JP7704429B2 - Swing control device and method - Google Patents

Description

The present invention relates to a turning control device and a turning control method for automatically turning a tracked vehicle equipped with crawlers (crawler tracks, tracks, track belts, caterpillars) for running on the left and right.

Tracked vehicles have crawlers on the left and right for travel. Tracked vehicles can achieve high maneuverability on rough ground. For example, Patent Document 1 shows a tracked vehicle that uses an electric motor as a power source.

Japanese Patent Application Publication No. 11-46403

When a tracked vehicle makes a pivot turn or a yaw turn, the crawlers push soil in the direction of the turn. For example, when a tracked vehicle makes a pivot turn to the left, soil clods are formed on the left side of the front half of each crawler and on the right side of the rear half of each crawler. As the turning angle of the tracked vehicle increases, the soil clods become larger and the ground becomes rough. Furthermore, when a tracked vehicle makes a pivot turn while pushing a large soil clod, the power source (such as an electric motor) needs to generate a large torque. This increases the amount of energy consumed by the tracked vehicle. For these reasons, there is a need for a turning method that damages fields as little as possible when the tracked vehicle turns and allows it to turn with little power.

The present invention aims to solve the above-mentioned problems.

The first aspect of the present invention is a turning control device that automatically turns a tracked vehicle equipped with crawlers for travel on the left and right, and includes an acquisition unit that acquires the load value of the power source of the left and right crawlers, a turning control unit that controls the left and right crawlers to make the tracked vehicle turn or pivot until the tracked vehicle faces a target direction, and a movement control unit that temporarily suspends the turning or pivot made by the turning control unit each time the load value reaches a predetermined value, and controls the left and right crawlers to move the tracked vehicle forward or backward a predetermined distance.

The second aspect of the present invention is a turning control method that uses a computer to automatically control the turning of a tracked vehicle equipped with crawlers for travel on the left and right, and includes an acquisition step of acquiring the load value of the power source of the left and right crawlers, a turning step of controlling the left and right crawlers to make the tracked vehicle turn in a pivot or yaw direction until the tracked vehicle faces a target direction, and a moving step of temporarily suspending the pivot or yaw direction in the turning step each time the load value reaches a predetermined value, and controlling the left and right crawlers to move the tracked vehicle forward or backward a predetermined distance.

The present invention can reduce damage to the ground and energy consumption.

FIG. 1 is a block diagram showing a tracked vehicle according to a first embodiment. FIG. 2 is a flowchart showing a flow of control performed by a computing device provided in the driving control device. FIG. 3 is an explanatory diagram showing a first example of turning operation of a tracked vehicle in a time series manner. FIG. 4 is an explanatory diagram showing a second example of the turning operation of the tracked vehicle in a time series manner. FIG. 5 is a block diagram showing a tracked vehicle according to the second embodiment.

[1 First embodiment]
[1-1 Configuration of tracked vehicle 10]
FIG. 1 is a block diagram showing a tracked vehicle 10. The tracked vehicle 10 is equipped with crawlers 12R, 12L on the left and right sides of the vehicle body. The tracked vehicle 10 can move forward, backward, and turn by driving the left and right crawlers 12R, 12L. The tracked vehicle 10 of this embodiment is a vehicle that automatically performs turning control. For example, the tracked vehicle 10 is an autonomous vehicle that automatically performs running control and turning control.

The tracked vehicle 10 of this embodiment has electric motors (travel motors 50R, 50L) as a power source, but may also have an engine, hydraulic motor, etc. as a power source. The tracked vehicle 10 of this embodiment has a pair of electric motors that correspond individually to the left and right crawlers 12R, 12L, but may also have a single electric motor. The output of the single electric motor is distributed and supplied to the left and right crawlers 12R, 12L. Note that in this embodiment, the tracked vehicle 10 is assumed to be a small transport machine that moves forward by following a preceding object to be followed (e.g. a person). The small transport machine transports, for example, agricultural crops harvested by a person in a field.

