Control Of Underwater Cable-driven Suspension Lift Platform

During the operation of the vehicle in the water,the fluid dynamics is very complicated due to the presence of the cavity.the hydrodynamic coefficients of the calculation of the vehicle mainly include wind tunnel,water tunnel test and numerical simulation.Wind tunnel and water tunnel test methods are the most effective methods,but the number of test data is limited by short trajectory distance and high speed.Pressure-release pond extends the underwater trajectory and meets highly similar environment simulation conditions.Highspeed cameras are used to obtain vehicle operating data,which are used for theoretical research.The lifting platform plays an important role in the depression model test,which is operated frequently equipped with valuable test specimens.Its working states affect the efficiency and safety of ejection test.The test is with high cost,with unsuitable environment for workers.So it is important to develop the lifting platform control subsystem to realize safe and remote control operation.The thesis is focused on dynamic modelling and control of the lifting platform.Combining with theoretical modeling,numerical simulation and experimental verification,the highly reliable,safe and practical control strategies and algorithms are designed with control performance and operating conditions.The topological structure of the lifting platform subsystem can be considered as a suspended four-rope drive statically indeterminate parallel force system.Based on the fourdrive force and six-degree-of-freedom motion analysis of the robot,the statically indeterminate parallel force system properties and rigid-flexible coupling are further studied.It qualitatively and quantitatively describes the physical constraints that affect the control performance of the system from the perspective of control objects,actuators and sensor feedback.The control strategy and algorithm are designed according to the specific motion conditions of the lifting platform,and the non-linear mapping relationship between the rope length space of the lifting platform and the platform working space is expressed with the aid of computer simulation software.The "coarse adjustment + fine adjustment" leveling strategy was determined,after comparing and analying a variety of control schemes,The modular control of "multi-function inverter + motor" is selected to improve system reliability.The command signal of the actuator is composed of three parts based on the cross-coupling deviation of the rope length space,depth deviation compensation of the working space and the upper limit of the cable tension mean square limit.Completed the design and development of the control subsystem of the lifting platform,and verified it by building a semi-physical simulation platform,single commissing,and partial system joint debugging.The results show that the analysis of the characteristics of the control object of the lifting platform and the theoretical research on the control strategy algorithm can better guide the engineering practice,Has practical value.