JP7120071B2 - autonomous mobile robot - Google Patents

Description

The present invention relates to autonomous mobile robots.

In facilities such as medical facilities and nursing care facilities, many staff come and go during the daytime, and it is possible for the staff 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 make regular patrols of the facility at regular intervals to find problems.

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

However, in the system described above, it is difficult to find a target person in the blind spot of the camera in the image. For example, if the patrol time interval of the night duty staff is one hour, it may be one hour later that the subject falling or wandering in the blind spot of the camera is found immediately after the patrol.

In order to improve this situation, it is possible to use an autonomous mobile robot that automatically patrols the facility. When an autonomous mobile robot automatically patrols the facility, if there are obstacles on the floor of the facility, it will be difficult for the robot to properly patrol unless it can determine the appropriate direction to avoid the obstacles. Become.

SUMMARY OF THE INVENTION 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 determines a direction of movement toward a target in a facility to avoid obstacles.

In order to solve the above problems, an autonomous mobile robot according to aspect 1 of the present invention is an autonomous mobile robot that automatically patrols a facility, and includes a sensor that detects the distance from the current position to an obstacle in each direction. and a controller for controlling the autonomous mobile robot with reference to the output signal of the sensor, wherein the controller is a weight function that gives a weight for each direction, and the weight in the target direction of automatic patrol is maximized. 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 are executed.

According to the above configuration, it is possible to realize an autonomous mobile robot that determines the direction of movement toward a target within a facility to avoid obstacles.

An autonomous mobile robot according to aspect 2 of the present invention is the above-described aspect 1, further comprising a driving device for moving the autonomous mobile robot, wherein the controller performs control for moving the autonomous mobile robot in the determined traveling direction. A signal may be provided 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 a facility while suitably avoiding obstacles.

An autonomous mobile robot according to aspect 3 of the present invention is an autonomous mobile robot according to aspect 1 or 2 above, wherein the sensor uses a laser to detect the distance from the current position to the obstacle in a specific cycle, and the controller detects the specified may be configured such that each of the above processes is executed in a period of .

According to the above configuration, it is possible to realize an autonomous mobile robot that cyclically determines a direction of movement to avoid obstacles and automatically patrols toward a target in a facility.

An autonomous mobile robot according to aspect 4 of the present invention is any one aspect of aspects 1 to 3 above, wherein the controller comprises at least one input interface that acquires the output signal of the sensor, and a predetermined program and at least one memory storing the program.

According to the above configuration, the processor executes processing with reference to the information stored in the memory, thereby realizing an autonomous mobile robot that automatically patrols toward a target within a facility while suitably avoiding obstacles. be able to.

A control method according to aspect 5 of the present invention is a control method for controlling an autonomous mobile robot that automatically patrols a facility, comprising a step of detecting a distance from a current position to an obstacle in each direction using a sensor; and a step of controlling the autonomous mobile robot with reference to the output signal of the sensor, wherein the step of controlling is a weight function that gives a weight for each direction, and the weight in the target direction of automatic patrol is the maximum. 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 the autonomous mobile robot that determines the direction of movement toward the target in the facility to avoid obstacles.

A control program for controlling an autonomous mobile robot according to aspect 6 of the present invention, characterized in that the control program causes the controller to execute each of the processes, in any one of aspects 1 to 4 above, A control program for controlling the autonomous mobile robot according to any one of claims 1 to 4, wherein the controller may be configured to execute each of the processes.

According to the above configuration, the same effects as those of the above control method can be obtained.

ADVANTAGE OF THE INVENTION According to one aspect of the present invention, there is an effect that it is possible to realize an autonomous mobile robot that determines a direction of movement toward a target in a facility to avoid obstacles.

