Sarah S. Gebai

Tremor Reduction at the Palm of a Parkinson’s Patient Using Dynamic Vibration Absorber

Parkinson’s patients suffer from severe tremor due to an abnormality in their central oscillator. Medications used to decrease involuntary antagonistic muscles contraction can threaten their life. However, mechanical vibration absorbers can be used as an alternative treatment. The objective of this study is to provide a dynamic modeling of the human hand that describes the biodynamic response of Parkinson’s patients and to design an effective tuned vibration absorber able to suppress their pathological tremor. The hand is modeled as a three degrees-of-freedom (DOF) system describing the flexion motion at the proximal joints on the horizontal plane. Resting tremor is modeled as dual harmonic excitation due to shoulder and elbow muscle activation operating at resonance frequencies. The performance of the single dynamic vibration absorber (DVA) is studied when attached to the forearm and compared with the dual DVA tuned at both excitation frequencies. Equations of motion are derived and solved using the complex transfer function of the non-Lagrangian system. The absorber’s systems are designed as a stainless steel alloy cantilevered beam with an attached copper mass. The dual DVA was the most efficient absorber which reduces 98.3%–99.5%, 97.0%–97.3% and 97.4%–97.5% of the Parkinson’s tremor amplitude at the shoulder, elbow and wrist joint.

Biomechanical treatment for rest tremor of Parkinson's patient

Vibration absorbers are effective devices used to reduce the unwanted motion of a vibrating system. It is recently used to reduce the involuntary tremor of a Parkinsons patient. The absorber can be attached to the forearm of the patient hand. Such system can be excited at resonance frequencies reflecting the resting tremor due to the shoulder and elbow muscles activation. Two single absorbers are designed and tested numerically in reducing the involuntary tremor: the conventional absorber having its spring and damper connected in parallel and the elastic-damper absorber having its spring and damper connected in series. Both absorbers are designed to satisfy the tuning conditions at the fundamental frequency of the primary system with the same total mass. The conventional absorber causes 75.5-97.4%, 11.1-48.0% and 41.2-49.7% reduction at the shoulder, elbow and the wrist joints, respectively. However, the elastic-damper absorber causes 74.0-78.7%, 5.0-35.0% and 29.3- 45.8% at the same positions, respectively. The elastic-damper absorber can cause this reduction with a device of shorter length.

Analytical Modeling: Three Stages Homogenization Method

A small to moderate sized modern computer system employs advanced features such as fault-tolerance ( see Fault-tolerant systems), resource sharing and contention, concurrency an d synchronization, timeliness ( see Real-time systems), and degradable performance. When such a computer system i being designed and implemented, it becomes essential to answer “what-if” questions and carry out trade-o ff studies to choose between a set of contending design alternatives. The broad classes of measures that need to be valuated are:

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

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.

Reduction of Parkinsonism disorder symptoms using passive dual absorbers

Passive vibration absorber can be used as an effective device for tremor reduction of the involuntary tremor at proximal joints in hand of elderly patients suffering from Parkinsonism. Dual vibration absorber are suggested to reduce the Parkinsons tremor of a dynamic hand system excited using two harmonic excitation resonance frequencies in range of resting tremor. The three degree of freedom hand is actuated by the shoulder, elbow and wrist joint muscles activation to produce the involuntary flexion motion. The dual parallel conventional absorber and the dual series absorber which is modeled as an elastic absorber and viscous damper connected in series are designed to satisfy the tuning condition at both resonance frequencies. The dual parallel absorber reduces 57.0-82.5%, 51.6-76.9% and 26.6-62.0% of the flexion motion at the shoulder, elbow and wrist joints in the time domain, respectively. The dual series absorber reduces 82.6-97.3%, 77.24-84.2% and 33.0-62.0% of the flexion motion at the shoulder, elbow and wrist joints in time domain, respectively. Both absorbers are very useful in controlling the rest tremor and can be used by elderly patients instead of medications which may risk their lives.

Passive vibration absorber for tremor in hand of parkinsonian patients: Tuned vibration absorber for rest tremor

Parkinsons disease is characterized by involuntary movement of body parts resulting from antagonistic muscle contractions. In this paper, an effective passive vibration absorber is modeled to control the involuntary pathological rest tremor in the right hand of Parkinsons disease patient. The three-degree-of-freedom dynamic hand model capable to describe the flexion-extension planar motion at shoulder, elbow, and wrist joints in horizontal plane is designed. The passive tuned vibration absorber is modeled to suppress flexion motion of shoulder, elbow and wrist joints. Active inputs producing motion are considered at shoulder and elbow joints, and driven at resonance frequencies. The equations of motion for the dynamically coupled modeled hand system are derived. The responses are represented in time and frequency domains using the complex transfer function method. Optimum position of the absorber on the forearm is determined in terms of its effectiveness in reducing tremors amplitude.