Discrete-time neural dynamics-based online quadratic programming for discrete-time trajectory tracking of cable-driven planar robot.

Abstract

Cable-driven planar robots have attracted increasing attention due to their simple mechanical structure and flexible workspace, while achieving accurate trajectory tracking in discrete-time settings remains challenging because of nonlinear kinematics and real-time computational requirements. In this paper, a discrete-time neural dynamics (DTND)-based online quadratic programming (QP) framework is developed for discrete-time trajectory tracking of a cable-driven planar robot with a structure consistent with typical wall-drawing (V-plotter) systems. The inverse kinematics problem of the robot is first formulated as an online QP by transforming the desired end-effector trajectory into a discrete-time velocity tracking objective. Inspired by DTND for time-varying quadratic programming, a DTND-based iterative solver is employed to compute the cable-length rates at each sampling instant, enabling real-time trajectory tracking without explicit offline optimization. The proposed method operates entirely in discrete-time form and is suitable for digital implementation. Numerical simulations based on a cable-driven planar robot demonstrate that the proposed DTND-based online QP approach achieves stable error convergence and accurate trajectory tracking. Furthermore, physical experiments on a cable-driven planar robot are conducted to validate the practical feasibility of the proposed DTND-based framework and demonstrate its applicability in real-world engineering scenarios.