Abstract
This paper presents a novel compensator-critic structure-based event-triggered decentralized tracking control of modular robot manipulators (MRMs). On the basis of subsystem dynamics under joint torque feedback (JTF) technique, the proposed tracking error fusion function, which includes position error and velocity error, is utilized to construct performance index function. By analyzing the dynamic uncertainties, a local dynamic information-based robust controller is designed to engage the model uncertainty compensation. Based on adaptive dynamic programming (ADP) algorithm and the event-triggered mechanism, the decentralized tracking control is obtained by solving the event-triggered Hamilton–Jacobi–Bellman equation (HJBE) with the critic neural network (NN). The tracking error of the closed-loop manipulators system is proved to be ultimately uniformly bounded (UUB) using the Lyapunov stability theorem. Finally, experimental results illustrate the effectiveness of the developed control method.
Highlights
The modular robot manipulators (MRMs) [1,2] equipped with standard modules adapt to severe working conditions through changing their configurations and increasing/reducing modules
The tracking control strategies of MRMs can be classified into centralized control [3,4], distributed control [5,6], and decentralized control [7,8,9] according to the recent literature
We propose a compensator-critic structurebased event-triggered decentralized tracking control of MRMs based on adaptive dynamic programming (ADP) algorithm
Summary
The modular robot manipulators (MRMs) [1,2] equipped with standard modules adapt to severe working conditions through changing their configurations and increasing/reducing modules. Remark 5 Different from the traditional ADP-based optimal control approaches that rely on actor NNs, critic NNs, and even model NNs, in this paper, the compensatorcritic structure-based event-triggered decentralized tracking control method, which consist of model-based robust compensator and only critic NNs-based approximated optimal controller, is proposed for MRMs. Through (38), (39) and (40), the approximate eventtriggered Hamiltonian is: Hi θi , ui θli , ∇Ξi (θi ). Theorem 3 Considering the n-DOF MRM whose subsystem dynamics described as (5), and Assumptions 1 and 2, the closed-loop MRM system is UUB via the approximate compensator-critic structure based event-triggered decentralized tracking control law (40) if the following condition is satisfied: Eli 2 ≤. Remark 7 Unlike existing works which presented timetriggered tracking controllers [37,38], in this paper, the event-triggered mechanism is introduced to develop the compensator-critic structure-based decentralized tracking control strategy based on the ADP approach with considering the optimal performance, reducing computational burden, and saving communication and energy consumption. According to Theorem 1 and Assumption 2, through Young’s inequality, (53) becomes: V1i ≤ θiT υi + Di ml1i Eli + Di u2i θli
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