JP2020135560A - Autonomous mobile robot - Google Patents

Abstract

To realize an autonomous mobile robot determining a travel direction toward a target in a facility while suitable avoiding an obstacle.SOLUTION: An autonomous mobile robot automatically patrolling the inside of a facility comprises a sensor for detecting distance from a current position to an obstacle for each direction, and a controller for controlling the autonomous mobile robot by referring to an output signal of the sensor. The controller executes processing for correcting the output signal of the sensor using a weight function which applies weight to each direction and whose weight in a target direction of automatic patrol becomes maximum, and processing for determining a travel direction of the autonomous mobile robot according to the corrected output signal.SELECTED DRAWING: Figure 1

Description

The present invention relates to an autonomous mobile robot.

In facilities such as medical facilities and long-term care facilities, many staff members come and go in the facility during the daytime, and it is possible for the staff members to quickly find the target person who has a problem in the facility. On the other hand, at night, the staff in charge of night duty patrols the facility at regular intervals to try to find problems.

In order to compensate for this situation, a system has been adopted in which a camera is installed at a predetermined position in the facility and the image (still image or moving image) captured by the camera is transferred to the living room where the staff is waiting. There is.

However, in the above-mentioned system, it is difficult to detect the target person in the blind spot of the camera by an image. For example, if the patrol time interval of the staff in charge of night duty is one hour, it may be one hour later to find the subject who has fallen or wandered in the blind spot of the camera immediately after the patrol.

In order to improve this situation, an autonomous mobile robot that automatically patrols the facility can be used. When an autonomous mobile robot automatically patrols the facility, if there is an obstacle on the floor in the facility, it will be difficult to patrol properly unless an appropriate avoidance direction to avoid the obstacle is determined. Become.

The present invention has been made in view of the above problems, and an object of the present invention is to realize an autonomous mobile robot that preferably determines a traveling direction for avoiding obstacles toward a target in a facility.

In order to solve the above problems, the autonomous mobile robot according to the first aspect of the present invention is an autonomous mobile robot that automatically patrols the facility, and is a sensor that detects the distance from the current position to an obstacle for each direction. A controller that controls the autonomous mobile robot by referring to the output signal of the sensor is provided, and the controller is a weighting function that gives weights for each direction, and the weight in the target direction of automatic patrol is maximized. It is configured to execute a process of correcting the output signal of the sensor using a weighting function and a process of determining the traveling direction of the autonomous mobile robot according to the corrected output signal.

According to the above configuration, it is possible to realize an autonomous mobile robot that preferably determines a traveling direction for avoiding obstacles toward a target in the facility.

In the above aspect 1, the autonomous mobile robot according to the second aspect of the present invention further includes a drive device for moving the autonomous mobile robot, and the controller controls the autonomous mobile robot to move in a determined traveling direction. The signal may be supplied to the drive device.

According to the above configuration, it is possible to realize an autonomous mobile robot that autonomously moves toward a target in the facility while avoiding obstacles.

In the autonomous mobile robot according to the third aspect of the present invention, in the above aspect 1 or 2, the sensor detects the distance from the current position to the obstacle at a specific cycle using a laser, and the controller detects the specific distance. Each process may be executed in the cycle of.

According to the above configuration, it is possible to realize an autonomous mobile robot that periodically determines a traveling direction that preferably avoids obstacles toward a target in the facility and automatically patrols.

The autonomous mobile robot according to the fourth aspect of the present invention has, in any one of the above aspects 1 to 3, the controller has at least one input interface for acquiring the output signal of the sensor and a predetermined program. It may be configured to include at least one processor that executes each of the processes according to the above, and at least one memory that stores the program.

According to the above configuration, the processor executes the process by referring to the information stored in the memory, thereby realizing an autonomous mobile robot that automatically patrols toward the target in the facility while avoiding obstacles. be able to.

