Towards engineering a portable platform for laparoscopic pre-training in virtual reality with haptic feedback

Laparoscopic surgery is a surgical technique in which special instruments are inserted through small incision holes inside the body. For some time, efforts have been made to improve surgical pre-training through practical exercises on abstracted and reduced models. The authors strive for a portable, easy to use and cost-effective Virtual Reality-based (VR) laparoscopic pre-training platform and therefore address the question of how such a system has to be designed to achieve the quality of today's gold standard using real tissue specimens. Current VR controllers are limited regarding haptic feedback. Since haptic feedback is necessary or at least beneficial for laparoscopic surgery training, the platform to be developed consists of a newly designed prototype laparoscopic VR controller with haptic feedback, a commercially available head-mounted display, a VR environment for simulating a laparoscopic surgery, and a training concept. To take full advantage of benefits such as repeatability and cost-effectiveness of VR-based training, the system shall not require a tissue sample for haptic feedback. It is currently calculated and visually displayed to the user in the VR environment. On the prototype controller, a first axis was provided with perceptible feedback for test purposes. Two of the prototype VR controllers can be combined to simulate a typical both-handed use case, e.g., laparoscopic suturing. A Unity-based VR prototype allows the execution of simple standard pre-trainings. The first prototype enables full operation of a virtual laparoscopic instrument in VR. In addition, the simulation can compute simple interaction forces. Major challenges lie in a realistic real-time tissue simulation and calculation of forces for the haptic feedback. Mechanical weaknesses were identified in the first hardware prototype, which will be improved in subsequent versions. All degrees of freedom of the controller are to be provided with haptic feedback. To make forces tangible in the simulation, characteristic values need to be determined using real tissue samples. The system has yet to be validated by cross-comparing real and VR haptics with surgeons.