Enhanced null space control using hierarchical workspace disturbance observer

Workspace disturbance observer was developed as further enhancement for the successful joint space observer. In its derivation it was assumed that the null space projector computation could be avoided. However limited performance has been reported for the workspace version. This work shows that the null space projector computation is essential for achieving the expected high performance in workspace. Experimental evaluation revealed the extra advantage of the workspace disturbance observer in terms of higher performance of the null space tasks.