Many applications in teleoperation and virtual reality call for the implementation of effective means of displaying to the human operator information on the softness and other mechanical properties of objects being touched. The ability of humans to detect softness of different objects by tactual exploration is intimately related to both kinesthetic and cutaneous perception, and haptic displays should be designed so as to address such multimodal perceptual channel. Unfortunately, accurate detection and replication of cutaneous information in all its details appears to be a formidable task for current technology, causing most of today's haptic displays to merely address the kinesthetic part of haptic information. In this paper we investigate the possibility of surrogating detailed tactile information for softness discrimination, with information on the rate of spread of the contact area between the finger and the specimen. Devices for implementing this new perceptual channel are described, and some preliminary psychophysical test results are reported, validating the effectiveness and practicality of the proposed approach.
The measurement of time-varying forces and torques applied to flexible mechanical structures cannot be pursued by relying on quasi-static approximations. However, the problem can be cast as a problem of dynamic system inversion, provided reliable models of the dynamic relationship among forces, torques and measurement gauges are available. Within this framework it is possible, in particular, to define optimality criteria for gauge placements in order to guide the design of such dynamic force/torque sensing devices. Experimental results show that the approach proposed is indeed capable of reconstructing forces, torques and point of contact applied to a flexible beam with a rigid part
Detection of softness by tactile exploration in humans is based on both kinesthetic and cutaneous perception, and haptic displays should be designed so as to address such multimodal perceptual channel. Unfortunately, accurate detection and replication of cutaneous information in all its details is difficlt and costly. In this paper we discuss a simplified model of haptic detection of softness (whereby only information on the rate of spread of the contact area between the finger and the specimen as the contact force increases is transmitted). We provide a thorough set of psychophysical tests, to support the feasibility (in at least some contexts) of a reduced-complicacy display of haptic features.