A combined university/industry team has developed a prototype system for handling protein crystals aboard the space station. This system uses a miniature direct drive robot, CCD television cameras, and a client-server computing system using Internet protocols to support the capture of protein crystals from aqueous growth solutions. The system was demonstrated between Huntsville AL. and Seattle WA. An operator in Huntsville controlled the mini robot by invoking predefined relative and absolute macro files. The operators observed results using video images sent through the Internet link using Cu-SeeMe video conferencing software. In 3 of 4 trials, the operators successfully captured 0.5 mm simulated protein crystals into a glass capillary. The system is a promising start for the development of a space-station based remote protein crystal analysis facility.

A method is described and validated for the automatic calibration of analog sine-wave quadrature sensors, such as optical encoders, embedded in a functioning system. The algorithm uses a Kalman filter to estimate the true position of the direct-drive actuator joint using a model of it's dynamics, an applied actuator command and measurements from the uncalibrated sensor. From the estimated true position, a lookup table is constructed which corrects sensor errors. Our results indicate that this method achieves accuracies typical of interferometric calibration, without requiring an external measurement device. The accuracy is surprisingly robust to modeling errors.

A previously developed 3 axis mini direct drive robot has been enhanced with two additional direct drive axes for general positioning and orientation of an axially symmetric tool. The arm has a work volume of about 50 cc and will have 5-10 micron or better resolution and repeatability. The arm forms an initial prototype for the NASA/University of Washington MicroTrex flight telerobotics experiment. The contemplated terrestrial applications include handling sub-microliter liquid samples for electrophoresis, and micro-manipulation with scaled force reflection.>

An enhanced teleoperation technique for time-delayed bilateral teleoperator control is discussed. The control technique selected for time delay is based on the use of a high-fidelity graphics phantom robot that is being controlled in real time (without time delay) against the static task image. Thus, the motion of the phantom robot image on the monitor predicts the motion of the real robot. The real robot's motion will follow the phantom robot's motion on the monitor with the communication time delay implied in the task. Real-time high-fidelity graphics simulation of a PUMA arm is generated and overlaid on the actual camera view of the arm. A simple camera calibration technique is used for calibrated graphics overlay. A preliminary experiment is performed with the predictive display by using a very simple tapping task. The results with this simple task indicate that predictive display enhanced the human operator's telemanipulation task performance significantly during free motion when there is a long time delay. It appears, however, that either two-view or stereoscopic predictive displays are necessary for general three-dimensional tasks.>