Real-Time Shape Estimation of an Elastic Rod Using a Robot Manipulator Equipped with a Sense of Force

摘要

This paper proposes a real-time method for estimating the shape of an elastic rod using a robot manipulator equipped with a sense of force. The proposed method does not use optical sensing devices, such as cameras or lasers, but relies only upon the sense of force in the manipulator. In the proposed method, the deformation of an elastic rod is calculated from the obtained force/torque information using the discretized Kirchhoff elastic rod model, and the three-dimensional shape of the rod is then estimated. Furthermore, by integrating the force information with the orientation of the manipulator end-effector, the proposed method can evaluate the effect of gravity on the shape estimation accurately. Experiments were carried out to verify the proposed method, where a thin elastic strip was employed as a typical elastic rod, attached to the end-effector of the robot manipulator, bent and twisted into various shapes. The results show that the proposed method that compensates for gravity is better than a method without gravity compensation, and it estimated the 142 mm length strip shape with a position error no greater than 7.76 mm and an average calculation time of 4.24 ms.