1 is a schematic diagram schematically showing the main components of an autonomous mobile robot according to an embodiment of the present invention; FIG. 1 is a schematic diagram schematically showing a block diagram according to one embodiment of the present invention; FIG. 4 is a flow chart showing a method of advancing an autonomous mobile robot in a target direction while avoiding obstacles. FIG. 4 is a schematic plan view schematically showing how obstacles detected by a range sensor are mapped. (a) shows an example of a grid map obtained by discretizing obstacle mapping information detected by the range sensor 12. FIG. (b) shows an example of morphology processing of the grid map of (a). FIG. 4 is a schematic diagram schematically showing digitization processing of an obstacle avoidance direction; FIG. 4 is a schematic diagram schematically showing a relationship between an obstacle avoidance direction and a target direction; (a) shows a graph representing the distance to an obstacle against the scan angle. (b) is a graph showing an example of a weighting function. (a) is a schematic plan view schematically showing a 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. FIG. 10 is a schematic plan view showing conditions used for obstacle avoidance direction selection processing; 1 is a schematic diagram schematically showing the hardware configuration of a controller included in an autonomous mobile robot according to one embodiment of the present invention; FIG.

[Embodiment 1]
An autonomous mobile robot 10 according to one embodiment of the present invention will be described with reference to FIGS. 1 to 11. FIG. The autonomous mobile robot 10 is an autonomous mobile robot for nursing care and medical care that patrols the facility in place of the staff of a medical facility or a nursing care facility. It is a running type autonomous mobile robot.

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

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

In a preferred embodiment, the receiver 15 acquires range sensor data from the range sensor 12 . The map information input unit 16 acquires block map information within the facility, which will be described later. The position information generator 19 generates current position information of the autonomous mobile robot 10 within the facility via the encoder 14 . The route information generation unit 17 determines a route for the autonomous mobile robot 10 to patrol within 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 output information corresponding to the generated route information to the driving device 13 . Based on the output information, the autonomous mobile robot 10 is circulated by the driving device 13 . The encoder 14 generates information on the traveling distance and moving direction of the autonomous mobile robot 10 based on the amount of movement of the driving device 13 for the autonomous mobile robot 10 to patrol within the facility.

(Block map information)
As described above, the map information input unit 16 acquires block map information within the facility. In the present invention, a block map refers to a map obtained by simplifying floor information within a facility into blocks.

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

(Position judgment on block map)
FIG. 3 is a flow chart 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, a final target block is set (S160). Next, the autonomous mobile robot 10 generates a block path from the current block to the final target block (S161). It is determined whether or not the block where the autonomous mobile robot 10 currently exists is the final target block (S162). If the block in which the autonomous mobile robot 10 currently exists is the final target block (YES in S162), the process ends. If the block where 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 generator 17 generates a speed command directed to the next target block while considering obstacle avoidance (S171). Here, in order to avoid obstacles, the route information generator 17 acquires range sensor data obtained by the range sensor 12 via the receiver 15 . The range sensor 12 is preferably arranged so as to be exposed on the surface of the housing of the autonomous mobile robot 10 . The range sensor 12 can be placed anywhere on the surface of the housing of the autonomous mobile robot 10, but is preferably placed 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 how 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 is defined as the origin, the forward direction of the autonomous mobile robot 10 is defined as the x-axis, and the direction orthogonal to the x-axis is 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 indicated by ±θ°. In a preferred embodiment, range sensor 12 detects obstacles in the range of ±θ=±115 degrees. Moreover, it is preferable that the detection distance is about 0.06 m to 10 m. Preferably the scan time is 25 ms. The angular resolution is preferably about 0.25 degrees. Without being limited to these values, range sensor 12 can have any detection distance, scanning angle, scanning time, and angular resolution.

(Processing of range sensor data)
The route information generator 17 determines the obstacle avoidance direction 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 generator 17 discretizes the obstacle mapping information detected by the range sensor 12 .

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

FIG. 5(b) shows an example of morphology processing of the grid map of FIG. 5(a). The route information generator 17 treats the autonomous mobile robot 10 as a point when determining the direction to avoid obstacles. Therefore, the route information generator 17 performs morphology processing to expand the obstacle area by the radius of the footprint of the autonomous mobile robot 10 on the grid map of FIG. 5(a). In the grid map ((b) of FIG. 5) after such dilation morphology processing, the autonomous mobile robot 10 can pass between obstacles if the grid is empty even by one square.

(Quantification of obstacle avoidance direction)
Using the grid map that has been subjected to dilation morphology processing as shown in FIG. 5B, the route information generator 17 digitizes the obstacle avoidance direction.

