| With the increasing aging of the population,the physical functions of the elderly gradually decline and are susceptible to various diseases,leading to a decrease in lower limb movement,which not only affects the quality of life and health status of individuals,but also brings a certain burden to society.Exoskeleton robots are a new type of robotic system that interacts with the human body through sensing,control,motion and computing technologies to achieve the purpose of enhancing human motor functions.Traditional rigid exoskeletons are usually composed of rigid rods with bulky structures,which can easily lead to fatigue and inconvenient movement.Compared with rigid exoskeletons,flexible exoskeletons are made of flexible materials,which can better adapt to human movement and posture,helping to improve the walking ability of the elderly and accelerate the rehabilitation process of patients.At present,most of the flexible exoskeletons developed in China are assisted for the unidirectional motion of single joint of human body,and the ability to assist and improve the gait of human body is not strong enough.To address the above problems,this paper designs and develops a flexible lower limb-assisted exoskeleton robot that assists hip and knee flexion and extension,and investigates the control strategy of this exoskeleton robot.The main contents of the paper are:1.A flexible lower limb-assisted exoskeleton robot is designed by analyzing the current status of research at home and abroad and combining the mechanism of human lower limb motion.The exoskeleton robot can provide assistance to the hip and knee joint movement of human walking,and consists of four parts: control box,flexible walking suit,conduction system and sensing system.The "double-slotted pulley" is used as the actuator,and the drive motor makes the "double-slotted pulley" rotate forward and backward to control the inner core of the Bowden wire to extend and retract,thus transmitting the force to the joints of the human lower limbs.2.The kinematics and dynamics of the flexible exoskeleton robot were analyzed.Through experiments,the kinematic equations of the flexible exoskeleton robot were obtained,which reflect the relationship between the displacement of the inner core of the Bowden wire and the motion angles of the human hip and knee joints.The kinetic equations of the flexible exoskeleton robot were derived,and the stiffness coefficients in the kinetic equations were obtained through the stiffness measurement experiments.According to the experimental test and human motion joint moment curve,the booster strategy of dummy and normal human body is designed,and the displacement curve of Bowden wire inner core is derived by combining the kinematics and dynamics model of the exoskeleton robot,so as to obtain the motion trajectory of the motor.3.Combining the established DC motor dynamics model and the flexible exoskeleton robot dynamics model,the control strategies were studied respectively.To improve the stability of the DC motor system and reduce the booster error of the exoskeleton robot system,a fuzzy adaptive PID controller and a PD-type iterative learning controller are designed,a Matlab/Simulink model is built,and simulations and analyses are performed.The simulation results demonstrate the effectiveness of the fuzzy adaptive PID controller and the PD-type iterative learning controller.4.An experimental prototype was built,and motor trajectory tracking experiments and boost tracking experiments were conducted to verify the correctness of the dynamics model of the flexible exoskeleton robot and the effectiveness of the fuzzy adaptive PID controller with PD-type iterative learning control.Finally,human walking assistance experiments were conducted,and the effectiveness of the flexible exoskeleton robot was demonstrated by collecting the actual assistance values of the flexible exoskeleton robot on the human body and comparing them with the desired assistance curve. |
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