The present application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2015-028975, filed Feb. 17, 2015. The contents of this application are incorporated herein by reference in their entirety.
1. Field of the Invention
The embodiments disclosed herein relate to a movable object controller and a method for controlling a movable object.
2. Discussion of the Background
Japanese Unexamined Patent Application Publication No. 2010-67144 discloses a movable object system that uses a movable object to perform predetermined kind of work such as conveying a workpiece using a conveyor.
Specifically, the movable object system causes the movable object to move, successively determines whether an obstacle is in the forward course of movement of the movable object, and controls the speed of the movable object based on the determination.
In the movable object system, an image sensor successively picks up images of the forward course of movement of the movable object, and a movable object controller sets a plurality of detection regions in each of the images. The plurality of detection regions respectively correspond to predetermined distances (collision imaginary distances) from the front of the movable object. When an obstacle that has a possibility of collision is in any of the detection regions, the movable object controller decelerates or stops the movable object in accordance with the collision imaginary distance corresponding to the detection region.
According to one aspect of the present disclosure, a movable object controller includes a speed controller and a region changer. The speed controller is configured to control a speed of a movable object based on whether an obstacle is in a monitor region. The region changer is configured to change a size of the monitor region based on the speed of the movable object.
According to another aspect of the present disclosure, a method for controlling a movable object includes controlling a speed of the movable object based on whether an obstacle is in a monitor region. A size of the monitor region is changed based on the speed of the movable object.
A more complete appreciation of the present disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
A movable object controller and a method for controlling a movable object according to embodiments will be described in detail below by referring to the accompanying drawings. It is noted that the following embodiments are provided for exemplary purposes only and are not intended for limiting purposes.
In the following embodiments, a self-movable type carriage (hereinafter referred to as “self-movable carriage”) for robot use is used a non-limiting example of the movable object. Other non-limiting examples of the movable object include AGVs (Automated Guided Vehicles).
First, a configuration of a self-movable carriage 1 according to an embodiment will be described by referring to
For ease of description,
The self-movable carriage 1 according to this embodiment is a self-movable carriage for a robot used in handling work. As illustrated in
A robot 5 is mounted on the movable portion 2. A non-limiting example of the robot 5 is a two-arm multi-articular robot as illustrated in
The robot 5 performs a predetermined kind of handling work and takes articles to and from the platform 4 while controlling the positions and postures of the end effectors by making multi-articular motions.
The motion mechanism 3 moves the robot 5 to a predetermined destination together with the articles on the platform 4. As illustrated in
Next, a method for detecting an obstacle according to an embodiment will be outlined by referring to
First, description will be made with regard to a method according to a comparative example, not illustrated, for detecting an obstacle. A known method for detecting an obstacle in moving movable objects such as the self-movable carriage 1 is to set a monitor region around the movable object for a laser scanner or a similar device to monitor, and to decelerate or stop the movable object in the monitor region when the laser scanner detects an obstacle in the monitor region.
This method, however, has only two options, namely, causing the movable object to travel at lower speed or to stop, regardless of whether the detected obstacle is at a substantial distance from the movable object in the monitor region. This situation is attributable to use of a fixed monitor region.
Thus, the method according to a comparative example for detecting an obstacle involves unnecessary low-speed travel or stopping of the movable object in the monitor region. This can make it difficult to shorten the tact time.
In view of this situation, this embodiment dynamically changes the monitor region in accordance with the environment surrounding the movable object. For example, in the embodiment illustrated in
In the embodiment illustrated in
Also in this embodiment, when no obstacle OB is detected in the monitor region MA as represented by the left picture of
In the embodiment illustrated in
While in
As illustrated in
This will be described in detail below by referring to
As used herein, the term “target region where speed control is performed” refers to a region where at least the self-movable carriage 1 is subjected to speed control, which includes stopping, deceleration, and acceleration. As illustrated in
The stopping region A1a is a region where the speed control is control of stopping the self-movable carriage 1 when the obstacle OB is in the stopping region A1a. The deceleration region A1b is a region where the speed control is control of decelerating the self-movable carriage 1 when the obstacle OB is in the deceleration region A1b (or accelerating the self-movable carriage 1 when no obstacle OB exists).
As used herein, the term “turn into a dead zone” means that a region turns into a zone where the control of the self-movable carriage 1 is to maintain the speed of the self-movable carriage 1. That is, the second region A2 is a region where the speed of the self-movable carriage 1 is maintained when the obstacle OB is in the second region A2. The second region A2 will be hereinafter occasionally referred to as “maintaining region A2”.
By arranging the maintaining region A2, which turns into a dead zone, on the circumference of the monitor region MA, this embodiment eliminates or minimizes chattering-like fluctuation of the speed of the self-movable carriage 1 at the time of precise and quick switch between reduction and increase of the size of the monitor region MA.
