Abstract:

BACKGROUND: Lower limb motion is complex. Proper human motion parameters detection is important for knee prosthesis control. Current lower limb prosthesis control information source is physical quantity related to motion information, which can directly reflect biomechanical characteristics of human motion. It is simple to collect and applicable for real-time control. The lower limb prosthesis utilizes one or several sensors to detect human motion information.
OBJECTIVE: To develop a sensor system that can collect human motion information controlled by intelligent lower limb prosthesis.
METHODS: Relationship between pivot axis installation potentiometer and knee joint flexion angle was acquired from analysis of four-bar linkage with a fixed pneumatic cylinder. In addition, the proper hall sensor installation position was selected to solve the two-solution problem. A sensor signal acquisition experiment was designed. The treadmill ensure that walking speed was completely under control. Knee joint flexion angle at toe-off in different walking speeds was measured. Curve fitting process provided the correspondence between them.
RESULTS AND CONCLUSION: Knee joint flexion angle at toe-off increased with increasing walking speed. Quadratic curve fitting obtained a good effect. Results show that under horizontal walking state, potentiometers and Hall-sensors can be used to detect walking speed of lower limb prosthesis, and distinguish support phase and swing phase.