JP2875498B2 - Automatic generation method of movement path of robot manipulator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for automatically generating a movement path of a robot manipulator, and more particularly, to a method for moving a robot manipulator element working in a three-dimensional space from an initial position while avoiding obstacles. The present invention relates to a method for automatically generating a route to be moved to a position.

[0002]

2. Description of the Related Art There are many disclosed examples of a method for automatically generating a path for moving an element of a robot manipulator working in a three-dimensional space from an initial position to a target position while avoiding obstacles. For example, Japanese Unexamined Patent Publication No. Hei.
In Japanese Patent Application Laid-Open No. 06 and Japanese Patent Application Laid-Open No. 4-280304, the configuration space method is used. However, since the computational complexity is enormous if the configuration space method is used as it is, in the former, the computational complexity is reduced by sequentially searching the free space near the boundary between the obstacle and the free space in the configuration space. . Also, in the latter, by providing a table in which a joint angle space, which is a type of configuration space, and a rectangular coordinate space are associated with each other, the amount of calculation is reduced and the speed is increased. In Japanese Patent Laid-Open No. 5-250023, a potential method is used, and a neural network is applied to generate the potential field. Here, the neural network is learned using the risk calculated from the distance between each link of the articulated manipulator and the obstacle, and the evaluation calculation regarding the risk of collision is facilitated. Note that the descent method is used for trajectory generation. Further, in Japanese Patent Laid-Open Nos. 5-119815 and 5-204436, both the configuration space method and the potential method are used.
That is, in the former, the tendency that the generated route is set very close to the obstacle is avoided by reflecting the evaluation function that changes according to the distance from the obstacle in the configuration space. ^{* Using an} algorithm. In the latter case, a chaotic steepest descent method is used as a search method for the potential space to reliably escape from a local minimum point (local minimum). As described above, all of the disclosed examples directly deal with the three-dimensional interference avoidance problem in which the robot manipulator moves from the initial posture to the target posture while avoiding the obstacle in the environment where the obstacle exists.

[0003]

The above-mentioned conventional method for automatically generating a movement path of a robot manipulator has the following problems. (1) A large storage area is required. In the configuration space method, it is necessary to store a free space in which no obstacle exists. JP-A-4-235606, JP-A-4-280304 and JP-A-5-250023
In Japanese Patent Application Laid-Open Publication No. H08-27566, the space is divided into cells to compress the amount of information handled, but a large amount of storage area is still required. (2) Calculation time is required. In the potential method, it takes time to calculate the potential field when an obstacle having a complicated shape exists. In JP-A-5-119815,
Although it claims high-speed collision avoidance processing that makes use of the parallel processing capability of neural networks, high-speed processing is not always possible when considering the learning time of neural networks. Also, in the configuration space method, a large amount of calculation is required for calculating the mapping between the rectangular coordinate space and the configuration space.
Therefore, when the dimension of the space increases, it is difficult to efficiently calculate the free space in the configuration space. In Japanese Patent Laid-Open No. 4-280304, the amount of calculation is reduced by using a table in which a rectangular coordinate space and a configuration space are associated with each other, but a correspondingly large amount of storage area is required.

(3) The generated route may be set very close to an obstacle. In the configuration space method, since the path planning is performed not in the rectangular coordinate space but in the configuration space, it is difficult to consider the position in the rectangular coordinate space. Therefore, the generated route may be set very close to the obstacle in the rectangular coordinate space. (4) The generated route may be set to bypass the obstacle more than necessary. For the same reason as (3) above,
In the configuration space method, a generated path may be set to bypass an obstacle more than necessary.
Further, in the potential method, it is possible to prevent a route from being set very close to an obstacle by adjusting parameters in generating a potential field, but it is difficult to prevent a detour more than necessary. Moreover, since the parameter adjustment is generally a trial and error process, it is difficult to make an accurate adjustment. Therefore, depending on the setting of the route, a local minimum point may be generated in the potential field and may stop during the search. For this reason, Japanese Patent Application Laid-Open No. 5-204436 discloses a method of exiting from a local minimum point by a vibration component generated from the time evolution equation of chaos. Could be. In order to solve the problems in the conventional technology, the present invention has improved an automatic generation method of a movement path of a robot manipulator, and has realized a high-speed path generation process with a relatively small storage capacity and a practical calculation time. It is an object of the present invention to provide a method of automatically generating a movement path of a robot manipulator that can be realized.

