Experimental Investigation of Free-Motion Task Implementation on a Serial Metamorphic Manipulator

This paper presents an experimental investigation into the implementation of free-motion tasks on a serial metamorphic manipulator (SMM). Utilizing a previously established task-based optimization methodology, the dynamic performance of the SMM is evaluated through a combination of theoretical performance metrics and experimental data. The study aims to validate the SMM’s ability to achieve optimized performance through structural reconfiguration. Theoretical models are compared against real-world free-motion task data, demonstrating strong correlations between analytical calculations and experimental outcomes. The discussion focuses on three key areas: the efficiency of joint controllers, end-effector acceleration capabilities, and joint controller performance. Results indicate that an optimized anatomy can achieve more than 40% reduction in produced torques during task execution and a 35% improvement in the torque-to-velocity ratio. While the simple controller implemented in the robot prototype exhibits adequate performance, notable limitations are observed in task segments with lower dynamic performance, particularly in terms of positional accuracy and energy efficiency. During XY-plane task execution, the Z-axis position error deviates by 1 to 2 cm in areas of lower dynamic performance. These findings provide key insights and establish a robust foundation for advancing SMM capabilities in practical applications, with future work focusing on addressing the identified limitations.