Research On Double Flexible Rope Towing Collaborative Control Technology Of Launching Experiment Vehicle In Constrained Space

The catapult launch technology of the navigating body is essentially a technology which can push the navigating body outside the launch tube or the water surface in a certain height with the help of an external power before the navigating body's own power system starts to work.During the surface or underwater dynamic ejection process,the navigating body is in an uncontrolled state,and its whole body is surrounded by a dramatic change in the shape resistance and the cavitation impact load,which can easily cause the instability of the movement attitude,and then affect the success or failure of the launch and accuracy.Therefore,a large number of ejection test facilities have been established in various countries around the world,and sustained research has been conducted on the surface and underwater dynamic ejection technology of navigation bodies.The constrained space double flexible rope towing vehicle system studied in this paper is a multi-conditions dynamic catapult experiment facility built on a ground pond.Due to tne space constraints and the requirements of high-speed camera perspective,the vehicle needs to be accelerated to the specified speed within the specified time,and maintain a constant speed movement within the specified stroke for the navigating body to complete the dynamic catapult experiment,and finally stop at the end of the track smoothly.However,in the motion control process of the double flexible rope towing vehicle,a complex time-varying system with strong coupling,nonlinearity,limited stroke and tension is formed between the traction flexible rope link and the braking flexible rope link.Therefore,how to weaken the coupling interferences within the variables,how to realize the rapid acceleration and deceleration in extremely short distances,and how to enhance the motion control accuracy and robust stability have become the key factors which affect the actual effect while the vehicle is conducting the surface and underwater dynamic catapult experiment.In view of those reasons,this paper focuses on a class of double flexible rope towing vehicle system in constrained space for multi-conditions dynamic catapult experiments,and conducts studies arounding the mathematical modeling,the model verification and double flexible rope towing collaborative control technology of launching experiment vehicle in constrained space.This research has overcome the strong coupling of the system structure,the relaxation nonlinear of the flexible rope,the state constraintion,the time-varying parameters and the uncertainties of the flow field disturbance,and achieved the stable and good collaboration of the double flexible rope towing vehicle on the limited water surface track and in the underwater constraint space,has high engineering application value and theoretical reference significance.The main research of this paper is as follows:Firstly,the actual characteristics of the multi-energy domain,multi-physical process,and multivariate coupling system are analyzed.A relatively complete mathematical model of the multi-conditions double flexible rope towing vehicle system is established using modular ideas and mechanism modeling methods.The mathematical model is validated combining the individual event test results of the actual system.Aiming at the cross coupling between the traction link and the braking link of the double flexible rope towing vehicle,a collaborative control strategy of forward traction speed and rear brake tension is proposed,which effectively enhenced the stability of the control system and improved the performance of collaborative control.Secondly,a collaborative controller based on decentralized control theory and ESO-NITSM variable suppression coefficient backstepping adaptive control algorithm is proposed for a class of double flexible rope towing vehicle coupling and restraint system facing dynamic catapult experiment on water surface.According to the decentralized control theory,the coupling term is regarded as an external disturbance,and the comprehensive external disturbance composed of the coupling term and the uncertain term can be dynamically observed by constructing an extended state observer(ESO).Then,the observed values are used as control compensation to design the Non-singular Integral Terminal Sliding Mode(NITSM)backstepping adaptive controllers for the traction link and the brake link of the vehicle respectively.At the same time,considering the limit of the tension of flexible rope,the tension suppression factor is introduced into the variable coefficient backstepping design process,and a satisfactory collaborative control performance of the double flexible rope towing links of the vehicle coupling and restraint system under the time-varying pressure dropping uncertainty is realized.Thirdly,for a class of double flexible rope towing vehicle coupling and restraint system facing underwater dynamic catapult experiment,the stability of the trolley is reduced,and the structural coupling disturbance of the system is also exacerbated because of the complex water disturbance in the restraint space.In order to further strengthen the robustness of the collaborative control system of the vehicle,a decoupling collaborative controller based on the inverse system theory and the RBF-NITSM variable suppression coefficient backstepping adaptive algorithm is proposed.The inverse system theory is used to decouple the vehicle system into a single-input single-output vehicle speed control and a braking tension control pseudo-linear system.Based on the variable suppression coefficient backstepping method and the double exponential terminal approach law,the NITSM controllers are designed respectively for the decoupled pseudo-linear systems.At the same time,the Radial Basis Function Neural Network(RBFNN)is constructed to approximate the total uncertain terms of the pseudo-linear system.Combining the actual system characteristic data,simulations of the dynamic catapult experiment in an underwater constrained space were carried out.It was verified that the designed decoupling collaborative controller can completely eliminate the cross-coupling characteristics of the double flexible rope towing structure,and realize an excellent collaborative control performance of the double flexible rope towing links of the vehicle coupling and restraint system facing underwater dynamic catapult experiment.Finally,after completing the on-site integration and joint adjustment of the actual double flexible rope towing vehicle system,the dynamic catapult experiments were performed on the limited water surface track and in the underwater constraint space,which can verify the excellent collaborative control performance of the double flexible rope towing vehicle system facing dynamic catapult experiment in constrained space.