A Study On The Identification System For Motion Pattern Of Unmaned Surface Vehicle

The paper aims to propose a multiple-objectives system identification method for motion pattern of unmanned surface vehicle(USV), then analyze and verify this method by the model test. The error functions of the angular velocity in roll, the angular velocity in pitch, the lateral velocity and the heading rate construct the loss function about the rolling motion, pitching motion and maneuvering,then the method with multiplication and division of the respective objective is used to construct the evaluation function about the USV multi-objectives optimization problem, which can be solved by calculating the minimum value of evaluation function by GA method.In order to do the model text, a trimaran USV is designed, the model is made, and also the propulsion system and controlling system are devised and installed. The USV’s motion data acquisition system is designed by using the MSComm serial controls which can collect the motion parameters including the three-axis acceleration, the three-axis angular velocity, the three-axis direction displacement, rudder angle and other parameters.We get the USV model angle, angular velocity, speed, acceleration and steering angle test data from hydrostatic rolling attenuation experiments, hydrostatic pitching attenuation experiments and free self-propulsion maneuverability experiments,build up the mathematical model by the rolling motion balance equation, pitching motion and planar linear manipulate equation,then compile the identification software by VB development platform,into which the experimental data is imported to calculate the identification parameters(hydrodynamic derivative),and finally get the equation of USV motion. Firstly, calculate and analyze the respective motion equation and verify the identifying reliability of each equation,then discuss the multiple-objectives identifying calculation of USV motion on different weights, estimate the relative error and the correlation coefficient between predicting data and experimental data by predicting the motions. If the basic error is limited to less than 10% and the correlation coefficients are above 0.9, it shows that the predicting data are in good tune with the experimental data.The paper finally introduces and verifies the reliability of the method, in which the wavelet analysis is applied to the ship model experimental data de-noising. This paper uses the db4 wavelet function to de-noise USV experimental data, calculates and identifies the processed data and then compares the results with the data which have not been processed to verify the reliability of this method.The main work is as follows:1. According to the parent ship transformation method, design the trisomy owner hull, make a two-meters long USV model,and then check the stability of hull and self-righting performance;design and install the unmanned boat propulsion and steering system, and select the MAU type propeller clover spiral to calculate the optimum speed which is 2800 r / s; calculate the number of rudder blade, rudder and hydrodynamic profile, and check steering gear selection.2. According to the error guidelines, construct the loss function about the rolling motion,pitching motion and maneuvering with the least squares method; and then according to the multi-objective optimization theory, construct the total identification objective function in the form of exponential weighted product with the methord of subgoals multiplication and division.Based on the genetic optimization algorithm,construct a algorithm for the multi-objective system identification, and compile a multi-target system identification program with VB language.3. Use RS232 serial port, MSComm control to compile the VB program and implement the communication between the PC and the sensor; design the data acquisition system about USV motion, mainly including sensor, laser rangefinder and MTi, which can simultaneously capture the USV angle, angular velocity, acceleration, displacement and other motion parameters. By comparing MTi user program, verify the reliability of the data captured by data acquisition system.4. Make the USV multi-target motion test, including hydrostatic roll attenuation experiment,hydrostatic pitching decay experiments and free self-propelled ship model manipulation experiments, the test data were processed and analyzed. While analyzing the hydrostatic roll attenuation experimental data, find that when the trimaran does the hydrostatic roll attenuation motion, it will pause during the fifth cycle,and the author makes a simple analysis about this phenomenon. Before the multi-objective comprehensive identification, the author makes the sub-target identification respectively, analyzes its identification accuracy, and get the result that the identification accuracy of USV rolling equation, pitching equation, horizontal and rotary drift equation is within earshot. Finally calculate and analyze the USV multi-target comprehensive identification from weight, ballast and disturbance.5. Based on the tower fast decomposition algorithm, compile a wavelet denoising program with VB language, which is used in de-noising USV motion data. Compare the de-noising data with the primary data, the results show that wavelet denoising can improve the accuracy of identification systems, which verify the wavelet de-noising effectiveness in the USV motion identification applications.