The tracked vehicle 10 has an input device group 16, a driving control device 18, a battery 20, two motor control circuits 22R, 22L, and left and right drive devices 24R, 24L. The input device group 16 includes one or more cameras 26, an inertial measurement device 28, and two current sensors 30R, 30L. The one or more cameras 26 are sensors that acquire information such as the position of the target to be followed. LiDAR may be used as a sensor that acquires information about the target to be followed. In addition, other tracking systems using beacons or the like may be used to automatically follow the target to be followed by the tracked vehicle 10. In addition, an attitude and orientation reference device may be used instead of the inertial measurement device 28. The drive device 24R includes a traveling motor 50R, a power transmission mechanism 52R, and a crawler 12R. The drive device 24L includes a traveling motor 50L, a power transmission mechanism 52L, and a crawler 12L. The traction motors 50R and 50L are the power sources for the tracked vehicle 10.

In the following, the current sensors 30R, 30L are also simply referred to as the current sensors 30. The motor control circuits 22R, 22L are also simply referred to as the motor control circuits 22. The travel motors 50R, 50L are also simply referred to as the travel motors 50. The power transmission mechanisms 52R, 52L are also simply referred to as the power transmission mechanisms 52. The crawlers 12R, 12L are also simply referred to as the crawlers 12.

The cameras 26 capture images of the area around the tracked vehicle 10. At least one of the cameras 26 captures images of the area in front of the tracked vehicle 10. The cameras 26 output image data acquired by capturing images to the cruise control device 18. The inertial measurement device 28 has a three-axis gyro and three-directional acceleration sensors. The inertial measurement device 28 measures the acceleration and turning angular velocity of the tracked vehicle 10. The inertial measurement device 28 outputs the measurement data to the cruise control device 18. The current sensor 30R detects the current supplied by the motor control circuit 22R to the travel motor 50R. The current sensor 30L detects the current supplied by the motor control circuit 22L to the travel motor 50L. The current sensor 30 outputs the detection data to the cruise control device 18.

The driving control device 18 controls the driving (forward, backward, turning, etc.) of the tracked vehicle 10. In other words, the driving control device 18 functions as a turning control device. The driving control device 18 has a calculation device 32 and a storage device 34.

The arithmetic device 32 is a computer and has a processing circuit. The processing circuit may be a processor such as a CPU. The processing circuit may be an integrated circuit such as an ASIC or an FPGA. The processor can execute various processes by executing programs stored in the storage device 34. The arithmetic device 32 functions as an acquisition unit 36, a target recognition unit 38, a position recognition unit 40, an operation determination unit 42, a travel control unit 44, a turning control unit 46, and a movement control unit 48. At least some of the multiple processes may be executed by electronic circuits including discrete devices.

The acquisition unit 36 acquires various data (image data from the camera 26, measurement data from the inertial measurement device 28, detection data from the current sensor 30, etc.) from the input device group 16. The target recognition unit 38 performs image recognition using the image data to recognize the target (person) to be followed. The position recognition unit 40 recognizes the position of the tracked vehicle 10 in the field and the orientation of the tracked vehicle 10 based on the measurement data. The operation determination unit 42 determines the operation of the tracked vehicle 10, such as the running direction (movement direction), running speed, whether or not turning is required, the angle to turn, etc., based on the recognition results of the target recognition unit 38 and the recognition results of the position recognition unit 40. The traveling control unit 44 performs running control of the tracked vehicle 10 based on the determination results of the operation determination unit 42. The turning control unit 46 performs turning control of the tracked vehicle 10 based on the determination results of the operation determination unit 42. The movement control unit 48 performs movement control of the tracked vehicle 10 based on the determination results of the operation determination unit 42.

The storage device 34 has a volatile memory and a non-volatile memory. Examples of the volatile memory include RAM. The volatile memory is used as a working memory for the processor. The volatile memory temporarily stores data and the like required for processing or calculation. Examples of the non-volatile memory include ROM and flash memory. The non-volatile memory is used as a storage memory. The non-volatile memory stores programs, tables, maps, and the like. At least a portion of the storage device 34 may be provided in the processor, integrated circuit, and the like as described above.

