| The lower limb exoskeleton designed in this paper is a kind of smart device which is worn beside elders’ lower limb, with a wide application prospect in many fields.The main contents in this paper include improvement mechanical structure design of the lower limb assistive exoskeleton, kinematics and dynamics analysis, the control system design of the lower limb assistive exoskeleton, the application of sliding mode algorithm based on proportion switching function, co-simulation and experiment. These make a good foundation for the further study of the lower limb exoskeleton.(1) Combined with the characteristics of human walking motion, a mechanical improvement design is shown to enhance the safety and comfort for human body. Adding the joints spacing and several bandages makes the structure more perfect. The mathematical model of seven links with six degrees of freedom is established. A dynamic analysis is developed using the Newton Euler method. In the software ADAMS human walking is simulated and the driving force of every joint is obtained during the simulation using ADAMS software.(2) The control system of the lower limb exoskeleton is established with STM32 MCU as the minimum system board. The motor control board and sensors’ data acquisition board are drawn. The sensors include encoder, straight rod displacement sensor, plantar pressure sensor and acceleration sensor.(3) The exoskeleton prototype build in software SolidWorks is imported into the software ADAMS. Material and color is changed and add the constraints and motion pairs. A sliding mode control algorithm based on proportional switching function is established in the software Simulink. Finish the establishment environment of collaborative simulation and the simulation with human.(4) After the exoskeleton parts processing and assembly is completed, human wearing test and stability test are carried out to verify that the exoskeleton can provide enough driving force in the walking process with a good stability. |
PDF Full Text Request