[0005]

In order to achieve the above object, the present invention provides a path for moving an element of a robot manipulator working in a three-dimensional space from an initial position to a target position while avoiding obstacles. Automatically generate the cross-sectional shape of an obstacle on a desired plane out of a plurality of planes including the initial position and the target position of the element, such that the element of the robot manipulator can avoid interference with the obstacle. When the route is initially generated by connecting the initial position and the target position of the element on the desired plane with a straight line, and the route interferes with the intrusion prohibited region, A method of automatically generating a movement path of a robot manipulator, wherein the path is corrected to a path passing through a vertex of the intrusion prohibited area so as to avoid interference with the intrusion prohibited area. It is configured as. Furthermore,
In the case where there are a plurality of corrected paths, a method for automatically generating a movement path of a robot manipulator that performs a predetermined evaluation and selects one path is provided. Further, when there are a plurality of the desired planes, a method for automatically generating a movement path of a robot manipulator for performing a predetermined evaluation and selecting one path from the paths obtained for each of the desired planes It is.

According to the present invention, when automatically generating a path for moving an element of a robot manipulator working in a three-dimensional space from an initial position to a target position while avoiding an obstacle, the initial position of the element is determined. A desired plane is selected from a plurality of planes including the target position and the target position. Then, an intrusion prohibition region is created in which the cross-sectional shape of the obstacle on this plane is enlarged to such an extent that the elements of the robot manipulator can avoid interference with the obstacle. To expand the robot manipulator elements to the extent that they can avoid interference with obstacles,
For example, the predetermined distance may be increased in consideration of safety, or the distance may be further increased according to the acceleration of the element. Next, the path is initially generated by connecting the initial position and the target position of the element on the desired plane with a straight line. When the path interferes with the intrusion prohibited area, the path is corrected to a path passing through the top of the intrusion prohibited area so as to avoid interference with the intrusion prohibited area. For example, of the paths passing through the vertices, a path passing through the intrusion prohibited area is invalidated. As described above, the obstacle avoidance in the three-dimensional space is reduced to a two-dimensional obstacle avoidance problem in the present invention. As a result, high-speed path generation processing with a practical calculation time can be realized with a relatively small storage area. Also, a route that does not cause interference with an obstacle and that does not detour more than necessary is generated. Further, when there are a plurality of corrected paths,
What is necessary is to perform a predetermined evaluation and select one path. Further, when considering a plurality of the desired planes in order to consider interference avoidance in three dimensions, one path may be selected by performing a predetermined evaluation from the paths obtained for each of the desired planes. . Thus, when a plurality of solutions are obtained, the narrowing down can be automatically performed.

[0007]

DETAILED DESCRIPTION OF THE INVENTION AND

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments and examples of the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention.
The following embodiments and examples are mere examples embodying the present invention, and do not limit the technical scope of the present invention. Here, FIG. 1 is a flowchart showing a schematic configuration of a method for automatically generating a movement path of a robot manipulator according to the embodiment and the example (first example) of the present invention,
FIG. 2 is a flowchart showing a schematic configuration of a method of automatically generating a movement path of a robot manipulator according to another embodiment (second embodiment) of the present invention, and FIG. 3 is a plane set in the method of the first embodiment. FIG. 4 is an explanatory view showing a specific example of FIG. 5, and FIG.
Is an explanatory diagram showing a state after execution of step S04 on the plane, and FIG. 6 is an explanatory diagram showing a final state of movement path generation on the plane.

