Gait Analysis And Its Application In Functional Electrical Stimulation

Gait is a kind of complex and regular movement process when human walking.Gait contains a lot of motion information,and the gait parameters which obtained by collecting and analyzing gait information can play an important role in the rehabilitation treatment.The number of patients with foot drop is huge in China,and functional electrical stimulation is the most widely used in rehabilitation treatment currently.Functional electrical stimulation is the use of low frequency pulse current stimulating the limb nerve to make muscle contraction and prevent muscle atrophy,thereby,limbs can restore or improve physical function.It promotes the active contraction of the anterior tibial muscle and makes the foot produce dorsiflexion motion by stimulating the tibialis anterior in the swing phase of walking,which treats the foot drop.Compared to other rehabilitation therapy,functional electrical stimulation can not only help patients resume normal walking ability,but also make the patients more confidence,stable gait and less fatigue,which is an effective method of rehabilitation for foot drop.In this paper,functional electrical stimulation instrument was designed,and data acquisition and real-time identification of the swing phase when walking were based on the MEMS sensor,and it triggered functional electrical stimulation output to give the anterior tibial muscle stimulation in the swing phase.The main research contents are as follows:(1)A wearable gait signal acquisition system was designed based on MPU6050 of MEMS sensor.In order to find the optimal sensor wearable position and research the algorithm,the system was composed of two parts:the lower computer which was responsible for data acquisition and transmission,and the upper computer which was responsible for receiving and the received data was transmitted to the computer for processing.Data communication between the upper and lower machine was through the low power Bluetooth 4.0.(2)The sensor was worn in the thigh,lower leg and ankle joint respectively,and experiments were carried out to acquire gait parameters of 8 volunteers under flat free walking pattern and treadmill platform.The gait segmentation algorithm based on the angular velocity threshold was proposed through detailed analysis of the curves,which could recognize the swing phase of gait in real time.Gait segmentation algorithm based on angular velocity threshold was tested under the flat free walking pattern and treadmill platform,and the recognition rate of heel off and heel strike was over 97%and 98%respectively,and the best wear position of sensor was shank,which verified the accuracy of the proposed algorithm.(3)A functional electrical stimulation system based on CC2541 was designed,which included the design of Boost circuit,digital potentiometer module and electrical stimulation output circuit and chose the appropriate electrical stimulation amplitude,frequency,waveform,and stimulating position,achieving the bipolar electrical stimulation trapezoidal envelope output.The gait segmentation algorithm was implemented in the CC2541 microcontroller of data acquisition module,which was applied to the designed functional electrical stimulation,achieving the integration of real-time data acquisition,processing and electrical stimulation.The output of the system functional electrical stimulation was tested under the free running mode,which verified the feasibility of the designed system.The results showed that the designed algorithm based on angular velocity threshold in this paper was simple and effective,which could accurately segment the gait and recognite the swing phase of gait in real time.It controlled the functional electrical stimulation system to output when detecting heel off and stop output when detecting heel strike.This system provides a safe and effective method for patients with foot drop in rehabilitation.