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On the Passivity of Persian literary Theory

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Stratospheric airships have introduced interesting solutions for challenges in aerospace industries. Buoyant and propulsion forces produced by airships makes them to be capable of long-time flight and efficient operation. In spite of many progresses, there are still many challenges in this interesting field of study. In this paper, first the dynamic model of fully-actuated stratospheric airship with 6-DOF expressed by the generalized coordinates, then desired values of the airship attitude, linear and angular velocities obtained according to desired path and using pseudo inversion of the kinematics and dynamics equations. In view of the unknown inertial parameters first in adaptive inverse dynamic control, inertial parameters estimated online by using linearization parameters and gradient update law. Next control law and nonlinear dynamic equation is deduced by designing control algorithm based on passivity, and according to that, adaptive and robust control based on passivity applied for controlling airship. The stability of the closed loop control system is proved by using the Lyapunov stability theory. Finally, comparison between the results of the all methods are shown.

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Stability and transparency are both very important conditions in bilateral teleoperation systems. For the design of such systems, different methods have been suggested. Among the approaches presented, passivity framework is widely utilized in which human and environment is considered passive. The operator does not make the closed-loop system unstable. In addition, it is passive against an external input. Thus the adoption of this assumption is correct for the human. Nevertheless it is a conservative presumption for the environment and according to some modern applications of teleoperation systems such as cardiac surgery, it is absolutely not acceptable. In this paper a novel control structure for nonlinear bilateral teleoperation systems interacting with active environments is addressed. In this approach, first a criterion for measuring activity of the environment is presented. Then by developing a PD controller, an algorithm that guarantees master-slave position coordination and static force reflection is introduced. The overall stability of closed loop system is proved using passivity concept and Lyapunov-Krasovskii technique. Simulations are performed to verify the performance of the proposed bilateral teleoperation systems in contact with passive and non-passive environments. Experimental results were carried out to validate the theoretical consequences.