Topology Optimization Design And Research Of Compliant Mechanisms Considering Parasitic Motion And Motion Coupling

Compliant mechanisms are widely used in micro-electromechanical systems(MEMS),precision positioning,biomedical engineering and other fields,but the parasitic motion and motion coupling of compliant mechanisms will increase the difficulty of motion control and reduce motion accuracy.The traditional approach is mostly based on experience,by adding compensation modules to suppress parasitic motion or motion coupling,which will increase the size and complexity of the mechanism,and may also reduce the other performance of the mechanism.For this reason,this paper uses the topology optimization method to consider the problem of parasitic motion and motion coupling in the conceptual design stage,and studies the topology optimization design method for compliant mechanisms with low parasitic motion and motion coupling,in order to design a compliant mechanism with better comprehensive performance.The main research contents of this paper are as follows:Topology optimization design of compliant mechanism with low parasitic displacement.In order to solve the problem of parasitic displacement of single-input multi-output compliant mechanism,a topology optimization model of compliant mechanisms considering parasitic displacement is proposed.The model takes into account the performance relationship between parasitic displacement and output displacement,and combines the weight factor to transform a multi-objective into a single-objective.The sensitivity of the objective function and constraint function is derived,and the OC method is used to solve the model.Taking the compliant displacement amplification mechanism with input and output in the same direction but with asymmetric structure as an example,the effects of weight factor and spring stiffness on the results of topology optimization are studied.According to the results of topology optimization,a topological compliant displacement amplification mechanism with low parasitic displacement has been designed.Through finite element analysis and experiments,the performances of new amplification mechanism and typical lever amplification mechanism are compared,and the effectiveness of the method is verified.Topology optimization method of compliant mechanism considering rotation.On the basis of considering the translation motion of the mechanism and considering the rotation of the mechanism,a topology optimization model of compliant mechanism considering rotation is proposed.The sensitivity of objective function and constraint function is deduced,and the Heaviside function is used for density filtering.Taking the compliant orthogonal displacement amplification mechanism as an example,the influence of different objectives on the results of topology optimization is studied.According to the results of topology optimization,a compliant orthogonal displacement amplification mechanism with low parasitic motion at the input end has been designed.The performances of the topological orthogonal displacement amplification mechanism and the Scott-Russell mechanism are compared by finite element analysis.In addition,the topology optimization design method of pure rotating mechanism is discussed,and the influence of different volume ratios on the optimization results is studied.Finally,the performance of the pure rotation mechanism is verified by finite element simulation and experiments.These two examples verify the effectiveness of the method.Topology optimization of low motion coupling compliant precision positioning mechanism.To solve the kinematic coupling problem of multi-input multi-output compliant mechanism,a topology optimization model of the compliant mechanism considering kinematic coupling is proposed with the goal of maximum expected output displacement and minimum undesired coupling displacement.The sensitivity of the objective function and constraint function is derived.Taking 2-DOF positioning mechanism and 3-DOF positioning mechanism as examples,the topology optimization results under different objective functions are studied and compared,and the effectiveness of the method is verified.According to the results of topology optimization,the decoupled 2-DOF positioning mechanism and the decoupled 3-DOF positioning mechanism are obtained respectively.