JP2010055422A - Autonomous mobile device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an autonomous mobile device capable of suppressing a deterioration in responsiveness to an ambient object, without increasing the resources, even when the number of sensors exceeds the number of resources that can be used in input processing. <P>SOLUTION: The autonomous mobile device 1 includes: its body 10, provided with omniwheels 13 driven by electric motors 12; eight ultrasonic sensors 20 to 27 for detecting the presence/absence of an ambient object and a distance to the ambient object; and an electronic control device 30 for controlling the electric motors 12 so as to take an avoiding operation, or the like, according to the detection results of the ultrasonic sensors 20 to 27. The electronic control device 30 is provided with a CPU 31, prepared with four interruption channels for receiving the interrupt requests from the ultrasonic sensors 20 to 27, and an input-output interface 32 for preferentially selecting an ultrasonic sensor that can detect the ambient object in the traveling direction, when the ultrasonic sensors to be allocated to four interruption channels is to be selected. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an autonomous mobile device, and more particularly to an autonomous mobile device that moves while detecting an object around its own device.

In recent years, research and development of an autonomous mobile device that moves autonomously while detecting obstacles and the like around its own device have been promoted, and has been put into practical use, for example, as a transport robot in a warehouse or factory. As such an autonomous mobile device, Patent Document 1 provides a plurality of ultrasonic sensors to detect the obstacle regardless of the angle at which the obstacle having the superstructure is approached. An autonomous mobile device configured to be able to perform is disclosed.
JP 2002-202815 A

  Here, for example, in order to be able to detect an object existing around the entire circumference of the autonomous mobile device, it is necessary to increase the number of sensors such as an ultrasonic sensor for detecting the object. On the other hand, resources for input processing of the electronic control device that controls the autonomous mobile device are limited, and resources that can be used in input processing of sensors such as ultrasonic sensors (hereinafter also referred to as “measurement resources”) are also limited. If the number of sensors such as ultrasonic sensors increases and exceeds the number of measurement resources, inputs from all sensors cannot be received at the same time. It is necessary to select and assign to measurement resources to perform input processing. For this reason, the time required to accept inputs from all the sensors, that is, the sensing cycle becomes longer. As a result, it takes a long time to detect an object such as an obstacle, and for example, there is a possibility that the responsiveness of an operation such as avoidance or stop for the object is lowered.

  The present invention has been made to solve the above-described problems. Even when the number of sensors exceeds the number of resources that can be used in input processing, the response to surrounding objects can be improved without increasing the resources. It aims at providing the autonomous mobile device which can suppress a fall.

  The autonomous mobile device according to the present invention includes a moving means for moving the own apparatus, a plurality of detecting means for detecting an object around the own apparatus, and a control means for controlling the moving means based on a detection result of the detecting means. The control means has a resource used in the detection result input process of the detection means and a management means for managing the resource allocation, and the management means has a plurality of detection means according to the traveling direction of the own device. The detection means to be allocated to the resource is selected from the above.

  According to the autonomous mobile device of the present invention, when the detection means to be allocated to the resource is selected, the detection means is not selected from all the detection means equally, but according to the traveling direction. Selected. Therefore, for example, it is possible to concentrate resources on detection means that can detect an object in a direction that is highly necessary to be detected with respect to the traveling direction. Further, the moving means is controlled based on the detection result of the detecting means selected and assigned to the resource. Therefore, even when the number of sensors exceeds the number of resources that can be used in input processing, it is possible to suppress a decrease in responsiveness to surrounding objects without increasing the resources.

  In the autonomous mobile device according to the present invention, it is preferable that the management unit preferentially selects the detection unit that can detect an object around the traveling direction of the own aircraft.

  In this case, since detection means that can detect objects around the direction of travel of the aircraft is preferentially selected, the sensing cycle for the direction of travel where there is a high possibility that there is an object that needs to respond during movement is shortened. Can do. As a result, it is possible to effectively suppress a decrease in responsiveness to an object such as an obstacle.

  In the autonomous mobile device according to the present invention, it is preferable that the moving means includes an electric motor and wheels driven by the electric motor and movable in all directions, front, rear, left and right.

  In this way, by driving the electric motor, the autonomous mobile device can be moved in all directions, front, rear, left, and right.

