Adaptive fuzzy control for tendon-sheath actuated bending-tip system with unknown friction for robotic flexible endoscope

Fan Ren; Xiangyu Wang; Ningbo Yu; Jianda Han

doi:10.3389/fnins.2024.1330634

Adaptive fuzzy control for tendon-sheath actuated bending-tip system with unknown friction for robotic flexible endoscope

Front Neurosci. 2024 Mar 26:18:1330634. doi: 10.3389/fnins.2024.1330634. eCollection 2024.

Authors

Fan Ren¹, Xiangyu Wang^{1

2}, Ningbo Yu^{1

2}, Jianda Han^{1

2}

Affiliations

¹ The Tianjin Key Laboratory of Intelligent Robotics, College of Artificial Intelligence, Institute of Robotics and Automatic Information Systems, Nankai University, Tianjin, China.
² The Institute of Intelligence Technology and Robotic Systems, Shenzhen Research Institute of Nankai University, Shenzhen, China.

Abstract

Introduction: The tendon-sheath actuated bending-tip system (TAB) has been widely applied to long-distance transmission scenes due to its high maneuverability, safety, and compliance, such as in exoskeleton robots, rescue robots, and surgical robots design. Due to the suitability of operation in a narrow or tortuous environment, TAB has demonstrated great application potential in the area of minimally invasive surgery. However, TAB involves highly non-linear behavior due to hysteresis, creepage, and non-linear friction existing on the tendon routing, which is an enormous challenge for accurate control.

Methods: Considering the difficulties in the precise modeling of non-linearity friction, this paper proposes a novel fuzzy control scheme for the Euler-Lagrange dynamics model of TAB for achieving tracking performance and providing accurate friction compensation. Finally, the asymptotic stability of the closed-loop system is proved theoretically and the effectiveness of the controller is verified by numerical simulation carried out in MATLAB/Simulink.

Results: The desired angle can be reached quickly within 3 s by adopting the proposed controller without overshoot or oscillation in Tracking Experiment, demonstrating the regulation performance of the proposed control scheme. The proposed method still achieves the desired trajectory rapidly and accurately without steady-state errors in Varying-friction Experiment. The angle errors generated by external disturbances are < 1 deg under the proposed controller, which returns to zero in 2 s in Anti-disturbance Experiment. In contrast, comparative controllers take more time to be steady and are accompanied by oscillating and residual errors in all experiments.

Discussion: The proposed method is model-free control and has no strict requirement for the dynamics model and friction model. It is proved that advanced tracking performance and real-time response can be guaranteed under the presence of unknown bounded non-linear friction and time-varying non-linear dynamics.

Keywords: friction compensation; fuzzy control; robotic flexible endoscope; robust control; tendon-sheath mechanism.

Grants and funding

The author(s) declare that financial support was received for the research, authorship, and/or publication of this article. This work was supported by National Key R&D Program of China (Grant No. 2022YFB4702800), National Natural Science Foundation of China (Grant No. 62303248), Guanddong Basic and Applied Basic Research Foundation (Grant Nos. 2024A1515010102 and 2023A1515110678), and China Postdoctoral Science Foundation Funded Project (Grant No. 2023M731804).