Travel control device for omnidirectional mobile vehicle

Abstract

To provide a traveling control device for an omnidirectional moving object that can shorten a stopping distance of the omnidirectional moving object on a downhill.SOLUTION: A traveling control device 10 comprises: four traveling motors 11 that independently rotate and drive four wheels 3; a traveling control unit 16 that controls the traveling motors 11 to cause an omnidirectional mobile robot 1 to travel; a downhill detection unit 17 that detects whether the omnidirectional mobile robot 1 travels a downhill S; and an orientation setting unit 18 that sets an orientation of the omnidirectional mobile robot 1. The orientation setting unit 18 sets the orientation of the omnidirectional mobile robot 1 to a two-wheel drive state in which two wheels 3 of the four wheels 3 facing each other are driven when the downhill detection unit 17 detects that the omnidirectional mobile robot 1 is traveling the downhill S.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a travel control device for an omnidirectional moving body. [Background technology]

[0002] As a travel control device for an omnidirectional moving body, for example, the technology described in Patent Document 1 is known. The travel control device described in Patent Document 1 is mounted on an omnidirectional moving dolly having four wheels. The travel control device includes four drive motors that independently drive the four wheels, an input device for setting and inputting target speeds in three degrees of freedom of the omnidirectional moving dolly, and a drive control controller that determines a target rotation speed of each wheel based on the target speeds in the three degrees of freedom set and input by the input device, and controls each drive motor according to the target rotation speed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2004-348678 A Summary of the Invention [Problem to be solved by the invention]

[0004] Omnidirectional vehicles that can move in all directions usually run in a four-wheel drive state in which all four wheels are driven, from the viewpoint of the drive efficiency of the motor that rotates the wheels. In this case, for example, if an obstacle is present in the direction of travel of the omnidirectional vehicle while traveling downhill, the vehicle is brought to an emergency stop. At this time, it is necessary to reduce the deceleration of the omnidirectional vehicle so that the rear wheels do not lift off the ground relative to the direction of travel of the omnidirectional vehicle even if the omnidirectional vehicle is suddenly decelerated. However, reducing the deceleration of the omnidirectional vehicle increases the stopping distance of the omnidirectional vehicle.

[0005] An object of the present invention is to provide a travel control device for an omnidirectional mobile body that can shorten the stopping distance of an omnidirectional mobile body on a downhill slope. [Means for solving the problem]

[0006] One aspect of the present invention is a driving control device for an omnidirectional mobile body that has four wheels and can move in all directions, the device comprising four driving motors that independently rotate and drive the four wheels, a driving control unit that controls the driving motors to drive the omnidirectional mobile body, a downslope detection unit that detects whether the omnidirectional mobile body is traveling downslope, and a setting unit that sets the orientation of the omnidirectional mobile body, wherein when the downslope detection unit detects that the omnidirectional mobile body is traveling downslope, the setting unit sets the orientation of the omnidirectional mobile body to an orientation for a two-wheel drive state in which two opposing wheels of the four wheels are driven, and when the setting unit sets the orientation of the omnidirectional mobile body to an orientation for a four-wheel drive state in which all four wheels are driven, the driving control unit controls the driving motors to drive the omnidirectional mobile body in the four-wheel drive state, and when the setting unit sets the orientation of the omnidirectional mobile body to an orientation for a two-wheel drive state, the driving control unit controls the driving motors to drive the omnidirectional mobile body in the two-wheel drive state.

[0007] In such a travel control device, when it is detected that the omnidirectional mobile body is traveling downhill, the orientation of the omnidirectional mobile body is set to the orientation of a two-wheel drive state in which two opposing wheels out of four wheels are driven. Then, the omnidirectional mobile body travels downhill in the two-wheel drive state. Here, since the wheel base of the omnidirectional mobile body is longer in the two-wheel drive state than in the four-wheel drive state in which four wheels are driven, even if the omnidirectional mobile body is suddenly decelerated on a downhill slope, the rear wheels are less likely to float in the traveling direction of the omnidirectional mobile body compared to the four-wheel drive state. Therefore, when the omnidirectional mobile body is stopped traveling on a downhill slope, the deceleration of the omnidirectional mobile body can be increased. This makes it possible to shorten the stopping distance of the omnidirectional mobile body on a downhill slope. In addition, since it is not necessary to reduce the speed and deceleration of the omnidirectional mobile body, the cycle time when the omnidirectional mobile body stops traveling can also be shortened.

[0008] When the downhill detection unit detects that the omnidirectional moving body is traveling downhill while the omnidirectional moving body is traveling in four-wheel drive state, the setting unit may control the travel motor to turn the omnidirectional moving body to switch the orientation of the omnidirectional moving body from an orientation in the four-wheel drive state to an orientation in the two-wheel drive state.

[0009] In this configuration, even if the omnidirectional vehicle is detected traveling downhill while traveling in four-wheel drive mode, the vehicle will turn and the orientation of the omnidirectional vehicle will smoothly switch from the orientation in four-wheel drive mode to the orientation in two-wheel drive mode.

