Self-sensing Grasping with Piezoelectric Manipulator

Abstract:
In manipulating process, it is important to detect the contact condition between a manipulator tip and a target object. Moreover, it is required to measure their softness or viscosity. However, in case of a miniaturized manipulator, it is difficult to implement sensors because a simplified structure is indispensable. In this study, we examined to detect the mechanical boundary condition’s change by using an equivalent circuit of a piezoelectric driven manipulator. In other words, the proposed method treats the piezoelectric material for not only as an actuator but also as a sensor. By superimposing sensing AC voltage to driving DC voltage for operating manipulators, the admittance at resonant frequency was simultaneously detected, which indicated the contact condition between the manipulator and the target object. Furthermore, a contact experiment using a silicone object was carried out to detect the mechanical impedance.