A bilateral teleoperation system can become unstable in the presence of a modest time delay. However, the wave variable algorithm provides stable operation for any fixed time delay using passivity arguments. Unfortunately, the wave variable method produces wave reflection that can degrade teleoperation performance when a mismatched impedance exists between the master and slave robot. In this work, we develop a novel bandstop wave filter and experimentally verify that the technique can mitigate the effects of wave reflections in bilaterally teleoperated systems. We apply the bandstop wave filter in the wave domain and filtered the wave signal along the communication channel. We placed the bandstop wave filter in the master-to-slave robot path to alleviate lower frequency components of the reflected signal. With the lower frequency components reduced, wave reflections that degrade teleoperation performance were mitigated and we obtained a better transient response from the system. Results from our experiment show that the bandstop wave filter performed better by 67% when compared to the shaping wave filter respectively.

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Parallel manipulators are widely used in industrial applications due to their rigid structures and ability to perform automated tasks at high speeds. However, because the links on a parallel manipulator are mechanically coupled, solving its kinematics and dynamics equations can be more difficult than for its serial counterpart. Nevertheless, the inverse kinematics and inverse dynamics models are a critical component of a manipulator's controller. Specifically, a more computationally simple formulation of the inverse kinematics and dynamics is necessary to achieve efficient and fast manipulator control. In this paper, both the inverse kinematics and dynamics equations for the Omega-3, a three degree-of-freedom (3-DOF) parallel manipulator, are developed. For the inverse kinematics problem, the concept of loop closure equations is used to simplify the analysis. The virtual work principle is used to create a numerically simple inverse dynamics model. Using the inverse kinematics and dynamics model, a trajectory tracking controller is implemented on the manipulator and the resulting experiments reveal good tracking behavior. (Abstract)