Control of Dual-User Teleoperation Systems Design, Stability Analysis, and Performance Evaluation
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Teleoperation systems broaden human ability to perform a task in a real or virtual, local or remote environment. An emerging application of such systems is in dual-user teleoperation or haptic simulation systems in which two users collaboratively perform a task in a shared real or virtual environment. Examples of this application are in human haptic guidance for rehabilitation therapy and medical surgical training. In such collaborative systems, users interact with each other and a user's decision is affected by the other user's decisions. This interaction between users bring out the need for new control architecture design methods. In addition, the controller should maintain system stability and achieve desired performance under various operational conditions, including contact with a wide range of environments and being interfaced with two users displaying highly variable arm dynamics. To this purpose, a class of shared control architectures for human haptic guidance has been developed. The architectures feature a dominance factor that adjusts the supremacy of the trainer over the trainee in the execution of a task. To tackle the stability issue, a novel robust stability analysis framework for unconditional stability analysis of multi-user teleoperation/haptic systems has been proposed. In terms of performance these systems have been evaluated kinesthetically, referring to the dynamics felt by the users, or task-based, referring to the quantities that measure task efficiency and effort. For kinesthetic performance evaluation of dual-user systems as opposed to the single-user systems, there are two users interacting with the environment and with each other. In these systems it may be desirable for a user to not only feel the environment but also to sense the other user dynamics. Hence, some of the previously defined performance measures for single-user systems have been extended for dual-user systems. Furthermore, two novel performance measures for multilateral dual-user systems have been introduced. Finally, to assess the task-based performance of the proposed architectures, a user study has been conducted for trajectory following tasks on a developed dual-user haptic simulation testbed under various environmental conditions, such as different environment geometries, environment view points and environment dynamics.