Research On Mechanism Design And Cooperative Control Strategy Of Sitting/lying Lower Limb Rehabilitation Robot

The current situation of the limb function rehabilitation in China is that the shortage of rehabilitative physicians is large,and the import price of intelligent high-end rehabilitation equipment is expensive.This paper presents the research on mechanism design and cooperative control strategy of lower limb rehabilitation robot.It has the important practical significance and social benefits for improving the rehabilitation quality of the patient,reducing the burden of the patient family and constructing the harmonious society.This paper studies the sitting/lying lower limb rehabilitation robot from five aspects that are configuration design and human-machine analysis,trajectory planning under variable workspace,dynamic equations of man-machine coordination,human-machine-cooperative control and more electrical sensing signals fusion,construction of experiment platform and clinical trials.The research contents include:Based on the etiological mechanism of lower limb dysfunction,applying the traditional rehabilitation techniques of rehabilitation physicians,embedding force/position sensors into mechanical legs,the evaluation method of rehabilitation robot based on the muscle strength and muscle tension of the lower extremities is determined.The length of the mechanical leg and the parameters of the range of motion of the joint are determined by the application of ergonomics.Combined with the requirements of the clinical application environment,a virtual prototype of the sitting/lying multi-joints lower limb rehabilitation robot is built for patients with different levels of injury.The length of the mechanical leg and the width between mechanical legs can be adjusted to adapt to the patients with different shapes,and the modular design of the movable seat is convenient to transfer patients for sitting down and droping off.Combined use of the mechanical and electrical limit,the electric-off motor brake,emergency stop switch is designed to ensure absolute safety of patients.D-H method is used to sovle the kinematic relationship between joint angles and terminal positions of the mechanical leg;based on the error transfer matrix of the rigid links,static posture error model of the three DOFs mechanical leg of lower limb rehabilitation robot is established.Through the Monte Carlo statistical test method,the connecting rod error source judgement of the mechanical leg is studied,while the connecting rod error is similar with patient leg gait abnormalities.So we can use mechanical leg moving accurately to achieve patient gait correction.The concept of the variable workspace of the sitting/lying rehabilitation robot is put forward,and the boundary of the mechanical leg workspace is solved through graphical method.Due to the application of patients recover stages with different requirements,dual biquadratic polynomial interpolation trajectory generation method with sitting posture in joint space,and five order polynomial interpolation trajectory generation method with lying posture in cartesian space are proposed.Based on amplitude limiting and sliding average filtering method,polynomial combination is applied to achieve flexibility and smoothness of physician teaching training trajectory.The dynamic equations of human lower limb/ mechanical leg are established by Lagrange energy balance method.The correctness of the dynamic model is verified by co-simulation form Adams simulation and Matlab analytical methods.Based on the terminal six-axis force sensor and joint torque sensors on the mechanical leg,the human-machine coordination dynamics equations are established respectively.Aiming at the problem of uneven mass distribution and variable length of the mechanical leg,the dynamic equations of the mechanical leg are transformed into the product form of the regression matrix and the parameter vector.The control strategy of lower limb rehabilitation robot is studied.Trajectory tracking control based on PID,passive teaching training control based on terminal force sensor,passive training incremental control based on fuzzy logic,and active training control strategy based on impedance control and fuzzy control are put forward.The methods of average,variance and rate of change were used to obtain the patient's heart rate,temperature and other physiological information extraction features.The fusion technology of sensing information of rehabilitation robot based on the classical DSm T theory is used to realize the on-line diagnosis of patient coupling multi-comfort situation.Finally,the experimental platform of rehabilitation robot for lower limbs is established.Through the noise suppression of the power module,ground,signal line and control line,the electromagnetic compatibility stability of the robot electrical system is designed.The basic performance and trajectory tracking control of the rehabilitation robot is verified by experiments.The effectiveness and safety of the designed rehabilitation robot is proved through clinical trials.