The storage device 34 stores various predetermined values used in various controls. For example, the storage device 34 stores, as predetermined values, the current threshold of the travel motor 50 and the predetermined distance that the tracked vehicle 10 moves forward and backward while turning.

The motor control circuit 22 has an inverter circuit and the like. The switching elements of the inverter circuit are switched in response to a control signal output by the calculation device 32. The motor control circuit 22 converts the direct current of the battery 20 into alternating current and outputs it to the driving motor 50.

The traveling motor 50 is an electric motor, for example a three-phase AC motor. The traveling motor 50 is driven by power supplied from the battery 20 via the motor control circuit 22. The output shaft of the traveling motor 50 is connected to a drive wheel (not shown) via a power transmission mechanism 52. The power transmission mechanism 52 has, for example, a reducer. The drive wheel rotates the crawler 12.

[1-2 Turning control and movement control]
FIG. 2 is a flowchart showing the flow of control performed by the arithmetic unit 32 provided in the travel control device 18. When the tracked vehicle 10 travels following a target, the operation determination unit 42 determines the rotation direction and rotation speed of each travel motor 50 so that the orientation of the tracked vehicle 10 coincides with the direction of the target. The operation determination unit 42 determines that turning is necessary when the angle difference between the orientation of the tracked vehicle 10 and the direction of the target is equal to or greater than a predetermined value. In this specification, this angle difference is referred to as the angle at which the vehicle should turn, that is, the target angle of turning. The operation determination unit 42 calculates the target angle and stores it in the storage device 34. The storage device 34 stores the target angle until the turning is completed. When the tracked vehicle 10 turns, the travel control device 18 performs the process shown in FIG. 2.

In step S1, the turning control unit 46 performs turning control. Here, the turning control unit 46 performs control of a whirlpool turn as the turning control. Note that the turning control unit 46 may also perform control of a whirlpool turn as the turning control. The turning control unit 46 performs a whirlpool turn by rotating the driving motor 50R and the driving motor 50L in opposite directions. During a whirlpool turn, the turning control unit 46 may make the rotation speed of the driving motor 50R and the rotation speed of the driving motor 50L equal to each other, or may make them different from each other. When step S1 ends, the process proceeds to step S2.

In step S2, the acquisition unit 36 acquires the detection data of each current sensor 30, i.e., the current value of each driving motor 50. When step S2 ends, the process proceeds to step S3.

In step S3, the acquisition unit 36 acquires measurement data from the inertial measurement unit 28. The position recognition unit 40 calculates a turning angle based on the measurement data. The turning angle is the angle that the tracked vehicle 10 has turned at one or more positions since the turning control unit 46 started turning control up to the current time. When step S3 ends, the process proceeds to step S4.

In step S4, the turning control unit 46 compares the turning angle with the target angle. If the turning angle is less than the target angle (step S4: YES), the process proceeds to step S5. At this stage, turning has not ended. Therefore, the turning control unit 46 continues turning control. On the other hand, if the turning angle is equal to or greater than the target angle (step S4: NO), the series of processes shown in FIG. 2 ends. At this stage, the tracked vehicle 10 is heading toward the target to be followed.

When moving from step S4 to step S5, the turning control unit 46 compares each of the current values acquired in step S2 with the current threshold value stored in the memory device 34. If any of the current values is equal to or greater than the current threshold value (step S5: YES), the process moves to step S6. On the other hand, if each of the current values is less than the current threshold value (step S5: NO), the process returns to step S1.

When the process moves from step S5 to step S6, the movement control unit 48 temporarily suspends the turning control performed by the turning control unit 46. When step S6 ends, the process moves to step S7.

In step S7, the movement control unit 48 rotates each of the travel motors 50 a predetermined amount in the same direction, thereby moving the tracked vehicle 10 forward or backward a predetermined distance. After rotating each of the travel motors 50 a predetermined amount in the same direction, the movement control unit 48 releases the suspension of the turning control. When step S7 ends, the process returns to step S1.

