The Newsletter of a Medical
Robotics project of the
Institute of Robotics and
Intelligent Systems, a
Federally Funded Network
of the Centres of Excellence

The research group is developing a prototype of a mechanism to hold a laparoscope at the surgical site. This "LaparoRobot" mechanism can be controlled in two ways:     

• through a master/slave configuration
• via an image tracking algorithm

The objective is to keep most of the actuator away from the pivotting point.

  Haptic Feedback Mechanism

A haptic interface is a mechanism which allows the surgeon to feel the reaction forces of the endoscopic surgery as if they were touching the area directly. The current developments aim to create a mechanism that can manipulate the tools in the same configuration as traditional surgery. This mechanism, when combined with haptic rendering and a graphic display, provides training surgeons with the same sensory input as they would have in an actual surgery. The figure shows a prototype of such a mechanism. The design has four degrees of freedom where two of the joints have force feedback capabilities.

  Haptic Rendering

An efficient and practical rendering scheme uses the output files of a number of standard graphics environments or the information from probing devices. Contact status between various objects can be determined using an efficient and fast collision detection algorithm. This produces contact profiles which can be interfaced with a haptic device or displayed graphically. The figure shows the basic block diagram of such rendering scheme.

  Tip Force/Surgeon Interface

The research group propose a sensor integration scheme, in which a sensor can be integrated into existing design of the endoscopic tools. The sensor can be encapsulated for effective usage in the wet environment. They also designed a force display for the handle of the tool to show the magnitude of the grasping forces. The design was tested in the wet environment and for various ranges of tip grasping force.

  Pulse Sensor

The three surgical tools in the picture to the left have been equiped with pressure-sensitive sensors. The Force Feedback Sensors are shown in more detail in the picture on the right. Clockwise from the top, a semiconductor strain gauge endoscopic sensor that measures the static applied load of tissue on the grasper. An endoscopic grasper incorporating piezoelectric Polyvinylidene Flouride (PVDF) film to detect dynamic stresses. A PVDF-based pulse sensor that detects arterial pulse beats to avoid cutting arteries in tissues which cannot be seen. It doubles as a heart rate monitor.

  Surgical Specialties

A researcher distributed a three page questionnaire to 1000 B.C. surgeons, from ten different specialties. The questionnaire asked questions related to minimally invasive surgery (MIS). It specifically targeted: constraints and difficulties experienced during surgical procedures; new tools and technologies and their effectiveness; alleviating specific constraints through new tools and technologies; and the general attitudes of surgeons surrounding future issues such as remote surgery and augmented training for surgery. The following graph shows the distribution of the surgical specialties represented in the returned questionnaires. Analyses of these questionnaires are currently underway (250 returned). Thanks to all the surgeons for their time and co-operation.

  Superimposing Display Space

We conducted an experiment to determine how the location of the image display influences task performance in endoscopic surgery. Subjects performed two tasks under two display conditions. The endoscopic camera view of the workspace was displayed either on a monitor in front of the subject or projected directly above the workspace. Timing results revealed significant order by display interactions. Overall, subjects performed faster at both pointing and grasping tasks with the superimposed display. In addition, the superimposed display improved the subject's calibration of the workspace with the display space. However, a post-test questionnaire revealed that the image quality was perceived to be superior on the monitor. A second experiment is in progress using virtual reality technology where the superimposed display will have a high image quality. We expect to find that subjects will show very efficient performance with the high resolution, superimposed display. Thanks to Karl-Storz Endoscopy for the use of their first-generation ViewSite equipment to evaluate the superimposed display.