The Research On The Control Techniques Of The Mairne Vairable Frequency Hydraulic Steering Gear

The marine variable frequency driving hydraulic steering gear combines the technique of AC Variable Frequency and speed regulation with hydraulic steering gear system. It takes the energy saving advantages of of the AC variable frequency driving hydraulic system and makes up for the low efficiency of the conventional hydraulic steering gear system. However, because the variable frequency AC Asynchronous Motor itself is a high order, nonlinear and strong coupling multi-variable system, it makes the relatively simple traditional hydraulic steering gear system complicated. The research must be carried out to make sure if this new type steering gear could meet the building standard of the marine steering gear in the response speed, control precision and robustness of the control system, so that this new variable frequency hydraulic steering gear can put into commercial applications as early as possible.This paper adopted both theoretical and experimental methods to do the deep researches for the control of the marine variable frequency hydraulic steering gear system and its load characteristics. And in combination with the requirements of Rules and Regulations for the Construction and Classification of Sea-going Steel Ship for the ship steering gear and its control system, this article mainly does the following jobs:First of all, this paper made the theoretical analysis on ship steering gear’s loads, and put forward and established simulation loading system for the ship steering gear, including hydrodynamic load, the sea-wave load and the random impact-load. The experiment shows that the load simulation system can replicate the actual working load of the ship steering gear.Secondly, by means of the experiment, the control dead zone and lagging of the marine variable frequency hydraulic steering gear system were found. Using Ziegler-Nichols principle and the secondary setting method, we optimize the parameters of PID Control Algorithm in the marine variable frequency hydraulic steering gear system primarily, The experiment reveals that the system control with the optimization PID parameter scan reach the requirements of the ship steering gear construction regulation.Moreover, through the analysis of the characteristics of the variable frequency hydraulic steering gear system, we choose the traditional PID, the adaptive neuron PID and the adaptive fuzzy PID algorithms to optimize control of the variable frequency hydraulic steering gear. Using Labview software to establish control programs, we studied the response times, the stabilities and the control precisions of the angle control of steering gear in the conditions of no-load, the hydrodynamic load, and the random impact load. Experiments show among the three control algorithms, the adaptive fuzzy PID control algorithm has obvious control advantages.Finally, in order to improve the robust performance of the control of the variable frequency hydraulic steering gear system in the condition of the random shock load, we select the rate of change of oil pressure in the cylinder on behalf of the random shock load, and introduce this rate of change to the adaptive fuzzy PID control algorithm. Thru experimental results show that the system control performance has been improved obviously.Based on the measurement and control programs in the Labview software, this paper establishes the load simulation system of marine steering gear, and finds out the adaptive fuzzy PID algorithm with load factor.. The experimental results show that the control accuracy reaches0.1degrees of the variable frequency drive hydraulic steering gear; there is no overshoot in the rudder angle control; there is no more than0.2degrees rudder angle change with the random impact load; the control performance of steering gear is greatly improved comparing with the requirement of Rules and Regulations for the Construction and Classification of Sea-going Steel Ship for the ship steering gear.This paper puts forward the control method based on the load, makes the system robust performance improved. This paper research lays a foundation for the practical vessel application of the variable frequency hydraulic steering gear system.