Last Update: June 27th, 1997 Comments
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Our goal is to support the teaching and training of the operators with a computer-based simulation system which imitates the operation area and provides a realtime 'synthetic` endoscopic view. The user can interactively manipulate the modelled objects and execute surgical tasks. The coordination of instruments, the hand-eye coordination and the teamwork can be practised, also the operation procedures and the use of new instruments. It is possible to implement several complications in a 'training parcours' as well as anatomic specialities. Structured training steps are repeatable and reproducible. An evaluation of training success can be performed, expert system feedback could be another useful feature.
More information about the Karlsruhe Endoscopic Surgery Trainer can be found here.
Don't miss our animated gif showing a virtual cholecystectomy !
The sense of presence in a virtual enviroment as provided by the Karlsruhe Endoscopic Surgery Trainer is highly correlated with the degree of perception of that environmet. In medical applications the sensation of forces is very important. Force Feedback, also known as force reflection or haptic feedback introduces this physical sensation into the virtual reality environment. At least 2 componenets are needed to provide force feedback for medical applications:
This page concentrates on the different force reflecting interfaces connected to our realtime simulation system and our force feedback concept. General informations about our realtime simulation system KISMET can be found here.
Different force reflecting interfaces can be connected to our Virtual Reality System KISMET, the core software of our Karlsruhe Endoscopic Surgery Trainer:
The Laparoscopic Impulse Engine from Immersion Corporation has 5 deegrees of freedom for motion and tracking with 3 deegrees of freedom providing feedback. It has been designed as an input/outout device for virtual reality simulations of laparoscopic and endoscopic surgical procedures. We use a pair of Impulse Engines acting as human-computer interface inside our Karlsruhe Endoscopic Surgery Trainer. The surgeon uses the devices like instruments. A PC tracks the position and orientation of the 2 devices. This information is used by our software system KISMET running on SGI workstations to calculate the interaction between instrument and virtual deformable objects. The resulting forces are calculated in realtime and sent back to the interfaces providing realistic physical feedback sensations.
Not only the Karlsruhe Endoscopic Surgery Trainer needs force feedback - other medical applications too! More information about our other force feeback applications using the PHANToM from SensAble Technologies can be found here.
This haptic device with 5 degrees of freedom has been designed by Hauptabteilung Ingenieurtechnik. 3 degrees of freedom are equipped with motors to provide force feedback. The picture on the left hand side shows this devices as simulated by KISMET.
The Force Feedback
Device (JPEG, 179kB)
The following picture shows the diagram of our Training System with the HIT Force-Feedback Device.
The surgeon uses the device like an instrument. The movements of the instrument are transferred to the graphics workstation using a PC-based measurement system. If an interaction between simulated instrument and an deformable object occurs, the forces acting on the tip of the instrument are calculated by our simulation system KISMET. After transformation into forces/torques acting on each degree of freedom these forces/torques are used as input for a microcontroller-box controlling the motors. As a result the surgeon will experience contact forces. Because the interface represents a wide range of different simulated instruments we introduced a force feedback concept giving the user a physical sensation for the different behaviour of the instruments. By calculating the dynamic behaviour of the interface and the simulated instrument simultaneously one gets the information necessary to compensate the different dynamic behaviour.
Institut für angewandte Informatik (IAI)
P.O.Box 3640, D-76021 Karlsruhe