Model and Control of the Floating Elastic Wrist

This paper presents a dynamic model and a control approach for a robotic system consisting of an elastic wrist connected to a floating base that can move and rotate in three-dimensional space. The motivation for this research stems from the fact that the elastic wrist is typically added as an end-effector to robotic manipulators, requiring the base to be non-fixed. Moreover, optimal control methods are implemented easily on simple systems that do not rely on the entire manipulator. The wrist is modeled as a Series Elastic Actuator (SEA) arm with one joint. A backstepping controller is developed, using the trajectory of the base and the wrist motor angle as inputs. The proposed controller seeks to get stability and accurate trajectory tracking despite the complexity introduced by the elastic elements.