Abstract:
This paper proposes an enhanced force limiting
gripper to avoid object deformation when it is in contact with the
slave due to excessive forces imposed by the master operator in
bilateral control. The force lock protects the gripped object on
the slave and the attainment of the force limit is notified to the
master operator via a small vibration. Master operator is
expected to experience a spring effect if the operator presses his
leaver towards the force increasing direction. The continuous
copying of the slave position as the reference to the virtual spring
controller’s spring equilibrium point allows smooth releasing. In
addition to vibration the loss of reaction force coming from the
slave environment could also be sensed by the master operator.
Reversing of the applied force on master handle releases the
object attached to the slave. In this proposed system sensor-less
sensing is used. Disturbance Observer is used to estimate
disturbances and Reaction Force Observer estimates reaction
forces. The proposed gripper is having a jaw opening of 0.15 m
which has linear 1-DOF. Simulation is conducted using real
world linear motor parameters and simulation results prove the
applicability of proposed system.
