Research On Toothed Jaw Optimization Of The Jacket Leveling Gripper And Its Synchronous Control Technology

Over the past decade, the practices of global large oil and gas field exploration show thatthe onshore oil and gas resources have reached a plateau, and its output growth has been closeto the peak, so that activities are turning to the sea and it will be a significant area of theworld’s oil and gas resource exploitation in the future. The offshore platforms are theessential equipment, among them the pile-supported steel jacket-type platform is widely used.Leveling jacket is a key step of platform installation. Leveling operation for deepwater jacketneeds some special tools, and leveling tool system is a specific hydraulic tool. Due to thegripping and leveling operations can be doing simultaneously, the tool is very important toimprove the installation efficiency and reduce cost. The studies are still in beginning stage inour country, so further research of the technique is necessary to speed up its nationalization.The project roots in the comprehensive project of Offshore Oil Engineering Co. Ltd“hydraulic equipment development for deepwater jacket installation”. In this paper, theleveling operating system both at home and abroad are summarized, the research progress ofthat technique is reviewed, and the problems which need further studied are described.Aiming at two key technologies of leveling tools system, gripping and leveling, the internalrelations between the structural parameters of the gripper’s toothed gripping jaw and levelingforce and bearing capacity of steel pile are studied further in this paper, the method todetermine these parameters is obtained, the mathematical model describing those innerrelations is built, the optimization simulation platform for toothed gripping jaw is constructed,the simplified mathematical model of the electro-hydraulic executive system with longpipeline is researched, which is convenient to apply to engineering, and the synchronizationcontrol strategy of the parallel long pipeline leveling system is presented.By analyzing force condition of the toothed gripping jaw, the stress componentsexpressions at any point in the tooth’s normal section are derived adopting elastic theory, anda reasonable structure is deduced from analysis results. On that basis, the effect of structureparameters on the leveling force is also discussed. And based on the thought of the toothedgripping jaw and pile materials meeting the greatest stress conditions, the methods that maybe used to determine the key parameters are given, which will make a foundation for theserial design of gripping jaw.For structural optimization of the gripping jaw, a comprehensive optimization approachis presented, which incorporates the numerical simulation orthogonal experiment optimization method, the support vector machine regression and the improved geneticalgorithm. Firstly, the orthogonal experiment factors and their levels of numerical simulationare confirmed. Then according to the solution method for multiple wedges contact problem ofthe irregular entities, the finite element model of clamping contact between gripping jaw andpile is established by using ANSYS software, and the finite analysis results for different levelcombination of those factors are obtained on condition that contact pressure between grippingjaw and pile and their stresses are taken as the orthogonal experiment indexes. On that basis,the support vector machine regression models of contact pressure, gripping jaw stress andpile stress are set up, and the forecasting accuracy of regression model are verified by anotherprediction sample set, which shows that these models are validity. Using the regression modelof contact pressure as a target function and that of gripping jaw and pile as constraintfunctions, an optimal tooth structure of gripping jaw is obtained by adopting a kind ofimproved genetic algorithm, and the comparative result between optimal values andcalculated ones of ANSYS indicates that the error is less than1%. In addition, a visiblesimulation platform of structure optimization is designed for the toothed gripping jaw so as tooffer a convenient method for the engineering practice.By analyzing leveling operation features, the pipeline arrangement form is determinedand a linear friction model of long hose is revised based on transmission pipeline dynamics.The leveling system mathematic model considering pipeline effect is derived and the effectson system dynamic characteristics are analyzed. To handle the problem that the model hasvery complex parameters and is difficult to solve, in line with the thought of constructing asuitable engineering model, this paper presents a fast modeling method of long pipeline byusing a spring-damper-mass model based on model reduction and the simplified formula isgiven. Compared with the original model, the simplified one has better approximation.For the movement coupling between different channels of the leveling system with longpipelines in parallel, a circular cross-coupling synchronous control model is set up based onthe idea of the minimum number of correlative axis control. An improved Smith sliding modeprediction control method is proposed to design a tracking error controller and comparisonwith an improved PID Smith predictor indicates that the approach is effective. Thesynchronization error controller of two adjacent channels is designed by employing slidingmode variable structure control method. The results of comparison with an equalsynchronization control show that the synchronous control strategy used in the parallelleveling system with long pipelines is feasible and effective.