Simplified robotic thumb inspired by surgical intervention

Years of empirical trials have refined set angles for the arthrodesis, or surgical fusion, of the metacarpophalangeal joint of the thumb. We capitalize on this knowledge to simplify the design and operation of the thumb throughout a similar range of motion by eliminating a degree of freedom, as inspired by the Steiger arthrodesis. A novel rolling Carpal-Metacarpal joint with magnetic closure is developed that encapsulates abduction/adduction and flexion/extension in the same joint. Thumb workspaces and their volumes were generated from kinematic chain models for different thumb parameters, showing that the prototype's experimental workspace was in agreement with the theoretical model.