Research And Development On Measurement And Control System For Wire-driven Support Mechanism Of Ship Model

In recent years,with its advantages,such as high accuracy,large loading capacity,small interference,light weight and little inertia,cable-driven parallel mechanism has been applied in medical rehabilitation,heavy load handing,air tunnel test and so on,but it has not yet been found in the towing tank test according to the domestic and foreign literature.In this paper,the application of cable-driven parallel mechanism in towing tank test is explored and studied.This paper is based on applied basic research subject study on flexible parallel support mechanism for performance testing of yachts and its control which is originated by ministry of transport.Based on the self-developed cable-driven support mechanism for ship model,the paper aims to develop a measurement and control system to realize six-dof motion of cable-driven support mechanism for ship model and research on kinematic position control strategy.The researches carried out in this paper include:1)According to the function of cable-driven flexible support mechanism and requirement of application environment,the structure of control scheme support mechanism and hardware platform of its measurement and control system were studied.Firstly,the correlation between structure of supporting mechanism and cable,and the requirements of connection between cable and controlled model were analyzed,and the six DOF support mechanism with eight cables was determinted.Based on vector analysis method and numerical analysis method,the kinematic model based on Cartesian coordinate system was established to obtain the mapping relationship between model pose and eight cables.According to the requirements of ship model’s attitude control in towing tank test,the multiple-input / multiple-output synchronization control hardware platform was designed.2)It was verified by experiment that the closed-loop control of Clipper can not meet the requirements of attitude control,so the cascade control scheme based on the cable length and attitude angle of controlled model was determined.Because of large calculation,the main circuit tries to adopt PID control algorithm and single neuron PID control algorithm,and the sampling period was different in the main and auxiliary circuits.3)With labview as software development platform,the software of measurement and control system was developed by modular structure method.The software system includes motion control module,data acquisition and storage module,parameter setting module and hardware test module,which achieve the six-dof motion control of controlled model,the real-time data acquisition,display and storage.4)The PID controller and single neuron PID controller were adopted as main loop controller for attitude angle control test respectively,and result of attitude angle control accuracy is 2% and 1%.The test results show that the software and hardware design of measurement and control system and its control strategy are feasible and effective.Due to the limitation of the experiment condition,the paper only used position control mode to study the kinematics control of supporting mechanism,which is useful to the try and explore of researching on follow-up force / hybrid control strategy and carrying out ship model resistance test.