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Development of Mobile and Stationary FES-cycling Systems with Motor Assist

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This research addresses the development of ergometers and recumbent tricycles with motor assist for handicapped people after stroke or spinal cord injury. The paralysed muscles of the cyclist are activated by Functional Electrical Stimulation (FES) using surface electrodes in order to support the cycling movement. The auxiliary electric motor is required in the case of a too weak musculature or when the muscles are already fatigued by the electrical stimulation.


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FES-cycling represents another promising rehabilitation tool for stroke patients and spinal cord injured people. Crank angle and cadence are measured and fed back to generate a suitable stimulation pattern for the major paralysed leg muscles. Additional moment/force sensors are used to tune the stimulation pattern. This is particularly important for hemiparetic patients, where voluntary muscle activity must be taken into account to achieve good results [1].

In cooperation with the Centre for Rehabilitation Engineering at the University of Glasgow and HASOMED GMBH, a biomedical engineering company, our group is developing motor assisted FES-cycling systems [2]. They are based on commercially available ergometers and recumbent tricycles (cf. Fig. 1 and 2). For the ergometer training, new methods for controlling the FES cycling in paraglegia have been accomplished [3] [4] [5] [6]. Currently, control strategies for mobile cycling with motor assist are under investigation [7]. The freewheeling of the drive wheel connected to the crank yields an hybrid and discrete event control system. Mechanical system properties are here changing dependent on the state of the sprag clutch.

The use of Variable Frequency Trains (VFT) in FES cycling was investigated in cooperation with the Bioengineering Department at Politecnico di Milano. A pilot study with neurologically intact subjects showed that power output can be increased and muscular fatigue can be delayed by the application of VFT [8].

Recumbent tricycle for spinal cord injured persons with Functional Electrical Stimulation (FES) of the paralysed muscles.

Leg-cycle ergometer with FES and motor assist.


  1. R.C. Salbert, T. Schauer, P.W. Schönle, V. Engler, and J. Raisch. Controlled Leg-Cycle Ergometry using Functional Electrical Stimulation after Stroke (in German). In Proc. of the Automed Workshop 2004, Saarbrücken, Germany, Oct. 2004.
  2. W. Liedecke, T. Schauer, C. Behling, and K. Hunt. Modulares System zur funktionellen Elektrostimulation. In Proc. der Gemeinsamen Jahrestagung der Deutschen, Österreichischen und Schweizerischen Gesellschaft für Biomedizinische Technik, Zürich, Schweiz, September 2006.
  3. T. Schauer, K.J. Hunt, N.-O. Negård, M.H. Fraser, and W. Stewart. Cadence control for recumbent cycling of paraplegics (in German). at - Automatisierungstechnik, 50(6):271-278, June 2002.
  4. K.J. Hunt, B. Stone, N.-O. Negård, T. Schauer, M.H. Fraser, A.J. Cathcart, C. Ferrario, S. Grant, and S.A. Ward. Control strategies for integration of electrical motor assist and functional electrical stimulation in paraplegic cycling: Utility for exercise testing and mobile cycling. IEEE Trans. Neural Syst. Rehabil. Eng., 12(1):89-101, 2004.
  5. T. Schauer, R. Salbert, N.-O. Negård, K. Hunt, and J. Raisch. Power control of electrical stimulation induced cycle ergometry (in German). at - Automatisierungstechnik, 53(12):607-614, 2005.
  6. T. Schauer, C. Behling, W. Liedecke, N.-O. Negård and J. Raisch. Feedback Control of an FES Lower Limb Cycling Ergometer. In Proc. 11th Annual Conf. of the International Functional Electrical Stimulation Society (IFESS 2006), Japan, pp. 130-132, 2006.
  7. S. Schmidt, T. Schauer, and J. Raisch. Regelung eines Liegedreirads für gelähmte Personen mit hybridem Antrieb. Im Tagungsband des Workshops Automatisierungstechnische Methoden und Systeme in der Medizin: Automed 2006, Rostock, März 2006.
  8. S. Ferrante, T. Schauer, G. Ferrigno and J. Raisch. The effect of variable frequency trains during FES cycling. In Proc. 11th Annual Conf. of the International Functional Electrical Stimulation Society (IFESS 2006), Japan, pp. 127-129, 2006.

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