Control device for automated guided vehicle

Abstract

To excellently secure the traveling stability of an automated guided vehicle on a slope.SOLUTION: A control device for an automated guided vehicle according to the present disclosure is provided to control an automated guided vehicle that includes a drive wheel driven by a drive source mounted on a vehicle body and a caster rotatably supported by the vehicle body. The control device determines whether a slope having a predetermined gradient or more is present or not ahead of the automated guided vehicle. When determining that the slope is present ahead of the automated guided vehicle, the control device sets a direction of the automated guided vehicle such that the drive wheel is located on an upper side and the caster is located on a lower side on the slope.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a control device for an automated guided vehicle that includes drive wheels driven by a drive source mounted on the vehicle body and casters rotatably supported by the vehicle body. [Background technology]

[0002] Conventionally, there is known an automated guided vehicle including a front caster supported on the front side of the vehicle body so as to be rotatable about a vertical axis, a rear caster supported on the rear side of the vehicle body so as to be rotatable about a vertical axis, a drive wheel unit supported by the vehicle body so as to be movable forward and backward and which applies a thrust to the vehicle body, and a caster lock release device (see, for example, Patent Document 1). When the drive wheel unit moves to one side of the front caster or the rear caster, the caster lock release device of this automated guided vehicle locks the other of the front caster and the rear caster so as to rotate in the axle direction and allows one of the front caster and the rear caster to be rotatable about the vertical axis. That is, when the automated guided vehicle moves forward, the drive wheel unit is moved forward, and the rotation of the rear caster is locked and the front caster becomes rotatable. Also, when the automated guided vehicle moves backward, the drive wheel unit is moved backward, and the rotation of the front caster is locked and the rear caster becomes rotatable. As a result, good steering performance is ensured when the automated guided vehicle is moving forward and backward. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2004-249896 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned automated guided vehicle, the casters on the front side in the traveling direction are rotatable, and the rotation of the casters on the rear side in the traveling direction is locked. However, when the automated guided vehicle travels uphill, if the direction of the vehicle body is misaligned due to the unevenness of the road surface or the difference in power between the left and right drive wheels, the direction of the casters on the front side in the traveling direction will change due to gravity acting on the vehicle body, etc., and the automated guided vehicle may travel in an unintended direction or slip down on the uphill road.

[0005] Therefore, a main object of the present disclosure is to ensure good running stability of an automated guided vehicle on a slope. [Means for solving the problem]

[0006] The control device for an unmanned guided vehicle disclosed herein is a control device for an unmanned guided vehicle that includes drive wheels driven by a drive source mounted on the vehicle body and casters supported by the vehicle body so as to be freely rotatable, and determines whether or not a slope with a predetermined gradient or greater exists in front of the unmanned guided vehicle, and when it is determined that a slope exists in front of the unmanned guided vehicle, sets the orientation of the unmanned guided vehicle so that the drive wheels are positioned on the upper side and the casters are positioned on the lower side of the slope.

[0007] The control device for an automated guided vehicle disclosed herein, when it is determined that a slope with a predetermined gradient or more exists ahead of the automated guided vehicle, sets the orientation of the automated guided vehicle so that the drive wheels are positioned on the upper side and the casters are positioned on the lower side on the slope. This reduces the effect of changes in the orientation of the casters due to gravity when the automated guided vehicle travels on a slope, and effectively prevents the automated guided vehicle from traveling in an unintended direction or slipping down on a slope. As a result, the control device for an automated guided vehicle disclosed herein makes it possible to effectively ensure the running stability of the automated guided vehicle on a slope. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic configuration diagram of an automated guided vehicle including a control device according to the present disclosure. [Diagram 2] 4 is a flowchart showing a routine executed by a control device for an automated guided vehicle according to the present disclosure. [Diagram 3] 3A, 3B, 3C, 3D, and 3E are explanatory diagrams showing the state of the automated guided vehicle when the routine of FIG. 2 is executed by the control device for the automated guided vehicle according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Next, an embodiment of the present disclosure will be described with reference to the drawings.

