| As a kind of new unmanned surface vehicle,the Semi-submersible Vehicle is made up of a high mast above in the surface and the maternal body at underwater.It has a bright development prospect,because it can not only be used as a drag platform for mine-hunting sonar,but also carry the detection equipment for ocean resource prospecting.The application of the Sliding Mode Control(SMC)on the Semi-submersible Vehicle at abominable sea state is studied in this paper.Firstly,the space motion movement models are established and linearized.In addition,the ocean wave model near the water surface is also presented.The analysis of the wave force in frequency domain is given.On the basis of the establishment of the space motion movement equations,the SMC is applied to the control of the Semi-submersible Vehicle under the ocean wave condition.The fundamental principle of the SMC is introduced at first,along with some theoretical analysis for the beingness and accessibility of the sliding mode.Then,aimed at the vehicle researched in this dissertation,the depth and course controllers are designed.The equivalent control which is in of accord with the principles of SMC is designed.The pole setting method is used to design switching function of SMC system.The control strategy based on the constant speed tendency ration is proposed to weaken chattering phenomenon.In the end,after fully proving the seakeeping of the Semi-submersible Vehicle according to the analysis of motion performance,simulation experiments and the water-tank experiment of the Semi-submersible Vehicle's reduced-scale model are performed.The simulation results show that the designed SMC system can converge more quickly and stably compared with the PID control.And the designed SMC system has excellent robust performance no matter whether the ocean wave model exists.As to the water-tank experiment,it completely proved the validity of the Sliding Mode Control in engineering practice. |
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