Stable Non-Linear Force/Position Mapping for Enhanced Telemanipulation of Soft-Environments:

README.txt

a. Description:

This video shows the experimental performance of a two-axis teleoperation system with the proposed adaptive controller. The device used is a Quansar dual planar Pantograph; one employed as the master and the other as the slave. Two ATI Mini40 force sensors are present at both master (top) and slave (bottom) pantographs. The control code runs under Matlab RTW/Tornado VxWorks RTOS at a sampling frequency of 2048Hz. Non-linear position mapping and linear force mapping was chosen for this video since the authors felt is was easier to show the non-linear mapping effect. The mappings used were those explained in section V.B of the paper. 

The video starts with the teleoperation system resting in a stable manner waiting for the operator. The non-linearity of the mapping is shown immediately with the user making two similar master circular motions in different places in the workspace. The size of slave motions is different in both places due to the non-linear position mapping. The user then makes some quick free-motion movements to show the tight position coupling. Afterwards stable soft-environment sponge contact is made by pressing various locations on the sponge and by feeling its corner. 

A zoom-in on a LCD screen shows real-time graphs of the position tracking, force tracking and master/slave adaptive parameters. The time scale on each graph is 1 sec, the graphs are refreshed every 0.5 seconds.  The position tracking shows the master position and mapped slave position such that ideal tracking results in overlapping curves. Graphs of free-motion are presented where due to the tight position tracking only two of four curves are distinguised. The oscillatory nature of the curves was intentionally made by the operator. In free motion the virtual tool dynamics are seen in the force-tracking graphs. Since there is no contact the slave adaptive parameters are all zero. The slave parameters mainly estimate the environment impedance. Next sponge contact results are shown. Position tracking is still tight, however the range of motion is less. Since contact is being made the forces begin to track each other. Slave parameter adaptation is also seen with soft-environment contact, the dominant numerical value in the slave parameters is the sponge stiffness which ranged from 300-500 N/m. Force tracking improves due to adaptation. The oscillatory nature of the curves was intentional to show non-static tracking capability.

Finally, a zoom-out again showing stable sponge contact and free motion of the system. The user then releases the system where it rests at a stable point.

b. Player Information:
Windows Media Player will be sufficient to view this video. There is no audio since it was intentionally left out. The video compression codec used is "Microsoft MPEG-4 Video Codec V1", hence it should play with the latest updates from Microsoft.

c. Contact Information:

This video was produced by Shahin Sirouspour and Pawel Malysz of McMaster University. Contact e-mails are as follows:

sirouspour@ece.mcmaster.ca, malyszp@mcmaster.ca



Attachment filename: 1103_VI.mpg (4453212 Bytes)