Technologies The NASA Space Telerobotics Program

Virtual Reality Calibration Technology and TELEGRIP

JPL recently developed a virtual reality calibration technique that enables reliable and accurate matching of a graphically simulated virtual environment in 3-D geometry and perspective with actual video camera views. This technique enables high-fidelity preview/predictive displays with calibrated graphic overlay on live video for telerobotic servicing applications. Its effectiveness was successfully demonstrated in a recent JPL/NASA-GSFC ORU (Orbital Replacement Unit) changeout remote servicing task. In September 1993, with NASA's recent thrust for industry collaborations, JPL and Deneb Robotics, Inc. established a technology cooperation agreement. In this JPL-Industry cooperative Deneb Commercialization Task, JPL transfers the virtual reality calibration software technology to Deneb, and Deneb inserts this software technology into its commercial product TELEGRIP. This joint technology collaborative work thus enables Deneb to commercialize an upgraded industry product that will greatly benefit both space and terrestrial telerobotics applications.

Key new features of the JPL calibration technique include;

  1. An operator-interactive method is adopted to obtain reliable correspondence data.
  2. A robot arm itself is used as a calibration fixture for camera calibration, eliminating a cumbersome procedure of using external calibration fixtures.
  3. The object localization procedure is added after the camera calibration as a new approach to obtain graphic overlay of both the robot arm and the object(s) on live video and enable effective use of the computer-generated trajectory mode in addition to the teleoperation mode.
  4. A projection-based linear least-squares algorithm is extended to handle multiple camera views for object localization.
  5. Nonlinear least-squares algorithms combined with linear ones are employed for both camera calibration and object localization. Details of the algorithms and their software listings can be found in the recent JPL Document D-11593, which was prepared as part of this JPL-Industry cooperative task.
The JPL virtual reality calibration option is currently being implemented on Deneb's TELEGRIP which is an open architecture based upon Dynamic Shared Objects (DSO's). The TELEGRIP video overlay implementation will be based upon an application programmers interface (API) layer which insulates the overlay developer from the specifics of video hardware, thus enabling support over a wide range of video products. Graphic models can be overlaid in wire-frame or in solid-shaded polygonal rendering, with varying levels of transparency to produce different visual effects.

The virtual reality calibration option implemented on TELEGRIP will provide 1) immediate benefits to NASA for ground-controlled telerobotics servicing in space, 2) immediate benefits to the National DOE (Department of Energy) Labs working on the disposal of nuclear waste, 3) significant enabling technology for the decontamination and decommissioning of commercial nuclear reactors, and 4) foreseeable applications in automotive, medical, and servicing industries.

For more information see:

W. S. Kim, Virtual Reality Calibration: Algorithms and Software Listings with an application to Preview/Predictive Displays for Telerobotic Servicing, Jet Propulsion Laboratory Internal Document D-11593, Feb. 1994.

W. S. Kim and A. K. Bejczy, "Demonstration of a High-Fidelity Predictive/Preview Display Technique for Telerobotic Servicing in Space," IEEE Trans. on Robotics and Automation, vol. 9, no. 5, pp. 698-702, 1993.

W. S. Kim, P. S. Schenker, A. K. Bejczy, S. Leake, and S. Ollendorf, "An Advanced Operator Interface Design with Preview/Predictive Displays for Ground-Controlled Space Telerobotic Servicing," SPIE Conference 2057: Telemanipulator Technology and Space Telerobotics, pp. 96-107, Boston, MA, Sept. 1993.


Point of Contact:
Won Soo Kim,
Mail Stop 198-219
Jet Propulsion Laboratory
4800 Oak Grove Drive
Pasadena CA 91109
818-354-5047
kim@telerobotics.jpl.nasa.gov



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