Research On Motion Control And Its Networked Technology For Wave Maker System

As the marine resources are exploited in depth, people desire more knowledge about ocean. The wave maker system, which is important equipment for simulating wave, is playing more important role in marine research. Wave maker system is large-scale automation equipment which is developed from multi-disciplinary integration such as wave theory, automatic control and mechanical engineering. Base on the fundamental principle of automatic control, motion control system is very significant in system building and could determine the performance of wave maker system. Moreover, The emergence of the networked motion control system brings new opportunities and technical challenges to the developing of wave maker system. Under this background, this dissertation further studies networked motion control system as the purpose for devising a high performance networked wave maker system. The specific content includes:First of all, motion control model of a wave maker system is established according to the actual physical system and the characteristics of system load and moment of inertia is analyzed. Combined with vector control and space vector pulse width modulation technique, an adaptive PID control algorithm is proposed based on wavelet neural network to overcome the difficulties encountered when applying traditional PID to a nonlinear, strong coupling, and multivariable motion control system. This control method well utilizes the good function approximating ability and adaptive capacity of wavelet neural network, and provides a new idea to solve the control problems existing in complex nonlinear, uncertain system. In order to improve the tracking accuracy of the position servo system, an adaptive backstepping control strategy based on wavelet neural network is proposed considering both current and position tracking performance so as to ensure the global asymptotic stability of the system variables and obtain good dynamic and static performance and robustness. On this foundation, sliding mode control is adopted in design to further improve the disturbance rejecting capability of the system. Meanwhile, new wavelet neural network architecture is applied to accelerate the system convergence. Therefore a new adaptive sliding mode backstepping control strategy is obtained, and the simulation results prove that the strategy has superior tracking performance and robustness.Then, networked wave maker motion control system is analyzed and modeled including single-axis and multi-axis model. For the problems brought to the system by network delay in model analysis, wavelet neural network is proposed to predict the network delay, which is able to output the predicted next sample latency value according to past delay sequence. This neural network is updated in real-time via training algorithm so as to ensure the accuracy of the predicted output. Through the experimental analysis for the actual Ethernet delay data, it shows that this prediction model can effectively estimate network delay, so it can be used in actual application. Delay effect in the motion control system is analyzed and Smith predictor is considered to remove the delay out of closed-loop system to ensure the stability of system. In order to overcome the shortcoming that Smith predictor is sensitive to model parameters, an adaptive predictive control algorithm with disturbance compensation is proposed. This algorithm utilizes wavelet neural network to adaptively adjust the reference model output to approach the actual system and feedforward the system disturbance. Simulation results show the proposed algorithm can effectively suppress the disturbances, automatically compensate for model uncertainty and has good dynamic and static performance. To satisfy the multi-axis synchronous control requirements of wave maker motion control system, an adjacent coupling sliding mode synchronous control strategy is proposed, suppressing the uncertainty of the system by sliding mode control in controller designing, to obtain good position servo synchronization performance by eliminate the tracking error and synchronization error together.Further more, a networked motion control system based on the EtherCAT standard industrial Ethernet protocol is constructed and the hardware and software design of the network controller and DSP controller is accomplished. The communication between the master and the DSP controller is realized by using real-time industrial control software in the master and network controller. DSP controller communicates with network controller and realizes the motion control algorithm. When the control commands from master are transmitted via the network to the controller, the controller makes use of the fuzzy PID control algorithm programmed inside to generate the drive signal, which is converted via differential circuit and transmitted to the driver for controlling the movement of the motor. Experimental results demonstrate the performance of this networked motion control system is good and prove the feasibility of this design.At last, on the basis of network controller and controller designed on previous text, a networked motion control system is constructed by designing the hardware of drive part and motion control software, and it is applied in actual wave maker system. A few of experiments is carried out including motor control performance test, single-axis tracking and multi-axis synchronization performance test and actual wave making capability test in experimental flume. The results demonstrate the proposed servo motion control system has excellent performance and reliable operation.