Modelling and control of a compliantly engineered anthropomimetic robot in contact tasks

This paper attempts to develop a dynamic model and design a controller for a fully anthropomorphic, compliantly driven robot. To imitate muscles, the robot's joints are actuated by DC motors antagonistically coupled through tendons. To ensure safe interaction with humans in a humancentered environment, the robot exploits passive mechanical compliance, in the form of elastic springs in the tendons. To enable simulation, the paper first derives a mathematical model of robot dynamics, starting from the "Flier" approach. The control of the antagonistic drives is based on a biologically inspired puller-and-follower concept where at any instant the puller is responsible for the joint motion while the follower keeps the inactive tendon from slackening. In designing the controller, it was necessary to use the advanced theory of nonlinear control for dealing with individual joints, and then to apply the theory of robustness in order to extend control to the multi-jointed robot body.