7 Conclusion
An important component of the system presented in this paper
has been affine stereo. The appendix contains a quantitative
comparison with perspective stereo.
Affine stereo provides a simple and
robust interpretation of image position and
disparity that degrades gracefully when cameras are disturbed.
Calibration is not only easier (fewer parameters and
amenable to linear techniques) but also less sensitive to
small perspective effects.
It is
suitable for uncalibrated and self-calibrating systems
and therefore the preferred stereo method for our visual servoing
application.
By defining the working coordinate system in terms of the robot's
abilities, linear errors in its kinematics are bypassed.
The remaining nonlinearities can be handled using image-based control
and feedback. We have shown that this can be achieved cheaply and
effectively using a
novel form of active contour to track planar features on the gripper
and target.
Such a system has been implemented and found to be highly robust,
without unduly sacrificing performance (in terms of speed to converge
on the target).
Appendix
References
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