The model reference adaptive impedance control for underwater manipulator compliant operation

Abstract

It is essential for the diversity of operation targets during the underwater manipulator’s task. The joint friction, the time-varying characteristics of physical parameters, and inaccurate measurement of the dynamic bring trouble of model uncertainty. For these problems, a model reference adaptive impedance controller is proposed to achieve the manipulator flexible operation. The desired impedance model is designed for the outer loop force tracking, and the model reference adaptive impedance controller is employed for the inner loop. At the same time, the adaptive law is designed based on the operation space position and the desired position of the desired impedance model output. To eliminate the time-varying characteristics of physical parameters, a new bounded-gain-forgetting adaptive law is designed to compensate the uncertain error between the manipulator model and estimate model. It is ensured that the closed-loop manipulator dynamic is consistent with the desired impedance model, correspondingly the manipulator end operation force tracking the standard force signal is realized, and the desired position error of the end position of the manipulator to the desired impedance model output asymptotically converges to zero. The simulation experiment of a two-degree-of-freedom manipulator is implemented on the Matlab/Simulink platform. The results show that the designed controller has good force–position tracking asymptotical convergence ability under the uncertain dynamic, and the controller has robustness and stability performance.

Event-triggered Stochastic Finite-time Tracking Control of Robot Manipulator with Uncertain Disturbance Neural Network Estimation

“…Moreover, with the extensiveness of manipulator workspace, saving control energy is also the focus of attention [23]. To obtain the expected control performance, most of the existing studies require the manipulator to periodically sample and continuously update the control signal [24][25][26]. Accordingly, this control approach consumes a lot of communication resources, and even affects the progress of the project in the case of limited computing power and information transmission [27].…”

Development of a Control System for Underwater Vehicles with Multilink Manipulators Performing Contact Manipulation Operations

“…Adaptive methods of impedance control of underwater manipulators were presented in [24,25], and in [25], a control system was built for a remote-controlled manipulator performing a contact operation. Both systems were investigated using computer modeling and showed high efficiency.…”

“…In turn, the effectiveness of the control system developed in [26] was investigated during a basin experiment taking into account underwater currents. However, in these works [24][25][26], the bases of the manipulators were fixed while performing contact operations, and, accordingly, the inevitable deviations of the AUV from the stabilization point, which affect the quality of manipulation operations, were not taken into account.…”

Impedance Force Control of Manipulator Based on Variable Universe Fuzzy Control

“…Considering the aforementioned current research status, both designing parameter estimators and modeling system dynamic models are difficult. So, this paper takes inspiration from the concept of model reference impedance control [24][25][26] and proposes a variable universe fuzzy model reference adaptive impedance controller to dynamically adjust impedance parameters online. Fuzzy, as the name suggests, means imprecise or incomplete information gathering.…”