Robust 3-D Path Following Control Framework for Magnetic Helical Millirobots Subject to Fluid Flow and Input Saturation

• Published in: IEEE transactions on cybernetics Vol. 54; no. 12; pp. 7629 - 7641
• Main Authors: Qi, Zhaoyang, Cai, Mingxue, Hao, Bo, Cao, Yanfei, Su, Lin, Liu, Xurui, Chan, Kai Fung, Yang, Chenguang, Zhang, Li
• Format: Journal Article
• Language: English
• Published: United States IEEE 01.12.2024
• Subjects: 3-D path tracking; Convergence; flow rates; Frequency control; helical millirobots; Kinematics; magnetic actuation; Navigation; Robots; Saturation magnetization; Vectors
• ISSN: 2168-2267; 2168-2275; 2168-2275
• DOI: 10.1109/TCYB.2024.3439708

Precise trajectory control is imperative to ensure the safety and efficacy of in vivo therapy employing the magnetic helical millirobots. However, achieving accurate 3-D path following of helical millirobots under fluid flow conditions remains challenging due to the presence of the lumped disturbances, encompassing complex fluid dynamics and input frequency saturation. This study proposes a robust 3-D path following control framework that combines a disturbance observer for perturbation estimation with an adaptive finite-time sliding mode controller for autonomous navigation along the reference trajectories. First, a magnetic helical millirobot's kinematic model based on the 3-D hand position approach is established. Subsequently, a robust smooth differentiator is implemented as an observer to estimate disturbances within a finite time. We then investigate an adaptive finite-time sliding mode controller incorporating an auxiliary system to mitigate the estimated disturbance and achieve precise 3-D path tracking while respecting the input constraints. The adaptive mechanism of this controller ensures fast convergence of the system while alleviating the chattering effects. Finally, we provide a rigorous theoretical analysis of the finite-time stability of the closed-loop system based on the Lyapunov functions. Utilizing a robotically-actuated magnetic manipulation system, experimental results demonstrate the efficacy of the proposed approach in terms of the control accuracy and convergence time.