Graphical display of tactile sensing data with application in minimally invasive surgery

In this paper, the design of a hardware and software system for graphical representation of tactile sensing data is described in detail. The signal processing is developed using LabView 7 software. The signals from the sensors are processed, and then various tactile properties of the grasped material are extracted. The tactile information includes softness, stress distribution, and lumps. This information is displayed by means of a colour coding method. The technical specifications of the hardware and data acquisition system are described in detail. The system receives signals from the sensors, transforms them into digital signals, and then transmits them to a personal computer. The developed software is also presented, and its capabilities are discussed. Using the designed system, it is possible to determine the softness of objects that come into contact with it. To serve as sensing elements, two piezoelectric films made of polyvinylidene difluoride are incorporated into the sensing assembly, and the combination of the resulting output voltages is related to the object softness. As a practical application, the sensor assembly is integrated with a commercially available endoscopic grasper which has been modified for the purpose of this research.