  In the autonomous mobile device according to the present invention, it is preferable to use an ultrasonic sensor as the detection means.

  According to the present invention, since the detection means to be allocated to the resource used in the input process is selected from a plurality of detection means according to the traveling direction of the own machine, the number of sensors is used in the input process. Even when the number of possible resources is exceeded, it is possible to suppress a decrease in responsiveness to surrounding objects without increasing the resources.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the same element and the overlapping description is abbreviate | omitted.

  First, the configuration of the autonomous mobile device 1 according to the embodiment will be described using FIG. 1 and FIG. 2 together. FIG. 1 is a block diagram showing the configuration of the autonomous mobile device 1. FIG. 2 is a plan view showing the arrangement of the ultrasonic sensors 20 to 27 in the autonomous mobile device 1.

  The autonomous mobile device 1 detects an object such as an obstacle existing around the aircraft and functions to move autonomously while taking an action such as avoidance or suspension when the obstacle is detected. It is what has. Therefore, the autonomous mobile device 1 includes the main body 10 provided with the electric motor 12 and the omni wheel 13 driven by the electric motor 12, and the presence or absence of an object (such as a wall or an obstacle) present in the surroundings. Eight ultrasonic sensors 20 to 27 for detecting the distance to the object are provided. In addition, the autonomous mobile device 1 reads the detection results of the ultrasonic sensors 20 to 27 at a predetermined timing, and controls the electric motor 12 so as to take, for example, avoidance and temporary stop according to the detection results. A control device 30 is provided. Hereinafter, each component will be described in detail.

  The main body 10 is, for example, a metal frame formed in a substantially bottomed cylindrical shape, and the eight ultrasonic sensors 20 to 27 and the electronic control device 30 described above are attached to the main body 10. The shape of the main body 10 is not limited to a substantially bottomed cylindrical shape. Four electric motors 12 are arranged in a cross shape and attached to the lower portion of the main body 10. Omni wheels 13 are attached to the drive shafts 12A of the four electric motors 12, respectively. That is, the four omni wheels 13 are mounted on the same circumference at intervals of 90 ° along the circumferential direction.

  The omni wheel 13 is provided so as to be rotatable around two wheels 14 that rotate about the drive shaft 12A of the electric motor 12 and an axis that is orthogonal to the drive shaft 12A of the electric motor 12 on the outer periphery of each wheel 14. Further, the wheel has six free rollers 15 and is movable in all directions. The two wheels 14 are attached with a phase shifted by 30 °. Due to such a configuration, when the electric motor 12 is driven and the wheel 14 rotates, the six free rollers 15 rotate together with the wheel 14. On the other hand, when the grounded free roller 15 rotates, the omni wheel 13 can also move in a direction parallel to the rotation axis of the wheel 14. Therefore, the autonomous mobile device 1 is moved in any direction (all directions) by independently controlling the four electric motors 12 and individually adjusting the rotation direction and the rotation speed of the four omni wheels 13. Can do.

  Each of the four electric motors 12 is provided with an encoder 16 that detects the rotation angle of the drive shaft 12A of the electric motor 12. Each encoder 16 is connected to the electronic control unit 30, and outputs the detected rotation angle of each electric motor 12 to the electronic control unit 30. The electronic control unit 30 calculates the movement direction (traveling direction) and movement amount of the autonomous mobile device 1 from the input rotation angle of each electric motor 12.

  On the side surface of the main body 10, eight ultrasonic sensors 20 to 27 are attached at equal intervals over the entire circumference. That is, the eight ultrasonic sensors 20 to 27 are attached on the same circumference at intervals of 45 ° along the circumferential direction. Each of the ultrasonic sensors 20 to 27 has directivity in the detection direction of the object, and an object in all directions (360 °) can be detected by combining the eight ultrasonic sensors 20 to 27. It is configured.

  As the ultrasonic sensors 20 to 27, reflective ultrasonic sensors are preferably used. The ultrasonic sensors 20 to 27 transmit ultrasonic waves and detect ultrasonic waves (reflected waves) that are reflected by an object and return. From the presence / absence of the reflected waves and the arrival time (propagation time) of the reflected waves, The presence / absence of an object and the distance to the object are detected. That is, the ultrasonic sensors 20 to 27 function as detection means described in the claims. The ultrasonic sensors 20 to 27 are connected to the electronic control device 30, and the detection results by the ultrasonic sensors 20 to 27 are output to the electronic control device 30.

