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Controlled Functional Electric Stimulation for Rehabilitation Purposes

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Abstract

Electrical nerve-stimulation of paralyzed muscles can be used to generate muscle contractions. In combination with appropriate sensor technology and feedback control, this can be exploited to elicit functional movements, such as walking [1] [2] [3] [4] [5] [6], cycling [7] [8], reaching and grasping [9] [10], and even swallowing [11] [12]. Depending on the degree of disability, the goal may be temporary assistance, e.g., during re-learning of gait, or permanent replacement of lost motor functions (neuro-prostheses). In the context of control, the most challenging aspects are the complex interaction between FES, robotic support [13] and residual motor function of the patients, and the fact that for certain tasks as, e.g., walking or grasping, control has to cope with discrete changes of otherwise continuous dynamics caused by interaction with the environment. In order to realize feedback control schemes, a number of sensor technologies are investigated such as inertial measurement units (IMUs) [3], bioimpedance [14] and electromyography [15] [16] for monitoring human movement.

Subprojects

Bioimpedance-Controlled Neuro-Prosthesis to Support Swallowing

People involved
Cooperation
Funding
  • Federal Ministry of Education and Research (BMBF), Innovation Award 2009 for Medical Technology

Iterative Learning Control of FES-Assisted Gait

People involved
Cooperation
Funding
  • TU Berlin, Federal Ministry of Education and Research (BMBF), Max Planck Society

Control of Endeffector-Based Rehabilitation Robotics in Combination with Electrical Stimulation for Gait Training after Stroke

People involved
Cooperation
Funding
  • Federal Ministry of Education and Research (BMBF), TU Berlin, Egyptian Government (scholarship)

Development of a Portable Endeffector-Based Hand/Arm Rehabilitation Robot combined with Functional Electrical Stimulation

People involved
Cooperation
Funding
  • TU Berlin, Chinese Academy of Sciences, Max Planck Society

Prospective Study on Breathing Synchronized Electrical Stimulation of the Abdominal Muscles in Patients with Acute and Chronic Tetraplegia

'People involved'
Cooperation
Funding
  • DGUV (Deutsche Gesetzliche Unfallversicherung), TU Berlin

Multimodal Neuro-Prosthesis for Daily Upper Limb Support

People involved
Cooperation
Funding

Description

The overall theme of this project is to investigate the application of controlled functional electrical stimulation (FES) for the rehabilitation of stroke patients and persons with spinal cord injuries. It is well-known that electrical nerve stimulation can be used to generate contractions of paralyzed muscles. In combination with appropriate sensor technology and feedback control, this can be exploited to elicit functional movements, such as walking and cycling, and hence to restore certain motor functions. Depending on the degree of disability, the intention may be temporary assistance, e.g., during relearning of gait, or permanent replacement of lost motor functions (neuro-prosthesis). Beside these functional effects, FES has several secondary therapeutic benefits: it improves muscle size and strength, increases the range of joint motion and improves cardiopulmonary fitness by providing significant training effects. FES is therefore potentially more attractive for rehabilitation purposes than conventional methods such as passive bracing of the joints. Fig. 1 explains the principle of controlled FES for a specific problem, the control of the knee joint angle by quadriceps stimulation. The knee joint angle is measured and fed back to the controller, which generates a suitable stimulation pattern to achieve tracking of a reference trajectory.

Figure 1: Functional Electrical Stimulation (FES) for knee-joint angle control.

Stimulation can either be applied directly to the peripheral motor nerves (as shown in Fig. 1) or, if the reflex arcs in the lower spinal cord are still intact, to the sensory nerves (neuro-modulation). The latter causes an indirect stimulation of motor nerves while ensuring the natural inhibition of antagonistic muscles. A general problem with FES is rapid muscle fatigue. External stimuli, which replace the missing commands from the central nervous system, tend to invert the recruitment order of muscle fibres: motorneurons with larger diameter are activated first as they have a lower threshold; they recruit the faster and more powerful (type 2 or white) fibres, which fatigue more quickly than the slower and less powerful (type 1 or red) muscle fibres. Electrical stimulation is realized by attaching surface electrodes to the skin, because the alternative, implanting electrodes, is much less convenient and carries a serious risk of infection. The project is currently organized within six subprojects (see above), addressing fundamental questions as well as aiming at transferring results into medical and therapeutical practice.

