Research On Driving Stability Of The Carrier-based Aircraft Tractor

The efficiency and safety of the carrier aircraft being transport and allocate on the carrier deck are the direct guarantee of the efficiency of the carrier aircraft.As one of the main dispatch equipment on the carrier,the tractor plays an important role.The carrier-based aircraft tractor is prone to run instability,because the narrow and complex operation environment of the carrier,the uncertainty of the carrier motion and the time-varying nonlinear of the traction motion,and so on.That affects the dispatch of carrier-based aircraft and even causes deck accidents,thus affecting the overall mission implementation of the carrier.Therefore,it is very necessary to study the driving stability and control of carrier-based aircraft tractor.The carrier-based aircraft tractor studied in this paper is designed independently by our team.The tractor driven by in-wheel motors is in line with the development trend of miniaturization and intelligence of carrier equipment.The remote control system not only reduces the need for staffing,but also provides more space for carrier-based intelligent equipment.In this paper,the driving stability and control strategy of the target carrier-based aircraft tractor on the deck are studied.The main contents are as follows:The target tractor relevant structural parameters are firstly analyzed for pertinence and accuracy of the follow-up research.The mathematical model of the carrier motion is analyzed,the coordinate system of the traction system is established,and the conversion sequence of the coordinate system is clarified,which lays the foundation for the subsequent kinematics and dynamics analysis of the tractor.According to the tractor actual structure and the focus of the research,the driving stability of the carrier-based aircraft tractor is mainly studied from the two directions: longitudinal dynamics and handling dynamics.In this paper,the mathematical model of longitudinal dynamics of the tractor is established combined with the knowledge of automobile system dynamics and automobile theory.The driving resistance encountered by the carrier-based aircraft tractor is defined and analyzed in detail.From the perspective of the power demand and supply of the tractor,the parameters of the power transmission system of the tractor are matched,and then the established mathematical model of the longitudinal dynamics is verified based on the power demand of the tractor operation.The influence of the two important use factors on the power of the tractor,that is,the quality of the carrier aircraft and the driving speed of the tractor,is determined and analyzed quantitatively.The stability condition of the tractor driving in a straight line is discussedThe mathematical model of two-degree-of-freedom time-varying nonlinear yaw motion of the carrier-based aircraft tractor is established in this paper based on the two-degree-of-freedom dynamic model of automobile and the established longitudinal dynamic mathematical model of the carrier-based aircraft tractor.The theory of a twodegree-of-freedom forced vibration system under extrinsic motivation is proposed to analyze the tractor straight line driving stability based on the stability margin and the steady-state solution amplitude theory,on the premise of not solving the stable solution of the equation.Furthermore,the conclusion of the poor stability of the tractor's driving is further verified by the Ross-Hurwitz criterion.By means of control variable method and sensitivity,the influence of two important use factors on the yaw stability of tractor is analyzed quantitatively.In this paper,considering the influence of complex external environment on the tractor and the time-varying nonlinear characteristics of yaw motion,a quasi-sliding mode control strategy is proposed to control the yaw stability of the carrier-based aircraft tractor.In order to verify the timeliness and robustness of the control strategy,a fuzzy adaptive PID control strategy which is also suitable for the system,is designed and compared.The yaw rate of the two-degree-of-freedom vehicle dynamics model with zero-side-slip angle is adopted as the expected response of the tractor,and the yaw stability of the tractor is controlled by generating a compensation yaw moment.The yaw stability controllers based on the two algorithms are designed separately,and the robustness and timeliness of the quasi-sliding mode control is verified better by the simulation model.The timeliness and robustness of the quasi-sliding mode control can be maintained under the sea level 5 and below,which meets the actual use needs of the tractor.Extremum seeking is proposed for the acceleration slip regulation of carrier-based aircraft tractor considering the actual accelerating condition.The bidirectional control of the acceleration slip regulation and antilock brake of the tractor can be achieved by in-wheel motor.Based on the established longitudinal dynamic model,the kinematics models of the tractor and its driving wheel are established.According to the characteristic of tire force-slip rate curve,there must be an extreme value.Due to the particularity of carrier deck surface and marine environment,the acceleration slip regulation of the carrier-based aircraft tractor based on extremum seeking algorithm is presented which does not need to identify the deck adhesion coefficient and optimum slip ratio in advance.The controllers based on two classical extremum seeking algorithms,sliding mode extremum search and disturbance extremum search,are designed separately.The convergence of the two algorithms is proved.The simulation model is established to analyze the slip ratio characteristics of the tractor based on Matlab/Simulink.It is confirmed that the optimal neighborhood of slip ratio can be searched online and the robustness is ensured by the two algorithms.The timeliness of the disturbance extremum search is better.Because the chattering problem exists in the both classical algorithms,the pre-demodulation extremum seeking algorithms without steady-state oscillation is proposed further to eliminate the problem of steady-state oscillation.While ensuring the timeliness of the algorithm,the efficiency and stability of the algorithm are improved.