[0010] FIG. 1 is a schematic diagram of an automated guided vehicle 1 including a control device 10 according to the present disclosure. The automated guided vehicle 1 shown in the figure is an autonomous mobile transport robot (AMR) capable of autonomously traveling with a load on the premises of, for example, a factory, a logistics facility such as a distribution center, or a large-scale commercial facility. As shown in the figure, the automated guided vehicle 1 includes a vehicle body 2 capable of carrying a load (not shown), a pair of left and right casters 3, a pair of left and right drive wheels 4, 5, a drive unit 6 for driving one of the drive wheels 4, and a drive unit 7 for driving the other drive wheel 5. Furthermore, the automated guided vehicle 1 includes a control device 10 for controlling the drive units 6, 7, a laser sensor 11 for acquiring travel route information of the automated guided vehicle 1, and an acceleration sensor 12 for detecting the acceleration of the automated guided vehicle 1 in the forward and backward directions.

[0011] Each caster 3 includes a rolling wheel 30, and is supported rotatably around an axis extending in the vehicle height direction at one end of the vehicle body 2 in the longitudinal direction so as to be spaced apart from each other in the vehicle width direction. A pair of drive wheels 4, 5 is provided at the other end of the vehicle body 2 in the longitudinal direction so as to be spaced apart from each other in the vehicle width direction and from the caster 3 in the longitudinal direction of the vehicle body 2. The drive units 6, 7 each include an electric motor or the like, and independently drive the corresponding drive wheel 4 or 5. In this embodiment, the automated guided vehicle 1 basically moves forward with each caster 3 positioned at the front side and the drive wheels 4, 5 positioned at the rear side, and moves backward with each caster 3 positioned at the rear side and the drive wheels 4, 5 positioned at the front side. In addition, when the automated guided vehicle 1 travels around a curve, the drive units 6, 7 are controlled by the control device 10 so as to generate a rotation difference between the drive wheels 4, 5.

[0012] The control device 10 includes a microcomputer having a CPU, ROM, RAM, input / output interface, etc. (not shown), and a plurality of drive circuits for driving the corresponding drive units 6, 7. The laser sensor 11 is a 3D LiDAR sensor that irradiates a plurality of laser beams ahead of the automatic guided vehicle 1 to obtain information about the travel path ahead of the automatic guided vehicle 1, and transmits the obtained information to the control device 10. In addition, the acceleration sensor 12 detects the acceleration in the forward and backward directions of the automatic guided vehicle 1, and transmits a signal indicating the detected value to the control device 10.

[0013] FIG. 2 is a flowchart showing a routine that is repeatedly executed by the control device 10 at predetermined time intervals (short time intervals) while the automatic guided vehicle 1 is traveling.

[0014] When the execution timing of the routine of Fig. 2 arrives, the control device 10 executes an acquisition process of information on the forward travel route of the automatic guided vehicle 1 acquired by the laser sensor 11 (step S100), and judges whether or not the information on the travel route has been acquired (step S110). If the information on the travel route has been acquired from the laser sensor 11 (step S110: YES), the control device 10 calculates (acquires) the road surface gradient θ (upward is "positive" and downward is "negative") of the forward travel route along which the automatic guided vehicle 1 is scheduled to travel, based on the acquired information on the travel route (step S120). Furthermore, the control device 10 judges whether or not the road surface gradient θ calculated in step S120 is equal to or greater than a predetermined threshold value θref (for example, about 1° to 5°) (step S130).

[0015] When it is determined that the road surface gradient θ is equal to or greater than the threshold value θref (step S130: YES), the control device 10 controls the drive units 6 and 7 to stop the automatic guided vehicle 1 from traveling (step S140). As shown in FIG. 3(a), after the automatic guided vehicle 1 stops, the control device 10 controls the drive units 6 and 7 to rotate the drive wheels 4 and 5 in the opposite directions, and changes the orientation of the automatic guided vehicle 1 so that the casters 3 are located on the rear side in the traveling direction and the drive wheels 4 and 5 are located on the front side in the traveling direction, as shown in FIG. 3(b) (step S150). That is, in step S150, if there is an uphill road S in front of the automatic guided vehicle 1 with a road surface gradient θ equal to or greater than the threshold value θref, the orientation of the automatic guided vehicle 1 is set so that the drive wheels 4 and 5 are located on the upper side and the casters 3 are located on the lower side on the uphill road S.

