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Coping with joint velocity limits in first-order inverse kinematics algorithms: analysis and real-time implementation

Published online by Cambridge University Press:  09 March 2009

Pasquale Chiacchio
Affiliation:
Dipartimento di Informatica e Sistemistica, Università degli Studi di Napoli “Federico II”, via Claudio 21, 80125 Napoli (Italy)
Stefano Chiaverini
Affiliation:
Dipartimento di Informatica e Sistemistica, Università degli Studi di Napoli “Federico II”, via Claudio 21, 80125 Napoli (Italy)

Summary

A major problem in inverse kinematics algorithms is that the generated joint velocities to be fed to the joint servos may cause violation of the speed limits of the joint actuators. In this paper, it is shown how to properly cope with joint velocity limits in first-order inverse kinematics algorithms; the proposed technique guarantees tracking of the desired end-effector path. This goal is achieved by suitably slowing down the task-space trajectory when joint velocity limits are encountered. The time law is modified through a time warp such that the introduced virtual time allows fulfillment of the velocity constraints. A case study is developed to show the effectiveness of the proposed method and a kinematic control scheme based on the presented technique is implemented to demonstrate feasibility under real-time constraints.

Type
Articles
Copyright
Copyright © Cambridge University Press 1995

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