A novel adaptive impedance control algorithm for underwater manipulators
- 1hanghai Ocean University, Shanghai, China
Abstract
IntroductionUnderwater manipulators performing precision operations are simultaneously affected by nonlinear hydrodynamic uncertainties and abrupt changes in environmental contact conditions, making it difficult for conventional fixed-parameter impedance control to maintain both trajectory-tracking accuracy and compliant interaction. To address this problem, this paper proposes an adaptive impedance control framework for underwater manipulators.MethodsA multi-degree-of-freedom dynamic model is first established by explicitly considering rigid-body dynamics, added-mass effects, nonlinear hydrodynamic damping, and lumped uncertainties. The lumped disturbance is then decomposed according to its functional dependence into a state-dependent unmodeled hydrodynamic component and a residual exogenous disturbance component. An RBF neural network is employed to approximate the state-dependent nonlinear component, while a nonlinear extended state observer estimates the remaining online disturbance, thereby forming a composite feedforward compensation mechanism. On this basis, a prescribed-performance-based adaptive impedance law is developed to regulate the virtual stiffness and damping according to the tracking and contact-force errors while constraining transient performance. Lyapunov analysis establishes the uniform ultimate boundedness of the resulting closed-loop signals. A MATLAB/Simulink–ROS/Gazebo co-simulation platform is constructed to evaluate the proposed controller under time-varying current disturbances and abrupt contact-stiffness transitions.ResultsRepeated simulation trials under multiple disturbance conditions are conducted to evaluate the statistical robustness of the performance indices. Compared with traditional fixed-parameter impedance control, the proposed method reduces the end-effector trajectory RMSE by 82.1%, the peak contact force by 57.9%, and the force-settling time by 49.4%.DiscussionThese results demonstrate improved disturbance rejection and compliant interaction within the tested operating conditions, validating the effectiveness of the proposed architecture without requiring prior knowledge of environmental stiffness.
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BibTeX
@article{liu2026novel,
title = {{A novel adaptive impedance control algorithm for underwater manipulators}},
author = {Xingchen Liu and Gaosheng Luo},
journal = {Frontiers in Marine Science},
year = {2026},
month = oct,
doi = {10.3389/fmars.2026.1927166},
url = {https://doi.org/10.3389/fmars.2026.1927166},
note = {CC BY},
}
RIS
TY - JOUR
TI - A novel adaptive impedance control algorithm for underwater manipulators
AU - Xingchen Liu
AU - Gaosheng Luo
PY - 2026
DA - 2026/10/28
JO - Frontiers in Marine Science
DO - 10.3389/fmars.2026.1927166
UR - https://doi.org/10.3389/fmars.2026.1927166
AB - IntroductionUnderwater manipulators performing precision operations are simultaneously affected by nonlinear hydrodynamic uncertainties and abrupt changes in environmental contact conditions, making it difficult for conventional fixed-parameter impedance control to maintain both trajectory-tracking accuracy and compliant interaction. To address this problem, this paper proposes an adaptive impedance control framework for underwater manipulators.MethodsA multi-degree-of-freedom dynamic model is first established by explicitly considering rigid-body dynamics, added-mass effects, nonlinear hydrodynamic damping, and lumped uncertainties. The lumped disturbance is then decomposed according to its functional dependence into a state-dependent unmodeled hydrodynamic component and a residual exogenous disturbance component. An RBF neural network is employed to approximate the state-dependent nonlinear component, while a nonlinear extended state observer estimates the remaining online disturbance, thereby forming a composite feedforward compensation mechanism. On this basis, a prescribed-performance-based adaptive impedance law is developed to regulate the virtual stiffness and damping according to the tracking and contact-force errors while constraining transient performance. Lyapunov analysis establishes the uniform ultimate boundedness of the resulting closed-loop signals. A MATLAB/Simulink–ROS/Gazebo co-simulation platform is constructed to evaluate the proposed controller under time-varying current disturbances and abrupt contact-stiffness transitions.ResultsRepeated simulation trials under multiple disturbance conditions are conducted to evaluate the statistical robustness of the performance indices. Compared with traditional fixed-parameter impedance control, the proposed method reduces the end-effector trajectory RMSE by 82.1%, the peak contact force by 57.9%, and the force-settling time by 49.4%.DiscussionThese results demonstrate improved disturbance rejection and compliant interaction within the tested operating conditions, validating the effectiveness of the proposed architecture without requiring prior knowledge of environmental stiffness.
SN - 2296-7745
ER -