Trajectory control with singularity points. Trayectory TT4

This video shows the execution of a trajectory (TT4) by the 4dof reconfigurable robot. The TT4 trajectory is an elliptical motion on Z_F axis as a function of 0.2m displacement on the X_F axis, while the pitch angle rotates 5º and yaw angle rotates 10º.

With this trajectory the robot reaches a singular point, so you can see that when it is on the singular point, the robot wins (at least) one DOF, so the robot gets to lose control and it is possible to move the robot with a finger.