This article reports on experiments about haptic perception aimed at measuring the force/torque differential thresholds applied to the hand-arm system. The experimental work analyzes how force is sent back to the user by means of a 6 degrees-of-freedom haptic device. Our findings on force perception indicate that the just-noticeable-difference is generally higher than previously reported in the literature and not constant along the stimulus continuum. We found evidence that the thresholds change also among the different directions. Furthermore, asymmetries in force perceptions, which were not described in previous reports, can be evinced for most of the directions. These findings support our claim that human beings perceive forces differently along different directions, thus suggesting that perception can also be enhanced by suitable signal processing, that is, with a manipulation of the force signal before it reaches the haptic device. We think that the improvement of the user perception can have a great impact in many applications and in particular we are focusing on surgical teleoperation scenarios.

Interactive simulations of deformable bodies are a growing research area with possible applications in several fields, i.e. computer aided surgery. The main implementation issue is to mimic the real behavior of the body at the extremely high rates required by haptic devices. Since even high-end computers have inadequate performance, one possible solution is to exploit the parallelism of modern Graphics Processing Units.In this paper we present our research aiming at moving the whole computational process from the CPU to the GPU taking advantage of the computational power of the graphics hardware. We use a mass-spring model, augmented with local damping coefficients and volume preservation forces. Collision detection is performed against external rigid bodies with high complexity mesh, such as the skeleton's one. The user interacts with the model by controlling virtual tools, i.e. probes or tweezers. Haptic forces are computed on GPU and the results are asyncronously transferred to the CPU. Our approach can simulate the deformation of complex models with gravity and interaction with environment and tools at a frame rate higher than 1 KHz, making it suitable for visual rendering and haptic feedback.

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Abslmcf-This paper describes our efforts and plans to develop a Virtual Laboratory for the education in Rohotics and Automation. These efforts are characterized by the need of blending R&A subjects into a traditional Computer Science curriculum, thus forcing a specific selection of development topics. In this context, the Robotics Laboratory must provide basic as well as advanced experiments, to address the needs of students at different education levels. In this paper, we present the development of three main applications, to support Control Systems and Robotics classes, as well as thesis and dissertation research. Of particular interest is the effort in the area of teleoperation, preliminary to the opening, next year, of a new curriculum on Medical Informatics, in which Computer Assisted Surgery will play an important role.