An improved force feedback method of object type recognition in a tele-manipulation system

The use of master torque gain k
_tm
can provide an operator with a higher sense of remote environment in tele-manipulation systems when compared with traditional master-slave systems. Works in previous literature have adequately demonstrated that force feedback can cover the shortage of virtual reality (VR) in a tele-manipulation system. However, the success rate of grasping objects without squashing them in such systems is still less than satisfactory. This paper contributes to this aspect by introducing a parameter named master torque gain (k
_tm
), which varies for the hardness of grasped objects. Moreover, the reaction force acting on the joystick varies for k
_tm
, and thus operators can sense a reasonable feedback force from this joystick. Simultaneously, the operator can judge the hardness of the grasped object through both the value of k
_tm
displayed on the screen and the object color changed with k
_tm
. Finally, the human operator can boost the success rate of grasping objects even further by integrating both k
_tm
and feedback force. A series of grasping experimentation trials were conducted with concrete, tire, urethane foam and sponge foam blocks. Results from these experiments demonstrated the effectiveness of object type recognition when introducing master torque gain k
_tm
in a tele-manipulation system.