Method For Optimizing A Work Cycle In A Robot System

Abstract

In a robot system including at least two manipulators with a common work area, a method for optimizing a work cycle having the steps of: defining a layout; and dividing the common work area between the at least two manipulators to thereby obtain a work area division. At least one of the previous steps is repeated to thereby obtain a plurality of different combinations of layouts and work area divisions. For each of the plurality of combinations, a cycle time for at least one work cycle is calculated. By calculating cycle times for work cycles on different combinations of layouts and work area divisions, the work area division becomes part of the optimization problem and a better optimized work cycle can be achieved.

Claims

1. A method for optimizing a work cycle in a robot system comprising at least two manipulators with a common work area, the method including the steps of: defining a layout; and defining a work area division by dividing the common work area between the at least two manipulators; characterized by repeating at least one of the previous steps to thereby obtain a plurality of different combinations of layouts and work area divisions, and, for each of the plurality of combinations, calculating a cycle time for at least one work cycle.

2. The method according to claim 1, wherein cycle times are calculated for a plurality of work cycles for each of the plurality of combinations.

3. The method according to claim 1, wherein the method further includes the step of running the work cycle with the shortest cycle time.

4. The method according to claim 1, wherein the step of defining the layout includes choosing a layout out of a limited number of possible layouts.

5. The method according to claim 1, wherein the step of defining the layout is executed by a computer.

6. The method according to claim 1, wherein the step of defining the work area division is executed by a computer.

7. The method according to claim 1, wherein the number of different combinations of layouts and work area divisions is at least five, such as at least ten, at least fifty, at least hundred, at least five hundred, at least thousand, at least five thousand, at least ten thousand, at least fifty thousand, or at least hundred thousand.

8. A robot system including: at least two manipulators with a common work area; and a robot controller including at least one layout, wherein the robot controller is configured to: define a work area division by dividing the common work area between the at least two manipulators, define a plurality of different combinations of layouts and work area divisions, and calculate a cycle time for at least one work cycle for each of the plurality of combinations.

9. The robot system according to claim 8, wherein cycle times are calculated for a plurality of work cycles for each of the plurality of combinations.

10. The robot system according to any of the claim 8, wherein the method further includes the step of running the work cycle with the shortest cycle time.

11. The robot system according to claim 8, wherein the robot controller is configured to define the layout.

12. The robot system according to claim 11, wherein the robot controller is configured to choose the layout out of a limited number of possible layouts.

13. The robot system according to any of the claim 8, wherein the number of different combinations of layouts and work area divisions is at least five, such as at least ten, at least fifty, at least hundred, at least five hundred, at least thousand, at least five thousand, at least ten thousand, at least fifty thousand, or at least hundred thousand.

14. The method according to claim 2, wherein the method further includes the step of running the work cycle with the shortest cycle time.

15. The method according to claim 2, wherein the step of defining the layout includes choosing a layout out of a limited number of possible layouts.

16. The robot system according to claim 9, wherein the method further includes the step of running the work cycle with the shortest cycle time.

17. The robot system according to claim 9, wherein the robot controller is configured to define the layout.

18. The robot system according to claim 9, wherein the number of different combinations of layouts and work area divisions is at least five, such as at least ten, at least fifty, at least hundred, at least five hundred, at least thousand, at least five thousand, at least ten thousand, at least fifty thousand, or at least hundred thousand.

19. The robot system according to claim 10, wherein the number of different combinations of layouts and work area divisions is at least five, such as at least ten, at least fifty, at least hundred, at least five hundred, at least thousand, at least five thousand, at least ten thousand, at least fifty thousand, or at least hundred thousand.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The invention will be explained in greater detail with reference to the accompanying drawings, wherein

[0020] FIG. 1 shows a robot system with a first layout and a first work area division,

[0021] FIG. 2 shows a robot system with the first layout and a second work area division, and

[0022] FIG. 3 shows a robot system with a second layout and the second work area division.