For two of these subprojects a detailed description can be found here:

Bioimpedance-Controlled Neuro-Prosthesis to Support Swallowing

Iterative Learning Control of FES-Assisted Gait Training/Drop Foot Stimulator

Publications

  1. Nahrstaedt, H., Schauer, T., Shalaby, R., Hesse, S., Raisch, J.. Automatic Control of a Drop-Foot Stimulator Based on Angle Measurement Using Bioimpedance. Artificial Organs, 32 pages 649–654, 2008.
  2. Nahrstaedt, H., Schauer, T., Hesse, S., Raisch, J.. Iterative Learning Control of a Gait Neuroprosthesis (Article in German). at - Automatisierungstechnik, 56 (9):494–501, 2008.
  3. 3.0 3.1
    Negard, N.-O.. Controlled FES-assisted gait training for hemiplegic stroke patients based on inertial sensors. Doctoral Thesis, TU Berlin, 2009.
  4. Schauer, T., Negaard, N.-O., Nahrstaedt, H., Raisch, J.. Control of Drop Foot Stimulation Devices for Compensation of Insufficient Dorsiflexion after Stroke. ORTHOPÄDIETECHNIK, 60 (2):78–83, 2009.
  5. Schauer, T., Negaard, N.-O., Liedecke, W., Hömberg, V., Raisch, J.. Real-time gait analysis by means of inertial sensors for the control of functional electrical stimulation assisted gait training after stroke (Article in German). Medizinisch-Orthopädische Technik, 130 (3):31–37, 2010.
  6. Seel, T., Schauer, T., Raisch, J.. Iterative Learning Control for Variable Pass Length Systems. In Preprints of the 18th IFAC World Congress, pages 4880–4885, Milan, Italy, 2011.
  7. Ferrante, S., Schauer, T., Ferrigno, G., Raisch, J., Molteni, F.. The effect of using variable frequency trains during functional electrical stimulation cycling. Neuromodulation, 11 (3):216­–226, 2008.
  8. Ambrosini, E., Ferrante, S., Schauer, T., Ferrigno, G., Molteni, F., Pedrocchi, A.. Design of a symmetry controller for cycling induced by electrical stimulation: preliminary results on post-acute stroke patients. Artificial Organs, 34 (8):663–667, 2010.
  9. Klauer, C., Schauer, T., Raisch, J.. High Performance Motion Control by Neuro-Muscular Electrical Stimulation applied to the Upper-Limb. In Proc. of 15th Annual International FES Society Conference and 10th Vienna Int. Workshop on FES, pages 318–320, Vienna, Austria, 2010.
  10. Klauer, C., Schauer, T., Raisch, J.. Joint-angle control by electrical stimulation of antagonistic muscles (Article in German). at - Automatisierungstechnik, 59 (10) 2011.
  11. Nahrstaedt, H., Schauer, T., Seidl, R. O.. Bioimpedance based measurement system for a controlled swallowing neuro-prosthesis. In Proc. of 15th Annual International FES Society Conference and 10th Vienna Int. Workshop on FES, pages 49–51, Vienna, Austria, 2010.
  12. Seidl, R. O., Nahrstaedt, H., Schauer, T.. Electric stimulation in dysphagia therapy – a review (Article in German). Laryngo-Rhino-Otologie, 88 (12):768–774, 2009.
  13. Luo, D., Carstens, J. H. H., Schauer, T., Raisch, J.. Haptic control of a table-placed mobile robot for arm/shoulder rehabilitation. In Proc. of the 3rd European Conference Technically Assisted Rehabilitation - TAR 2011, 2011.
  14. Nahrstaedt, H., Schauer, T.. A bioimpedance measurement device for sensing force and position in neuroprosthetic systems. In 4th European Conference of the International Federation for Medical and Biological Engineering, pages 1642-1645, Antwerp, Belgium, 2008.
  15. Shalaby, R., Schauer, T., Liedecke, W., Raisch, J.. Amplifier design for EMG recording from stimulation electrodes during functional electrical stimulation leg cycling ergometry. Biomedizinische Technik. Biomedical Engineering, 56 (1):23–33, 2011.
  16. Shalaby, R.. Development of an Electromyography Detection System for the Control of Functional Electrical Stimulation in Neurological Rehabilitation. Doctoral Thesis, TU Berlin, 2011.

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