| Parallel manipulator is a new type of mechanical structure with the advantages of large bearing capacity,high precision and easy control.It has been widely used in parallel machine tools,parallel robots,positioning devices,biomedical,entertainment and other fields.Therefore,parallel manipulator is introduced into the artificial joint testing machine,which can improve the mechanical properties and the performance in the artificial hip joint friction and wear test.With the rapid development of science and technology,higher requirements are put forward to meet the demand of hip joint testing machine.In the context of artificial hip joint friction and wear test research,a novel 2(3HUS+S)parallel manipulator for hip joint was designed.The kinematics,dynamics,dynamic parameter identification and dynamic characteristic of the parallel manipulator are researched in this dissertation.The main research contents can be summarized as follows:1)The kinematics and dynamics of the parallel manipulator were researched: Based on Euler transform,the inverse kinematics model of the parallel manipulator was established.Combing the motion law curve of artificial hip joint,the position,velocity and acceleration of the linear module slider were obtained with numerical simulation.Upon the principle of virtual work,the dynamic models of the parallel manipulator under the condition of friction and frictionless were established,and the numerical simulation was obtained.The driving torque and driving power of the parallel manipulator in two cases were obtained.According to Adams simulation model,the kinematics and dynamic simulation were carried out,and the correctness of the kinematics and dynamic model were verified.2)The dynamic parameters identification of the parallel manipulator was research: On the basis of the dynamic models and matrix transformation principle,the identification models of the dynamic parameters were established.According to the structure and motion characteristics of the parallel manipulator,the identification strategies were designed with the disassembly measurement and system identification.Meanwhile,the verification trajectory and evaluation index of the identification results were designed.Based on identification strategies,the experimental scheme of dynamic parameters identification was designed.Based on the least square method,the parameters of the measured dates were identified,and the identification values of the dynamic parameters were obtained.3)The elastic dynamic modeling and dynamic characteristics of the parallel manipulator were researched: Based on the finite element method,the elastic model of spatial cantilever beam element was established.The finite element model and elastic dynamic model of the linear module were established.According to the coordination condition of motion and force,the relationship was established between the elastic dynamic equations of each linear module and the moving platform.In addition,the elastic dynamic model of the system was established.In order to analyze the dynamic characteristics,the theoretical analysis model was established.Finally,the dynamic characteristics were analyzed under the different position.4)The experimental verification of the parallel manipulator was researched: According to the topology structure and friction test standard,the mechanical system,electrical system and software system were designed.The experimental platform system of parallel bionic hip joint test machine was built.Moreover,the displacement sensor and attitude gyro were used to collect the experimental data.Furthermore,the kinematics performance dynamics performance and dynamic parameter identification of the experimental platform system were verified.By using the Donghua test system and sensors,the modal experiments were carried out,and relevant experimental dates were collected.Based on the modal analysis,under different positions,the natural frequencies and mode shapes of the parallel manipulator were obtained by using the Donghua test software. |
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