[1-3 Operation of the tracked vehicle 10]
[1-3-1 First Example]
3 is an explanatory diagram showing a first example of a turning operation of the tracked vehicle 10 in a time series. The first example is a control example in which the movement control unit 48 moves the tracked vehicle 10 forward in the movement control (step S7 in FIG. 2).

Between time t0 and time t1, the turning control unit 46 makes the tracked vehicle 10 make a pivot turn counterclockwise (arrow A) (step S1 in Figure 2). While the tracked vehicle 10 is turning, a lump of soil 56 is formed to the left of the front half of the crawler 12 and to the right of the rear half of the crawler 12. In Figure 3, the dotted area is the lump of soil 56. As the lump of soil 56 becomes larger, the current value of the travel motor 50 detected by the current sensor 30 becomes larger.

At time t1, the turning control unit 46 determines that the current value of any of the current sensors 30 is equal to or greater than the current threshold (step S5 in FIG. 2: YES). The turning control unit 46 temporarily suspends turning control (step S6 in FIG. 2).

Between time t1 and time t2, the movement control unit 48 moves the tracked vehicle 10 forward (arrow B) a predetermined distance. (Step S7 in FIG. 2). By moving the tracked vehicle 10 forward by more than half L/2 of the crawler length L, the front half of the crawler 12 can move to a position where there is no soil mass 56 on the left side, and the rear half of the crawler 12 can move to a position where there is no soil mass 56 on the right side. On the other hand, if the moving distance of the tracked vehicle 10 is too long, the positional deviation of the turning center of the tracked vehicle 10 becomes large until the turning angle of the tracked vehicle 10 reaches the target angle. In order to reduce the positional deviation of the turning center, it is preferable that the predetermined distance is as small as possible. From the above, it is preferable that the predetermined distance that the tracked vehicle 10 moves during one turning interruption is more than half L/2 of the crawler length L and is less than the crawler length L. More specifically, it is preferable that the predetermined distance is half L/2 of the crawler length L. The crawler length L is the length from the front end of the crawler 12 to the rear end of the crawler 12.

From time t2 onwards (time t2 to time t5), the turning control unit 46 performs the same control as that performed from time t0 to time t2 until the turning angle reaches the target angle. When the turning angle reaches the target angle, the turning control unit 46 ends the turning control. At this point, the tracked vehicle 10 is facing the target to be followed. The driving control unit 44 controls each driving motor 50 so that the tracked vehicle 10 drives while following the target to be followed.

In this way, in the first example, the travel control device 18 (turning control device) alternates between turning control and movement control when turning the tracked vehicle 10 by the target angle. In other words, the tracked vehicle 10 turns by the target angle while moving the turning position (turning center position). The size of each earth lump 56 formed by the first example is smaller than the size of the earth lump 56 formed by turning by the target angle at one location. Therefore, the travel control device 18 can reduce the size of the earth lump 56 formed when the tracked vehicle 10 turns. As a result, the torque required for the travel motor 50 when the tracked vehicle 10 turns is reduced. In other words, the travel control device 18 can reduce roughness of the ground and reduce power consumption by performing the operation of the first example.

[1-3-2 Second Example]
4 is an explanatory diagram showing a second example of the turning operation of the tracked vehicle 10 in a time series. The second example is a control example in which the movement control unit 48 alternates between moving the tracked vehicle 10 forward and moving the tracked vehicle 10 backward.

The operation from time t0 to time t3 in the second example is the same as the operation from time t0 to time t3 in the first example. The first and second examples differ in the movement direction of the tracked vehicle 10 from time t3 to time t4, i.e., the movement direction of the second movement control. In the first example, from time t3 to time t4, the movement control unit 48 moves the tracked vehicle 10 forward (arrow B) a predetermined distance (a distance half the crawler length L). On the other hand, in the second example, from time t3 to time t4, the movement control unit 48 moves the tracked vehicle 10 backward (arrow C) a distance equal to the crawler length L.

