel in the turning direction among the right command value and the left command value is calculated based on the base command value and the outer correction value.

6. The control device for an electric vehicle according to claim 2, wherein the base value calculation process is a first base value calculation process, the command value calculation process includes a second base value calculation process, the second base value calculation process calculates a decrease in the base command value as an operand for feedback control of the acquired deviation amount to 0, the base command value is calculated based on the calculated decrease and the reference rotational speeds of the right drive wheel and the left drive wheel, and the command value calculation process includes a process of selecting and executing the first base value calculation process or the second base value calculation process based on the acquired deviation amount.

7. The control device for an electric vehicle according to claim 3, wherein the individual calculation process is a first individual calculation process, the command value calculation process includes a second individual calculation process, in the second individual calculation process, an inner correction value is calculated as an operation variable for feedback control to set the acquired deviation amount to zero, to lower the rotational speed of the drive wheel on the inside in the turning direction of the electric vehicle to a lower value than the base command value, and an outer correction value is calculated as an operation variable for setting the rotational speed of the drive wheel on the outside in the turning direction of the electric vehicle to a higher value than the base command value, among the right command value and the left command value, a command value corresponding to the drive wheel on the inside in the turning direction is calculated based on the base command value and the inner correction value, among the right command value and the left command value, a command value corresponding to the drive wheel on the outside in the turning direction is calculated based on the base command value and the outer correction value, and the command value calculation process includes a process of selecting and executing the first individual calculation process or the second individual calculation process based on the acquired deviation amount.

8. The control device for an electric vehicle according to any one of claims 1 to 7, wherein the command value calculation process includes a process to reduce the base command value when either the calculated right command value or the left command value reaches an upper limit.

9. The control device for an electric vehicle according to any one of claims 1 to 7, wherein the vehicle is provided with a sensor (78) that passes through the center of the vehicle width direction of the electric vehicle and extends in the vehicle width direction, and detects the amount of displacement, and the sensor is provided on the vehicle body at a position in front of the right drive wheel and the left drive wheel in the vehicle length direction of the electric vehicle.

10. A program applied to an electric vehicle (10) comprising: a vehicle body (11); a left drive wheel (12L) and a right drive wheel (12R) rotatably supported with respect to the vehicle body; a left motor (31) for driving the left drive wheel; and a right motor (31) for driving the right drive wheel, which travels along guide lines (200, 201) and turns by creating a rotational speed difference between the rotational speed of the left drive wheel and the rotational speed of the right drive wheel, wherein at least one of the processor and circuit is made to perform: a command value calculation process that calculates a right command value which is a command value for the rotational speed of the right drive wheel and a left command value which is a command value for the rotational speed of the left drive wheel; a process that executes drive control of the right motor to control the rotational speed of the right drive wheel to the right command value and a process that executes drive control of the left motor to control the rotational speed of the left drive wheel to the left command value, wherein the command value calculation process is A program comprising: a base value calculation process for calculating a base command value for the rotational speed of the right drive wheel and the left drive wheel; and an individual calculation process for calculating the right command value and the left command value such that the rotational speed of the drive wheel on the inside in the turning direction of the electric vehicle is lower than the base command value, while the rotational speed of the drive wheel on the outside in the turning direction of the electric vehicle is higher than the base command value, wherein in the base value calculation process, the amount of deviation of the vehicle body in the vehicle width direction between the guide line and the center position of the vehicle body is obtained, and the larger the obtained amount of deviation, the smaller the calculated base command value.

11. A control method applied to an electric vehicle (10) comprising: a vehicle body (11); a left drive wheel (12L) and a right drive wheel (12R) rotatably supported with respect to the vehicle body; a left motor (31) for driving the left drive wheel; and a right motor (31) for driving the right drive wheel, wherein the electric vehicle (10) travels along guide lines (200, 201) and turns by creating a rotational speed difference between the rotational speed of the left drive wheel and the rotational speed of the right drive wheel, wherein at least one of the processor and circuit performs: a command value calculation process that calculates a right command value which is a command value for the rotational speed of the right drive wheel and a left command value which is a command value for the rotational speed of the left drive wheel; a process that performs drive control of the right motor to control the rotational speed of the right drive wheel to the right command value and a process that performs drive control of the left motor to control the rotational speed of the left drive wheel to the left command value, wherein the command value calculation process is A control method comprising: a base value calculation process for calculating a base command value for the rotational speed of the right drive wheel and the left drive wheel; and an individual calculation process for calculating the right command value and the left command value such that the rotational speed of the drive wheel on the inside in the turning direction of the electric vehicle is lower than the base command value, while the rotational speed of the drive wheel on the outside in the turning direction of the electric vehicle is higher than the base command value, wherein in the base value calculation process, the amount of deviation of the vehicle body in the vehicle width direction between the guide line and the center position of the vehicle body is obtained, and the larger the obtained amount of deviation, the smaller the base command value is calculated to be.

Images