Effect of Passive Springs on Taskspace Stiffness of a Cable-Driven Serial Chain Manipulator

Understanding the end-effector stiffness of a manipulator is an effective tool to interpret manipulators’ interaction capabilities in the taskspace environment.A manipulator having the ability to alter its stiffness characteristics provides an advantage to make it suitable for versatile applications.Recently, cable-driven serial chain manipulators, CDSMs, have emerged as an important robotic architecture for various applications due to their promising features, such as low moving inertia, large payload handling capacity, and flexibility in altering its system architecture.Owing to the unidirectional force application property of cables, these systems are redundantly actuated.The flexibility in architecture modulation within a CDSM implies the possibility of varying system performance.Accordingly, system parameters of CDSM can be altered to modulate the stiffness behavior of the manipulator.In this work, we attempt to modify the stiffness characteristics of CDSMs through the addition of passive springs.Two different modalities of passive spring attachments were considered, and preliminary results on their effect on taskspace stiffness are presented.