The control method according to the fifth aspect of the present invention is a control method for controlling an autonomous mobile robot that automatically patrols the facility, and includes a step of detecting the distance from the current position to an obstacle for each direction using a sensor. The step of controlling the autonomous mobile robot with reference to the output signal of the sensor is included, and the step of controlling is a weighting function that gives weights for each direction, and the weight in the target direction of automatic patrol is maximum. This is a method including a process of correcting the output signal of the sensor using a weighting function, and a process of determining the traveling direction of the autonomous mobile robot according to the corrected output signal.

According to the above configuration, it is possible to control an autonomous mobile robot that preferably determines a traveling direction for avoiding obstacles toward a target in the facility.

The control program for controlling the autonomous mobile robot according to the sixth aspect of the present invention, wherein the controller executes each of the above processes, is the control program according to any one of the above aspects 1 to 4. The control program for controlling the autonomous mobile robot according to any one of claims 1 to 4 may be configured to cause the controller to execute each of the above processes.

According to the above configuration, the same effect as that of the control method is obtained.

According to one aspect of the present invention, it is possible to realize an autonomous mobile robot that preferably determines a traveling direction for avoiding obstacles toward a target in the facility.

It is the schematic which shows typically the main structure which the autonomous mobile robot which concerns on one Embodiment of this invention has. It is the schematic which showed typically the block diagram which concerns on one Embodiment of this invention. It is a flowchart which shows the method of advancing an autonomous mobile robot in a target direction while avoiding an obstacle. It is a schematic plan view which shows typically the state of mapping the obstacle detected by the range sensor. (A) shows an example of a grid map in which the obstacle mapping information detected by the range sensor 12 is discretized. (B) shows an example in which the grid map of (a) is morphologically processed. It is the schematic which showed typically the digitizing process of the obstacle avoidance direction. It is the schematic which showed typically the relationship between the obstacle avoidance direction and the target direction. (A) shows a graph showing the distance to an obstacle with respect to the scanning angle. (B) is a graph showing an example of a weighting function. (A) is a schematic plan view schematically showing the positional relationship in which the autonomous mobile robot 10 is arranged between obstacles. (B) is a graph showing the relationship between the traveling direction and the target direction after applying the weighting function. It is a schematic diagram which showed the condition used for the obstacle avoidance direction selection process in a plan view. It is the schematic which shows typically the hardware composition of the controller provided in the autonomous mobile robot which concerns on one Embodiment of this invention.

[Embodiment 1]
The autonomous mobile robot 10 according to the embodiment of the present invention will be described with reference to FIGS. 1 to 11. The autonomous mobile robot 10 is an autonomous mobile robot for long-term care that patrols the facility on behalf of staff of medical facilities and long-term care facilities, and moves around in a target direction while avoiding obstacles. It is a running autonomous mobile robot.

(Main configuration of autonomous mobile robot 10)
FIG. 1 is a block diagram showing a main hardware configuration of the autonomous mobile robot 10. As shown in FIG. 1, the autonomous mobile robot 10 includes at least a controller 11, a range sensor 12, a drive device 13, and an encoder 14.

The controller 11 has at least a receiving unit 15, a map information input unit 16, a route information generation unit 17, an output unit 18, and a position information generation unit 19. In FIG. 1, the controller 11 is functionally shown using a functional block diagram, but in FIG. 11, which will be described later, the hardware configuration of the controller 11 is shown.

In a preferred embodiment, the receiving unit 15 acquires the range sensor data from the range sensor 12. The map information input unit 16 acquires block map information in the facility, which will be described later. The position information generation unit 19 generates the current position information in the facility of the autonomous mobile robot 10 via the encoder 14. The route information generation unit 17 is a route in which the autonomous mobile robot 10 patrols the facility based on the generated current position information of the autonomous mobile robot 10 in the facility, block map information, and range sensor data. Generate information. The output unit 18 outputs the output information corresponding to the generated route information to the drive device 13. Based on the output information, the driving device 13 patrols the autonomous mobile robot 10. The encoder 14 generates information on the mileage and the moving direction of the autonomous moving robot 10 based on the amount of movement of the driving device 13 for the autonomous moving robot 10 to patrol the facility.

(Block map information)
As described above, the map information input unit 16 acquires the block map information in the facility. In the present invention, the block map refers to a map in which floor information in a facility is simplified and blocked.

