Control of a mobile rehabilitation robot using exact feedback linearisation

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.This contribution is concerned with the feedback control of a table-placed mobile rehabilitation robot using exact feedback linearisation to precisely track arbitrary position and orientation profiles. An outer control loop exactly linearises and decouples the nonlinear kinematic robot model. This loop also generates reference velocities for the three omnidirectional wheels of the robot that are feedback controlled by individual digital controllers on a inner loop level. The concept was validated in simulations

Feedback control of cycling in spinal cord injury using functional electrical stimulation

This thesis is concerned with the realisation of leg cycling by means of FES in SCI individuals with complete paraplegia. FES lower-limb cycling can be safely performed by paraplegics on static ergometers or recumbent tricycles. In this work, different FES cycling systems were developed for clinical and home use. Two design approaches have been followed. The first is based on the adaptation of commercially available recumbent tricycles. This results in devices which can be used as static trainers or for mobile cycling. The second design approach utilises a commercially available motorised ergometer which can be operated while sitting in a wheelchair. The developed FES cycling systems can be operated in isotonic (constant cycling resistance) or isokinetic mode (constant cadence) when used as static trainers. This represents a novelty compared to existing FES cycling systems. In order to realise isokinetic cycling, an electric motor is needed to assist or resist the cycling movement to maintain a constant cadence. Repetitive control technology is applied to the motor in this context to virtually eliminate disturbance caused by the FES activated musculature which are periodic with respect to the cadence. Furthermore, new methods for feedback control of the patient’s work rate have been introduced. A one year pilot study on FES cycling with paraplegic subjects has been carried out. Effective indoor cycling on a trainer setup could be achieved for long periods up to an hour, and mobile outdoor cycling was performed over useful distances. Power output of FES cycling was in the range of 15 to 20 W for two of the three subjects at the end of the pilot study. A muscle strengthening programme was carried out prior and concurrent to the FES cycling. Feedback control of FES assisted weight lifting exercises by quadriceps stimulation has been studied in this context

Enhancing the smoothness of joint motion induced by functional electrical stimulation using co-activation strategies

The motor precision of today’s neuroprosthetic devices that use artificial generation of limb motion using Functional Electrical Stimulation (FES) is generally low. We investigate the adoption of natural co-activation strategies as present in antagonistic muscle pairs aiming to improve motor precision produced by FES. In a test in which artificial knee-joint movements were generated, we could improve the smoothness of FES-induced motion by 513% when applying co-activation during the phases in which torque production is switched between muscles – compared to no co-activation. We further demonstrated how the co-activation level influences the joint stiffness in a pendulum test.BMBF, 16SV7069K, Bewegungsfähigkeit und Mobilität wiedererlangen - BeMobi

Amplifier design for EMG recording from stimulation electrodes during functional electrical stimulation leg cycling ergometry

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Functional electrical stimulation leg cycle ergometry (FESLCE), which is often used as exercise for people with spinal cord injury (SCI), has recently been applied in the motor rehabilitation of stroke patients. Recently completed studies show controversial results, but with a tendency to positive training effects. Current technology is identical to that used in FES-LCE for SCI, whereas the pathology of stroke differs strongly. Most stroke patients with hemiparesis are able to drive an ergometer independently. Depending on the degree of spasticity, the paretic leg will partially support or hinder movements. Electrical stimulation increases muscle force and endurance and both are prerequisites for restoring gait. However, the effect of FES-LCE on improving impaired motor coordination is unclear. To measure motor coordination during FES-LCE, an EMG-amplifier design has been investigated which suppresses stimulation artifacts and allows detection of volitional or reflex induced muscle activity. Direct measurement of EMG from stimulation electrodes between stimulation pulses is an important asset of this amplifier. Photo-MOS switches in front of the preamplifier are utilized to achieve this. The technology presented here can be used to monitor the effects of FES-LCE to adapt the stimulation strategy or to realize EMG-biofeedback training.BMBF, 01EZ0766, Verbundprojekt RehaRobES: Regelungsverfahren für endeffektor-basierte Reha-Robotik in Kombination mit Elektrischer Stimulation in der Gangtherapie nach Schlaganfall - Teilprojekt Fahrradergometer etc

Continuous wrist blood pressure measurement with ultrasound

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Blood pressure is an important parameter for the development of cardiovascular disease. By monitoring the blood pressure over 24 hours hypertension can be detected and treatment can be started. A new noninvasive long term blood pressure measurement method measures the blood pressure continuously on the wrist using ultrasound, a small balloon and a controller. The pressure is controlled with a voice coil actuator. The wrist blood pressure changes during motion. These movements are assessed with a water filled tube to calibrate the measurement to aortic blood pressure

Continuous wrist blood pressure measurement with ultrasound

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Blood pressure is an important parameter for the development of cardiovascular disease. By monitoring the blood pressure over 24 hours hypertension can be detected and treatment can be started. A new noninvasive long term blood pressure measurement method measures the blood pressure continuously on the wrist using ultrasound, a small balloon and a controller. The pressure is controlled with a voice coil actuator. The wrist blood pressure changes during motion. These movements are assessed with a water filled tube to calibrate the measurement to aortic blood pressure

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

Long-term consequences of traumatic experiences: an assessment of former political detainees in romania

BACKGROUND: Research has suggested that organized violence and torture have long-term psychological effects that persist throughout the lifespan. The present survey aimed at examining the prevalence of posttraumatic stress disorder (PTSD), and other disorders and symptoms, all present in old age, as long-term consequences of politically motivated violence in a comparison design. METHODS: A group of former political detainees (N = 59, mean age 73.5 years) who had been arrested by the Romanian communist regime were compared to an age- and gender-matched control group (N = 39). PTSD was assessed using a structured clinical interview (CIDI). The investigation of the clinical profile was further accomplished by self-rating measures for anxiety, depression, and health-related functioning, as well as by clinician-administrated interviews for substance abuse, dissociation, and somatization symptoms. RESULTS: Lifetime prevalence of PTSD was 54%. In the case of participants left untreated, PTSD persisted, often over four decades, such that current PTSD was diagnosed still in a third of the survivors. Other clinical conditions such as somatization, substance abuse, dissociative disorders, and major depression were also common among the former political detainees and often associated with current PTSD. CONCLUSION: Our findings suggest that political detention may have long-term psychological consequences that outlast the changes in the political system