[0010] The driving control device may further include a map data storage unit that stores map data of an area in which the omnidirectional moving body travels, and the downhill detection unit may detect whether the omnidirectional moving body travels downhill based on the map data stored in the map data storage unit.

[0011] In this configuration, there is no need for a sensor to detect whether the omnidirectional vehicle is traveling downhill, and therefore it is possible to inexpensively detect whether the omnidirectional vehicle is traveling downhill.

[0012] The downhill detection unit may determine whether or not the omnidirectional moving body has reached the front of a downhill slope based on the map data, and the setting unit may control the travel motor to switch the orientation of the omnidirectional moving body from that of the four-wheel drive state to that of the two-wheel drive state by turning the omnidirectional moving body just before the downhill slope when the downhill detection unit determines that the omnidirectional moving body has reached the front of a downhill slope while the omnidirectional moving body is traveling in four-wheel drive state.

[0013] In this configuration, when the omnidirectional vehicle is traveling in four-wheel drive mode and reaches the front of a downhill slope, the omnidirectional vehicle turns just before the slope, switching the orientation of the omnidirectional vehicle from the four-wheel drive state to the two-wheel drive state. This causes the omnidirectional vehicle to travel downhill in two-wheel drive mode from the start of the downhill slope. This allows the omnidirectional vehicle to travel downhill stably.

[0014] The driving control device may further include a tilt angle detection unit that detects the tilt angle of the omnidirectional moving body, and the downhill detection unit may determine whether the omnidirectional moving body is traveling downhill based on the tilt angle of the omnidirectional moving body detected by the tilt angle detection unit.

[0015] In this configuration, even when the omnidirectional vehicle is autonomously traveling without using map data, it is possible to detect whether the omnidirectional vehicle is traveling downhill.

[0016] The driving control device may further include an obstacle detection unit that detects whether an obstacle is present in the traveling direction of the omnidirectional moving body, and a stop control unit that controls the driving motor to stop the traveling of the omnidirectional moving body when the downslope detection unit detects that the omnidirectional moving body is traveling downslope and the obstacle detection unit detects that an obstacle is present in the traveling direction of the omnidirectional moving body.

[0017] In this configuration, when the omnidirectional vehicle is traveling downhill in two-wheel drive mode and an obstacle is detected in the vehicle's direction of travel, the vehicle is forced to stop. At this time, the deceleration of the omnidirectional vehicle can be increased as described above. Therefore, even if an obstacle is detected in the vehicle's direction of travel on a downhill slope, the vehicle can be stopped in a short distance. Effect of the Invention

[0018] According to the present invention, the stopping distance of an omnidirectional vehicle traveling downhill can be shortened. [Brief description of the drawings]

[0019] [Figure 1] 1 is a side view showing an omnidirectional mobile robot, which is an omnidirectional mobile body equipped with a travel control device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a rear view of the omnidirectional mobile robot shown in FIG. [Diagram 3] 1 is a block diagram showing a configuration of a driving control device according to a first embodiment of the present invention. [Figure 4] 3 is a rear view showing how the orientation of the omnidirectional mobile robot shown in FIG. 2 is switched from a four-wheel drive state orientation to a two-wheel drive state orientation. FIG. [Diagram 5] 4 is a flowchart showing a procedure of a driving control process executed by a controller shown in FIG. 3. [Figure 6] 4 is a flowchart showing a procedure of a stop control process executed by a controller shown in FIG. 3. [Figure 7] 1 is a side view showing a state in which an obstacle is present in the moving direction of an omnidirectional mobile robot when the omnidirectional mobile robot is traveling downhill. FIG. [Figure 8] FIG. 5 is a block diagram showing the configuration of a cruise control device according to a second embodiment of the present invention. [Figure 9] 9 is a flowchart showing a procedure of a driving control process executed by a controller shown in FIG. 8. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the drawings, the same or equivalent elements are designated by the same reference numerals, and duplicated explanations will be omitted.

[0021] Fig. 1 is a side view showing an omnidirectional mobile robot, which is an omnidirectional mobile body equipped with a driving control device according to an embodiment of the present invention, Fig. 2 is a rear view of the omnidirectional mobile robot shown in Fig. 1.

[0022] 1 and 2, the omnidirectional mobile robot 1 is an autonomous mobile robot used, for example, in picking work to transport luggage M. In picking work, the omnidirectional mobile robot 1 tracks a worker (not shown) while the worker loads luggage M onto the omnidirectional mobile robot 1. The omnidirectional mobile robot 1 is an omnidirectional mobile body that can move in all directions within a horizontal plane. The omnidirectional directions within the horizontal plane include forward / backward, left / right, diagonal directions, and turning directions.

[0023] The omnidirectional mobile robot 1 comprises a robot body 2 which is a vehicle body, and four wheels 3 arranged on the front, rear, left and right sides of the robot body 2. The robot body 2 has a substantially cylindrical base 4 and upper and lower two-tiered loading platforms 5, 6 arranged above the base 4. A load M is placed on the placement surfaces 5a, 6a of the loading platforms 5, 6. The loading platform 6 is attached to the base 4. The loading platform 5 is attached to the loading platform 6.

