A portable gait analysis and correction system using a simple event detection method

Microcontrollers are widely used in the area of portable control systems, though they are only beginning to be used for portable, unobtrusive Functional Electrical Stimulation (FES) systems. This paper describes the initial prototyping of such a portable system. This has the intended use of detecting time variant gait anomalies in patients with hemiplegia, and correcting for them. The system is described in two parts. Firstly, the portable hardware implementing two independent communicating microcontrollers for low powered parallel processing and secondly the simplified low power software. Both are designed specifically for long term, stable use and also to communicate with PC based visual software for testing and evaluation. The system operates by using bend sensors to defect the angles of the hip, knee and ankle of both legs. It computes an error signal with which to produce a stimulation wave cycle, that is synchronised and timed for the new gait cycle from that in which the error was observed. This system uses a PID controller to correct for the instability inherent with such a large time delay between observation and correction.