Shape estimation of flexible cable

In this paper, an estimation method using the flexible multi-body dynamics model, inertial/magnetic sensor system, and probabilistic state estimation is proposed for estimating the shape of a flexible cable. Sensors mounted on flexible cables, such as endoscopes, are often picked up noise, and their size and number are restricted. The proposed method can estimate motion using the flexible dynamics model if there are few sensors. In addition, this method is robust against noise because it can integrate some types of sensor information by probabilistic state estimation. The proposed method uses the Absolute Nodal Coordinate Formulation (ANCF) as a flexible dynamics model and the Unscented Kalman Filter (UKF) for probabilistic state estimation. It can model a greatly deformed cable at any point using ANCF, and it can fit nonlinear motion and achieve high versatility about models because of UKF. In the second half of this paper, experiments using Active Scope Camera (ASC) are conducted to evaluate the proposed method. The ASC is a snake-like rescue robot, and its sensor system picks up strong noise. In the experiments, the proposed method estimates three types of motion, and it shows the effectiveness if the number of sensors decreases.