FIG. 2 is a schematic plan view schematically showing a block map according to an embodiment of the present invention. An example of setting a block map will be described below. In a preferred embodiment, a place where the autonomous mobile robot 10 can pass is set from a floor diagram of a facility such as a medical facility or a long-term care facility. Next, the corridor in front of one room is divided into blocks so as to form one block (21a, 21b, 21c, 21d). Here, it is preferable to divide a large block into 1 to 2 m as a guide. The center points (22b, 22c, 22d) of each block are set. It is not necessary to set a center point for the block (block 21a in FIG. 2) in which the autonomous mobile robot 10 currently exists. Set the center point of each block as the target point. In FIG. 2, starting from the autonomous mobile robot 10 existing in the block 21a, the center point of the block next to the block in which the autonomous mobile robot 10 exists is connected by a dotted arrow from the current position of the autonomous mobile robot 10. The route to move to the final block 21d is shown. 23b in the block 21b of FIG. 2 indicates an obstacle. By setting the center point of each block as the target point, it is possible to generate rough movement direction information of the autonomous mobile robot 10. In a preferred embodiment, the generation of a movement block route combining the movement direction information can be artificially set, but it is automatically set by an algorithm that generates the shortest path by setting a target point (center point of the final block). It is also possible to set a moving block route. The information of the block map generated in this way is input to the map information input unit 16.

(Position judgment on block map)
FIG. 3 is a flowchart showing a method of advancing the autonomous mobile robot 10 in the target direction while avoiding obstacles. The route information generation unit 17 receives the block map information input to the map information input unit 16 and executes the following processing. First, the final target block is set (S160). Next, the autonomous mobile robot 10 generates a block path from the currently existing block to the final target block (S161). The autonomous mobile robot 10 determines whether or not the block in which the robot 10 currently exists is the final target block (S162). When the block in which the autonomous mobile robot 10 currently exists is the final target block (YES in S162), the process ends. When the block in which the autonomous mobile robot 10 currently exists is not the final target block (NO in S162), a speed command for the next target block is generated while considering obstacle avoidance (S171).

(Obstacle detection by range sensor)
As described above, the route information generation unit 17 generates a speed command for the next target block while considering obstacle avoidance (S171). Here, in order to avoid obstacles, the route information generation unit 17 acquires the range sensor data obtained by the range sensor 12 via the reception unit 15. It is preferable that the range sensor 12 is arranged so as to be exposed on the surface of the housing of the autonomous mobile robot 10. The range sensor 12 can be arranged at an arbitrary position on the surface of the housing of the autonomous mobile robot 10, but it is preferably arranged in front of the autonomous mobile robot 10 in the forward direction. As the range sensor 12, for example, a laser type range sensor such as UST-10LX manufactured by Hokuyo Electric Co., Ltd. can be adopted.

FIG. 4 is a schematic plan view schematically showing a state in which obstacles detected by the range sensor 12 are mapped. The position of the range sensor 12 mounted on the housing of the autonomous mobile robot 10 was set as the origin, the forward direction of the autonomous mobile robot 10 was defined as the x-axis, and the direction orthogonal to the x-axis was defined as the y-axis. In FIG. 4, obstacles are indicated by small circles. As shown in FIG. 4, the scanning angle of the range sensor 12 is shown by ± θ °. In a preferred embodiment, the range sensor 12 detects an obstacle in the range of ± θ = ± 115 degrees. Further, the detection distance is preferably about 0.06 m to 10 m. The scanning time is preferably 25 ms. The angular resolution is preferably about 0.25 degrees. Without being limited to these values, the range sensor 12 can have any detection distance, scanning angle, scanning time, and angular resolution.

(Processing of range sensor data)
The route information generation unit 17 determines the direction to avoid the obstacle based on the obstacle mapping information detected by the range sensor 12 shown in FIG. In order to reduce the amount of calculation associated with the determination process, the route information generation unit 17 discretizes the obstacle mapping information detected by the range sensor 12.

FIG. 5A shows an example of a grid map in which the obstacle mapping information detected by the range sensor 12 is discretized. In a preferred embodiment, as shown in FIG. 5A, obstacle mapping information of 4 m in the x-axis direction and 5 m in the y-axis direction can be discretized into a grid of 0.1 m × 0.1 m.

