Based on the im provem ent on the conventional sectional lum ped param eter bond graph and introduction of the kinetic friction factor， a new sectional lum ped param eter m odel using bond graphs for dynam ic response investigation of lam inar line was w orked out．The goodness of identity betw een the sim ulation results curves and that of M O C is com paratively ideal，w hich implies that the new model has adequate accuracy． The new model has less calculated param eters，sim pler structure，and is suitable for m odeling com plex line system s．

Slipper socket is one of the m ost im portant friction pairs in water hydraulic piston pump．which endures the highest contact stress in the pump．Due to the bad lubricity of water，slipper socket of w ater hydraulic pum p always encounters serious tribology problem s．To ravel out this m atter ultimately，new structures of slipper socket were designed introducing hydrostatic bearing in the friction pair．which could increase hydrostatic action，while the contact area did not reduce at the same time．The new structures can cut down 30% of the contact stress between slipper socket pairs．Less abrasion dnd a long life-span can be obtained through the structure improvement of the water hydraulic piston pump．

T he structure and application of hydrostatic slipring are introduced．Com pared with hydrostatic bearing and port plate，hydrostatic slipring is a self—balance com ponent and its function is sim ilar to that of brush slipirng． The conclusion is that hydrostatic slipring is the best choice when the fluid power is transferred between rotating and static com ponents．

The general m ethod for the design of the digital valve controller is presented． In the digital valve a stepper m otor is adopted as the electrical to m echanical interface．To sustain both response speed and the accuracy，the conventional stepping control can no longer meet the requirem ents in the digital valve．Therefore，a special algorithm is developed to control the stepper m otor continuously． he designs for both the software and hardware of the digital valve controller are discussed．

A construction tele—robotic system that has wide applications is developed such as restoration work in a stricken area．The system consists of a servo—controlled construction robot，two joysticks to operate the robot from a remote place and a 6-DOF motion base．The operator sits on a seat attached on the m otion base．A vital problem that m ust be solved in such a system is how to convey adequate presence of working site to the operator in high quality．In this paper，a control m ethod of em ploying the 6 DOF m otion base is investigated to generate such a 6-DOF realistic motion just only according to the signals of six acceleration sensors on the construction tele-robot．The validity of this m ethod has been confirm ed experim entally，i．e．， not only the
each motion of roll，pitch，yaw ，surge，sway and heave of the construction tele-robot can be simulated accurately by the 6-DOF motion base，but also the complex motion can be done in high quality．

In order to improve the work efficiency of the automatic power steering system ，the energy consum ing of the center-opened and center-closed kinds of hydraulic power steering system are analyzed by using the statistic data acquired from experim ents in the condition of the typical route．After evaluating the econom y and environm ental protection of the four kinds of steering system in different principle， we can get the conclusion that several technological problems should be solved before the center—closed hydraulic pow er steering system can be widely used in practice though it has great advantage in energy saving．

To design a pneum atic system and choose an elem ent m odel more rapidly and handily，a model choice system for single pneum atic elem ent and the pneumatic sim ulation system are founded based on the internet WWW service．That system was integrated pneumatic technology and net technology．It was constituted by ASP(active server page)and SQI server．The client cooperated with the server in simulation．The systems update can be carried out only in the server，so it is easy and rapid to m anage． If those system s are available，anybody can use that service to design and simulate pneum atic system at anyw here as long as he or she connects to Internet．

Some comm on questions are discussed and analyzed in w hich the hydraulic system design of electro—hydraulic servo static＆．dynamic universal test machine，which include load matching，servo valve applying，actuator natural frequency improving，clamping device and cooling system design．Some principles are put forward to which design the sim ilar hydraulic system ，the principles was verified by to design 1 MN electro-hydraulic servo static＆dynamic universal test machine and yield good  result，it can serve as a reference for engineers w ho w ant to design this kind of test machines．

How to eliminate the superfluous force of a loading system is one of the key problems to design a load simulator．In order to analyze the load simulator，using the bond graph modeling and simulation method，the expanded bond graph model of the load simulator combined with a ship steering electrohydraulic position servo system was established．And then，a hybrid control based on CMAC neural network was proposed．The performances of the proposed controller were evaluated through sim ulations．The sim ulation results show that the proposed controller can effectively eliminate the superfluous force and fairly im prove the dynam ic loading perform ances of the electrohydraulic load sim ulator than that of conventional constant PID controller with the compensation network based on the structure invariance principle．

Aimed at the problem of high precision sychronism of two hydraulic cylinders in engineering，this design adopted a new function m aterial，a giant m agnetostrictive material，which realized the transition from electro-signal to mechanical signal，and utilized a Singlechip that collected and disposed the displacem ent feedback signal of two hydraulic cylinders．Consequently the high precision synchronous control could be achieved． The results of the analysis for the valve characteristic show that this valve can realize the high precision synchronous control of two hydraulic cylinders and has the anti-jamming capacity on a certain extent．Therefore this valve can solve the problem commendably．

The servo-screw mechanism which is designed according to the double-degree-freedom theory of a single spool possesses such characteristics as simple structure and strong anti-pollution capability etc．Mathematical modeling and parametric optimization of this mechanism are presented，and the performances of this mechanism are introduced．

The relationship between the bending angular degree of the artificial joint and the pressure of com pressed air is first established by using the theory of elasticity m echanics． Then，the mathematical model of the system is built up and the pulse response of the system is theoretically investigated though numerical simulation．The artificial joint is at last experimentally tested and it is concluded that the joint has a quick response to the input of signal and fits to simulate the bending or stretching motion of human join．

Special designs are used tO fit the usage of hydraulic pum ping unit on ocean platform ．It is completely controlled by hydraulic circuit，and a close loop hydraulic circuit with several hydraulic accum ulators is used to save energy． Experimental results show that the design of hydraulic control system is correct and it works properly．

The structure of the pulse valve was analyzed．According to the theory of hydromechanics， with the study of failure and the domestic and foreign new technology of valve， the structure of the pulse valve which was not effective enough was improved． Significant benefit has been made with the use of the improved structure for a long period．

The optimum water film thickness of slipper in water hydraulic axial piston pump were caculated and analyzed．The results show that balance style hydrostatic bearing design of slipper is not suitable to be used． Structure，structural param eter and m aterials of slipper in water hydraulic axial piston pump are analyzed and designed．