In this way, in the second example, the movement control unit 48 moves the tracked vehicle 10 forward during odd-numbered movement controls (step S7 in FIG. 2) and moves the tracked vehicle 10 backward during even-numbered movement controls (step S7 in FIG. 2). The movement control unit 48 may also move the tracked vehicle 10 backward during odd-numbered movement controls and move the tracked vehicle 10 forward during even-numbered movement controls. In short, the movement control unit 48 makes the movement direction of the tracked vehicle 10 at the nth (n is a natural number equal to or greater than 2) turning interruption the opposite direction to the movement direction of the tracked vehicle 10 at the n-1th turning interruption.

The movement control unit 48 may also move forward and backward in a pre-set sequence.

By performing the operation of the second example, the travel control device 18 not only achieves the same effect as the first example, but can also further reduce the positional deviation of the turning center. In addition, by alternately switching the movement direction of the tracked vehicle 10 by the travel control device 18, the tracked vehicle 10 moves over a part of the soil lump 56 formed immediately before during the nth movement. The soil lump 56 is then compacted. In other words, by performing the operation of the second example, the travel control device 18 can further reduce roughness of the ground compared to the first example.

[2 Second embodiment]
FIG. 5 is a block diagram showing the tracked vehicle 10 according to the second embodiment. The tracked vehicle 10 according to the second embodiment has further functions in addition to the functions of the tracked vehicle 10 according to the first embodiment. The tracked vehicle 10 according to the second embodiment has each of the components of the tracked vehicle 10 according to the first embodiment. In the second embodiment, the same components as those in the first embodiment are given the same reference numerals. In the first embodiment, the current threshold is a constant value stored in advance in the storage device 34. In contrast, in the second embodiment, the current threshold is a variable value. The differences between the second embodiment and the first embodiment will be described.

In the second embodiment, the calculation device 32 also functions as a remaining capacity acquisition unit 60 and a setting unit 62. The remaining capacity acquisition unit 60 acquires the remaining capacity of the battery 20. For example, the remaining capacity acquisition unit 60 acquires the current value, voltage value, and temperature of the battery 20, and calculates the SOC (State of Charge) of the battery 20. The setting unit 62 sets the current threshold based on the SOC of the battery 20. For example, the storage device 34 stores a map that associates the SOC of the battery 20 with the current threshold, or an arithmetic expression that calculates the current threshold from the SOC of the battery 20. The setting unit 62 sets the current threshold using the map or arithmetic expression stored in the storage device 34 immediately before step S1 shown in FIG. 2.

If the tracked vehicle 10 turns when the SOC of the battery 20 is low, it may not be able to turn even if the earth block 56 is relatively small. According to the second embodiment, the travel control device 18 can turn the tracked vehicle 10 even when the SOC of the battery 20 is low.

[3 Other embodiments]
The tracked vehicle 10 of the first and second embodiments advances by following a target (person). However, the tracked vehicle 10 may advance along a preset travel route. In this case, the target recognition unit 38 recognizes the travel route. The operation determination unit 42 determines the direction in which the tracked vehicle 10 should travel, the angle at which the tracked vehicle 10 should turn, etc., based on the travel route recognized by the target recognition unit 38 and the position and orientation of the tracked vehicle 10 recognized by the position recognition unit 40.

Alternatively, the tracked vehicle 10 may be a manned vehicle in which the user controls everything other than turning, and only turning is performed automatically. The tracked vehicle 10 may also be a remote-operated vehicle operated by a user from a remote location. When the tracked vehicle 10 is a manned or remote-operated vehicle, for example, the user issues a turning instruction (such as a button operation), and the turning control unit 46 and the movement control unit 48 perform the automatic control shown in FIG. 2.

The position recognition unit 40 does not need to use the measurement data of the inertial measurement unit 28 when calculating the turning angle of the tracked vehicle 10. For example, the position recognition unit 40 can calculate the turning angle of the tracked vehicle 10 based on the turning time, the load of the power source (the current value of the driving motor 50 in the above embodiment), etc.

[4. Invention Obtained from the Embodiments]
The invention that can be understood from the above embodiment will be described below.

