Fig. 1

The 3-segment pendulum with 3 IMU sensors marked as IMU1, IMU2 and IMU3 and markers for optical system marked as R1, R2, W1, W2, W3, W4, W5, and W6
The 3-segment pendulum with 3 IMU sensors marked as IMU1, IMU2 and IMU3 and markers for optical system marked as R1, R2, W1, W2, W3, W4, W5, and W6