Force reflection, shared control, and time delay in telemanipulation

Time delays of between 2 ms and 4096 ms were introduced between master and slave manipulators in advanced 6-DOF (degrees-of-freedom) force-reflecting telemanipulation system. The effects of the imposed delay were quantified in terms of completion time (CT) and sum-of-squared-force (SOSF) with six test operators and two modes of control: kinesthetic force feedback (KFF) and shared compliant control (SCC). KFF applies forces and torques proportional to those sensed by the slave robot to the human operator through the master. SCC uses the force/torque information entirely at the slave side to implement a variation on impedance control in parallel with the operator´s position commands. Experiments measured effects of human operator grasp variation on stability of contact with KFF. CT and SOSF performance in a peg-in-hole task decreased linearly with imposed time delay using KFF, and decreased at a lower rate with SCC. SCC enabled task performance for 2 and 4 second delays, critical values for low-earth-orbit applications