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This paper presents the design and simulation of a handheld device for people with hand tremor, such as Parkinson's and essential tremor patients. This device can be used as a pen for smartphones or as a spoon. The designed system includes two links, which are connected to two servomotors, which are mounted in orthogonal directions. To attenuate the effect of hand tremor on the tip of device, PID and computed torque methods are used to actively control the system. These controllers are used to control the rotation of the motors for moving the links in opposite directions of the hand tremor. Performance of the device with mentioned controllers is studied for different applications and finally, the results of both controllers are discussed and compared. Based on the presented results in this study, the designed device is able to suppress the hand tremor up to 75% during eating and 65% during following a spiral pattern. Graphical abstract Design of a noninvasive and smart hand tremor attenuation system: a simulation study.

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In this study, ongoing investigations to apply piezoelectric materials as an energy harvester are extended. In doing so, effectiveness of single unit impact dampers is increased using piezoelectric materials. For this reason, barriers of the impact damper are replaced with cantilever beams, which are equipped with the piezoelectric patches. For convenience, this kind of impact dampers is named as “piezo-impact dampers.” The piezo-impact damper is not only a vibration suppressor but also it is an energy harvester. An analytical approach is presented to formulate the voltage and power generation in the barriers of the piezo-impact dampers. Variation in output voltage is studied with changing the main parameters of the piezo-impact damper. Furthermore, damping inclination, which presents the ability of vibration suppressing in impact dampers, is calculated with varying the main parameters of the impact damper. Regarding calculated output voltage and damping inclination in the piezo-impact dampers, two “energy-based” and “vibratory-based” design methods are presented. Finally, using several user-oriented charts, the discussed design methods are combined to provide a powerful piezo-impact damper.