FIG. 6 is a schematic diagram schematically showing the numerical processing of the obstacle avoidance direction. In the grid map after dilation morphology processing, rays are set at regular angles within a scanning angle range of ±θ° centering on the current position of the autonomous mobile robot 10 . In a preferred embodiment, the spacing angle between rays is 5 degrees. The spacing angle between rays shown in FIG. 6 is 10 degrees. Also, 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 the radiation, the number of intersections that do not correspond to obstacles subjected to expansion morphology processing and that exist between the current position of the autonomous mobile robot 10 and the obstacle is counted for each radiation. (scoring). 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 radiation around θ=+10 degrees is counted as 12 points, which is the highest score. As a result, the distance from the current position of the autonomous mobile robot 10 to the obstacle can be quantified.

The route information generation unit 17 can set the direction of the radiation with the highest score as the obstacle avoidance direction. FIG. 7 is a schematic diagram schematically showing the relationship between the obstacle avoidance direction and the target direction. The route information generator 17 sets the current position of the autonomous mobile robot 10 as a starting point, the center point of the next block as a target position, and sets the direction of the target position as a 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 the direction 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. 9(a) is a schematic plan view schematically showing the positional relationship in which the autonomous mobile robot 10 is arranged between obstacles subjected to expansion morphology processing. Assuming that the front of the autonomous mobile robot 10 equipped with the range sensor 12 is 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 A direction than in the B direction.

FIG. 8(a) is a graph showing the distance to an obstacle against the scanning angle of the range sensor 12 mounted in front of the autonomous mobile robot 10 in the positional relationship shown in FIG. 9(a). . More specifically, (a) of FIG. 8 detects obstacles in a range of scanning angles ±θ=approximately ±115 degrees by the range sensor 12 with the position where the autonomous mobile robot 10 is arranged as the origin, and each Fig. 3 is a graph plotting the distance to obstacles at scan angles; The vertical axis of the graph represents the normalized value of the distance to the obstacle. The result of digitizing the obstacle avoidance direction by the value of the vertical axis is shown. Based on the positional relationship shown in FIG. 9(a), it is specified that the direction of about -20 degrees is the target direction. From the graph of FIG. 8(a), it can be confirmed that the distance from the autonomous mobile robot 10 to the obstacle is longer in the A direction than in the B direction.

(b) of FIG. 8 is a graph showing an example of the weighting function. Any weighting function, such as a COS function, a Gaussian function, a parabolic function, etc., that maximizes the weight in the target direction can be used. What kind of weighting function is applied is a parameter dependent on the floor configuration/block map configuration, and is preferably set off-line. In the present embodiment, a linear function with the maximum weight (=1) in the target direction (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). FIG. 9(b) shows the result of superimposing the weighting function on the graph of FIG. 8(a).

From the result of FIG. 9B, it can be confirmed that the distance from the autonomous mobile robot 10 to the obstacle is longer in the B direction than in the A direction by applying a weighting function that considers the influence of the target direction. . Therefore, the route information generator 17 determines that the traveling direction is the B direction. Based on the judgment of the route information generator 17, the obstacle avoidance direction closest to the target direction can be selected.

FIG. 10 is a schematic plan view showing the conditions used for such a series of obstacle avoidance direction selection processes. 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 weighting function, and vi represents the obstacle after superimposing the weighting function. vii represents the direction of travel.

(Drive of drive device)
As described above, the route information generator 17 selects the obstacle avoidance direction and generates a speed command directed to the next target block (S171). A preset speed is preferably used as the driving speed. The output unit 18 outputs to the driving device 13 output information for driving at a predetermined driving speed in the obstacle avoidance direction determined by the route information generating unit 17 . In a preferred embodiment, the drive 13 consists of at least two motors, one on the left and one on the right. By controlling the number of rotations 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 distance traveled and the direction of travel from the rotational motion of the shafts of the left and right motors. Based on the travel distance and movement direction information generated by the encoder 14, the position information generator 19 generates 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 generator 19, it is determined whether or not the block where the autonomous mobile robot 10 currently exists is the final target block (S162).

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

(Hardware configuration of controller)
FIG. 11 is a schematic diagram schematically showing the main hardware configuration of the autonomous mobile robot 10 according to one 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 in FIG. 1 functionally expresses 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.

