Dynamic Modeling and Motion Control of a TCA-Actuated Robotic Arm With Elbow and Wrist Joints

Twisted and coiled actuators (TCAs) have found extensive application in robotic devices due to their inherent compliance, large force generation, and lightweight characteristics. These attributes endow the TCA-driven robotic arm with significant potential in human-robot interaction. This paper presents a TCA-actuated robotic arm system, where one module emulates the motion of the human upper arm with an elbow joint and the other mimics the wrist, resulting in a highly anthropomorphic structural design. For such a robotic arm system, this paper develops both a motion kinematics model and a Lagrangian dynamics model. Additionally, a nonlinear model predictive controller (NMPC) is designed for trajectory tracking while ensuring the safe TCA actuation of the dynamic system. Experiments are systematically conducted, the results of which demonstrate that the robotic arm system offers a wide range of motion, capable of tracking three-dimensional reference movements with relatively high accuracy.