A Proposal of Real-Time Configuration Control System for Redundant Manipulators

Abstract

This paper is concerned with a real-time control system of trajectory tracking and obstacle avoidance using an avoidance manipulability measure for redundant manipulators. To perform the tasks adaptively without path-planning, information on the local environment is naturally restricted by limited recognition time. This means an adaptive configuration control has to manage its shape in real-time and without adequate information on its surroundings. Therefore, when the manipulator executes a task adaptively in a dynamic environment, its avoidance manipulability should always be maintained as high as possible to prepare for sudden avoiding. As a measure for gauging avoidance manipulability, we first propose a new index, “AMSIP.” By combining a concept of ”preview control” with real-time optimization of AMSIP distribution found by “1-step GA,” we next propose a new configuration control method, with future information being referred locally but effectively. The proposed system has been evaluated in simulations in terms of real-time configuration optimization, and the complete system has been proved to be feasible and practical.

Analysis for configuration prediction of redundant manipulators based on AMSIP distribution

“…Then we proposed Avoidance Manipulability Shape Index with Potential (AM-SIP) which considers AMSI and the distance between the manipulator and target object. And we verified the superiority of AMSIP through the simulation in [7].…”

“…WITH POTENTIAL We proposed Avoidance Manipulability Ellipsoid and Avoidance Manipulability Shape Index (AMSI) in [9], and Avoidance Manipulability Shape Index with Potential (AM-SIP) in [7]. Avoidance Manipulability Ellipsoid is applied from Manipulability Ellipsoid proposed by Prof. Yoshikawa in [10].…”

“…Multi-Preview Control can refer to many shapes of manipulator optimized by avoidance manipulability to induce the current manipulator's shape [1], and avoid collisions with the obstacles. However, because Multi-Preview Control can not immediately compensate the error when manipulator is tracking trajectory or avoiding obstacle, there are still existing possible situations that manipulator could not avoid collision effectually.…”

“…On the other hand, there are interesting researches on trajectory tracking and configuration control of robot by [5] using rapid exploring random trees, [6] using path searching and pruning algorithm, and so on. This paper also deals with trajectory tracking and configuration control of manipulator, and the difference from their methods is the use of predictive values of manipulator's configuration due to approaching actual manipulator's configuration to imaginary manipulator's configuration with on-line calculation of high AMSIP [7] value using 1-step GA [8]. And also the proposed method assumes that the collision avoidance problem in unstructured and dynamic environment is included as shown in Fig.2.…”

“…In other words, the future reference trajectory is unknown and therefore it is noticed that the problem has to been solved on-line and adaptively in limited recognition time. In order to make the manipulator avoid obstacles The 2012 IEEE/ASME International Conference on Advanced Intelligent Mechatronics July 11-14, 2012, Kaohsiung, Taiwan and track working object successfully, we have defined the AMSIP [7] and we have proposed multi-preview control method which based on 1-step Genetic Algorithm (1-step GA) (please refer to [8] about the detail of 1-step GA) to calculate the future configuration of imaginary manipulator. About the redundant part l(t) which denotes in control formula of multi-preview control, we have proposed a concept named predictive control which based on future time to make the configuration of imaginary manipulator and the predictive configuration of actual manipulator closer.…”