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Human telehaptic perception of stiffness using an adaptive impedance reflection bilateral teleoperation control scheme

In present days, teleoperation is used in many challenging applications where the tasks to be accomplished from a distance are very complex and require accurate and reliable reproduction of the haptic sensations involved. The main factor that can cause a certain degradation of the quality of teleoperation is the presence of time delays. An effective way of alleviating the consequences of time-delays is the use of an adaptive impedance reflection teleoperation scheme, aiming to reconstruct at the master site a local model of the impedance of the remote environment. The goal of this paper is to show the effectiveness of such a controller via experiments that involve a real remote environment. In these experiments, a forced-choice procedure has been used, where each subject is presented in every trial with two spring fields (remotely located and telehaptically perceived) and is asked to identify the stiffer. The proposed adaptive teleoperation control scheme is compared to a typical direct force-reflection telemanipulation, in the presence of an emulated time delay of 100 msec. Experimental results show the superior performance of the proposed adaptive impedance reflection scheme, which, as opposed to classical direct teleoperation, seems to maintain the thresholds of human haptic perception close to the ones obtained when no time delay is present in the bilateral communication and control loop.