[0024] The wheels 3 are, for example, 45-degree omni wheels. The wheels 3 are rotatably attached to the base 4 of the robot body 2. The wheels 3 are arranged at equal intervals along the circumferential direction of the base 4. Adjacent wheels 3 are arranged so as to face in directions perpendicular to each other.

[0025] Fig. 3 is a block diagram showing the configuration of a driving control device according to a first embodiment of the present invention. In Fig. 3, a driving control device 10 of this embodiment is mounted on an omnidirectional mobile robot 1. The driving control device 10 is a device that causes the omnidirectional mobile robot 1 to drive autonomously. Specifically, after baggage M is loaded onto platforms 5, 6 of the omnidirectional mobile robot 1, the driving control device 10 causes the omnidirectional mobile robot 1 to automatically drive to a destination.

[0026] The driving control device 10 includes four driving motors 11, an instruction switch 12, two laser sensors 13, a map data storage unit 14, and a controller 15.

[0027] The traveling motor 11 independently rotates and drives each wheel 3. The traveling motor 11 is attached to the base 4. The traveling motor 11 is disposed radially inward of the wheels 3 on the base 4 (see FIG. 2).

[0028] Although not specifically shown, the instruction switch 12 is provided, for example, on the platform 6 of the robot main body 2. The instruction switch 12 is a manually operated switch that allows an operator to instruct the omnidirectional mobile robot 1 to start autonomous traveling.

[0029] The laser sensor 13 is attached to the upper surface of the base 4 (see FIG. 1). The laser sensors 13 are located at the front and rear ends of the omnidirectional mobile robot 1 when the omnidirectional mobile robot 1 is in a four-wheel drive state (described later). The laser sensor 13 detects objects present around the omnidirectional mobile robot 1 by emitting a laser toward the surroundings of the omnidirectional mobile robot 1 and receiving the reflected laser light. As the laser sensor 13, for example, a LIDAR (Light Detection and Ranging) or a laser range finder is used.

[0030] The map data storage unit 14 stores map data of the area in which the omnidirectional mobile robot 1 travels. The map data includes not only data on objects such as shelves, walls, and pillars, but also data on slopes and the like.

[0031] The controller 15 is composed of a CPU, a RAM, a ROM, an input / output interface, etc. The controller 15 has a travel control unit 16, a downhill detection unit 17, a direction setting unit 18, an obstacle determination unit 19, and a stop control unit 20.

[0032] When the instruction switch 12 instructs the omnidirectional robot 1 to start autonomous driving, the driving control unit 16 controls the driving motor 11 to drive the omnidirectional robot 1 based on the detection data from the laser sensor 13 and the map data stored in the map data memory unit 14.

[0033] Specifically, the driving control unit 16 estimates the self-position of the omnidirectional mobile robot 1 by matching the detection data of the laser sensor 13 with the map data stored in the map data storage unit 14, for example, using a SLAM (simultaneous localization and mapping) method, and controls the driving motor 11 to drive the omnidirectional mobile robot 1 toward the destination. SLAM is a self-position estimation technology that estimates the self-position using sensor data and map data.

[0034] 4(a), the omnidirectional mobile robot 1 normally travels in four-wheel drive mode from the viewpoint of drive efficiency of the travel motor 11. In the four-wheel drive mode, all four wheels 3 are driven to rotate in a direction B that corresponds to the traveling direction A of the omnidirectional mobile robot 1. Traveling in the four-wheel drive mode is called translation.

[0035] In the four-wheel drive state, the omnidirectional mobile robot 1 can move in any direction throughout 360 degrees horizontally without changing the orientation of the omnidirectional mobile robot 1 by changing the rotation speed of the four wheels 3. However, the omnidirectional mobile robot 1 can be most efficiently driven in the four-wheel drive state by rotating all four wheels 3 at the same speed using the travel motor 11.

[0036] The omnidirectional mobile robot 1 can also travel in a two-wheel drive state, as shown in Fig. 4(c). In the two-wheel drive state, two opposing wheels 3 of the four wheels 3 are driven to rotate in a direction B corresponding to the traveling direction A of the omnidirectional mobile robot 1, and the other two wheels 3 are not driven to rotate. In this case, only the two wheels 3 having axes perpendicular to the traveling direction A of the omnidirectional mobile robot 1 are driven to rotate. Traveling in the two-wheel drive state is called diagonal traveling.

[0037] When the orientation of the omnidirectional mobile robot 1 is set to a four-wheel drive orientation by the orientation setting unit 18 described below, the travel control unit 16 controls the travel motor 11 to make the omnidirectional mobile robot 1 travel in four-wheel drive mode. When the orientation of the omnidirectional mobile robot 1 is set to a two-wheel drive orientation by the orientation setting unit 18 described below, the travel control unit 16 controls the travel motor 11 to make the omnidirectional mobile robot 1 travel in two-wheel drive mode.

