Adaptive pose output decoupling for a hydraulically-driven 6-DOF parallel manipulator

Since kinematic and dynamic coupling phenomena occur in a parallel manipulator, the outputs of the system corresponding to a sinusoidal pose contains coupling poses besides the fundamental input, causing coupling pose outputs. The method for pose output decoupling based on adaptive noise cancellation, a method for noise control and vibration control, is proposed here. The task is accomplished by generating a reference signal with the same frequency of the input pose. The reference input is weighted by the least mean square (LMS) algorithm in such a way that it closely matches the coupling pose output. The weighted reference signal is added to the fundamental signal such that the coupling pose output is cancelled leaving the desired pose alone. The weights of the LMS algorithm are adjusted by the coupling pose output, which is to be cancelled. The system is based on linkspace control, and its pose output is calculated in real-time from the actuator lengths by forward kinematics. The above concept is used a...