Robust and Decoupled Position and Stiffness Control for Electrically-Driven Articulated Soft Robots

The control of articulated soft robots, i.e. robots with flexible joints and rigid links, presents a challenge due to their intrinsic elastic elements nonlinear force-deflection dependency. This letter first proposes discrete-time delayed unknown input-state observer based on nominal robot model that reconstructs the total torque disturbance vector, resulting from imperfect knowledge characteristic, external torques, other uncertainties. Then, it introduces robust controller, actively compensates for estimated uncertainty allows bounded stability tracking independent link position joint stiffness reference signals. convergence estimator overall system’s in closed loop is proven analytically, while effectiveness proposed design evaluated simulations respect large conditions, then demonstrated through experiments real multi-degree-of-freedom robot.