[0038] The downhill detection unit 17 detects whether the omnidirectional mobile robot 1 is traveling downhill S (see FIG. 7) based on the map data stored in the map data storage unit 14. Specifically, the downhill detection unit 17 determines whether the omnidirectional mobile robot 1 has reached the front of the downhill S based on the map data. The downhill detection unit 17 also determines whether the omnidirectional mobile robot 1 has reached the end of the downhill S based on the map data.

[0039] The orientation setting unit 18 sets the orientation of the omnidirectional mobile robot 1. When the downhill detection unit 17 detects that the omnidirectional mobile robot 1 is traveling downhill S, the orientation setting unit 18 sets the orientation of the omnidirectional mobile robot 1 to the orientation of a two-wheel drive state.

[0040] When the omnidirectional mobile robot 1 is traveling in four-wheel drive mode and the downhill detection unit 17 detects that the omnidirectional mobile robot 1 is traveling downhill S, the orientation setting unit 18 controls the traveling motor 11 to turn the omnidirectional mobile robot 1 to switch the orientation of the omnidirectional mobile robot 1 from the orientation in the four-wheel drive mode to the orientation in the two-wheel drive mode.

[0041] Specifically, when the omnidirectional mobile robot 1 is traveling in four-wheel drive mode and the downhill detection unit 17 determines that the omnidirectional mobile robot 1 has reached the front of a downhill slope S, the orientation setting unit 18 controls the travel motor 11 to rotate the omnidirectional mobile robot 1 just before the downhill slope S to switch the orientation of the omnidirectional mobile robot 1 from the orientation in four-wheel drive mode to the orientation in two-wheel drive mode.

[0042] When the orientation of the omnidirectional mobile robot 1 is in a four-wheel drive state orientation (see FIG. 4(a)), by rotating all four wheels 3 in the same direction C along the circumferential direction of the base 4 as shown in FIG. 4(b), the omnidirectional mobile robot 1 will turn 45 degrees, causing the orientation of the omnidirectional mobile robot 1 to become a two-wheel drive state orientation (see FIG. 4(c)).

[0043] In addition, when the omnidirectional mobile robot 1 is traveling in two-wheel drive state and the downhill detection unit 17 detects that the omnidirectional mobile robot 1 is not traveling on a downhill slope S, the orientation setting unit 18 controls the traveling motor 11 to turn the omnidirectional mobile robot 1 to switch the orientation of the omnidirectional mobile robot 1 from the orientation in the two-wheel drive state to the orientation in the four-wheel drive state.

[0044] Specifically, when the omnidirectional mobile robot 1 is traveling in two-wheel drive state and the downhill detection unit 17 determines that the omnidirectional mobile robot 1 has reached the bottom of the downhill slope S, the orientation setting unit 18 controls the traveling motor 11 to rotate the omnidirectional mobile robot 1 to switch the orientation of the omnidirectional mobile robot 1 from the orientation in the two-wheel drive state to the orientation in the four-wheel drive state.

[0045] The obstacle determination unit 19 determines whether or not an obstacle X (see FIG. 7) exists in the traveling direction A of the omnidirectional mobile robot 1 based on the detection data of the laser sensor 13. The obstacle X may be a worker, baggage, or another omnidirectional mobile robot 1. The obstacle determination unit 19 cooperates with the laser sensor 13 to constitute an obstacle detection unit that detects whether or not an obstacle X exists in the traveling direction A of the omnidirectional mobile robot 1.

[0046] When the downhill detection unit 17 detects that the omnidirectional mobile robot 1 is traveling downhill S, and the obstacle determination unit 19 detects that there is an obstacle X in the traveling direction A of the omnidirectional mobile robot 1, the stop control unit 20 controls the traveling motor 11 to stop the traveling of the omnidirectional mobile robot 1.

[0047] 5 is a flow chart showing the procedure of the travel control process executed by the controller 15. This process is executed when the instruction switch 12 is turned ON by the operator. In this process, the instruction switch 12 is turned ON when the omnidirectional mobile robot 1 is stopped in a flat work area in a four-wheel drive state orientation. The omnidirectional mobile robot 1 then travels toward the destination along a travel route that includes a downhill slope S (see FIG. 7). The omnidirectional mobile robot 1 constantly estimates its own position.

[0048] 5, the controller 15 first acquires map data stored in the map data storage unit 14 (step S101). Next, as shown in FIG. 4(a), the controller 15 controls the traveling motor 11 to make the omnidirectional mobile robot 1 travel in a four-wheel drive state (step S102).

[0049] Next, the controller 15 judges whether the omnidirectional mobile robot 1 has reached the destination based on the map data and the self-position of the omnidirectional mobile robot 1 (step S103). If the controller 15 judges that the omnidirectional mobile robot 1 has not reached the destination, the controller 15 judges whether the omnidirectional mobile robot 1 has reached the front of the downhill slope S based on the map data and the self-position of the omnidirectional mobile robot 1 (step S104). If the controller 15 judges that the omnidirectional mobile robot 1 has not reached the front of the downhill slope S, the controller 15 executes the above step S103 again.

