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Session: Poster session I
Session starts: Thursday 24 January, 15:00

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Vera Bulsink (Laboratory of Biomechanical Engineering, University of Twente)
Marc Beusenberg (Laboratory of Design, Production and Management, University of Twente)
Bart Koopman (Laboratory of Biomechanical Engineering, University of Twente)

Abstract:
Elderly people experience problems of stability while cycling. The exact nature of these stability problems is not well understood, but is believed to be related to a reduced motion feedback ability of elderly, health issues that reduce power or force, and insecurity due to slower information processing in heavy traffic or situations where multiple tasks are required. With the use of an advanced multi-body computer model we are able to simulate the behavior of elderly on the bicycle in different problem scenario’s. This model covers the bicycle dynamics, the tire-road contact, the biomechanics and balance control of the rider, and influences from the environment. The model is fully parameterized, to be able to test the influence of various design variables of the bicycle and parameters of the rider on the behavior of the system. The final goal is to develop countermeasures to decrease problems during bicycling, like instability. As a first validation, the self-stability of the bicycle model and passive rider model are compared to linearized models in literature [1,2]. The software ‘JBike’ calculates the eigenvalues of the system and shows the self-stability of the bicycle at certain forward speeds [3]. The forward speed where the bicycle becomes stable is comparable between both models (around 4 m/s). The system becomes unstable at low speeds when a passive rider is added to the bicycle model, also shown by Schwab et al. [2]. At higher speeds the system of a bicycle with a passive rider can be stable depending on the impedance of the rider’s arms on the handlebars. Further validation of the model is needed, using experimental data. First experiments include normal cycling on a treadmill, while measuring the lean and steer angles and rates of the bicycle and the tire contact forces on the ground. Also the center of mass of the whole system can be calculated and compared to the results of the numerical simulations. The center of mass with respect to the heading of the bicycle is expected to be a way of expressing the stability of the system [4]. First results of the validation experiments are shown and further steps for validation of the rider movements are discussed.