Research On The Design Of An Electromagnetic Compliant Linear Actuator

To meet the demand of innovation of compliant actuators,a compact and fast response electromagnetic compliant linear actuator that can achieve force-position decoupling control is proposed in this thesis.According to the principle of electromagnetic actuation,the conceptual model of the compliant actuator is designed.The actuator is mainly composed of a variable stiffness device and a position adjusting device.The variable stiffness device adopts double coil-permanent magnet with symmetrical structure,and adjusts the electromagnetic force by dynamically changing the input current in the coil to realize the variation of stiffness.The mathematical model of the magnetic field around the electrified coil is derived,by which the explicit expressions of the electromagnetic force and the stiffness of the compliant actuator can be achieved using the equivalent magnetic charge method.Sequentially,with the considering of the design requirements of the actuator,the influences of design parameters on the electromagnetic force are analyzed,and then the design variables and objective function are determined.With the aid of the spectral analysis and the method of PSO based genetic algorithm,the optimization problem is solved.Through the comparative study of the optimization results,the superiority of the PSO based genetic algorithm method is demonstrated.Finally,the force-displacement,force-current,stiffness-displacement and stiffness-current characteristics of the compliant actuator are analyzed by using the electromagnetic force model and the stiffness model,which are further verified by comparing the results of simulation and experiment with those of the theoretical analysis.The results show that the designed compliant linear actuator can achieve the output force and stiffness control by adjusting the input current,meaning while has good stability in the working state.The obtained optimal design results and the experimental results of force-displacement and force-current characteristics are of great importance to the practical application of the compliant actuator.