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The efficiency of single-degree-of-freedom (SDOF) vibration-based energy harvesters significantly drops when the resonance frequency of the harvester is different from that of the ambient vibration. In this study, a novel piezoelectric-based energy harvesting mechanism is introduced for rotary motion applications, which can generate power over a broad range of angular velocities of the wheel. The proposed design, which comprises a coupled spring-mass system attached to a PZT beam, has the advantage that it can easily be tuned in an off-line position by simply changing the tip mass and/or spring stiffness. A theoretical and experimental study is undertaken to check the performance of the proposed design for the range of speeds typical of commercial tires. It is shown that by tuning the resonance frequency of the massspring system the design can significantly increase the frequency bandwidth of the energy harvester.

This paper presents the design and performance analysis and experimental study of a 3- R RR spherical parallel manipulator in the context of hip exoskeleton applications. First, the mechanism’s inverse kinematics analysis and Jacobian matrix development are revisited. Manipulability, dexterity, and rotational sensitivity indices are then evaluated for two different methods of attachment to the human body. The superior attachment method in terms of these performance measures is indicated, and an experimental study based on the selected method is conducted; the experiment involves testing the capability of a 3- R RR manipulator’s end-effector in tracking the motions experienced by a human hip joint during normal gait cycles. Finally, the results of the experimental study indicate that the manipulator represents a feasible hip exoskeleton solution providing total kinematic compliance with the human hip joint’s 3-degree-of-freedom motion capabilities.