Thus, in this embodiment, the monitor region MA has such a shape that the self-movable carriage 1 is at the center of the monitor region MA and surrounded by the stopping region A1a, the deceleration region A1b, and the maintaining region A2 in this order. That is, this embodiment sets the omni-directional monitor region MA, leaving no blind spots, for the self-movable carriage 1, which is capable of making omni-directional movements realized by the omni-directional wheels 3a. This configuration ensures safety in the travel of the self-movable carriage 1 in accordance with the surrounding environment. This configuration also contributes to the shortening of the tact time.
The monitor region MA is formed using a laser scanner RS, which is equipped in the self-movable carriage 1.
The laser scanner RS is provided in plural and thus capable of detecting obstacles in omni-directions of the self-movable carriage 1, which is capable of making omni-directional movements. In this embodiment, three laser scanners RS1 to RS3 are provided as illustrated in
Specifically, the laser scanner RS1 forms, for example, a region indicated by the shaded portions of the monitor region MA illustrated in
The laser scanner RS2 forms, for example, a region indicated by the shaded portions of the monitor region MA illustrated in
Then, the regions formed by the laser scanners RS1 to RS3 are combined into the monitor region MA, which covers omni-directions of the self-movable carriage 1.
In this embodiment, the laser scanners RS1 to RS3 are of binary output type. This is because being of binary output type enables binary determination of ON/OFF as to whether the obstacle OB exists, eliminating the need for more complicated and higher-load processing such as image analysis. Thus, being of binary output type facilitates detection of the obstacle OB. Moreover, generally, more binary output-type sensors comply with safety standards than sensors of other types do.
Next, a block configuration of the self-movable carriage 1 according to this embodiment will be described by referring to
The following description by referring to
As illustrated in
The storage 24 is a storage device such as a hard disc drive and a nonvolatile memory, and stores monitor region information 24a.
It is noted that not all the components of the controller 20 illustrated in
A non-limiting example of the control section 21 is a Central Processing Unit (CPU) that is in charge of overall control of the controller 20. The obstacle detector 22 is a detector that includes the laser scanners RS1 to RS3 and that forms the monitor region MA based on instructions from the monitor region setter 21a and the monitor region changer 21c. The obstacle detector 22 scans the inside of the monitor region MA to determine whether the obstacle OB is in the monitor region MA. Then, the obstacle detector 22 outputs the determination in binary form to the obstacle determiner 21b.
The indicator detector 23 is a detector that includes a sensor mounted on the self-movable carriage 1 and separate from the laser scanners RS1 to RS3. The indicator detector 23 detects an indicator arranged in the travel region of the self-movable carriage 1 along the travel path of the self-movable carriage 1. Then, the indicator detector 23 outputs a detection result to the direction distance controller 21db. A non-limiting example of the indicator is a plate with a light reflecting material on the surface. The indicator is attached to a wall or any other surface along the travel path of the self-movable carriage 1.
Thus, a sensor separate from the laser scanners RS1 to RS3, which detect obstacles, is provided to detect the indicator. This configuration facilitates the control of obstacle detection and the control of indicator detection.
Based on the monitor region information 24a, the monitor region setter 21a gives an instruction to the obstacle detector 22. A non-limiting example of the instruction is an instruction for initial setting of the monitor region MA at the time of initial activation of the self-movable carriage 1.
A non-limiting example of the monitor region information 24a will be described by referring to
For example, as illustrated in
In the embodiment illustrated in
Also as illustrated in
The monitor region MA2 is correlated with “Speed of equal to or lower than 200 mm/s”. The monitor region MA3 is correlated with “Speed of equal to or lower than 300 mm/s”. The monitor region MA4 is correlated with “Speed of equal to or lower than 400 mm/s”.
Referring back to
Based on the determination from the obstacle determiner 21b and based on the monitor region information 24a, the monitor region changer 21c instructs the obstacle detector 22 to change the size of the monitor region MA. Based on the determination from the obstacle determiner 21b and based on the monitor region information 24a, the speed controller 21da controls the speed of the self-movable carriage 1.
By referring to
First, as represented by the left picture of
When the self-movable carriage 1 is accelerated, the monitor region changer 21c instructs the obstacle detector 22 to enlarge the monitor region MA from the monitor region MA1 to the monitor region MA2. The acceleration of the self-movable carriage 1 and the enlargement of the monitor region MA may be repeated, enlarging the monitor region MA2 to the monitor region MA3 or enlarging the monitor region MA3 to the monitor region MA4, until the obstacle OB enters the monitor region MA.
Thus, when no obstacle OB is in the monitor region MA, the self-movable carriage 1 is accelerated and thus the monitor region MA is enlarged. This configuration contributes to the shortening of the tact time while keeping the self-movable carriage 1 moving at speeds that accord with the surrounding environment.
Next, as represented by the left picture of
Thus, the speed of the self-movable carriage 1 and the size of the monitor region MA are maintained. This configuration eliminates or minimizes chattering-like fluctuation of the speed of the self-movable carriage 1, that is, repeated acceleration and deceleration. This, in turn, ensures stable travel of the self-movable carriage 1.
