Design And Optimization Of Camber Continuously Morphing Wing Mechanism With Multiple Joints

Along with the advance of the world aviation technology,another revolution of aircraft design has been opened.Some requirements,including supersonic speed,super stealth,far voyage,long endurance and high mobility,are put forward for a new generation of multi-purpose aircraft design in the future.In order to meet these requirements,morphing aircraft gradually steps into people's horizons.The morphing part usually refers to the wings of the aircraft.It can change the aerodynamic shape smoothly and continuously according to the flight mission and environment.As the main part to achieve camber adjustment function for morphing wing,camber continuously morphing wing mechanism has been widely studied by international scholars in recent years.It has a very broad application prospects in the field of aviation.This dissertation,taking planar linkage mechanism with multiple joints as the research object,carries on deeply research on the key technology which includes type synthesis,mechanism design method,structure optimization algorithm,theoretical analysis of mechanism with clearance,model-free adaptive control and etc.Due to planar closed-loop linkage mechanism with multiple joints has multitudinous structure types,it can provide more mechanism schemes for design of camber continuously morphing wing mechanism.Therefore,this dissertation takes planar closed-loop linkage mechanism with multiple joints as the research object,doing type synthesis.In order to reduce the number of kinematic chain isomorphism judgment,this dissertation does research on the mathematic expression of multiple joints and the concept of multiple joints type spectrum to do more detailed classification.Based on the characteristic invariants,this dissertation establishes the mathematic relationship between the characteristic invariants.Then a novel type synthesis method for planar kinematic chains with multiple joints based on characteristic spectrum analysis has been proposed.To verify this method,this dissertation does type synthesis to 7 bar mechanism with multiple joints.In order to simplify the process and improve the efficient of type synthesis,this dissertation writes a computer aided type synthesis program for 8 bar mechanism with multiple joints and does type synthesis to 8 bar mechanism.From the perspective of theory of mechanism,this dissertation proposes a novel design method for a class of camber continuously morphing wing mechanism with multiple joints,achieving systemically design for this class mechanism.Based on this method and the type synthesis results of planar closed-loop 8 bar mechanism,this dissertation proposes three design schemes for camber continuously morphing wing mechanism,establishes the mathematic models and 3D models,and does trajectory simulation and kinematic simulation to verify the performance on adjusting the mechanism camber.Because there are many nonlinear equations in the mathematic model for multiple closed-loop mechanism,the optimization algorithm depending on the function gradient will no longer apply.Based on the traditional artificial fish swarm(AFS)algorithm,this dissertation proposes the idea of weighted adaptive search scope and iteration step.Combining the Hooke search method which has a stronger ability on local search with AFS optimization algorithm,the weighted adaptive AFS optimization algorithm based on Hooke search method is proposed.In order to simplify the process of optimization,this dissertation develops a multi-platform collaborative optimization system.By this system,this dissertation does optimization to camber continuously morphing wing mechanism.In view of the existing joint clearance problem in the process of manufacturing and assembling,clearance theory is applied to camber continuously morphing wing mechanism.By use of the continuous contact model,a dynamic model for camber continuously morphing wing mechanism with clearance is set up.According to different quantity,different positions and different kinds of clearance joints,this dissertation does detailed analysis on the influence of kinematic accuracy for the end of the mechanism and obtains four significant conclusions,which can provide some references to the prototype manufacturing.For a more comprehensive evaluation of volatility curves,this dissertation improves the traditional fitting curve formula and integrates it into the multi-platform collaborative optimization system.By this system,this dissertation has achieved the optimization for clearance error of camber continuously morphing wing mechanism.Because of the complex structure and strong nonlinearity of camber continuously morphing wing mechanism,it is difficult to establish the accuracy mathematic model for the control system.In order to solve this problem,this dissertation applies model-free adaptive control theory to camber continuously morphing wing mechanism.Camber continuously morphing wing mechanism will frequently change its camber when it works.In order to avoid systematic huge oscillation caused by input frequently rising and falling,differential in advance PID control is combined with unfalsified control.This control algorithm can effectively restrain systematic oscillation.However,the artificial controller parameters could lead to the controller unreasonable.In order to solve this problem,this dissertation combines the weighted adaptive AFS optimization algorithm based on Hooke search method with the differential in advance PID unfalsified control algorithm.It achieves the function of system automatically identifying the optimal controller and significantly improves the control effect.In order to validate the fesasibility of the proposed mechanism scheme,t he experiment prototype is designed and manufactured.The experiment platform is established.This dissertation finishes the morphing experiment,the rigidity experiment,repetition morphing error experiment,the continuous deflection experiment and control accuracy experiment.The experiment results indicate that the camber continuously morphing wing mechanism with multiple joints proposed by this dissertation has strong ability on camber adjustment.It can achieve smoothly and camber continuously changing,with high rigidity and low motion error.The control algorithm has a high accuracy.This dissertation can provide theory and project basis for intensive study of camber continuously morphing wing mechanism in the future.