Design and Performance of a Prototype Tactile Shape Display for Minimally Invasive Surgery

The design of a tactile shape display intended for Minimally Invasive Surgery (MIS) is presented. It consists of 32 micro brushless motors arranged in a 4-by-8 configuration, and the total size is 27 mm × 20 mm × 18 mm. The main restrictive design parameter is the size of the display as it will be attached to a laparoscopic grasper. Modularity is also crucial since it might be desirable to do experiments with other pins or effectors attached to the actuators. The tactel (TACTile ELement) spacing is 2.7 mm with a tactel diameter of maximum 2.6 mm. The display is tested with respect to pin force, positioning accuracy, bandwidth and stiffness. Results show that the tactels can provide an active force of 0.4-0.5 N at a frequency of close to 0.7 Hz at full excursion (3 mm). The testing also show that positioning accuracy is approximately 40 μm, while the stiffness is close to 50 N/mm.