[0016] After the process of step S150, the control device 10 controls the drive units 6, 7 to resume the travel of the automated guided vehicle 1 (step S160), and temporarily ends the routine of FIG. 2. As a result, the automated guided vehicle 1 travels on the uphill road S in a state where the drive wheels 4, 5 are located on the upper side and the casters 3 are located on the lower side (front-wheel drive state). Also, when it is determined that the road surface gradient θ of the forward travel path is less than the threshold value θref (step S130: NO), the control device 10 allows the automated guided vehicle 1 to continue traveling as it is (step S135), and temporarily ends the routine of FIG. 2. As a result, when there is a downhill road ahead of the automated guided vehicle 1, the automated guided vehicle 1 travels on the uphill road S in a state where the casters 3 are located on the front side and the drive wheels 4, 5 are located on the rear side, without changing its direction. That is, the automated guided vehicle 1 travels downhill in a state where the drive wheels 4, 5 are positioned on the upper side and the casters 3 are positioned on the lower side (rear-wheel drive state).

[0017] On the other hand, if information regarding the travel route is not acquired from the laser sensor 11 due to, for example, a communication interruption or the like (step S110: NO), the control device 10 acquires a detection value from the acceleration sensor 12, and calculates the road surface gradient φ of the travel route on which the automated guided vehicle 1 is traveling based on the acquired detection value (step S170). Next, the control device 10 determines whether the road surface gradient φ calculated in step S170 is equal to or greater than a predetermined threshold value φref (step S180). The threshold value φref used in step S180 is adapted to a value smaller than the threshold value θref used in step S130 through experiments, analyses, etc.

[0018] When it is determined that the road surface gradient φ is equal to or greater than the threshold value φref (step S180: YES), the control device 10 controls the drive units 6, 7 to stop the travel of the automated guided vehicle 1 (see FIG. 3(c)), and then controls the drive units 6, 7 to cause the automated guided vehicle 1 to move backward to a flat road F and stop (step S190). As shown in FIG. 3(d), when the automated guided vehicle 1 stops on the flat road F, the control device 10 changes the direction of the automated guided vehicle 1 so that the casters 3 are positioned on the rear side in the traveling direction and the drive wheels 4, 5 are positioned on the front side in the traveling direction, as shown in FIG. 3(e) (step S150). That is, in this embodiment, when the automated guided vehicle 1 approaches an uphill road S without acquiring information on the travel route ahead of the automated guided vehicle 1 and the road surface gradient φ becomes equal to or greater than the threshold value φref, it is deemed that an uphill road S with a road surface gradient θ equal to or greater than the threshold value θref exists ahead of the automated guided vehicle 1, and the automated guided vehicle 1 is temporarily moved backward to the flat road F. Then, the orientation of the automated guided vehicle 1 is set so that the drive wheels 4, 5 are positioned on the upper side and the casters 3 are positioned on the lower side on the uphill road S ahead on the flat road F. In this way, the automated guided vehicle 1 that has come close to the uphill road S is temporarily reversed to the flat road F, so that the orientation of the automated guided vehicle 1 can be changed without disturbing its behavior.

[0019] After the process of step S150, the control device 10 controls the drive units 6 and 7 to resume the travel of the automated guided vehicle 1 (step S160), and temporarily ends the routine of FIG. 2. As a result, the automated guided vehicle 1 travels on the uphill road S in a state where the drive wheels 4 and 5 are located on the upper side and the casters 3 are located on the lower side (front-wheel drive state). In addition, when it is determined that the road surface gradient φ of the travel route on which the automated guided vehicle 1 is traveling is less than the threshold value φref (step S180: NO), the control device 10 allows the automated guided vehicle 1 to continue traveling as is (step S185), and temporarily ends the routine of FIG. 2. As a result, when the automated guided vehicle 1 approaches a downhill road without acquiring information about the travel route ahead, it travels on the downhill road without changing its direction in a state where the casters 3 are located on the front side and the drive wheels 4 and 5 are located on the rear side, that is, the drive wheels 4 and 5 are located on the upper side and the casters 3 are located on the lower side (rear-wheel drive state).