[0050] When the controller 15 determines that the omnidirectional mobile robot 1 has reached the front of the downhill slope S, it controls the traveling motor 11 to turn the omnidirectional mobile robot 1 by 45 degrees just before the downhill slope S, as shown in Figures 4(b) and (c) (step S105). This causes the orientation of the omnidirectional mobile robot 1 to switch from a four-wheel drive state orientation to a two-wheel drive state orientation on the flat ground or uphill just before the downhill slope S. The controller 15 then controls the traveling motor 11 to make the omnidirectional mobile robot 1 travel in two-wheel drive mode (step S106).

[0051] Next, the controller 15 judges whether the omnidirectional mobile robot 1 has reached the bottom of the downhill S based on the map data and the self-position of the omnidirectional mobile robot 1 (step S107). When the controller 15 judges that the omnidirectional mobile robot 1 has reached the bottom of the downhill S, it controls the travel motor 11 to turn the omnidirectional mobile robot 1 by 45 degrees (step S108). As a result, the orientation of the omnidirectional mobile robot 1 changes from the orientation of the two-wheel drive state to the orientation of the four-wheel drive state on flat ground or on an uphill slope after passing the downhill S. The controller 15 then executes the above step S102 again.

[0052] When it is determined in step S103 that the omnidirectional mobile robot 1 has reached the destination, the controller 15 controls the traveling motor 11 to stop the traveling of the omnidirectional mobile robot 1 (step S109), and this process ends.

[0053] Here, the driving control unit 16 executes the above steps S101 to S103, S106, and S109. The downhill detection unit 17 executes the above steps S104 and S107. The orientation setting unit 18 executes the above steps S105 and S108.

[0054] 6 is a flowchart showing the procedure of the stop control process executed by the controller 15. This process is also executed when the instruction switch 12 is turned ON.

[0055] 6, the controller 15 first acquires map data stored in the map data storage unit 14 (step S111). Then, the controller 15 determines whether the omnidirectional mobile robot 1 is traveling downhill S based on the map data and the self-position of the omnidirectional mobile robot 1 (step S112).

[0056] When the controller 15 determines that the omnidirectional mobile robot 1 is traveling downhill S, it acquires detection data from the laser sensor 13 (step S113). Then, based on the detection data from the laser sensor 13, the controller 15 determines whether or not an obstacle X (see FIG. 7) is present in the traveling direction of the omnidirectional mobile robot 1 (step S114). When the controller 15 determines that no obstacle X is present in the traveling direction of the omnidirectional mobile robot 1, it executes the above step S112 again.

[0057] When the controller 15 determines that an obstacle X is present in the traveling direction of the omnidirectional mobile robot 1, it controls the traveling motor 11 to bring the omnidirectional mobile robot 1 to an emergency stop (step S115). As a result, the omnidirectional mobile robot 1 comes to an emergency stop in front of the obstacle X.

[0058] Here, the downhill detection unit 17 executes the above steps S111 and S112. The obstacle determination unit 19 executes the above steps S113 and S114. The stop control unit 20 executes the above step S115.

[0059] However, when the omnidirectional mobile robot 1 travels (translates) downhill S in four-wheel drive mode, the following problem occurs. That is, as shown in Fig. 7, when the omnidirectional mobile robot 1 travels downhill S, if an obstacle X is present in the traveling direction A of the omnidirectional mobile robot 1, the obstacle X is detected by the laser L emitted from the laser sensor 13, and the omnidirectional mobile robot 1 decelerates and comes to an emergency stop.

[0060] However, when the omnidirectional mobile robot 1 is in four-wheel drive mode, the wheelbase W of the omnidirectional mobile robot 1 is short (see FIG. 4(a)). The wheelbase W is the distance between the front and rear wheels 3 in the direction of travel A of the omnidirectional mobile robot 1. For this reason, when the omnidirectional mobile robot 1 suddenly decelerates on a downhill slope S, it is necessary to reduce the speed or deceleration of the omnidirectional mobile robot 1 so that the rear wheels 3 in the direction of travel A of the omnidirectional mobile robot 1 do not lift off the surface of the downhill slope S. However, in this case, the cycle time required to stop the omnidirectional mobile robot 1 from traveling becomes longer. Furthermore, if the deceleration of the omnidirectional mobile robot 1 is reduced, the stopping distance of the omnidirectional mobile robot 1 becomes longer.