  The electronic control unit 30 comprehensively governs the movement of the autonomous mobile device 1. The electronic control unit 30 includes a CPU 31 that performs calculations, a ROM that stores programs for causing the CPU 31 to execute each process, a RAM that temporarily stores various data such as calculation results, and the storage contents thereof. It consists of a backup RAM and the like. Further, the electronic control device 30 includes an input / output interface 32 that electrically connects the ultrasonic sensors 20 to 27 and the CPU 31, a driver circuit that drives the electric motor 12, and the like.

  For example, the electronic control device 30 controls each electric motor 12 so that the autonomous mobile device 1 autonomously moves to a target position along a planned route while detecting an object such as an obstacle. Moreover, when performing the autonomous movement, the electronic control unit 30 reads the detection results of the ultrasonic sensors 20 to 27 at a predetermined timing, and performs operations such as avoiding or stopping according to the detection results. The electric motor 12 is controlled. That is, the electronic control unit 30 functions as a control unit described in the claims.

  In this embodiment, when the ultrasonic sensors 20 to 27 detect the reflected waves, the terminals of the input / output interface 32 corresponding to the ultrasonic sensors 20 to 27 that have detected the reflected waves become active, and an interrupt is applied to the CPU 31. It is configured as follows. Therefore, in order to receive an IRQ (Interrupt ReQuest) signal for requesting an interrupt from the ultrasonic sensors 20 to 27 to the CPU 31, four interrupt channels are prepared in the CPU 31. That is, in the present embodiment, the interrupt channel of the CPU 31 that accepts interrupt requests from the ultrasonic sensors 20 to 27 corresponds to the resources described in the claims.

  As described above, in the present embodiment, since eight ultrasonic sensors 20 to 27 are provided for four interrupt channels, all the ultrasonic sensors 20 to 27 are assigned to the interrupt channels of the CPU 31 at one time. I can't. For this reason, the input / output interface 32 has a function of managing the allocation of interrupt channels of the CPU 31. For example, by using a multiplexer whose output channel is switched by a control signal from the CPU 31, the eight ultrasonic sensors 20˜ The ultrasonic sensors to be assigned to the four interrupt channels are selected from 27. That is, in the present embodiment, the CPU 31 and the input / output interface 32 function as management means described in the claims.

  Here, when the input / output interface 32 selects an ultrasonic sensor to be assigned to the interrupt channel of the CPU 31 from among the eight ultrasonic sensors 20 to 27, the ultrasonic sensor that can detect an object around the traveling direction is prioritized. To select. More specifically, for example, when the autonomous mobile device 1 travels in the direction of the arrow A1 shown in FIG. 2, the three ultrasonic sensors 20, 21, and 27 that can detect objects around the arrow A1 direction are selected. Is done. That is, among the four interrupt channels, three ultrasonic sensors 20, 21, and 27 are preferentially assigned to three interrupt channels with the ultrasonic wave transmission direction being the same as or close to the travel direction. Further, one of the other five ultrasonic sensors 22 to 26 other than those described above is assigned to the remaining interrupt channel in order (for each switching period).

  Here, the traveling direction of the own device, which is a reference for selecting the ultrasonic sensors 20 to 27 assigned to the interrupt channel, is acquired as follows. The electronic control unit 30 calculates a route to go to the target position based on the position of the own device and the environment map. Here, the position of the own machine is determined by comparing the information of surrounding objects obtained from, for example, a laser range finder (not shown) with the environment map, and the output shaft 12A of each electric motor 12 that drives the omni wheel 13. It is determined by comprehensively considering the information of the rotation angle. In addition, when an obstacle is detected and it is determined that it is necessary to avoid the obstacle, the electronic control device 30 determines the direction (avoidance direction) and speed for moving the own device to avoid the obstacle. calculate. These calculations can be performed based on a known virtual potential method. Then, the electronic control unit 30 determines the traveling direction based on the calculated route and the avoidance direction, and controls the rotation of the four electric motors 12 so as to move in the determined traveling direction. Therefore, the ultrasonic sensor assigned to the interrupt channel is selected from the traveling direction determined based on the set moving route and the obstacle avoidance direction.

