Practical Stabilisation of Robots Interacting with Dynamic Environment by Decentralised Control

Abstract

Although a high number of papers^1–8 has been devoted to the problem of the so-called constrained motion control of robots, the model uncertainties, representing the crucial problem in control of robots interacting with the dynamic environment, still have not been appropriately addressed. Especially the uncertainties in a dynamic model of the environment in different technological tasks may have high influences, due to difficulties in the identification/prediction of the environment parameters and behaviour of the environment. Therefore, it may be difficult to achieve the asymptotic (exponential) stability of the system. It is of practical interest to require more relaxed stability condition, i.e. to consider the so-called practical stability of the system. An approach to analysis of the practical stability of manipulation robots interacting with the dynamic environment has been presented in our previous papers^9–10. In this paper a new approach is presented following the basic idea of a decomposition/aggregation method for the stability analysis of large-scale systems in which the system is decomposed into ‘subsystems’, but without ignoring dynamic interactions among these ‘subsystems’. The objective of the paper is to establish for the first time less conservative conditions for the practical stability of the robots which are suitable for the analysis and synthesis of decentralised control laws.