FIG. 5B shows an example in which the grid map of FIG. 5A is morphologically processed. The route information generation unit 17 treats the autonomous mobile robot 10 as a point when determining a direction for avoiding an obstacle. Therefore, the route information generation unit 17 performs a morphology process on the grid map of FIG. 5 (a) to expand the obstacle area by the radius of the footprint of the autonomous mobile robot 10. In the grid map ((b) of FIG. 5) after the expansion morphology processing is performed, the autonomous mobile robot 10 can pass between obstacles as long as the grid is empty even by one square.

(Quantification of obstacle avoidance direction)
Using the grid map after the expansion morphology processing as shown in FIG. 5B, the route information generation unit 17 performs the numerical processing in the obstacle avoidance direction.

FIG. 6 is a schematic view schematically showing the digitization process in the obstacle avoidance direction. In the grid map after the expansion morphology processing is performed, radiation is set at a constant angle within a scanning angle range of ± θ ° around the current position of the autonomous mobile robot 10. In a preferred embodiment, the spacing angle between the radiations is 5 degrees. The interval angle between the radiations shown in FIG. 6 is 10 degrees. Further, a plurality of concentric circles are set around the current position of the autonomous mobile robot 10. In a preferred embodiment, the maximum radius of the concentric circles is about 3 m, and the radius of each concentric circle is set at intervals of 0.1 m. The maximum radius of the concentric circles shown in FIG. 6 is 2.4 m, and the radius of each concentric circle is set at intervals of 0.2 m.

Among the intersections of the concentric circles and radiation, the number of intersections that do not correspond to obstacles that have undergone expansion morphology processing and exist between the current position of the autonomous mobile robot 10 and the obstacle is counted for each radiation. (Score). In the example shown in FIG. 6, radiation near θ = −100 degrees is counted as 4 points, and radiation near θ = +100 degrees is counted as 5 points. It can be confirmed that the highest score is counted as 12 points for radiation near θ = +10 degrees. This makes it possible to quantify the distance to the obstacle centering on the current position of the autonomous mobile robot 10.

The route information generation unit 17 can set the direction of the radiation having the highest score as the obstacle avoidance direction. FIG. 7 is a schematic view schematically showing the relationship between the obstacle avoidance direction and the target direction. The route information generation unit 17 sets the current position of the autonomous mobile robot 10 as the starting point, the center point of the next block as the target position, and the direction of the target position as the target direction. As is clear from FIG. 7, when the autonomous mobile robot 10 is moved in the obstacle avoidance direction, it cannot reach the target position because it is different from the target direction.

(Obstacle avoidance behavior)
In order to solve the situation where the target position cannot be reached as described above, the route information generation unit 17 calculates the traveling direction as follows.

FIG. 9A is a schematic plan view schematically showing a positional relationship in which the autonomous mobile robot 10 is arranged between obstacles subjected to expansion morphology processing. When the front of the autonomous mobile robot 10 equipped with the range sensor 12 is in the positive x-axis direction, it can be confirmed that the target direction is about -20 degrees. It can also be confirmed that the distance to the obstacle is longer in the direction of A than in the direction of B.

FIG. 8A is a graph showing the distance to an obstacle with respect to the scanning angle of the range sensor 12 mounted on the front surface of the autonomous mobile robot 10 in the positional relationship shown in FIG. 9A. .. More specifically, in FIG. 8A, obstacles are detected by the range sensor 12 with the position where the autonomous mobile robot 10 is arranged as the origin within a scanning angle of ± θ = about ± 115 degrees. It is a graph which plotted the distance to an obstacle at a scanning angle. The vertical axis of the graph is represented by using a normalized value of the distance to an obstacle. The result of quantifying the obstacle avoidance direction by the value on the vertical axis is shown. Based on the positional relationship shown in FIG. 9A, it is clearly stated that the direction of about -20 degrees is the target direction. From the graph of FIG. 8A, it can be confirmed that the distance from the autonomous mobile robot 10 to the obstacle is longer in the direction A than in the direction B.

