Real-time shape estimation of Kirchhoff elastic rod based on force/torque sensor

In this paper, we propose a real-time spatial shape estimation method for an elastic rod. Our proposed method does not use any image sensor nor shape sensor, but does use a six-axis force/torque sensor placed near one end of the elastic rod. In the proposed shape estimation method, the occlusion problem never occurs principally because the shape of a flexible object will be estimated based on an elastic rod model. We utilize the discretized Kirchhoff elastic rod for shape estimation, which can be viewed as a serial chain of rigid bodies connected with three-degree-of-freedom rotational spring joints. We show that real-time spatial shape estimation is possible based on real-time sensing of force/torque information. The computational time of the proposed shape estimation algorithm is linear in the number of rigid-body partition. Moreover, the required calculations are very simple owing to deep understanding of robot manipulator kinematics. Thus we can compute the spatial rod shape in realtime. We show experimental results in order to validate our proposed method.