Voluntary-Driven Elbow Orthosis with Speed-Controlled Tremor Suppression

Abstract

Robotic technology is gradually becoming commonplace in the medical sector and in the service of patients. Medical conditions that have benefited from significant technological development include stroke, for which rehabilitation with robotic devices is administered, and surgery assisted by robots. Robotic devices have also been proposed for assistance of movement disorders. Pathological tremor, among the most common movement disorders, is one such example. In practice, the dissemination and availability of tremor suppression robotic systems has been limited. Devices in the marketplace tend to either be non-ambulatory or to target specific functions, such as eating and drinking. We have developed a one degree-of-freedom (DOF) elbow orthosis that could be worn by an individual with tremor. A speed-controlled, voluntary-driven suppression approach is implemented with the orthosis. Typically tremor suppression methods estimate the tremor component of the signal and produce a canceling counterpart signal. The suggested approach instead estimates the voluntary component of the motion. A controller then actuates the orthosis based on the voluntary signal, while simultaneously rejecting the tremorous motion. In this work, we tested the suppressive orthosis using a one DOF robotic system that simulates the human arm. The suggested suppression approach does not require a model of the human arm. Moreover, the human input along with the orthosis forearm gravitational forces, of non-linear nature, are considered as part of the disturbance to the suppression system. Therefore, the suppression system can be modeled linearly. Nevertheless, the orthosis forearm gravitational forces can be compensated by the suppression system. The electromechanical design of the orthosis is presented, and data from an essential tremor patient is used as the human input. Velocity tracking results demonstrate an RMS error of 0.31 rad/s, and a power spectral density shows a reduction of the tremor signal by 99.8%, while the intentional component power was reduced by <1%.

Assistive Robot to Aid with Catheter Insertion

“…However, models such as these have a hard time distinguishing between the movement of the tremor (involuntary moment) and the movement of the limb (voluntary movement). As stated by Herrnstadt and Menon, "an impedance-controlled system that models the tremor signal may, therefore, experience fluctuation in the suppression performance due to the impedance variability" [7] meaning that trying to suppress the tremor via sensors sending an equal and opposite reaction is difficult to master and control because the voluntary movements cause the overall frequency of the system to fluctuate, and the sensors then have a hard time deciphering which part of this frequency is from the tremor and which part is from the voluntary movement. The fact that this system is difficult to master and is still being researched made this option a poor selection for tremor suppression in the CIA.…”

“…The fact that this system is difficult to master and is still being researched made this option a poor selection for tremor suppression in the CIA. Furthermore, active tremor suppression is mostly seen in exoskeleton devices, such as those seen in papers [7], [8], and [16], meaning the patient wears the device. It was decided that the tremor cancellation system should be built into CIA rather than requiring the user to put on an additional exoskeleton because, as stated previously, exoskeletons are bulky and would inhibit rather than aid with the cathing process.…”

“…Ideas have been proposed to reduce the effect of tremors in patients; however, each of these solutions have downfalls that would inhibit rather than aid in the cathing process. Exoskeleton solutions, such as those seen in papers [7], [8], and [16], propose a wearable device that monitors and counteracts the tremor motion. However, exoskeletons are bulky and would obstruct the patient's mobility when trying to insert a catheter.…”

Controlling a motorized orthosis to follow elbow volitional movement: tests with individuals with pathological tremor

“…The aim of this work is to show viability of the suppression approach, using an elbow orthosis prototype [37], tested with individuals with pathological tremor. The above aim can be explored as two separate questions.…”

Avaliação ergonômica de uma órtese ativa de punho para a reabilitação da rigidez em pessoas com a doença de Parkinson

“…Uma busca na literatura aponta que a maioria dos estudos envolvendo dispositivos robóticos na reabilitação dos sinais motores da DP são destinados a marcha, como é o caso de Furnari et al[28], Alwardart[29], Picelli et al[30] e Pilleri et al[31]. Durante a revisão da literatura foi observado que poucos dispositivos robóticos são desenvolvidos para reabilitação do membro superior em indivíduos com DP e os trabalhos encontrados nessa área focam no desenvolvimento de dispositivos robóticos para supressão de tremores, como é o caso dos trabalhos realizados por Herrnstadt[32,33], Perry[34] e Seki[35].No entanto, uma atenção especial deve ser dada ao estudo ergonômico desses dispositivos robóticos[18], uma vez que dispositivos destinados a reabilitação fisioterapêutica precisam ser projetados para adaptar-se às necessidades individuais do paciente, levando em consideração e apoiando paradigmas terapêuticos que promovam independência funcional e a avaliação da progressão da terapia.5 2.2 PARÂMETROS IMPORTANTES NA AVALIAÇÃO ERGONÔMICA DE DISPOSITIVOS ROBÓTICOSA ergonomia pode ser definida como a ciência de projetar o trabalho para se adequar ao trabalhador[36]. Em outros termos, mais adequados a esta pesquisa, seria desenvolver um dispositivo adaptável ao usuário.…”