Reserch On Stiffness And Dynamics Of Elastic Hinge Rehabilitation Mechanism

Compared to traditional rigid mechanism, the flexible mechanism has the advantageof many aspects. As a kind of flexible mechanism, the elastic hinge mechanism can beapplied to many other fields. This paper conducts research on kinematics, stiffness,dynamics of three kinds of elastic hinge mechanism used in the field of medicalrehabilitation.Based on the CPM knee rehabilitation mechanism, we join the translational elastichinge, rotational elastic hinge to it in three ways, coming into being different biologicalintegration mechanisms. Kinematics of the original CPM mechanism and single closedloop elastic hinge mechanisms with different elastic hinges is researched, and knee anglediagrams in different mechanisms are made. By comparison buffer protective effect onrehabilitation exercise of the elastic hinge is proved. Based on influence coefficient,flexibility model of single loop double elastic hinge mechanism and the actual analysis ofcompliance characteristic diagrams made by programming is made.For the joint of human legs and the kinematic pair of mechanical mechanisms do notcoincide, we construct the bicyclic elastic hinge knee rehabilitation mechanism. Based onscrew theory, the degree of freedom is given. Combining with the influence coefficientand the principle of virtual work, we derive the expression of stiffness. We make thevelocity diagram of the mechanical branch and the corresponding stiffness characteristicdiagram. By analysis, we obtained when the leg and mechanism have some deviation, themechanism is still able to use the advantages of the elastic hinge to serve kneerehabilitation patients with convenience.Then, the 3-RRR elastic hinge parallel mechanism is used in the human lower limbrehabilitation of small-scale training. Influence coefficient of this mechanism is evaluated.Based on the general equation of dynamics, this paper establishes the dynamic model ofthe mechanism, and on this basis, the dynamic stiffness model is established. We use thefinite element method and data analysis software to fit the dynamic stiffness curve, andanalyze the dynamic stiffness characteristics combining with lower limb rehabilitation needs.Through software emulation, we contrast the kinematics and dynamics characteristicsof 3-RRR inelastic hinge and elastic hinge parallel mechanisms. And the feasibility of the3-RRR elastic hinge parallel mechanism applied to the lower limb rehabilitation training isanalyzed combining with the rehabilitation range of human lower limb and therequirement of smooth and safety rehabilitation process.Elastic hinges are integrated into the rehabilitation mechanism. Research onkinematics, static stiffness, dynamics and dynamic stiffness of those mechanisms, whichhas important theoretical significance for the future development of the bio-syncreticrehabilitation mechanism.