Next, as represented by the left picture of
When the self-movable carriage 1 is decelerated, the monitor region changer 21c instructs the obstacle detector 22 to diminish the monitor region MA from the monitor region MA2 to the monitor region MA1.
Thus, when the obstacle OB is in the monitor region MA, the self-movable carriage 1 is decelerated and thus the monitor region MA is diminished. This configuration eliminates or minimizes unnecessary low-speed travel of the self-movable carriage 1 at least in the monitor region MA, enabling the self-movable carriage 1 to travel at substantial speed. This configuration, as a result, contributes to the shortening of the tact time while keeping the self-movable carriage 1 moving at speeds that accord with the surrounding environment.
Next, as represented by the left picture of
As illustrated in
Referring back to
The guide 21d outputs an output signal to the motion mechanism 3 so as to guide the self-movable carriage 1. The output signal includes a value for the speed control performed by the speed controller 21da and a value for the direction and distance control performed by the direction distance controller 21db. In response to the output signal received from the guide 21d, the motion mechanism 3 drives the driving devices (not illustrated) of the omni-directional wheels 3a to cause the self-movable carriage 1 to travel along the travel path specified by the indicator.
Next, a procedure for processing performed by the controller 20 according to this embodiment will be described by referring to
As illustrated in
Then, during the travel of the self-movable carriage 1, the obstacle detector 22 scans the monitor region MA at predetermined time intervals, for example (step S103).
Then, based on the detection result detected by the obstacle detector 22, the obstacle determiner 21b determines whether the obstacle OB is in the stopping region A1a (step S104). When a determination is made that the obstacle OB is in the stopping region A1a (step S104, Yes), the speed controller 21da immediately stops the self-movable carriage 1 (step S105), and the processing at and later than step S103 is repeated.
When a determination is made that no obstacle OB is in the stopping region A1a (step S104, No), the obstacle determiner 21b determines whether the obstacle OB is in the deceleration region A1b (step S106).
When a determination is made that the obstacle OB is in the deceleration region A1b (step S106, Yes), the speed controller 21da decelerates the self-movable carriage 1 (step S107) and the monitor region changer 21c reduces the size of the monitor region MA (step S108). Then, the controller 20 repeats the processing at and later than step S102.
When a determination is made that no obstacle OB is in the deceleration region A1b (step S106, No), the obstacle determiner 21b determines whether the obstacle OB is in the maintaining region A2 (step S109).
When a determination is made that the obstacle OB is in the maintaining region A2 (step S109, Yes), the speed controller 21da maintains the speed of the self-movable carriage 1 (step S110), and the monitor region changer 21c maintains the size of the monitor region MA (step S111). Then, the controller 20 repeats the processing at and later than step S102.
When a determination is made that no obstacle OB is in the maintaining region A2 (step S109, No), the speed controller 21da accelerates the self-movable carriage 1 (step S112), and the monitor region changer 21c increases the size of the monitor region MA (step S113). Then, the controller 20 repeats the processing at and later than step S102.
As has been described hereinbefore, the controller (movable object controller) according to this embodiment includes a speed controller and a monitor region changer (region changer). The speed controller controls the speed of the self-movable carriage (movable object) based on whether an obstacle is in the monitor region. The monitor region changer changes the size of the monitor region based on the speed of the self-movable carriage.
Thus, the controller according to this embodiment shortens the tact time while enabling the self-movable carriage to travel at speeds that accord with the surrounding environment.
While in the above-described embodiment the monitor region has been mainly described as a two-dimensional shape by referring to plan views of the self-movable carriage, the monitor region will not be limited to two-dimensional shape. Another possible embodiment is that the monitor region has a three-dimensional shape.
While in the above-described embodiment the monitor region information contains a plurality of sets of the monitor region different from each other at least in size of the monitor region, the plurality of sets of the monitor region may be different from each other in shape of the monitor region.
The monitor region will not be limited to the above-described shape surrounding the self-movable carriage. Another possible embodiment is that the self-movable carriage is capable of travelling only in the front and rear directions, and the monitor region has such a shape that covers only the front side and the rear side of the self-movable carriage.
While in the above-described embodiment the laser scanners have been described as being of binary output type, the laser scanners will not be limited to binary output type.
While in the above-described embodiment the self-movable carriage has been described as being for robot use, this should not be construed as limiting the use of the self-movable carriage. While in the above-described embodiment the robot-use self-movable carriage has been described as including a two-arm multi-articular robot to engage in handling work, the two-arm multi-articular robot should not be construed in a limiting sense. Other possible examples include a single-arm multi-articular robot and an orthogonal robot.
The movable object may not necessarily make only horizontal movements on a floor and other surfaces. Another possible embodiment is that the movable object is capable of making horizontal and vertical movements on a wall and a ceiling.
Obviously, numerous modifications and variations of the present disclosure are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the present disclosure may be practiced otherwise than as specifically described herein.
Number | Date | Country | Kind |
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2015-028975 | Feb 2015 | JP | national |