FIG. 8B is a graph showing an example of the weighting function. Any weight function that maximizes the weight in the target direction, such as the COS function, Gaussian function, and parabolic function, can be used. What kind of weighting function is applied is a parameter that depends on the floor configuration / block map configuration, and is preferably set offline. In this embodiment, a linear function in which the weight in the target direction is maximized (= 1) (however, the slope is negative in the positive direction from the target direction and the slope is positive in the negative direction from the target direction) is adopted. The result of superimposing the weighting function on the graph of FIG. 8A is shown in FIG. 9B.

From the result of (b) of FIG. 9, it can be confirmed that the distance from the autonomous mobile robot 10 to the obstacle is longer in the direction B than in the direction A when the weighting function considering the influence of the target direction is applied. .. Therefore, the route information generation unit 17 determines the traveling direction as the direction B. Based on the determination of the route information generation unit 17, the obstacle avoidance direction closest to the target direction can be selected.

FIG. 10 is a schematic view showing the conditions used in such a series of obstacle avoidance direction selection processes in a plan view. i represents the block, ii represents the distance to the obstacle, iii represents the obstacle avoidance direction, iv represents the target direction, v represents the weight function, and vi represents the obstacle after superimposing the weight function. Represents the distance to, and vii represents the direction of travel.

(Drive of drive device)
As described above, the route information generation unit 17 selects the obstacle avoidance direction and generates a speed command for the next target block (S171). It is preferable to use a preset speed as the driving speed. The output unit 18 outputs the output information for driving at a predetermined driving speed in the obstacle avoidance direction determined by the route information generation unit 17 to the driving device 13. In a preferred embodiment, the drive device 13 is composed of at least two left and right motors. By controlling the rotation speeds of the left and right motors, the autonomous mobile robot 10 can be moved in the obstacle avoidance direction (S181).

(Location information generation)
The encoder 14 can generate information on the mileage and the moving direction from the rotational movement of the shafts of the left and right motors. Based on the mileage and movement direction information generated by the encoder 14, the position information generation unit 19 generates the position information of the autonomous mobile robot 10 and estimates its own position on the block map (S191).

Based on the post-movement position information generated by the position information generation unit 19, the autonomous mobile robot 10 determines whether or not the block in which the autonomous mobile robot 10 currently exists is the final target block (S162).

The application period of the weight function for the loop processing is preferably 25 ms.

(Hardware configuration of controller)
FIG. 11 is a schematic view schematically showing a main hardware configuration included in the autonomous mobile robot 10 according to the embodiment of the present invention. As shown in FIG. 11, the autonomous mobile robot 10 has at least one controller 130. The controller 130 has a hardware configuration corresponding to the controller 11 in FIG. The controller 11 of FIG. 1 is a functional representation of the components of the controller 11, and only one controller 11 is described. On the other hand, the controller 130 as a hardware configuration may include a plurality of controllers 130 depending on the target of information processing.

The controller 130 includes at least an input interface 133, an output interface 114, a processor 135, and a memory 136.

For example, the controller 130 processes information about the first controller 130a that processes information about the range sensor 12 that detects the distance from the current position to the obstacle for each direction, and information about the driving device 13 that moves the autonomous mobile robot. A configuration in which control may be shared by a plurality of controllers such as the second controller 130b may be used.

More specifically, the first controller 130a can control the autonomous mobile robot with reference to the output signal of the range sensor 12. Specifically, the first controller 130a can control the receiving unit 15, the map information input unit 16, and the route information generating unit 17. For example, a weighting function that gives weights for each direction and uses a weighting function that maximizes the weight in the target direction of automatic patrol to correct the output signal of the sensor, and the output signal after correction. It is possible to execute a process of determining the traveling direction of the autonomous mobile robot.

The second controller 130b can execute a process of supplying the drive device 13 with a control signal for moving the autonomous mobile robot in the determined traveling direction. Specifically, the second controller 130b can control the output unit 18 and the position information generation unit 19.

