A Variable Stiffness Actuation Based Robotic Hand Designed for Interactions

This research presents the design, modeling, and control for a bio-inspired robotic hand with antagonistic variable stiffness (AVS). A key design character is the integrated modular finger unit. The modular finger unit is developed based on the variable stiffness actuation principle and has physical impact absorption and stiffness adjustment capabilities to achieve safer grasping and manipulation in interactions and adjustable system bandwidth. Compared with the design of the previous version, the finger unit is optimized in terms of mechanism, cable path, transmission gap, and manufacturing process, and specially designed torque sensors are added to achieve the force perception of the fingertip in three dimensions. A modularized finger unit integrating mechanical parts, sensors, and electronic devices with more compact size, higher precision, and low friction is developed, which eventually lead to the implementation of the fully actuated AVS hand with three fingers and eight degrees of freedom (DOF). The hand controller hardware developed based on a field programmable gate array (FPGA) chip is integrated in the palm. These have guaranteed the real-time and stable grasping and manipulation performance of the hand.