A method for automatically generating a movement path of a robot manipulator according to an embodiment and an embodiment (first embodiment) of the present invention is a method for avoiding obstacles by removing elements of a robot manipulator working in a three-dimensional space. This is similar to the conventional example in that a route for moving from the initial position to the target position is automatically generated. However, in the first embodiment, as shown in FIG. 1, the cross-sectional shape of an obstacle on a desired plane out of a plurality of planes including the initial position and the target position of the above element is determined by the element of the robot manipulator. An intrusion prohibition area enlarged to such an extent that interference with an obstacle can be avoided is created (S01, S0
2) The path is initially generated by connecting the initial position and the target position of the element on the desired plane with a straight line, and when the path interferes with the intrusion prohibited area, the path is changed to the intrusion prohibited area. This is different from the conventional example in that a correction is made to a path passing through the vertex of the intrusion prohibition area so as to avoid interference with the area (S03, S04). Further, when there are a plurality of corrected paths, a predetermined evaluation may be performed to select one path (S05). Enlarging the robot manipulator element to such an extent that it can avoid interference with an obstacle means, for example, expanding a predetermined distance in consideration of safety, or further expanding the distance in accordance with the acceleration of the element.

The hand route planning of the robot manipulator according to the method of the first embodiment will be described below in more detail. In FIG. 1, first, the cross-sectional shape of an obstacle is determined on a representative plane (corresponding to a desired plane) selected by an operator from an infinite number of planes including two points of an initial position and a target position of a robot manipulator hand. Create (S0
1). On this plane, the initial position of the hand, the target position, and the cross section of the obstacle exist as shown in FIG. In FIG. 3, the initial position of the tip of the manipulator (corresponding to one of the elements) is Start, the target position is Goal, and the three hatched closed regions Obs1, Obs2, and Obs3 all indicate the cross section of the obstacle. FIG. 4 shows a state after executing steps S02 and S03 on such a plane. In FIG. 4, in step S02, based on a given avoidance distance r for avoiding interference between the hand of the robot manipulator and the obstacle, an intrusion prohibition area in which the cross section of the obstacle is enlarged by the distance r is set. This distance r may be a uniform value specified by the user, or may be a value automatically set at a fixed ratio according to the size of the obstacle cross section. Further, the distance r may be expanded or contracted according to the acceleration of the robot. In FIG. 4, the obstacle cross-sections Obs1 and Obs are shown.
In No. 2, the entry prohibition areas overlap each other because they are near each other. Therefore, these two areas are integrated and displayed as one intrusion prohibition area. That is, after the execution of step S02 is completed, the intrusion prohibited areas A1 and A2 are generated.

Subsequently, in step S03, an interference check between the intrusion prohibition area generated in step S02 and the virtual route is performed. In the first execution of step S03,
Since an avoidance point for avoiding interference has not been generated yet, an interference check is performed on a virtual path Tr01 connecting the initial position Start and the target position Goal with a straight line. In FIG. 4, since the intrusion prohibition area A1 interferes with the virtual route Tr01, step S04 is subsequently performed on the virtual route Tr01. Step S04, S03
5 is shown in FIG. In FIG. 5, in step S04, the immediately preceding step S03
The avoidance point is set based on the interference information. In the step S03 executed immediately before the above, the intrusion prohibited area A1 and the virtual route Tr01 interfered. Therefore, using the vertex information of the intrusion prohibition area A1, an avoidance point for avoiding interference with the intrusion prohibition area A1 is set. In this case, the avoidance point P1
1 and P12 are set.

