Design and experimental evaluation of a tactile display featuring magnetorheological fluids

This paper proposes a novel type of tactile display utilizing magnetorheological (Mr) fluid which can be applied to a robotic system in minimally invasive surgery to provide a surgeon with tactile information on remote biological tissues or organs. As a first step, an actuation mechanism for tactile function is devised utilizing the Mr fluid with a pin array mechanism. Based on the force responses of a human body, the tactile display is appropriately designed and a magnetic analysis is carried out to determine the design parameters using the finite element method. After evaluating the field-dependent force characteristics of the manufactured tactile display, a feed-forward control algorithm based on fuzzy logic is formulated to obtain the desired palpation force. Control performance is demonstrated via palpation force evaluation and psychophysical evaluation. In the results, the actual repulsive forces agreed well with the desired forces and the averaged relative error was less than 1.3%. In addition, the volunteers successfully recognized tactility with a favorable rating value of 3.36 on a five-point scale.