  Despite being one of the most robust methods in bilateral teleoperation, Time
Domain Passivity Approach (TDPA) presents the drawback of accumulating position
drift between master and slave devices. The lack of position synchronization
poses an obstacle to the performance of teleoperation and may prevent the
successful accomplishment of such tasks. Several techniques have been developed
in order to solve the position-drift problem in TDPA-based teleoperation.
However, they either present poor transparency by over-conservatively
constraining force feedback or add high impulse-like force signals that can be
harmful to the hardware and to the human operator. We propose a new approach to
compensate position drift in TDPA-based teleoperation in a smoother way, which
keeps the forces within the normal range of the teleoperation task while
preserving the level of transparency and the robust stability of energy-based
TDPA. We also add a way of tuning the compensator to behave in accordance with
the task being performed, whether it requires faster or smoother compensation.
The feasibility and performance of the method were experimentally validated.
Good position tracking and regular-amplitude forces are demonstrated with up to
500 ms round-trip constant and variable delays for hard-wall contacts.
