Research On Muscle Motion Information Collection Based On PVDF Knee Joint Control

Knee on the human body is critical, because it’s quite complicated structure and function, and is the body’s largest joint pulley. In daily life, work, labor, especially in sports, the knee plays a very important role. In ball games, track and field matches and other sports, the knee injuries often occur, and then lead to lower limb dysfunction even paraplegia, for the reason of improper posture, center of gravity, overloading, lack of exercise, and lower extremity muscle fatigue ready, etc. Control muscles around the knee determine the safety of the knee. So research knee control muscles will have a profound impact on the field of rehabilitation medicine, pathology, Exercise Science, Physical Education and so on, which has direct significance in terms of disease prevention and knee strain.To control the muscles of the knee joint research, we need to collect information about the movement of the muscles during exercise. Based on the collection and analysis of EMG can only describe neuromuscular movement in some way. With respect to the use of a needle electrode body contact by piercing the muscle fibers get muscle EMG, sEMG acquisition using surface electrodes, non-invasive and has no side effects and other improvements. However, EMG and sEMG are very susceptible to the body’s own electrical conductivity, ECG, temperature changes and individual physical differences. What’s more, EMG is very weak and its spectral distribution is very narrow. So information acquisition often lacks reliability and consistency, and acquisition process requires expensive equipment and quiet environment. It’s difficult to collect and monitor the process in real movement.For the current research is limited to information gathering muscle EMG and sEMG, this paper presents a new collection method:gathering the piezoelectric information of the control muscles of the knee during exercise, thus to get accurate kinematic parameters muscle mechanics and reveal quantitative biomechanical characteristics and kinetics of the knee control muscles. PVDF-based sensors have been designed and fabricated to collect the electric information of knee control muscles. PVDF piezoelectric film has the advantages of light, soft, thin, impact resistance and corrosion resistance, etc. It is particularly suited to work in a dynamic environment. Compared testing and simulation, the sensor’s cantilever finally defined be round with a simply supported cantilever structure. Signal conditioning circuits have been developed for the performance of the sensor. The sensor has been tested: When pressure signal is between 500N～1500N, the sensor has a good output signal; To control excitation frequency at about 750Hz, the sensor will receive a minimum deviation of response frequency; When excitation frequencies is below 6Hz or above 2000Hz, the sensor response frequency deviation will be more than 5%. The sensor array layout scheme was designed and is processed using motion tights according to clinical anatomy of the knee. Using the squat movement for dynamic test, it proved that this sports information acquisition method is economical, reliable and practical. The method will be able to collect and monitor the electrical information of knee control muscles effectively when the body is dong sports.