The first aspect of the present invention is a turning control device (18) that automatically turns a tracked vehicle (10) equipped with left and right crawlers (12) for traveling, and includes an acquisition unit (36) that acquires the load value of the power source of the left and right crawlers, a turning control unit (46) that controls the left and right crawlers to make the tracked vehicle turn or pivot until the tracked vehicle faces the target direction, and a movement control unit (48) that temporarily suspends the turning or pivot made by the turning control unit each time the load value reaches a predetermined value, and controls the left and right crawlers to move the tracked vehicle forward or backward a predetermined distance.

In a first aspect, the movement control unit may move the tracked vehicle forward or backward a distance equal to or greater than half (L/2) of the crawler length (L), which is the length from the front end of the crawler to the rear end of the crawler, and equal to or less than the crawler length.

In a first aspect, the movement control unit may move the tracked vehicle forward or backward a distance equal to half the crawler length.

In a first aspect, the movement control unit may set the movement direction of the tracked vehicle at the nth (n is a natural number equal to or greater than 2) turning interruption to be opposite to the movement direction of the tracked vehicle at the n-1th turning interruption.

In the first aspect, the power source may be an electric motor (50).

The turning control device of the first aspect may include a battery (20) that supplies power to the electric motor, a remaining charge acquisition unit (60) that acquires the remaining charge of the battery, and a setting unit (62) that sets the predetermined value based on the remaining charge acquired by the remaining charge acquisition unit.

The second aspect of the present invention is a turning control method that uses a computer to automatically control the turning of a tracked vehicle equipped with crawlers for travel on the left and right, and includes an acquisition step of acquiring the load value of the power source of the left and right crawlers, a turning step of controlling the left and right crawlers to make the tracked vehicle turn in a pivot or yaw direction until the tracked vehicle faces a target direction, and a moving step of temporarily suspending the pivot or yaw direction in the turning step each time the load value reaches a predetermined value, and controlling the left and right crawlers to move the tracked vehicle forward or backward a predetermined distance.

10: Tracked vehicle 12: Crawler 18: Travel control device (turning control device) 20: Battery 36: Acquisition unit 46: Turning control unit 48: Movement control unit 50: Travel motor (electric motor)
60: remaining amount acquisition unit 62: setting unit

Claims (7)

A turning control device for automatically turning a tracked vehicle having crawlers for traveling on the left and right sides,
An acquisition unit that acquires load values of power sources of the left and right crawlers;
a turning control unit that controls the left and right crawlers to make the tracked vehicle turn in a pivot or pivot direction until the tracked vehicle faces a target direction;
a movement control unit that temporarily suspends the pivot turn or pivot turn performed by the turning control unit each time the load value reaches a predetermined value, and controls the left and right crawlers to move the tracked vehicle forward or backward a predetermined distance. The turning control device according to claim 1,
The movement control unit is a turning control device that moves the tracked vehicle forward or backward a distance equal to or greater than half the crawler length, which is the length from the front end of the crawler to the rear end of the crawler, and less than or equal to the crawler length. The turning control device according to claim 2,
The movement control unit is a turning control device that moves the tracked vehicle forward or backward a distance equal to half the crawler length. The turning control device according to any one of claims 1 to 3,
The movement control unit is a turning control device that changes the movement direction of the tracked vehicle at the nth (n is a natural number greater than or equal to 2) turning interruption to the opposite direction to the movement direction of the tracked vehicle at the n-1th turning interruption. The turning control device according to any one of claims 1 to 4,
A turning control device, wherein the power source is an electric motor. The turning control device according to claim 5,
a battery for supplying power to the electric motor;
a remaining capacity acquisition unit for acquiring a remaining capacity of the battery;
a setting unit that sets the predetermined value based on the remaining amount acquired by the remaining amount acquisition unit. A method for automatically controlling the turning of a tracked vehicle having crawlers for traveling on the left and right sides, comprising the steps of:
an acquisition step of acquiring load values of power sources of the left and right crawlers;
a turning process for controlling the left and right crawlers to perform a pivot turn or a pivot turn of the tracked vehicle until the tracked vehicle faces a target direction;
a moving process of temporarily suspending the pivot turn or the swivel turn in the turning process each time the load value reaches a predetermined value, and controlling the left and right crawlers to move the tracked vehicle forward or backward a predetermined distance.

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