Design and preliminary testing of a low-cost balance perturbation system for the evaluation of real life postural adjustment on public transport.

Balance recovery mechanisms are of paramount importance in situations like public transport where sudden loss of equilibrium can occur. These mechanisms can be altered by aging or pathological disorders. However it is almost impossible to investigate these phenomena in real-life conditions, and the safe environment of a laboratory is needed. This paper investigates how jerk perturbations in the transverse plane similar to those experienced on public transport can be simulated in a controlled manner. A platform capable of producing horizontal perturbations with a person standing on it was developed. Accuracy, repeatability, and load sensitivity of the system were assessed with repeated trials in all four directions of movement. Comparison between the destabilising effect experienced on public transport and the postural response to perturbations from the platform was also made by tracking acceleration of the centre of mass of four subjects in these two situations. Results show that balance perturbations representative of real-life situations, such as standing on public transport, can accurately and repeatedly be produced in a safe and controlled environment with a low-cost and low-maintenance system. Coupled to motion capture technology, the system can be used for pathology assessment and rehabilitation treatments.