Structural control and biomechanical tremor suppression: Comparison between different types of passive absorber

Abstract

Active and semi-active control devices can be used as advanced and accurate controllers to reduce the undesired vibration of a structure. However, some of these controllers may have a complex design, especially for systems excited with multi-degree-of-freedom frequencies, which demand the use of high anti-fatigue material properties, and others that may require a large power source. So, improvements in the design of passive controllers are of high interest for researchers. These controllers have a very simple design and aim to counteract vibration with no power requirements. In this paper, six different passive controllers were designed to analyze and compare their performance. The performance is considered in terms of the percentage of reduction in the primary system’s displacement amplitude and the bandwidth of each designed passive controller. The system of interest is taken as the three-degree-of-freedom dynamic hand system reflecting the behavior of Parkinsonian patients. Four joint muscles operating at two resonance harmonic excitation frequencies are considered to produce movements. Each controller was attached to the forearm of the hand set in the horizontal plane to analyze their capability in reducing the rest tremor (3–7 Hz) at the proximal joint. The dual series elastic–viscous absorber is shown to be a very effective controller. It is formed from a series connection between an elastic absorber (mass–spring) and a viscous absorber (mass–dashpot). It causes about 80% reduction in tremor amplitude with 4 Hz wide frequency band at the shoulder, elbow and wrist joints. This range of operational frequency is close to that of healthy cases, 4.5 Hz.

Upper limb involuntary tremor reduction using cantilever beam TMDs

“…Cantilever-type TMD with an active auto-tuning control method (Nagaya et al, 1999) was effective in reducing the amplitude of a structure subjected to a sinusoidal excitation with variable frequency. A cantilever-type TMD suggested in Gebai et al (2018) is tuned to reduce the resonant frequency of an upper limb system modeled in the horizontal plane. This system was used to represent the tremor of an upper limb resting on a table that is excited by a sinusoidal moment.…”

“…Increasing the number of degrees of freedom (DOF) of the TMD system requires the determination of the optimal parameters, numerically, as it is not possible to obtain their closed analytical forms (Harik and Issa, 2015). Gebai et al (2018) conducted a comparative study for different passive TMDs modeled as cantilever beams, tuned by calculating the position of the mass required to reach the resonance frequency. Two STMDs were tuned to the first and second resonance frequencies and used separately as STMDs or combined in series or parallel.…”

Parkinson’s Disease Treatment as Seen from a Mechanical Point of View

“…Damping and stiffness coefficient of muscles are assumed to be linearly proportional [23]. Equation of motion describing the dynamics of the hand at its proximal joints is derived [24]- [30] and used for designing the tremor suppression device.…”

Analytical and experimental studies on particle damper used for tremor suppression

“…Wearable orthosis for tremor assessment and suppression provided an approach to reduce the upper limb tremor in three degrees of freedom (Rocon et al, 2007a(Rocon et al, , 2007b. Gebai et al (2018) compared the performance of different types of passive absorber with a three-degree-offreedom upper limb model.…”