Shape characterization of a multi-modal tactile display device for biomedical applications

Tactile display has recently been attracting much attention in medical applications such as Minimally Invasive Surgery-MIS. It is needed for surgeons to feel the tissue hardness during MIS. In this paper, a multi modal tactile display device is presented for displaying both shape and stiffness of soft tissues. The concept of design is built upon simple use of several springs which are made from Shape Memory Alloy, SMA, to control shape and stiffness. The mechanical design of the device is described, and sensors (displacement, current and force) are integrated with the device to control the SMA springs. The elongation spring, responsible for displaying the shape is characterized and controlled experimentally. The device shows it can display a displacement of 5 mm in 5 seconds with PI controller using LabVIEW software.