DETAILED DESCRIPTION

[0023] In the context of the present disclosure a cycle time may refer to a time needed for a robot system to execute a task sequence once. However, because of cyclic nature of work cycles a subsequent work cycle may start before a previous work cycle is ready. Therefore, the term cycle time may also refer to an average time needed for a robot system to execute the task sequence when a (large) number of task sequences is executed.

[0024] Referring to FIG. 2, the given layout is the same as in FIG. 1, and also the overall task is the same (to assemble the three components together at the fixture). However, the work area division is different in that the first and second feeders are allocated to the first manipulator, and only the third feeder is allocated to the second manipulator. Supposing that with the work area division of FIG. 2 it is possible to achieve a shorter cycle time than with the work area division of FIG. 1, limiting the optimization problem to the single combination of layouts and work area divisions according to FIG. 1 would prevent the shorter cycle time from being discovered. That is, by increasing the number of different combinations of layouts and work area divisions for which cycle times are calculated, the possibility of arriving at the best solution also increases.

[0025] There are at least two more alternative options for the work area division with the given layout of FIGS. 1 and 2. Namely, all the three feeders can be allocated to the first manipulator, or all the three feeders can be allocated to the second manipulator. A work area division where all the three feeders are allocated to the first manipulator can be advantageous for example in a situation where the first manipulator is for light loads and fast movements, and the second manipulator is for heavy loads and slow movements. If the payload of the first manipulator suffice for all the given tasks, then the shortest cycle time may be achieved by using only the first manipulator.

[0026] Referring to FIG. 3, the given work area division is the same as in FIG. 2, and also the allocation of the feeders between the two manipulators is the same. The overall task, to assemble the three components together at the fixture, is also considered to be the same. However, the layout is different in that the second feeder is located within the exclusive work area of the first manipulator. With the given layout of FIG. 3 there are at least two more alternative options for the work area division. Namely, all the three feeders can be allocated to the first manipulator, or the first and third feeders can be allocated to the second manipulator.

[0027] It is to be understood that none of the FIGS. 1 to 3 as such represents neither the prior art nor the present invention. In fact, any of the FIGS. 1 to 3 on its own can be considered to represent prior art where the work area division is done manually and only once on a given layout. However, combinations of layouts and work area divisions corresponding to the combination of e.g. any two figures out of the FIGS. 1 to 3 are not known from the prior art in the context of work cycle optimization.

[0028] In the given examples according to FIGS. 1 to 3 the number of layout options is limited as the feeder locations and the locations of the fixture and the maximum work areas are predefined. However, if the feeder locations or the locations of the fixture and/or the maximum work areas can be chosen freely, the number of layout options becomes indefinite. As also the number of possibilities to allocate the feeders between the two manipulators can become very high, the exercise of manually arriving at an optimal or even satisfactory work area division in one try may become very demanding, and consequently a possibility to arrive at a close to optimal work cycle becomes low. However, when cycle times are optimized for a (large) number of different combinations of layouts and work area divisions, the possibility of arriving at a close to optimal work cycle becomes high.

[0029] According to the present invention the layouts and the work area divisions can be defined manually, but preferably they are defined automatically. By applying appropriate constraints in defining layouts, a computer can be programmed to automatically define layouts and for each layout all available possibilities to allocate the feeders between the manipulators. A computer can thereby be configured to calculate e.g. hundreds of cycle times for each of thousands of different combinations of layouts and work area divisions, and thereby be in a position to choose the best solution among millions of alternatives. This would of course not be feasible in the case of manual definition of layouts and work area divisions, but on the other hand an experienced operator can achieve satisfactory results with only a couple of different combinations of layouts and work area divisions.

[0030] The invention is not limited to the embodiments shown above, but the person skilled in the art may modify them in a plurality of ways within the scope of the invention as defined by the claims. Thus, for example, layouts are not limited to comprise maximum work areas, feeders and fixtures, but can comprise any devices present in a robot system such as cameras, air guns, quality control jigs, etc. Moreover, instead of feeders, any appropriate means for presenting components to manipulators can be used.