06-09-2017, 03:12 PM
The hand is conceived to be applied to the prosthesis as well as to humanoid and personal robotics; therefore, anthropomorphism is a fundamental requirement that must be addressed both in the physical aspect and in the functional behavior. In this work, a biomechanical approach is approached to harmonize the mechanical design of the artificial anthropomorphic hand with the design of the manual control system. More in detail, this work focuses on the hand control system and the optimization of the hand design to obtain a kinematic and human-type dynamic. When evaluating the performance of the simulated hand, the mechanical design is refined iteratively. The mechanical structure and the relationship between the number of actuators and the number of degrees of freedom (DOFs) have been optimized to meet the strict restrictions of size and weight that are typical of the application of artificial hands to prostheses and humanoid robotics. The proposed hand has a kinematic structure similar to the natural hand with three articulated fingers (thumb, index and middle finger with 3 DOF for each finger and 1 DOF for abduction / adduction of the thumb) driven by four dc motors. A special underactuated transmission has been designed to keep the number of engines as low as possible while achieving a self-adaptive grip, as a result of the passive compliance of the distal DOF. A manual control scheme suitable for the study and optimization of manual motor performance has been designed and implemented in order to achieve human motor behavior. To this end, available data on human finger movement are collected from neuroscience literature in order to derive an entry reference for control. Simulation tests and computer aided mechanical design (CAD) tools are used to obtain a model of fingers that includes its dynamics. We also simulate the closed-loop control system to study the effect of iterative mechanical redesign and define the final set of mechanical parameters for the optimization of the hand.