Subsequently, in step S03, an interference check between the intrusion prohibited area and the virtual route is performed. Step S0
In the second and subsequent executions of Step 3, an avoidance point has already been generated. Therefore, a virtual path Tr11 connecting the initial position Start and the avoidance point P11 with a straight line, a virtual path Tr12 connecting the avoidance point P11 and the avoidance point P12 with a straight line, and a virtual path Tr12 connecting the avoidance point P12 and the target position Goal. An interference check is performed for each of the virtual paths Tr13 connecting the lines with a straight line. Then, step S04 is executed for each of the interfering virtual routes. In FIG. 5, the virtual route T
r11 and the virtual route Tr12 do not interfere with the intrusion prohibition region, but the virtual route Tr13 interferes with the intrusion prohibition region A2. Therefore, after that, step S04 is executed for the virtual route Tr13. FIG. 6 shows the final state of the path generation on this plane. Here, the avoidance point P1 causing the interference in FIG.
The avoidance point P21 in step S04 is set between the target position Goal and the target position Goal. New virtual route Tr2
Since no interference has occurred in 1 and Tr22, the route generation processing ends here. Thereby, the initial position Star
Tr11, Tr12, Tr21 and Tr22 could be obtained as the hand route of the robot manipulator from t to the target position Goal.

Although an example of the route generation at the upper part of the plane in FIG. 3 has been described above, another path can be generated at the upper part or the lower part of the plane by the same processing procedure. For example, Start
It is also possible to generate another virtual route passing through → P13 → P14 → Goal. Also, Start → P15 → P16
→ The route of Goal is also conceivable, but in this case, since the route passes through the intrusion prohibition area, it is not adopted. That is, the present invention does not limit the generation range of the path on the plane. Therefore, when a plurality of routes are generated as described above, the interference avoidance trajectory is selected based on the evaluation function, and 1
One path is selected (S05). Specifically, first, the one that optimizes the evaluation function is selected from the remaining ones, excluding the trajectory that causes interference. This evaluation function uses the distance of the trajectory, the distance between the manipulator arm and the obstacle,
Alternatively, by using the number of avoidance points or by switching an evaluation function to be used depending on the application, it is possible to flexibly select an interference trajectory corresponding to various requirements.

Incidentally, in order to avoid three-dimensional interference, it may be necessary to consider on a plurality of planes.
When there are a plurality of the desired planes as described above, one path is selected by performing a predetermined evaluation from the paths obtained for each of the desired planes as shown in FIG. 2 (S11).
To S13) (Another embodiment of the present invention (second embodiment)). Hereinafter, the hand route planning method of the robot manipulator according to the second embodiment will be described in further detail. In FIG. 2, first, some representative planes are selected from an infinite number of planes including two points of an initial position and a target position of the hand of the robot manipulator according to the application (S11). This selection may be made arbitrarily by the operator, or may be automatically selected according to a predetermined rule. The predetermined rule is, for example, horizontal + vertical with reference to the robot or the obstacle + a plane is selected at a constant inclination interval between them.

Next, an interference avoidance locus on each of the selected planes is generated (S12). The specific contents of step S12 are the same as steps S01 to S05 in the method of the first embodiment. Then, from the interference avoidance trajectories generated on the respective planes, an interference avoidance trajectory is selected and determined based on the evaluation function (S1).
3). If many planes are selected in step S11,
As a result, more interference avoidance trajectory candidates are generated. Regarding this selection method, the same method as in step S05 in the first embodiment may be adopted. However,
Instead of executing step S05, one may be selected from a plurality of trajectory groups at once in step S13. As described above, in any of the embodiments, the problem of avoiding interference in three dimensions can be reduced to the generation of the path of the manipulator hand in a plane.
Therefore, in the present invention, the used storage area can be relatively reduced. This is because the configuration space in the conventional example is not handled, so that an area for storing the free space is not required. Also, the calculation time can be reduced. This is because no mapping calculation between the configuration space and the rectangular coordinate space is required. Further, performing a route search in a three-dimensional space requires a large amount of information to be handled, but the necessity is small.
By limiting the search space to a plane, the amount of information to be handled can be reduced, and the amount of calculation can be reduced accordingly.

