Design And Control Study Of Force Feedback Device For Elbow Exoskeleton

With the development of teleoperation technology and virtual reality technology,a single feedback method through vision reduces the authenticity of people in teleoperation and virtual experience,and also reduces the ability to grasp details in interaction,resulting in a lack of accuracy in operation.Tactile feedback system can provide additional feedback methods to make up for the defects of single visual feedback.Force feedback technology is one of the important research directions.In this paper,an elbow exoskeleton force feedback device for teleoperation and virtual reality applications is designed.Based on this,the system modeling and simulation are carried out to study the control strategy of force feedback and verify it.The main research contents and results of this paper are as follows:On the basis of kinematics and anatomy of human upper limb,the structure of elbow exoskeleton is designed.The joint size and motor drive system selection of the elbow exoskeleton were determined.In order to reduce the impact force of the elbow exoskeleton and improve the safety of human-computer interaction,a series elastic actuator was adopted at the exoskeleton joint.The three-dimensional model of the elbow exoskeleton was established to check the strength.Under the condition of satisfying the strength,the overall mass of the elbow exoskeleton is controlled within1 kg to improve the comfort of wearing.In order to determine the expected feedback torque of the elbow exoskeleton,the structure of the human upper limb was simplified,and the dynamics model of the human upper limb was established by Lagrange method.Based on dynamic model of human upper extremity is analyzed in the upper arm suspension,forearm do bending elbows dynamic equations of the motion,through the establishment of the Adams simulation model of dynamic equation for validation,hand elbow torque with different loads are analyzed,according to the dynamics equation of elbow exoskeleton expect feedback torque is calculated.According to the elbow exoskeleton model,the human-computer interaction of elbow exoskeleton based on series elastic actuator is analyzed,and two control methods based on position control and torque control are analyzed.Combined with the impedance control algorithm,the impedance control strategy of the elbow exoskeleton based on position control was established.The influence of the impedance parameters and the degree of spring stiffness coefficient of series elastic actuator on the control system was analyzed.A fuzzy adaptive controller was designed to dynamically adjust the parameters of impedance control,and the control algorithm was simulated and analyzed under two working modes: the exoskeleton with weak feedback and the exoskeleton with strong feedback.According to the 3D model and control strategy of the elbow exoskeleton,the experimental prototype of the elbow exoskeleton was made by 3D printing,and the experimental platform of the elbow exoskeleton was built.The wearability and actual force feedback ability of the elbow exoskeleton were evaluated.The experimental results show that the elbow exoskeleton is comfortable to wear,the control algorithm runs normally,and the force feedback function can be effectively realized.