Sequential Robotic Manipulation for Active Shape Control of Deformable Linear Objects

Manipulating a linear deformable object (DLO, e.g. wires, cables, ropes) into the desired shape is very challenging for robots, because the DLO exhibits high degrees of freedom (DOFs), and multiple feature points along the DLO are closely coupled. This paper proposes a model-based control scheme for robot manipulators to deal with the shape control problem of DLOs. The shape of DLO is represented with multiple feature points, and the desired shape is then determined after multiple feature points are manipulated to the reference positions. The proposed controller guarantees the feasibility of shape control in twofold. First, the control objective is specified as a series of dynamic regions where a feature point can move freely inside the corresponding region to suit the movement of other points. Second, multiple feature points are manipulated in a sequential manner such that the controllable inputs are always more than or equal to the error outputs. The stability of closed-loop system is rigorously proved using Lyapunov methods, and experimental results are presented to illustrate the performance of the proposed controller.