SUMMARY
In a conventional bilateral teleoperation, transmission delay over the internet can potentially cause instability. Wave variables algorithm guarantees stability under varying transmission delay at the cost of poor transient performance. Adding a predictor on the master side can reduce this undesirable side-effect, but that would require a slave model. Inaccurate slave model used in the predictor as well as variations in transmission delay, both of which are likely under realistic situations, can result in steady state errors. A direct drift control algorithm is used to drive this error to zero regardless of the source of error. A semi-adaptive predictor that can distinguish between free space and rigid contact environment is used to provide a more accurate force feedback on the master side. A full adaptive predictor is also used that estimates the slave environment parameters using recursive least square with a forgetting factor. This research presents the experimental results and evaluations of the previously mentioned wave variable based methods under realistic operation environment using real master and slave. The effectiveness of this algorithm is fully evaluated using human subjects with no previous experience in haptics. Three algorithms are tested using Phantom haptic devices as master and slave: conventional bilateral teleoperation with no transmission delay as control, wave variable teleoperation with approximate 200 ms transmission delay one way, and wave variable with adaptive predictor and direct drift control with approximate 200 ms transmission delay one way. For each algorithm the human subjects are asked to perform three simple tasks: use the master to force the slave to track a reference trajectory in free space, identify a contour surface on the slave side using only haptic information from the master, and navigate a simple maze on the slave side using haptic information from the master.