A Tangible Solution for Hand Motion Tracking in Clinical Applications

Objective real-time assessment of hand motion is crucial in many clinical applications including technically-assisted physical rehabilitation of the upper extremity. We propose an inertial-sensor-based hand motion tracking system and a set of dual-quaternion-based methods for estimation of finger segment orientations and fingertip positions. The proposed system addresses the specific requirements of clinical applications in two ways: (1) In contrast to glove-based approaches, the proposed solution maintains the sense of touch. (2) In contrast to previous work, the proposed methods avoid the use of complex calibration procedures, which means that they are suitable for patients with severe motor impairment of the hand. To overcome the limited significance of validation in lab environments with homogeneous magnetic fields, we validate the proposed system using functional hand motions in the presence of severe magnetic disturbances as they appear in realistic clinical settings. We show that standard sensor fusion methods that rely on magnetometer readings may perform well in perfect laboratory environments but can lead to more than 15 cm root-mean-square error for the fingertip distances in realistic environments, while our advanced method yields root-mean-square errors below 2 cm for all performed motions.DFG, 414044773, Open Access Publizieren 2019 - 2020 / Technische Universität Berli

Intention recognition for FES in a grasp-and-release task using volitional EMG and inertial sensors

Functional Electrical Stimulation (FES) facilitates the motor recovery of the hand function after stroke. The integration of biofeedback and other strategies to actively involve a patient in the therapy is important for the rehabilitation progress. We introduce a combined control approach for a FES-driven neuroprosthesis using volitional electromyo-graphy (vEMG) and motion capturing via a novel inertial sensor network for patients that still possess a residual activity in the paralyzed muscles. A real-time vEMG measurement and signal processing in between stimulation pulses has been realized during active FES. Experiments showed that our system allows for quick adaption to individual users.BMBF, 16SV7069K, Verbundprojekt: Bewegungsfähigkeit und Mobilität wiedererlangen - BeMobil -; Teilvorhaben: Nutzerzentrierte Entwicklung technischer Methoden für eine optimale Mensch-Technik-Interaktion in der Bewegungsrehabilitatio

A new semi-automatic approach to find suitable virtual electrodes in arrays using an interpolation strategy

Functional Electrical Stimulation via electrode arrays enables the user to form virtual electrodes (VEs) of dynamic shape, size, and position. We developed a feedback-control-assisted manual search strategy which allows the therapist to conveniently and continuously modify VEs to find a good stimulation area. This works for applications in which the desired movement consists of at least two degrees of freedom. The virtual electrode can be moved to arbitrary locations within the array, and each involved element is stimulated with an individual intensity. Meanwhile, the applied global stimulation intensity is controlled automatically to meet a predefined angle for one degree of freedom. This enables the therapist to concentrate on the remaining degree(s) of freedom while changing the VE position. This feedback-control-assisted approach aims to integrate the user's opinion and the patient's sensation. Therefore, our method bridges the gap between manual search and fully automatic identification procedures for array electrodes. Measurements in four healthy volunteers were performed to demonstrate the usefulness of our concept, using a 24-element array to generate wrist and hand extension.BMBF, 16SV7069K, Verbundprojekt: Bewegungsfähigkeit und Mobilität wiedererlangen - BeMobil -; Teilvorhaben: Nutzerzentrierte Entwicklung technischer Methoden für eine optimale Mensch-Technik-Interaktion in der Bewegungsrehabilitatio

Development of an Automated Testbed for Electrical Stimulation Devices with Electrode Array Support

La tesis resume el diseño, construcción y fabricación de un banco de pruebas automático para aparatos de estimulación eléctrica funcional (FES) utilizados, por ejemplo, en reha- bilitación muscular. El banco de pruebas dará la posibilidad de poder evaluar la detección y medición de las señales estimulantes propias de estos aparatos. Esta tarea puede llegar a ser tediosa y requerir de mucho tiempo al realizarla manualmente dada la rápida y corta naturaleza de las señales estimulantes típicas de dichos aparatos. El banco de pruebas aportará al usuario, junto al software relevante, una herramienta intuitiva para medir y evaluar de una manera simple las señales estimulantes a partir del canal o canales de entrada de los aparatos de estimulación eléctrica funcional y también para detectar los canales activos así como de la matriz de electrodos activa, normalmente conectada a la piel. El trabajo detrás de la tesis se basa fundamentalmente en el diseño del hardware y construcción del banco de pruebas. El banco de pruebas fue diseñado como una caja cuyas entradas eran las señales de estimulación y cuyas salidas eran los paquetes de in- formación comunicados al PC por conexión USB. También fue desarrollado el esqueleto principal del programa de software para el microcontrolador. Por último, un prototipo fue construido para probar el diseño y demostrar el concepto desarrollado. El banco de pruebas también podrá ser utilizado para depurar cualquier futuro software desarrollado. El software CAD EAGLE se usó para diseñar el hardware y para crear la placa de circuito impreso (PCB), la cual luego fue mandada a imprimir y fue soldada con los componentes seleccionados en la etapa de diseño. El banco de pruebas implementa el microcontrolador STM32F412RE de STMicroelectronics, el cual está respaldado por el software gráfico STM32CubeMX y que fue utilizado para ayudar en la generación del programa de inicialización en lenguaje C. El código en lenguaje C fue construido con el entorno SW4STM32 para Eclipse, también suministrado por STMicroelectronics. El programa básico desarrollado para probar el hardware fue flasheado al microcontrolador apoyado por la placa Nucleo-F411RE y el programa STM32CubeProgrammer, ambos también desarrollados por STMicroelectronics

