The Bionic Design And Research On Properities Of Assisted Lower Exoskeleton

An exoskeleton is a wearable device that integrates with the user for power assistance.It has broad application prospects in the fields of national defense and military,medical rehabilitation,and daily life.Aiming at the existing problems of poor wearing comfort of traditional rigid exoskeletons and weak carrying capacity of flexible exoskeletons,this paper designs a rigid-flexible coupling exoskeleton system.It is comfortable to wear,can efficiently match human-robot joints,and can withstand a certain load.The system can realize the function of assisting human walking by passively assisting knee extension and actively assisting plantar flexion.The main work and innovations of this paper are as follows:(1)Starting from the anatomical structure and motion mechanism of the joints of the lower limbs,the general design principles of the exoskeleton system are put forward according to the joint characteristics and range of motion of the joints of the lower limbs.Focusing on the bionic design of the joints of the lower limbs,the rotation centers of the human-machine at the hip and ankle joints can be coincident,and the trajectory curves of the human-machine knee joint can be matched.The exoskeleton drive system was designed,and the 3D model of the exoskeleton was built in SolidWorks.(2)For the knee joint six-bar mechanism,the relationship between the instantaneous center coordinates and the rod length parameters is established,and the six-bar mechanism is optimized.The instantaneous center trajectory curve matching of the human-machine knee joint and the self-locking in the standing state are realized.The kinematics modeling of the designed exoskeleton system was then performed.The D-H coordinate method is used to describe the geometric relationship between the exoskeleton links and the transformation matrix between each coordinate system,and the positive kinematics solution of the robot is obtained.The theoretical model is verified by the dynamic simulation software Adams.(3)Due to the complexity of the human body system and the limitations of ethics and morality,it is difficult for some existing experimental methods to truly detect the muscle strength and metabolism of human muscles.In this paper,the coupling modeling and muscle control calculation of the gait2392 musculoskeletal model and the exoskeleton system are completed through the OpenSim platform.The power-assisting effect of the exoskeleton system is analyzed through simulation.The simulation results show that the exoskeleton system has a certain effect on the user”s ankle plantar flexion and knee extension.(4)The research on the experimental prototype and the design of the control system have been completed.A series of experiments were conducted to verify the rationality of the design of the exoskeleton system.In the wearing comfort test,the subjects can normally complete various daily actions and some complex actions,and the exoskeleton system has good human-machine coupling and motion following performance.In the load capacity detection test,the foot pressure of the subjects wearing the exoskeleton while standing still with load was slightly lower than that when the exoskeleton was not worn.The exoskeleton system can maintain rigidity in a standing state and has a certain auxiliary bearing capacity.In the test of boosting effect,the muscle activation degree of the gastrocnemius muscle,soleus muscle,rectus femoris muscle and tibialis anterior muscle of the subjects was obtained by detecting the EMG signal strength before and after wearing the exoskeleton and walking with or without load.The test results show that the exoskeleton system has a certain boosting effect on the dorsiflexion and knee extensor muscles of the subjects with or without load.