A reliable, gyroscope based gait phase detection sensor embedded in a shoe insole

This paper describes a new gait phase detection sensor (GPDS) and its application together with a functional electrical stimulation (FES) system for subjects with a drop-foot walking dysfunction. The gait phase detection sensor (sensors and processing unit) is entirely embedded in a shoe insole and detects in real time four gait phases (events) during the gait cycle: stance, heel-off, swing and heel-strike. The gait phase signal is used in a finite state control scheme to time the electrical stimulation sequences in order to generate a motion in the affected leg that is close to a physiological motion. The GPDS uses a miniature gyroscope that measures the rotational velocity of the foot and three force sensitive resistors that measure the force load on the shoe insole. Contrary to other systems using only force sensors, our system can easily differentiate between true walking and weight shifting from one leg to the other during standing. This is achieved through the combination of force sensors and a gyroscope sensor.