The program that executes the algorithm that executes the processing of the information input from the input interface 133 is stored in the memory 136. By executing the program stored in the memory 136 on the processor 135, the input information can be processed. The processed information is output from the output interface 114 as output information. The drive device 13 can be controlled by the information output from the output interface 114.

[Embodiment 2]
Other embodiments of the present invention will be described below. For convenience of explanation, the same reference numerals will be added to the members having the same functions as the members described in the above embodiment, and the description will not be repeated.

In the first embodiment, the configuration in which the range sensor 12 and the driving device 13 are controlled by one controller 11 is shown. In another embodiment, the first controller 130a that controls the range sensor 12 and the second controller 130b that controls the drive device 13 can be composed of different controllers. The second controller 130b receives the output information generated by the first controller 130a, and the second controller 130b can control the drive device 13 based on the output information.

[Example of realization by software]
The controller 11 of the autonomous mobile robot 10 may be realized by a logic circuit (hardware) formed in an integrated circuit (IC chip) or the like, or may be realized by software.

In the latter case, the autonomous mobile robot 10 includes a computer that executes instructions of a program that is software that realizes each function. The computer includes, for example, one or more processors and a computer-readable recording medium that stores the program. Then, in the computer, the processor reads the program from the recording medium and executes it, thereby achieving the object of the present invention. As the processor, for example, a CPU (Central Processing Unit) can be used. As the recording medium, a "non-temporary tangible medium", for example, a ROM (Read Only Memory) or the like, a tape, a disk, a card, a semiconductor memory, a programmable logic circuit, or the like can be used. Further, a RAM (Random Access Memory) for expanding the above program may be further provided. Further, the program may be supplied to the computer via an arbitrary transmission medium (communication network, broadcast wave, etc.) capable of transmitting the program. It should be noted that one aspect of the present invention can also be realized in the form of a data signal embedded in a carrier wave, in which the above program is embodied by electronic transmission.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and the embodiments obtained by appropriately combining the technical means disclosed in the different embodiments. Is also included in the technical scope of the present invention.

10 Autonomous mobile robot 11 Controller 12 Survey sensor 13 Drive device 14 Encoder 15 Receiver 16 Map information input unit 17 Route information generation unit 18 Output unit 19 Position information generation unit 21a, 21b Block 21d Final block 22d Center point 114 Output interface 130 Controller 130a First controller 130b Second controller 133 Input interface 135 Processor 136 Memory

Claims (6)

An autonomous mobile robot that automatically patrols the facility
A sensor that detects the distance from the current position to an obstacle in each direction,
A controller that controls the autonomous mobile robot by referring to the output signal of the sensor is provided.
The controller
A processing that corrects the output signal of the sensor by using a weighting function that gives a weight for each direction and maximizes the weight in the target direction of automatic patrol.
The process of determining the traveling direction of the autonomous mobile robot according to the corrected output signal is executed.
An autonomous mobile robot characterized by this. Further equipped with a drive device for moving the autonomous mobile robot,
The controller supplies a control signal for moving the autonomous mobile robot in a determined traveling direction to the driving device.
The autonomous mobile robot according to claim 1, wherein the robot is characterized by the above. The sensor uses a laser to detect the distance from the current position to an obstacle at a specific cycle.
The controller executes each of the processes in the specific cycle.
The autonomous mobile robot according to claim 1 or 2. The controller
With at least one input interface that acquires the output signal of the sensor,
At least one processor that executes each of the above processes according to a predetermined program, and
It comprises at least one memory that stores the program.
The autonomous mobile robot according to any one of claims 1 to 3. It is a control method that controls an autonomous mobile robot that automatically patrols the facility.
The process of detecting the distance from the current position to the obstacle in each direction using a sensor,
Including a step of controlling the autonomous mobile robot with reference to the output signal of the sensor.
The control step is
A processing that corrects the output signal of the sensor by using a weighting function that gives a weight for each direction and maximizes the weight in the target direction of automatic patrol.
Including a process of determining the traveling direction of the autonomous mobile robot according to the corrected output signal,
A control method characterized by that. A control program for controlling an autonomous mobile robot according to any one of claims 1 to 4, wherein the controller executes each of the above processes.

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