Gait Phase Detection System – Second Generation

With the advent of the functional electrical stimulation (FES) technology and its application as a walking aid, the need emerged to detect accurately specific phases (events) in the human gait cycle in order to time the stimulation sequences applied to the muscles [1]. In the recent literature, several sensor combinations (foot switches [2,3,4], goniometers [3,4], tilt sensors [5], accelerometers [6], gyroscopes [7,8], nerve-cuff electrodes [9,10]) and various algorithms have been proposed for the identification or classification of specific phases (events) in the human or animal gait cycle. However to the best of our knowledge, there is no report in the literature of a gait phase detection system with sensors small enough to fit inside a shoe, which detects four different gait phases with reliability above 99% under real-world conditions (standing and walking indoors and outdoors, walking on irregular ground and inclinations and stepping over small obstacles). This paper presents and describes a new portable gait phase detection system (GPDS), which detects in real-time the following four gait phases: stance, heel-off, swing and heel-strike. The GPDS is an integrated sensory system, which consists of a gyroscope that measures the angular velocity of the foot during walking and three force sensitive resistors that measure the load of the foot on the shoe sole. The measured signals are processed in a real-time with a rule-based observer that provides accurate information about the current gait phase of the subject’s foot. The GPDS was tested with ten ablebodied subjects and six subjects with impaired gait. The tests indicate that the system is sufficiently reliable for potential commercial applications. Methods and Materials