Controlling Compliance: Robotic Finger Design with Variable Stiffness for Deflections from the Target Position

Abstract

In dexterous robotics, the available actuators are largely sorted into rigid or compliant actuators, which are characterized by strong or gentle grasps and by precise or simple controls, respectively. This division limits the abilities of any given dexterous robotic platform to only the tasks suited to the chosen actuator type. This thesis endeavors to provide an third option: a variable stiffness actuator that can shift between soft and rigid states, but that is small enough to be used in a robotic hand. An antagonistic configuration of progressively-coiled nonlinear springs enables one motor to control the level of compliance in the system and a second independent motor to control the position.