[0061] In response to such a problem, in this embodiment, when it is detected that the omnidirectional mobile robot 1 is traveling downhill S, the orientation of the omnidirectional mobile robot 1 is set to the orientation of a two-wheel drive state in which two opposing wheels 3 out of the four wheels 3 are driven. Then, the omnidirectional mobile robot 1 travels downhill S in the two-wheel drive state. Here, in the two-wheel drive state, the wheelbase W of the omnidirectional mobile robot 1 is longer than in the four-wheel drive state in which the four wheels 3 are driven (see FIG. 4(c)). Therefore, even if the omnidirectional mobile robot 1 is suddenly decelerated on the downhill S, the rear wheels 3 are less likely to float in the traveling direction A of the omnidirectional mobile robot 1 compared to the four-wheel drive state. Therefore, when the omnidirectional mobile robot 1 is stopped traveling on the downhill, the deceleration of the omnidirectional mobile robot 1 can be increased. This makes it possible to shorten the stopping distance of the omnidirectional mobile robot 1 on the downhill S. In addition, since it is not necessary to reduce the speed and deceleration of the omnidirectional mobile robot 1, the cycle time when the omnidirectional mobile robot 1 stops traveling can also be shortened.

[0062] Furthermore, in this embodiment, even if the omnidirectional mobile robot 1 is detected to be traveling downhill S while traveling in four-wheel drive state, the omnidirectional mobile robot 1 turns and the orientation of the omnidirectional mobile robot 1 smoothly switches from the orientation in four-wheel drive state to the orientation in two-wheel drive state.

[0063] Furthermore, in this embodiment, whether the omnidirectional mobile robot 1 is traveling downhill S is detected based on map data of the area in which the omnidirectional mobile robot 1 is traveling. This eliminates the need for a sensor or the like to detect that the omnidirectional mobile robot 1 is traveling downhill S. This makes it possible to inexpensively detect whether the omnidirectional mobile robot 1 is traveling downhill S.

[0064] Furthermore, in this embodiment, when the omnidirectional mobile robot 1 is traveling in four-wheel drive mode and reaches the front of a downhill slope S, the omnidirectional mobile robot 1 turns just before the downhill slope S, switching the orientation of the omnidirectional mobile robot 1 from the orientation in four-wheel drive mode to the orientation in two-wheel drive mode. As a result, the omnidirectional mobile robot 1 travels downhill S in two-wheel drive mode from the start point of the downhill slope S. This allows the omnidirectional mobile robot 1 to travel downhill S stably.

[0065] Furthermore, in this embodiment, when the omnidirectional mobile robot 1 is traveling downhill S in two-wheel drive mode, if the presence of an obstacle X is detected in the traveling direction A of the omnidirectional mobile robot 1, the omnidirectional mobile robot 1 is forced to stop traveling. At this time, the deceleration of the omnidirectional mobile robot 1 can be increased as described above. Therefore, even if an obstacle X is detected in the traveling direction A of the omnidirectional mobile robot 1 on the downhill S, the omnidirectional mobile robot 1 can be stopped in a short distance.

[0066] Fig. 8 is a block diagram showing the configuration of a driving control device according to a second embodiment of the present invention. In this embodiment, instead of estimating the self-position of the omnidirectional mobile robot 1 using the SLAM technique and causing the omnidirectional mobile robot 1 to travel, the omnidirectional mobile robot 1 is caused to travel along a magnetic tape (not shown) installed on the surface of the road where the robot travels.

[0067] 8, a driving control device 10A of this embodiment includes a magnetic sensor 25 and a gyro sensor 26 instead of the map data storage unit 14 in the first embodiment. The magnetic sensor 25 detects a magnetic tape installed on the road surface of the driving path. The gyro sensor 26 is an inclination angle detection unit that detects the inclination angle of the omnidirectional mobile robot 1.

[0068] Moreover, the driving control device 10A includes a controller 15A instead of the controller 15 in the first embodiment. The controller 15A includes a driving control unit 16A, a downhill detection unit 17A, the above-mentioned direction setting unit 18, an obstacle determination unit 19, and a stop control unit 20.

[0069] When the instruction switch 12 instructs the omnidirectional mobile robot 1 to start autonomous traveling, the traveling control unit 16A controls the traveling motor 11 to make the omnidirectional mobile robot 1 travel based on the detection data of the magnetic sensor 25. Specifically, the traveling control unit 16A estimates the self-position of the omnidirectional mobile robot 1 based on the detection data of the magnetic sensor 25, and controls the traveling motor 11 to make the omnidirectional mobile robot 1 travel toward the destination.

[0070] The downslope detection unit 17A detects whether the omnidirectional mobile robot 1 is traveling downslope S based on the tilt angle of the omnidirectional mobile robot 1 detected by the gyro sensor 26. Specifically, the downslope detection unit 17A determines whether the omnidirectional mobile robot 1 is traveling downslope S based on the tilt angle of the omnidirectional mobile robot 1. The downslope detection unit 17A also determines whether the omnidirectional mobile robot 1 has reached the bottom of the downslope S based on the tilt angle of the omnidirectional mobile robot 1.

[0071] FIG. 9 is a flowchart showing the procedure of the driving control process executed by the controller 15A, and corresponds to FIG.

[0072] 9, the controller 15A first controls the travel motor 11 so that the omnidirectional mobile robot 1 travels in four-wheel drive mode (step S121). Next, the controller 15A determines whether the omnidirectional mobile robot 1 has reached its destination based on the self-position of the omnidirectional mobile robot 1 (step S122).

