  This paper proposes a soft sensor embedded in a soft ring actuator with five
fingers as a soft hand to identify the bifurcation of manipulated objects
during the in-hand manipulation process. The manipulation is performed by
breaking the symmetry method with an underactuated control system by
bifurcating the object to clockwise or counter-clockwise rotations. Two soft
sensors are embedded in parallel over a single soft finger, and the difference
in the resistance measurements is compared when the finger is displaced or bent
in a particular direction, which can identify the bifurcation direction and aid
in the break of symmetry approach without the need of external tracking
devices. The sensors performance is also characterised by extending and bending
the finger without an object interaction. During an experiment that performs a
break of symmetry, manipulated objects turn clockwise and counter-clockwise
depending on the perturbation and actuation frequency, sensors can track the
direction of rotation. The embedded sensors provide a self-sensing capability
for implementing a closed-loop control in future work. The soft ring actuator
performance presents a self-organisation behaviour with soft fingers rotating
an object without a required control for rotating the object. Therefore, the
soft fingers are an underactuated system with complex behaviour when
interacting with objects that serve in-hand manipulation field.
