Singularities of a 3RRR mechanism

This video corresponds to the pictures in Chapter 2 of our book: O. Bohigas, M. Manubens, L. Ros. “Singularities of Robot Mechanisms: Numerical Computation and Avoidance Path Planning“. Springer Verlag. 2017. The video shows the forward and inverse singularities of a 3RRR mechanism. This prototype is not actuated, but the ground joint of each leg can be locked to realise the effect of forward singularities due to motors mounted on such joints. We show, in sequence: A non-singular configuration. A forward singularity. An inverse singularity. A configuration that is both a forward and an inverse singularity. In a non-singular configuration, the mechanism is rigid when we lock the ground joints or the platform pose. In a forward singularity, the three distal joints are CONCURRENT, and the mechanism is shaky after locking the ground joints. In an inverse singularity, the joints of one of the legs are ALIGNED, and the leg is shaky after locking