Research On Key Technology Of SMA-driven Space High-load & Low-impact Connection And Separation Device

Space connection and separation device is widely used in rocket stage separation,satellite(ship)separation,solar wing(antenna)deployment,payload release and other missions,and its performance directly affects the success or failure of spacecraft launch and in-orbit work.The traditional connection and separation mechanism uses fire to carry out structural destruction and separation,which has some problems,such as large separation impact,explosion pollution,unable to be reused,and so on,which seriously limits its application in space missions.With the development of manned spaceflight,earth observation,deep space exploration and other aerospace applications,the demand of space system for low impact separation in orbit is becoming more and more urgent.Since the 1990 s,a variety of new non-pyrotechnic space separation technologies based on thermal,electrical and magnetic driving have been gradually developed and applied.Among them,the non-pyrotechnic separation device driven by shape memory alloy(SMA)has attracted wide attention because of its diversified design,small separation impact,reusability and so on.However,most of the existing researches focus on the configuration design of a single device,and a systematic design method for high load and low impact connection separation device has not been formed,and there is little research on the synchronization control method of multi-point unlocking of separation device.the reliability evaluation method of this kind of separation device is still blank.The above problems limit the popularization and application of non-pyrotechnic separation technology in space missions.Therefore,this paper carries out the research on the key technologies of SMA-driven space high-load and low-impact connection and separation device,in order to provide reference for the design and application of this kind of nonpyrotechnic space separation device.The design method of point connection and separation device based on energy flow is carried out.Based on the analysis of DOF constraint function of the device,combined with its specific work requirements,a generalized kinematic model of is established.According to the study of freedom constraint and release,the key role of force constraint in freedom constraint of separation device is obtained,and the separation configuration which can realize the application and release of force constraint is synthesized.Secondly,based on the energy flow analysis,the system design method of low-impact separation device is put forward,and the specific configuration is designed.The separation configuration is optimized with the goal of high-load connection and low-impact separation.According to the multi-point use requirements of the device,synchronization of device unlocking is analyzed and the control method is studied.First of all,the unlocking stability of a single device under the same working condition is analyzed,the influence parameters of friction coefficient and mechanism clearance are optimized,and the optimal combination of mechanism influence parameters is determined to ensure that its unlocking performance meets the design requirements.The separation time fluctuation is minimized and the robustness is optimized.For synchronous use of multi-points separation in space,the effects of uncontrollable factors such as connection position and ambient temperature are analyzed,and the driving response characteristics of SMA drivers with specific configurations are studied to identify the coupling relationship of the influencing factors,so as to realize the fast response and accurate control of the drive components.The kinematic reliability analysis method of connection separation device based on CPSO-BR-BP neural network was proposed to verify its kinematic reliability under the action of uncertain parameters.The training set and prediction set were obtained to characterize the relationship between the uncertain parameters and the recovery displacement of the shape memory alloy actuator.The mapping relationship between the uncertain parameters and the response based on BP neural network was constructed,and the optimized network relationship was obtained.The probability distribution characteristics of recovery displacement of SMA wire under the condition of parameter uncertainty were obtained,and the unlocking reliability of SMA wire was calculated.Combined with the reliability model of the device,the motion reliability of the whole separation device was obtained.The mode and frequency response function of the separation device are analyzed.The circular distribution method is adopted,which is convenient to analyze the vibration transfer characteristics between the layers of the star-rocket separation device.Collecting the signal of measuring point,expanding the measured impulse response signal into modal components of each order step by step by VMD decomposition,removing noise and interference components,extracting the required impulse response components,and determining the main frequency of each component;The frequency response function of excitation point and response point is obtained by frequency domain method,and the transmission law of vibration in the satellite and rocket device is determined.The accuracy of the analysis results is verified by comparing the peak value of frequency response curve with the main frequencies of each mode of VMD decomposition.