EKF-based method for kinematic configuration estimation of finger-like structure using low grade multi-IMU system

In this article, a method for kinematic configuration estimation of a structure similar to a human finger, is presented. The method is based on the EKF and a model reflecting kinematic constraints of a finger-like structure (2-DOF metacarpophalangeal joint, and one 1-DOF proximal interphalangeal rotational joint), using 3 low cost IMUs. During tests, the IMUs were attached to a 3D-printed setup equipped with encoders. The setup was fixed to the flange of a UR3 robotic arm. System accuracy and robustness was tested during various kinds of movement, including fast and slow movements in all joints (maximum angular rate of 550 deg/s), and simultaneous base rotation (up to 170 deg/s) and linear acceleration (up to 0.25 g). The obtained RMSE of estimated joint angle was 3.5 deg for all joints and all types of performed movements. In case of joint rotations around an axis parallel to gravity vector, RMSE of 4 deg was achieved.