  On the other hand, for example, when moving randomly without setting a target position (movement route), that is, when it does not have a target traveling direction, as described above, The traveling direction can be obtained from the rotation angle detected by the attached encoder 16, that is, the actual wheel rotation amount of each omni wheel 13.

  Next, the operation of the autonomous mobile device 1 will be described with reference to FIGS. Here, FIG. 3 is a timing chart showing the relationship between the traveling direction of the autonomous mobile device 1 and resource allocation to the ultrasonic sensors 20 to 27.

  First, when the autonomous mobile device 1 moves autonomously, the traveling direction is determined by the electronic control device 30 based on the movement route and the avoidance direction. Then, the rotation of the four electric motors 12 is controlled so as to move in the determined traveling direction. Further, in accordance with the determined traveling direction, an ultrasonic sensor assigned to the four interrupt channels of the CPU 31 is selected from the eight ultrasonic sensors 20 to 27 in the input / output interface 32 of the electronic control unit 30. .

  Here, in the input / output interface 32, when an ultrasonic sensor assigned to the interrupt channel of the CPU 31 is selected from the eight ultrasonic sensors 20 to 27, an ultrasonic sensor capable of detecting an object around the traveling direction. Is preferentially selected. More specifically, as shown in FIG. 3, for example, when autonomous mobile device 1 travels in the direction of arrow A1 shown in FIG. 2 (between times t0 and t5 in FIG. 3), the direction of arrow A1 Three ultrasonic sensors 20, 21, and 27 that can detect peripheral objects are selected. That is, among the four interrupt channels, three ultrasonic sensors 20, 21, and 27 are preferentially assigned to three interrupt channels with the ultrasonic wave transmission direction being the same as or close to the travel direction. Further, one of the other five ultrasonic sensors 22 to 26 other than those described above is assigned to the remaining interrupt channel in order (for each switching period).

  On the other hand, for example, when the autonomous mobile device 1 travels in the direction of arrow A2 shown in FIG. 2 (between times t5 and t10 in FIG. 3), three ultrasonic sensors that can detect objects around the arrow A2 direction. 21, 22, 23 are selected. That is, among the four interrupt channels, three ultrasonic sensors 21, 22, and 23 are preferentially assigned to three interrupt channels, with the ultrasonic transmission direction being the same as the traveling direction or close to the traveling direction. Further, one of the five ultrasonic sensors 20 and 24 to 27 other than the above is assigned to the remaining one interrupt channel in order (for each switching period).

  In the present embodiment, the switching cycle of the ultrasonic sensors 20 to 27 (time tn to tn + 1 shown in FIG. 3) is set to 25 msec. That is, selection of the ultrasonic sensors 20 to 27 and detection of an object such as an obstacle are repeatedly performed every 25 msec. When the ultrasonic sensors 20 to 27 detect the reflected wave within 25 msec after transmitting the ultrasonic wave, the terminals of the input / output interface 32 corresponding to the ultrasonic sensors 20 to 27 detecting the reflected wave become active, and the CPU 31 Is interrupted.

  Upon receiving the interrupt request, the CPU 31 executes an interrupt process corresponding to the interrupt request, and detects the distance to the object from the time from when the ultrasonic wave is transmitted until the reflected wave is detected. On the other hand, when the reflected wave cannot be detected during the switching period (25 msec), that is, when no interruption occurs, the CPU 31 determines that the object does not exist or the distance from the object is 25 msec or more away at the speed of the sound wave. Then, the next ultrasonic sensors 20 to 27 are selected and a new detection process is executed.

  When an object such as an obstacle is detected, the electronic control unit 30 calculates a direction (avoidance direction), a speed, and the like for moving the own device in order to avoid the detected object. Then, the electronic control unit 30 determines the traveling direction based on the calculated avoidance direction and the movement route, and controls the rotation of the four electric motors 12 so as to move in the determined traveling direction. And the electronic control apparatus 30 moves autonomously to the set target position by repeatedly performing the above process.