Controller 130 comprises at least input interface 133 , output interface 114 , processor 135 and memory 136 .

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

More specifically, the first controller 130a can refer to the output signal of the range sensor 12 to control the autonomous mobile robot. Specifically, the first controller 130 a can control the receiving section 15 , the map information input section 16 and the route information generating section 17 . For example, a process of correcting the output signal of the sensor using a weight function that gives a weight for each direction, the weight function maximizing the weight in the target direction of the automatic tour; and a process of determining the traveling direction of the autonomous mobile robot.

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

Programs for executing algorithms that implement processing of information input from input interface 133 are stored in memory 136 . Input information can be processed by executing the program stored in the memory 136 by the processor 135 . The processed information is output from the output interface 114 as output information. The information output from the output interface 114 can be used to control the driving device 13 .

[Embodiment 2]
Other embodiments of the invention are described below. For convenience of description, members having the same functions as those of the members described in the above embodiments are denoted by the same reference numerals, and description thereof will not be repeated.

In Embodiment 1, the configuration in which one controller 11 controls the range sensor 12 and the driving device 13 is shown. In another embodiment, the first controller 130a controlling the range sensor 12 and the second controller 130b controlling the driving device 13 may comprise different controllers. The output information generated by the first controller 130a is received by the second controller 130b, and the second controller 130b can control the driving device 13 based on the output information.

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

In the latter case, the autonomous mobile robot 10 is equipped with a computer that executes program instructions, which are software that implements each function. This computer includes, for example, one or more processors, and a computer-readable recording medium storing the program. 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" such as a ROM (Read Only Memory), a tape, a disk, a card, a semiconductor memory, a programmable logic circuit, or the like can be used. In addition, a RAM (Random Access Memory) for developing the above program may be further provided. Also, the program may be supplied to the computer via any transmission medium (communication network, broadcast wave, etc.) capable of transmitting the program. Note that one aspect of the present invention can also be implemented in the form of a data signal embedded in a carrier wave in which the program is embodied by electronic transmission.

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

10 autonomous mobile robot 11 controller 12 range sensor 13 drive device 14 encoder 15 receiver 16 map information input unit 17 route information generator 18 output unit 19 position information generator 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 location to an obstacle in each direction;
a controller that controls the autonomous mobile robot by referring to the output signal of the sensor;
The controller is
The output signal of the sensor is calculated using a weighting function that gives a weight for each direction and is composed of a combination of linear functions, a cos function, a Gaussian function, or a parabolic function that maximizes the weight in the target direction of the automatic tour. a correction process;
determining the direction corresponding to the maximum output signal among the corrected output signals as the traveling direction of the autonomous mobile robot;
An autonomous mobile robot characterized by: further comprising a driving device for moving the autonomous mobile robot,
The controller supplies a control signal to the driving device for moving the autonomous mobile robot in the determined traveling direction.
The autonomous mobile robot according to claim 1, characterized in that: The sensor uses a laser to detect the distance from the current location to the obstacle at a specific cycle,
The controller executes each of the processes in the specific cycle,
3. The autonomous mobile robot according to claim 1 or 2, characterized in that: The controller is
at least one input interface for obtaining an output signal of the sensor;
at least one processor that executes each process according to a predetermined program;
at least one memory storing the program;
The autonomous mobile robot according to any one of claims 1 to 3, characterized in that: A control method for controlling an autonomous mobile robot that automatically patrols a facility, comprising:
A step of detecting the distance from the current position to the obstacle in each direction using a sensor;
a step of controlling the autonomous mobile robot by referring to the output signal of the sensor;
The controlling step includes:
The output signal of the sensor is calculated using a weighting function that gives a weight for each direction and is composed of a combination of linear functions, a cos function, a Gaussian function, or a parabolic function that maximizes the weight in the target direction of the automatic tour. a correction process;
A process of determining the direction corresponding to the maximum output signal among the output signals after correction as the traveling direction of the autonomous mobile robot,
A control method characterized by: A control program for controlling the autonomous mobile robot according to any one of claims 1 to 4, wherein the control program causes the controller to execute each of the processes.

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