John W. Hill

Telepresence surgery demonstration system

Endoscopic surgical methods are replacing open surgery in many procedures, but dexterity and force feedback are not adequate with current tools. To enhance the ability of surgeons to operate endoscopically, we have developed a telepresence system with integrated 3D stereo viewing, a prototype force-reflecting manipulator, and aural feedback. Careful attention was paid to the human factors in the endoscopic surgery setting to make the system natural to use in the hope of eliminating the long training period normally required. The 4-axis (plus gripper) manipulator provides the same degrees of freedom as the laproscopic tools now being used for surgery. The bilateral control system provides for magnified motion and/or force reflection. This approach eliminates the motion reversal, or fulcrum effect, in operating through the abdominal wall. Preliminary dexterity experiments with different force feedback and viewing conditions verify intuitive use and fast learning.<<ETX>>

Vascular applications of telepresence surgery: Initial feasibility studies in swine

PURPOSE Telepresence surgery is a novel technology that will allow procedures to be performed on a patient at locations that are physically remote from the operating surgeon. This new method provides the sensory illusion that the surgeons hands are in direct contact with the patient. We studied the feasibility of the use of telepresence surgery to perform basic operations in vascular surgery, including tissue dissection, vessel manipulation, and suturing. METHODS A prototype telepresence surgery system with bimanual force-reflective manipulators, interchangeable surgical instruments, and stereoscopic video input was used. Arteriotomies created ex vivo in segments of bovine aortae or in vivo in femoral arteries of anesthetized swine were closed with telepresence surgery or by conventional techniques. Time required, technical quality (patency, integrity of suture line), and subjective difficulty were compared for the two methods. RESULTS All attempted procedures were successfully completed with telepresence surgery. Arteriotomy closures were completed in 192+/-24 sec with conventional techniques and 483+/-118 sec with telepresence surgery, but the precision attained with telepresence surgery was equal to that of conventional techniques. Telepresence surgery was described as intuitive and natural by the surgeons who used the system. CONCLUSIONS Blood-vessel manipulation and suturing with telepresence surgery are feasible. Further instrument development (to increase degrees of freedom) is required to achieve operating times comparable to conventional open surgery, but the system has great potential to extend the expertise of vascular surgeons to locations where specialty care is currently unavailable.

Perception of sequentially presented tactile point stimuli

Either two or three brief (10 msec) airjet stimuli were sequentially presented to any of the 24 interjoint regions of the fingers (thumbs excluded). The stimulus onset interval (SOI) ranged from zero (simultaneous presentation) through 200 msec. The S’s task in one part of the experiment was to report the positions stimulated in the order that the stimuli were presented; in a second part it was to rate the apparent motion produced by the stimulus sequence. While the ability of Ss to spatially localize the stimuli was a constant independent of SOI, their ability to temporally order the stimuli depended strongly on SOI. With two stimuli, these sequential errors decayed exponentially with SOI with a time constant of 26 msec. With three stimuli, however, both the sequential errors and equivalent temporal Urnen were more than twice as large as with two stimuli, indicating that the three-stimulus task is considerably more difficult than the two, and that the same simple temporal resolution model does not explain both cases. A model with a constant rate of information uptake, however, can explain both of these cases.

A Describing Function Analysis of Tracking Performance Using Two Tactile Displays

A display consisting of two vibrators attached to the body was tested using three different error signal-to-vibration amplitude transformations. In addition, a novel ripple display consisting of seven sequentially activated air-jet stimulators was tested on a compensatory tracking task. For both displays the range of gains and body locations were determined by both describing-function and error-power analyses. The results showed that the two-vibrator display was equally effective on all five body areas tested, but that the ripple display produced best tracking performance only when widely spaced or situated on an anatomical landmark. The best ripple display, however, was better than the best vibrator display and provided tracking performance nearly equivalent to visual displays. It was found that the ripple display was not enhanced by apparent motion but produced equivalent operator time delays shorter than those measured with visual displays.

Comparison of Seven Performance Measures in a Time-Delayed Manipulation Task

Real-time performance data was collected during a pick-up task carried out with a Rancho master-slave manipulator using a minicomputer-based data taker. Motions on all seven master and all seven slave joints as well as instantaneous electrical power consumed were continuously monitored. In addition to the usual task-time measurements, computer algorithms to integrate the energy consumed and to count and time the number of moves were implemented. In addition to these measures, several derived measures such as the fraction of time moving (MRATIO) and mean time per move (MBAR) were obtained in an off-line analysis. A major goal of these experiments is to compare the seven different measures of performance to determine which are best for evaluating particular experimental conditions. Preliminary results of the time delay experiment indicate that two new measures, MRATIO and MBAR, are almost an order of magnitude more sensitive than task time, the conventional measure, in determining performances changes with transmission delays in the range from 0.0 to 1.0s. Taking advantage of the operators move-and-wait strategy, we also show how the energy consumed in carrying out a task can be reduced by a factor of three in the one-second transmission-delay case.

Quantitative evaluation of surgical task performance by remote-access endoscopic telemanipulation

AbstractBackground: The performance limitations inherent in minimally invasive surgery may be overcome by using an interface that provides intuitive orientation for video display and tool manipulation. A prototype remote-access endoscopic telemanipulator was designed to fulfill these requirements and used for a surgical anastomosis task. Methods: A remote-access telemanipulator system, employing remote center-of-motion geometry, was used to complete distant in vitro tubular anastomoses. The performance of four surgeons using this system was compared with that achieved in completing the same anastomosis task in an open environment using open surgical techniques and in a minimally invasive environment using standard laparoscopic methods. Results: The average performance times for completion of the anastomosis task was 1448 ± 130 s using the telemanipulator system compared with 2108 ± 291 s with laparoscopic instruments and 296 ± 25 s with conventional techniques. Leakage rates from the tubular anastomoses were 5.2 ± 1.4 ml/s in the telemanipulator group, 6.9 ± 2.0 ml/s in the laparoscopic group, and 3.2 ± 0.9 ml/s in the conventional methods group. All experimental subjects were able to complete the assigned task in each experimental condition successfully without complications. Conclusions: Our results in this pilot study suggest that remote-access endoscopic telemanipulation can execute complex three-dimensional manipulations, and that the intuitive orientation of the surgeons workstation may contribute to easier task completion.

Telepresence microsurgery system

In current practice, microsurgery involves dexterous manipulations on small tissues viewed through a stereo microscope. Surgeons hold special grasping and cutting instruments in a pencil-like grip, with their palms supported, to optimize fine motor control and minimize hand tremor and fatigue. Telepresence-based microsurgery has the potential to provide the surgeon with a magnified workspace in which he can comfortably work with his hands on full-size instrument handles, using normal hand motions and experiencing the feel he would expect from the magnified tissues that he sees. To address the needs for performing microsurgical procedures, the SRI telepresence surgery workstation has been combined with a pair of micromanipulator arms. The prototype microsurgery system has been tested with ex-vivo tasks similar to those required for surgical procedures, such as cutting, grasping, suturing, and knot tying. Initial animal testing has been done on a rat model in which end-to-end anastomosis of the femoral artery was completed with 10 rats, and 100% patency was obtained.