A measurement method of the 2DOF joint angles and angular velocities using inertial sensors

This paper proposes a measurement method of the 2DOF (two degrees of freedom) joint angles and angular velocities using inertial sensors. A 3-axis gyro sensor and a 3-axis accelerometer are attached on the base link, and two 3-axis accelerometers are attached on the motion link in this method. The 2DOF joint angles and the angular velocities such as the hand and finger joints can be measured by applying Extended Kalman filter. The nonlinear state equation and the nonlinear measurement equation are established by the rotational component, the translational and gravity components of acceleration on the motion link and the angular velocity and the acceleration on the base link. The rotational component and the translational and gravity components on the motion link are calculated from accelerometers attaching on the motion link. The experiment was conducted to clarify the precision of the proposed method using the experimental setup installing the rotary encoders. The results indicated the effectiveness of this method.