Continuum Mechanisms And Their Applications In Prosthetic Hand Designs

Even though substantial progresses have been made in research for dexterous multi-fingered robotic hands,designing a prosthesis for hand function restoration for amputees still remains a long-term challenge,since prosthetic applications impose multiple additional design priorities,such as light-weight,grasp pattern versatility,cost-efficiency and simple control method,etc.To address these challenges,this dissertation focuses on design,modeling and applications of two novel continuum mechanisms.Continuum mechanisms realize motions and transmit forces via their structural deformations.They have been widely used in various applications,such as safe interaction with environments,maneuver in confined spaces,grasping of unstructured objects,etc.This dissertation introduces two new continuum mechanisms particularly for prosthetic hand designs and presents how the challenges mentioned above can be addressed by utilizing these two novel continuum transmissions.The first mechanism is the Composed Continuum Mechanism(CCM),which can linearly scale and combine two inputs to generate multiple translational outputs.Its working principles and kinematics are first presented.Then,the hand postural synergies were experimentally examined to show that it is possible to approximate the high-dimensional hand poses by combining two primary postural synergies and the synergy inputs.A hand prototype was built to prove the efficacy of the mechanical synergy implementation using a CCM.The hand is able to perform various hand poses and grasp different daily-life objects.With proper miniaturization,the CCM can be valuable in designing dexterous prosthetic hands with more joints and less actuators.The second one is the Continuum Differential Mechanism(CDM),which utilizing the inherent elasticity of continuum structure to generate differential outputs.A spatial and a planar CDM were proposed and their force transmission properties were thoroughly studied.Using the CDM,one wrist-powered partial hand prosthesis for transmetacarpal amputees and one single-actuator myoelectric hand prosthesis for trans-radial amputees were designed and experimentally verified.Both hand achieved excellent outcomes in preliminary clinical evaluations.With the principles,properties and application paradigms of the two novel continuum mechanisms elaborated,they have been shown to become viable solutions for designing cost-effective,light-weight and versatile robotic prosthetic hands.