[0073] If the controller 15A determines that the omnidirectional mobile robot 1 has not reached the destination, it acquires the detection value of the gyro sensor 26 (step S123). Then, the controller 15A determines whether the omnidirectional mobile robot 1 is traveling downhill S based on the detection value of the gyro sensor 26 (step S124). If the controller 15A determines that the omnidirectional mobile robot 1 is not traveling downhill S, it executes the above step S122 again.

[0074] When the controller 15A determines that the omnidirectional mobile robot 1 is traveling downhill S, it controls the traveling motor 11 to turn the omnidirectional mobile robot 1 by 45 degrees (step S125). Next, the controller 15A controls the traveling motor 11 to travel the omnidirectional mobile robot 1 in two-wheel drive mode (step S126).

[0075] Next, the controller 15A acquires the detection value of the gyro sensor 26 (step S127). Then, the controller 15A determines whether the omnidirectional mobile robot 1 has reached the bottom of the downward slope S based on the detection value of the gyro sensor 26 (step S128). If the controller 15A determines that the omnidirectional mobile robot 1 has not reached the bottom of the downward slope S, it executes the above step S127 again.

[0076] When the controller 15A determines that the omnidirectional mobile robot 1 has reached the bottom of the downward slope S, it controls the traveling motor 11 to turn the omnidirectional mobile robot 1 by 45 degrees (step S129), and executes the above step S121 again.

[0077] When it is determined in step S122 that the omnidirectional mobile robot 1 has reached the destination, the controller 15A controls the traveling motor 11 to stop the traveling of the omnidirectional mobile robot 1 (step S130), and this process ends.

[0078] Here, the traveling control unit 16A executes the above steps S121, S122, S126, and S130. The downhill detection unit 17A executes the above steps S123, S124, S127, and S128. The orientation setting unit 18 executes the above steps S125 and S129.

[0079] As described above, in this embodiment as well, when it is detected that the omnidirectional mobile robot 1 is traveling downhill S, the orientation of the omnidirectional mobile robot 1 is set to a two-wheel drive orientation in which two opposing wheels 3 out of the four wheels 3 are driven. The omnidirectional mobile robot 1 then travels downhill S in the two-wheel drive state. Therefore, similar to the first embodiment, the stopping distance of the omnidirectional mobile robot 1 on the downhill S can be shortened.

[0080] Furthermore, in this embodiment, it is determined whether the omnidirectional mobile robot 1 is traveling downhill S based on the tilt angle of the omnidirectional mobile robot 1. Therefore, even if the omnidirectional mobile robot 1 is made to travel autonomously without using map data, it is possible to detect whether the omnidirectional mobile robot 1 is traveling downhill S.

[0081] The present invention is not limited to the above embodiment. For example, in the first embodiment, when the omnidirectional mobile robot 1 reaches the front of the downhill slope S, the orientation of the omnidirectional mobile robot 1 is switched from the orientation of the four-wheel drive state to the orientation of the two-wheel drive state in front of the downhill slope S, but the present invention is not particularly limited to such an embodiment. For example, it may be determined based on the map data stored in the map data storage unit 14 whether the omnidirectional mobile robot 1 is traveling downhill S, and the orientation of the omnidirectional mobile robot 1 may be switched from the orientation of the four-wheel drive state to the orientation of the two-wheel drive state while the omnidirectional mobile robot 1 is traveling downhill S.

[0082] In the above embodiment, since the starting point of the autonomous traveling of the omnidirectional mobile robot 1 is flat ground, the omnidirectional mobile robot 1 first travels in four-wheel drive mode, and when the omnidirectional mobile robot 1 approaches the downhill slope S, the orientation of the omnidirectional mobile robot 1 is switched from the orientation of the four-wheel drive mode to the orientation of the two-wheel drive mode, but this is not particularly limited to the above embodiment. For example, if the starting point of the autonomous traveling of the omnidirectional mobile robot 1 is midway up the downhill slope S or just before the downhill slope S, the orientation of the omnidirectional mobile robot 1 may be set to the orientation of the two-wheel drive mode by turning the omnidirectional mobile robot 1 on the spot or turning the omnidirectional mobile robot 1 while traveling, and then the omnidirectional mobile robot 1 may travel in two-wheel drive mode.

[0083] Also, the omnidirectional mobile robot 1 may be allowed to travel in two-wheel drive mode until it approaches the downhill slope S. In this case, even when the omnidirectional mobile robot 1 approaches the downhill slope S, it is not necessary to turn the omnidirectional mobile robot 1.

[0084] In the above embodiment, the destination of the omnidirectional mobile robot 1 is also flat ground, but this is not limited to this form and the destination of the omnidirectional mobile robot 1 may be downhill or uphill. Even if the destination of the omnidirectional mobile robot 1 is downhill, the omnidirectional mobile robot 1 can be stopped at the destination in a short distance.

