Abstract-In this paper, the problem of online estimation of the mechanical impedance during the contact of a robotic system with an unknown environment is considered. This problem is of great interest when controlling a robot in an unstructured and unknown environment, such as in telemanipulation tasks, since it can be easily shown that the exploitation of the knowledge of the mechanical properties of the environment can greatly improve the performance of the robotic system. In particular, a single-point contact is considered, and the (nonlinear) Hunt-Crossley model is taken into account, instead of the classical (linear) Kelvin-Voigt model. Indeed, the former achieves a better physical consistency and also allows describing the behavior of soft materials. Finally, the online estimation algorithm is described and experimental results are presented and discussed.
Abstract-Teleoperation systems have been developed in order to allow a human operator to perform complex tasks in remote environments. Mobile robots can be considered as a particular example of telemanipulation systems, since they can be operated remotely to perform particular tasks. As an example, the inspection of underwater structures and the removal of mines are performed by mobile platforms controlled by a remote operator, which generally takes advantage only of the visual feedback provided by vision systems. In this sense, the nature and completeness of the data provided to the operator about the state of the remote system are of crucial importance for proper task execution, and it is generally accepted that a more efficient achievement of the task can be obtained by increasing the number of data feedback and by using proper MMI. In this paper, the use of a haptic interface is proposed in order to increase the user's perception of the workspace of the mobile robot. In particular, a virtual interaction force is computed on the basis of obstacles surrounding the mobile vehicle in order to prevent dangerous contacts, so that navigation tasks can be carried out with generally better performances. In addition, passivity of the overall system is taken into account, so that stability of the virtual interaction is guaranteed.
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