[0020] As described above, the control device 10 controls the automated guided vehicle 1 including a pair of drive wheels 4, 5 driven by drive units 6, 7 mounted on the vehicle body 2, and a pair of casters 3 rotatably supported by the vehicle body 2. The control device 10 judges whether or not there is an uphill road S ahead of the automated guided vehicle 1, the road surface gradient θ of which is equal to or greater than a threshold value θref (predetermined gradient) (steps S120, S170), and when it judges that there is an uphill road S ahead of the automated guided vehicle 1 (steps S120: YES, S170: YES), it sets the orientation of the automated guided vehicle 1 so that the drive wheels 4, 5 are positioned on the upper side and the casters 3 are positioned on the lower side on the uphill road S (step S150).

[0021] This reduces the effect of the change in the orientation of each caster 3 due to gravity acting according to the vehicle weight and the weight of the load when the automated guided vehicle 1 travels on an uphill road S, and effectively prevents the automated guided vehicle 1 from moving in an unintended direction or slipping down on the uphill road S. In addition, the control device 10 causes the automated guided vehicle 1 to travel downhill in a state in which the drive wheels 4, 5 are positioned on the upper side and the casters 3 are positioned on the lower side (rear-wheel drive state). As a result, the control device 10 makes it possible to effectively ensure the running stability of the automated guided vehicle 1 on slopes, i.e., on the uphill road S and downhill roads.

[0022] In addition, when the automated guided vehicle 1 is capable of measuring the weight of the load, the threshold value θref used in step S130 and the threshold value φref used in step S180 may be set to change according to the weight of the measured load. Furthermore, the automated guided vehicle 1 is not limited to one capable of autonomous driving, and may be one that travels along a designated route to a destination (so-called AGV). In this case, in step S120, the road surface gradient θ of the forward travel route along which the automated guided vehicle 1 is scheduled to travel may be acquired from route information prepared in advance. Furthermore, the automated guided vehicle 1 may include one or three or more casters 3 that are supported by the vehicle body 2 so as to be rotatable away from the drive wheels 4, 5 in the front-rear direction of the vehicle body 2. Furthermore, the automated guided vehicle 1 may include a 3D camera instead of the laser sensor 11. Furthermore, the automated guided vehicle 1 may include a gyro sensor in addition to the acceleration sensor 12. In this case, in step S170, the road surface gradient φ of the travel route on which the automated guided vehicle 1 is traveling may be calculated based on both the detection value of the acceleration sensor 12 and the detection value of the gyro sensor. This can further improve the calculation accuracy of the road surface gradient φ, making it possible to quickly determine that the automated guided vehicle 1 has approached an uphill road S. In addition, the control device 10 may be applied to an automated guided vehicle that does not include a laser sensor 11 or the like that acquires information about the travel route ahead. In such an automated guided vehicle, the control device 10 may execute the processes of steps S170-S190, S150-S160, and S185 of the routine in FIG. 2.

[0023] The present disclosure is not limited to the above embodiment, and various modifications can be made within the scope of the present disclosure. Furthermore, the above embodiment is merely a specific form of the invention described in the Summary of the Invention, and does not limit the elements of the invention described in the Summary of the Invention. [Industrial Applicability]

[0024] The presently disclosed invention can be used in the manufacturing industry, logistics industry, service industry, and the like that utilize automated guided vehicles. [Explanation of symbols]

[0025] 1 automated guided vehicle, 2 vehicle body, 3 caster, 30 rolling wheel, 4,5 drive wheel, 6,7 drive unit, 10 control device, 11 laser sensor, 12 acceleration sensor, F flat road, S uphill road.

Claims

[Claim 1] A control device for an automated guided vehicle including a drive wheel driven by a drive source mounted on a vehicle body and a caster rotatably supported by the vehicle body, A control device for an unmanned guided vehicle that determines whether or not a slope with a predetermined gradient or more exists ahead of the unmanned guided vehicle, and when it is determined that a slope exists ahead of the unmanned guided vehicle, sets the orientation of the unmanned guided vehicle so that the drive wheels are positioned on the upper side and the casters are positioned on the lower side on the slope.

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