Modular finger and hand motion capturing system based on inertial and magnetic sensors

The assessment of hand posture and kinematicsis increasingly important in various fields. This includesthe rehabilitation of stroke survivors with restricted handfunction. This paper presents a modular, ambulatory mea-surement system for the assement of the remaining handfunction and for closed-loop controlled therapy. The de-vice is based on inertial sensors and utilizes up to fiveinterchangeable sensor strips to achieve modularity and tosimplify the sensor attachment. We introduce the modularhardware design and describe algorithms used to calculatethe joint angles. Measurements with two experimentalsetups demonstrate the feasibility and the potential of such a tracking device.BMBF, 16SV7069K, Verbundprojekt: Bewegungsfähigkeit und Mobilität wiedererlangen - BeMobil -; Teilvorhaben: Nutzerzentrierte Entwicklung technischer Methoden für eine optimale Mensch-Technik-Interaktion in der Bewegungsrehabilitatio

Multichannel FES parameterization for controlling foot motion in paretic gait

Stroke and other neurological disorders often lead to reduced motor function and to pathological foot motion during gait. We consider Functional Electrical Stimulation (FES) of the shank muscles that control dorsiflexion (related to pitch) and eversion (related to roll) of the foot. We describe the nonlinear domain of stimulation intensities that are tolerated by subjects in combined two-channel FES via surface electrodes. Two piecewise linear parameterizations of this domain are suggested and compared in terms of the cross-couplings between the newly defined stimulation intensity coordinates and the foot motion caused during swing phase in drop foot patients walking on a treadmill. Both parameterizations are found to yield almost monotonous input-output behavior and therefore facilitate decentralized control of the foot pitch and roll angle

Intention recognition for FES in a grasp-and-release task using volitional EMG and inertial sensors

Functional Electrical Stimulation (FES) facilitates the motor recovery of the hand function after stroke. The integration of biofeedback and other strategies to actively in-volve a patient in the therapy is important for the rehabili-tation progress. We introduce a combined control approach for a FES-driven neuroprosthesis using volitional electromyo-graphy (vEMG) and motion capturing via a novel inertial sensor network for patients that still possess a residual activity in the paralyzed muscles. A real-time vEMG measurement and signal processing in between stimulation pulses has been realized during active FES. Experiments showed that our system allows for quick adaption to individual users

Modular finger and hand motion capturing system based on inertial and magnetic sensors

The assessment of hand posture and kinematics is increasingly important in various fields. This includes the rehabilitation of stroke survivors with restricted hand function. This paper presents a modular, ambulatory measurement system for the assement of the remaining hand function and for closed-loop controlled therapy. The device is based on inertial sensors and utilizes up to five interchangeable sensor strips to achieve modularity and to simplify the sensor attachment. We introduce the modular hardware design and describe algorithms used to calculate the joint angles. Measurements with two experimental setups demonstrate the feasibility and the potential of such a tracking device

RehaMovePro: A versatile mobile stimulation system for transcutaneous FES applications

Functional Electrical Stimulation is a commonly used method in clinical rehabilitation and research to trigger useful muscle contractions by electrical stimuli. In this work, we present a stimulation system for transcutaneous electrical stimulation that gives extensive control over the stimulation waveform and the stimulation timing. The system supports electrode arrays, which have been suggested to achieve better selectivity and to simplify electrode placement. Electromyography (EMG) measurements are obtained from the active stimulation electrodes (between the stimulation pulses) or from separate surface EMG electrodes. The modular design enables the implementation of sophisticated stimulation control systems including external triggers or wireless sensors. This is demonstrated by the standalone implementation of a feedback-controlled drop foot neuroprosthesis, which uses a wireless inertial sensor for real-time gait phase detection and foot orientation measurement