Redundancy in planar robotic manipulator: a comparison of redundancy configurations for force production tasks

Abstract

In this study, we investigate the role of joint redundancy in robotic manipulators to enhance force production capabilities during task execution. Drawing inspiration from the adaptability found in nature and the benefits of redundancy in human arm manipulation, we propose that higher redundancy can lead to superior force production. In this context, the influence of prismatic and revolute joints from a redundancy perspective has not been thoroughly examined. We conduct a systematic analysis to assess the impact of joint type on the optimisation of force production or rejection. A novel secondary objective function is introduced to minimize required torques, which also serves as a performance metric for manipulators. We incorporate a prismatic joint in conjunction with traditional revolute joints, to examine the potential benefits of alternative redundancy configurations. Our simulations reveal a significant impact of joint type on manipulator performance, with revolute joints boosting force production and prismatic joints augmenting the isotropy of force handling. Notably, an alternating revolute-prismatic (RPRP) joint sequence significantly enhances force production, suggesting a promising direction for future research.