[0085] In the above embodiment, the laser sensor 13 detects whether or not there is an obstacle X in the traveling direction A of the omnidirectional mobile robot 1. However, the present invention is not limited to this form, and a camera or the like may be used to detect whether or not there is an obstacle X in the traveling direction A of the omnidirectional mobile robot 1.

[0086] In the above embodiment, the self-position of the omnidirectional mobile robot 1 is estimated using a SLAM method based on detection data from the laser sensor 13 or a magnetic tape, but the present invention is not limited to such a method. Methods for estimating the self-position of the omnidirectional mobile robot 1 may include, for example, a SLAM method based on image data from a camera, an odometry sensor that detects the amount and direction of movement of the omnidirectional mobile robot 1, or an inertial measurement unit (IMU) that measures the angular velocity and acceleration of the omnidirectional mobile robot 1.

[0087] When the SLAM technique using camera image data is employed, whether the omnidirectional mobile robot 1 is traveling downhill S is detected based on map data, as in the above-described first embodiment. When an odometry sensor or inertial measurement unit is employed, map data is not used to estimate the robot's own position, so whether the omnidirectional mobile robot 1 is traveling downhill S is detected based on the inclination angle of the omnidirectional mobile robot 1 detected by the gyro sensor 26, as in the above-described second embodiment.

[0088] In addition, the above embodiment is a driving control device that controls the autonomous driving of an omnidirectional mobile robot 1 that transports luggage M, but the present invention can be applied to any omnidirectional mobile body that has four wheels and can move in all directions other than transporting luggage M. [Explanation of symbols]

[0089] 1...Omnidirectional mobile robot (omnidirectional mobile body), 3...Wheel, 10, 10A...Driving control device, 11...Driving motor, 13...Laser sensor (obstacle detection unit), 14...Map data memory unit, 16, 16A...Driving control unit, 17, 17A...Downhill detection unit, 18...Orientation setting unit (setting unit), 19...Obstacle determination unit (obstacle detection unit), 20...Stop control unit, 26...Gyro sensor (tilt angle detection unit), A...Direction of travel, S...Downhill, X...Obstacle.

Claims

1. A travel control device for an omnidirectional mobile body having four wheels and capable of moving in all directions, Four travel motors that independently rotate and drive the four wheels, respectively; a travel control unit that controls the travel motor so as to travel the omnidirectional vehicle; a downhill detection unit that detects whether the omnidirectional vehicle is traveling downhill; A setting unit that sets the orientation of the omnidirectional moving object, the setting unit sets the orientation of the omnidirectional vehicle to an orientation for a two-wheel drive state in which two opposing wheels of the four wheels are driven when the downhill detection unit detects that the omnidirectional vehicle is traveling on the downhill slope; The driving control unit controls the driving motor to cause the omnidirectional moving body to travel in the four-wheel drive state when the orientation of the omnidirectional moving body is set by the setting unit to an orientation of a four-wheel drive state in which the four wheels are driven, and controls the driving motor to cause the omnidirectional moving body to travel in the two-wheel drive state when the orientation of the omnidirectional moving body is set by the setting unit to an orientation of the two-wheel drive state.

2. 2. The travel control device for an omnidirectional mobile body according to claim 1, wherein, when the downhill detection unit detects that the omnidirectional mobile body is traveling downhill while the omnidirectional mobile body is traveling in the four-wheel drive state, the setting unit controls the travel motor to turn the omnidirectional mobile body to switch the orientation of the omnidirectional mobile body from the orientation of the four-wheel drive state to the orientation of the two-wheel drive state.

3. a map data storage unit that stores map data of an area in which the omnidirectional vehicle travels; 3. The travel control device for an omnidirectional vehicle according to claim 1, wherein the downhill detection unit detects whether the omnidirectional vehicle is traveling downhill based on the map data stored in the map data storage unit.

4. the downhill detection unit determines whether the omnidirectional vehicle has reached a point just before the downhill slope based on the map data; 4. The travel control device for an omnidirectional mobile body according to claim 3, wherein when the downhill detection unit determines that the omnidirectional mobile body has reached the front of the downhill slope while the omnidirectional mobile body is traveling in the four-wheel drive state, the setting unit controls the travel motor to turn the omnidirectional mobile body just before the downhill slope to switch the orientation of the omnidirectional mobile body from the orientation of the four-wheel drive state to the orientation of the two-wheel drive state.

5. a tilt angle detection unit that detects a tilt angle of the omnidirectional moving body, 3. The travel control device for an omnidirectional mobile body according to claim 1, wherein the downhill detection unit detects whether the omnidirectional mobile body is traveling downhill based on the inclination angle of the omnidirectional mobile body detected by the inclination angle detection unit.

6. an obstacle detection unit that detects whether an obstacle is present in a traveling direction of the omnidirectional mobile object; 6. The travel control device for an omnidirectional mobile body according to claim 1, further comprising: a stop control unit that controls the travel motor to stop travel of the omnidirectional mobile body when the downhill detection unit detects that the omnidirectional mobile body is traveling on the downhill slope and the obstacle detection unit detects that the obstacle is present in the traveling direction of the omnidirectional mobile body.

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