Further, it is possible to prevent a robot element passing through the generated route from interfering with an obstacle. This is because no route is generated in the intrusion prohibition area set around the obstacle based on the avoidance distance r between the robot manipulator hand and the obstacle. Further, it is possible to prevent a route that is detoured more than necessary from an obstacle from being set. The route can be generated by setting several avoidance points, but since the avoidance points are set using the vertex information of the interfering intrusion-prohibited area, they are larger than the avoidance distance r. For they will not leave. As a result, according to the present invention, in the problem of automatically generating a path from the initial position to the target position while avoiding interference of the elements of the robot manipulator with surrounding obstacles, a relatively small storage area and a practical use It is possible to realize a high-speed path generation process with a short calculation time. Also,
Since the route does not interfere with the obstacle and does not detour more than necessary, a safe and efficient route can be obtained. In the above embodiment, the generation of the hand route of the robot manipulator has been described as an example of the applicable range. However, the same applies to the other elements of the robot manipulator, and furthermore, the movement route of a moving object other than the robot is obtained. Is also applicable.

[0016]

As described above, the method for automatically generating a movement path of a robot manipulator according to the present invention is configured as described above, so that obstacle avoidance in a three-dimensional space is avoided. Make it a problem. As a result, high-speed path generation processing with a practical calculation time can be realized with a relatively small storage area. Also, a route that does not cause interference with an obstacle and that does not detour more than necessary is generated. Further, when there are a plurality of corrected paths, it is possible to perform a predetermined evaluation and select one optimal path. Further, when considering a plurality of the desired planes, a predetermined evaluation is performed from the paths obtained for each of the desired planes, and one path is selected. An efficient route can be obtained. As described above, when a plurality of solutions are obtained, the narrowing down can be automatically performed, which can contribute to labor saving.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a schematic configuration of a method for automatically generating a movement path of a robot manipulator according to an embodiment and an example (a first example) of the present invention.

FIG. 2 is a flowchart showing a schematic configuration of a method for automatically generating a movement path of a robot manipulator according to another embodiment (second embodiment) of the present invention.

FIG. 3 is an explanatory diagram showing a specific example of a plane set in the first embodiment method.

FIG. 4 is an explanatory diagram showing a state after execution of step S02 on the plane.

FIG. 5 is an explanatory diagram showing a state after execution of step S04 on the plane.

FIG. 6 is an explanatory diagram showing a final state of moving path generation with respect to the plane.

[Explanation of symbols]

 S01: Cross section creation step S02: Creation and integration step of entry prohibited area S03: Interference check step between entry prohibited area and route S04: Subgoal setting step S05: Selection step of interference avoidance trajectory

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-127730 (JP, A) JP-A-4-291403 (JP, A) JP-A-63-24305 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) G05B 19/4093 B25J 9/10 B25J 9/16 B25J 19/06

Claims (3)

(57) [Claims] 1. A method for automatically generating a path for moving an element of a robot manipulator working in a three-dimensional space from an initial position to a target position while avoiding obstacles, the method comprising: And creating an intrusion-inhibited area by enlarging the cross-sectional shape of an obstacle on a desired plane out of a plurality of planes including an obstacle so that the robot manipulator element can avoid interference with the obstacle. The path is initially generated by connecting the initial position of the element and the target position with a straight line, and when the path interferes with the intrusion prohibited area, the path is prevented from interfering with the intrusion prohibited area. A method of automatically generating a movement path of a robot manipulator, wherein the path is corrected to a path passing through a vertex of a simple intrusion prohibition area. 2. When there are a plurality of corrected paths, one path is selected by performing a predetermined evaluation.
Automatic generation method of the movement path of the robot manipulator described. 3. The method according to claim 1, wherein when there are a plurality of the desired planes, a predetermined evaluation is performed to select one of the paths obtained for each of the desired planes. A method for automatically generating a movement path of a robot manipulator.