RESEARCH ON SMALL FIDUCIAL MARK USE FOR ROBOTIC MANIPULATION AND ALIGNMENT OF OPHTHALMIC LENSES

Abstract -Robotic manipulation and alignment of ophthalmic lenses during their manufacturing process can take advantage of machine vision location of smallPducia1 marks engraved or printed on the lens surface. Industry research efSorts are currently devoted to obtain a proper fiducial mark design that optimises the reliability of robotic lens manipulation. In this paper the work in progress in this area is presented

Machine vision based teleoperation aid

When teleoperating a robot using video from a remote camera, it is difficult for the operator to gauge depth and orientation from a single view. In addition, there are situations where a camera mounted for viewing by the teleoperator during a teleoperation task may not be able to see the tool tip, or the viewing angle may not be intuitive (requiring extensive training to reduce the risk of incorrect or dangerous moves by the teleoperator). A machine vision based teleoperator aid is presented which uses the operator's camera view to compute an object's pose (position and orientation), and then overlays onto the operator's screen information on the object's current and desired positions. The operator can choose to display orientation and translation information as graphics and/or text. This aid provides easily assimilated depth and relative orientation information to the teleoperator. The camera may be mounted at any known orientation relative to the tool tip. A preliminary experiment with human operators was conducted and showed that task accuracies were significantly greater with than without this aid

An Inexpensive 6D Motion Tracking System for Posturography

Computerized posturography is most often performed with a force plate measuring center-of-pressure (COP). COP is related to postural control actions but does not monitor the outcome of those actions, i.e., center-of-mass (COM) stability. For a more complete analysis of postural control COM should also be measured; however, existing motion tracking technology is prohibitively expensive and overcomplicated for routine use. The objective of this work was to create and validate an inexpensive and convenient stereo vision system which measured a trunk-fixed target's 3D position and orientation relating to COM. The stereo vision system would be complementary to typical force plate methods providing precise 6D position measurements under laboratory conditions. The developed system's measurement accuracy was worst in the inferior-superior axis (depth) and pitch coordinates with accuracy measures 1.1 mm and 0.8°, respectively. The system's precision was worst in the depth and roll coordinates with values 0.1 mm and 0.15°, respectively. Computer modeling successfully predicted this precision with 11.3% mean error. Correlation between in vivo target position (TP) and COP was above 0.73 with COP generally demonstrating larger excursions oscillating around TP. Power spectral analysis of TP revealed 99% of the signal was bound below 1.1 Hz matching expectations for COM. The new complementary measurement method enables identification of postural control strategies and as a result more complete analysis. Stereo vision is a useful complement to typical force plate equipment. The system presented here is inexpensive and convenient demonstrating potential for routine use in clinic and research. In order to use this system in clinic, future work is required in interpretation of this system's data and normal reference values must be established across gender and age in a healthy population followed by values from patients with different pathologies

Enhanced Reality Visualization in a Surgical Environment

Enhanced reality visualization is the process of enhancing an image by adding to it information which is not present in the original image. A wide variety of information can be added to an image ranging from hidden lines or surfaces to textual or iconic data about a particular part of the image. Enhanced reality visualization is particularly well suited to neurosurgery. By rendering brain structures which are not visible, at the correct location in an image of a patient's head, the surgeon is essentially provided with X-ray vision. He can visualize the spatial relationship between brain structures before he performs a craniotomy and during the surgery he can see what's under the next layer before he cuts through. Given a video image of the patient and a three dimensional model of the patient's brain the problem enhanced reality visualization faces is to render the model from the correct viewpoint and overlay it on the original image. The relationship between the coordinate frames of the patient, the patient's internal anatomy scans and the image plane of the camera observing the patient must be established. This problem is closely related to the camera calibration problem. This report presents a new approach to finding this relationship and develops a system for performing enhanced reality visualization in a surgical environment. Immediately prior to surgery a few circular fiducials are placed near the surgical site. An initial registration of video and internal data is performed using a laser scanner. Following this, our method is fully automatic, runs in nearly real-time, is accurate to within a pixel, allows both patient and camera motion, automatically corrects for changes to the internal camera parameters (focal length, focus, aperture, etc.) and requires only a single image

Adapting Multi-touch Systems to Capitalise on Different Display Shapes

The use of multi-touch interaction has become more widespread. With this increase of use, the change in input technique has prompted developers to reconsider other elements of typical computer design such as the shape of the display. There is an emerging need for software to be capable of functioning correctly with different display shapes. This research asked: ‘What must be considered when designing multi-touch software for use on different shaped displays?’ The results of two structured literature surveys highlighted the lack of support for multi-touch software to utilise more than one display shape. From a prototype system, observations on the issues of using different display shapes were made. An evaluation framework to judge potential solutions to these issues in multi-touch software was produced and employed. Solutions highlighted as being suitable were implemented into existing multi-touch software. A structured evaluation was then used to determine the success of the design and implementation of the solutions. The hypothesis of the evaluation stated that the implemented solutions would allow the applications to be used with a range of different display shapes in such a way that did not leave visual content items unfit for purpose. The majority of the results conformed to this hypothesis despite minor deviations from the designs of solutions being discovered in the implementation. This work highlights how developers, when producing multi-touch software intended for more than one display shape, must consider the issue of visual content items being occluded. Developers must produce, or identify, solutions to resolve this issue which conform to the criteria outlined in this research. This research shows that it is possible for multi-touch software to be made display shape independent

Integrated analog focal plane processing for automatic alignment

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1995.Includes bibliographical references (p. 161-168).by Christopher Bruce Umminger.Ph.D