Transparency and stability of scaled tele-haptic cell manipulation systems

Abstract

Haptic Cell manipulation systems require interaction between macro and micro worlds. Such systems have still not been able to employ accurate force feedback. Accurate force feedback depends on accurate sensing as well as transmission of force signals. Accurate sensing is possible through the selection of appropriate sensors with low noise and high resolution capable of measuring the micro-scale forces. On the other hand, accurate transmission needs complete cancellation of device dynamics like friction, inertia, gravity effects and proper choice of control parameters. The presence of sensors to sense the position and force in the master and slave robots, however, poises problems as sensor measurements are noisy. This noise can also affect the performance of the system which becomes more prominent for macro-micro world interactions. This research aims at maximizing the transparency for micro-scale haptic cell manipulation systems while maintaining the stability in presence of sensor noise and device disturbances. This research also ensures that a proper sensor is chosen which can sense the micro-scale forces accurately. The transparency is enhanced by cancelling the master and slave dynamics using the disturbance observer. Simulation results show that the position tracking capability is enhanced by employing the disturbance observer in force-position and four-channel control architectures. The effect of the sensor noise on the transparency of scaled teleoperation architectures is also analyzed and low-pass filters are employed to cancel the high frequency components of the noise. New criteria have been developed relating the scaling factors with the control gains to achieve perfect transparency in the presence of sensor noise. Simulation results show that by following the newly developed criteria the transparency of the tele-haptic system is enhanced. This thesis also aims at analyzing the system stability in presence of low-pass filters to counteract t...