  As described above, in this embodiment, since three ultrasonic sensors that can detect objects around the traveling direction are selected every switching cycle, the sensing cycle ahead in the traveling direction is 25 msec (one switching cycle). (See FIG. 3). On the other hand, for directions other than the traveling direction, one of the five ultrasonic sensors other than the above is assigned in turn for each switching period, so the sensing period in the direction other than the traveling direction is 125 msec (5 switching periods). (See FIG. 3). Here, if the eight ultrasonic sensors 20 to 27 are evenly assigned to the four interrupt channels regardless of the traveling direction, as shown in FIG. 4, both the traveling direction and the direction other than the traveling direction are obtained. Similarly, the sensing cycle is 50 msec (2 switching cycles). Therefore, according to the present embodiment, it is possible to sense an object ahead in the traveling direction with a shorter sensing cycle as compared with the case of evenly allocating, and for example, it is possible to more reliably avoid or stop an obstacle. .

  According to the present embodiment, when the ultrasonic sensors 20 to 27 allocated to the interrupt channel (resource) of the CPU 31 are selected, the ultrasonic sensor capable of detecting an object around the front in the traveling direction is preferentially selected. . Therefore, many resources can be allocated to the traveling direction in which there is a high possibility that an object that needs to respond is present, and the sensing cycle for the traveling direction can be shortened. As a result, even when the number of the ultrasonic sensors 20 to 27 exceeds the number of interrupt channels of the CPU 31 that can be used, the responsiveness to an object can be improved without increasing the interrupt channels of the CPU 31.

  According to this embodiment, it has four electric motors 12 and four omni wheels 13 driven by the electric motors 12 as moving means. Therefore, the autonomous mobile device 1 is moved in any direction (all directions) by independently controlling the four electric motors 12 and individually adjusting the rotation direction and the rotation speed of the four omni wheels 13. Can

  Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made. For example, in the above embodiment, the number of the ultrasonic sensors 20 to 27 is set to eight and the interrupt channel of the CPU 31 used for the input processing of the ultrasonic sensors 20 to 27 is set to four. The number of channels is not limited to 8 and 4.

  In the above embodiment, an ultrasonic sensor is used as a detection unit for detecting surrounding objects. However, for example, an infrared radar, a laser radar, or the like may be used instead of or in addition to the ultrasonic sensor. Furthermore, in the above embodiment, the interrupt channel of the CPU 31 is given as an example of the resource. However, the resource is not limited to the interrupt channel of the CPU. For example, the CPU time and the CPU allocation when the multi-CPU configuration is adopted. There may be. Further, the resource is not limited to a hardware resource, and may be a software resource.

  In the above embodiment, an omni wheel that can move in all directions is adopted as a wheel, but normal wheels (steering wheels and driving wheels) may be used.

  In the above-described embodiment, the ultrasonic sensor is selected with priority on the traveling direction, but the priority direction is not limited to the traveling direction. Depending on the movement situation and the surrounding environment, for example, a direction perpendicular to the traveling direction or a direction opposite to the traveling direction may be prioritized.

It is a block diagram which shows the structure of the autonomous mobile apparatus which concerns on embodiment. It is a top view which shows arrangement | positioning of the ultrasonic sensor in the autonomous mobile apparatus which concerns on embodiment. It is a timing chart which shows the relationship between the advancing direction of the autonomous mobile device which concerns on embodiment, and the resource allocation with respect to each ultrasonic sensor. It is a timing chart which shows the resource allocation with respect to each ultrasonic sensor in case the some ultrasonic sensor is allocated equally.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Autonomous mobile device 10 Main body 12 Electric motor 13 Omni wheel 14 Wheel 15 Free roller 16 Encoder 20, 21, 22, 23, 24, 25, 26, 27 Ultrasonic sensor 30 Electronic control device 31 CPU
32 I / O interface

Claims (4)

Moving means for moving the aircraft;
A plurality of detection means for detecting objects around the aircraft;
Control means for controlling the moving means based on the detection result of the detecting means,
The control means includes
Resources used in input processing of detection results of the detection means;
Management means for managing allocation of the resource,
The autonomous mobile device, wherein the management unit selects a detection unit to be allocated to the resource from the plurality of detection units according to a traveling direction of the own device.   The autonomous mobile device according to claim 1, wherein the management unit preferentially selects a detection unit capable of detecting an object around the traveling direction of the own aircraft.   The autonomous moving apparatus according to claim 1, wherein the moving unit includes an electric motor and wheels that are driven by the electric motor and are movable in all directions of front, rear, left, and right. The autonomous mobile device according to claim 1, wherein the detection unit is an ultrasonic sensor.

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