nternational ournal of Engineering Trends and Technolog (ETT) olue 9 Nuer 6 - Mar 04 Research on the haracteristics of Electro-hdraulic Proportional Steering Sste in Self-Propelled Modular Transporter LU Liqun WNG iujing FN Yujuan WNG Hantao School of Transportation and ehicle Engineering, Shandong Universit of Technolog, Zio, Shandong 55049, hina stract ccording to the steering ode of self-propelled odular transporter, the ke coponent of the steering sste with electro-hdraulic proportional directional valve was designed The odel of the transporter steering single loop sste was estalished through the ethod of power ond graph and was siulated The dnaic characteristics of steering circuit were analzed Results indicate that the sste has good steering stailit and dnaic response Kewords self-propelled odular transporter, electro-hdraulic proportional valve, power ond graph, siulation, dnaic characteristics NTROUTON The self-propelled odular transporter(spmt) is ultiple axis vehicle which has various steering odel such as straight, olique line, transverse, spin The operation, stailit and securit of the SPMT depend on its steering perforance in the process of working [] single SPMT has either six or four axle lines, with each axle line consisting of four wheels arranged in pairs Each pair of wheels can pivot 360 aout its support point The SPMTs can e rigidl coupled longitudinall and laterall to for ultiple units The traffic safet is influenced f the design of SPMT steering sste is unreasonale which can cause utual influence etween different tire angle [] Electro-hdraulic proportional control sste is widel used in ulti-axis tred vehicle which has high control precision, rapidit and stailit copared with the traditional switch control sste [3] The steering sste of SPMT can effectivel perfor its straight, olique line, and spin various steering odes with strong anti-pollution ailit, high stailit of steering ecause it adopts electro-hdraulic proportional valve as the ke coponent [4] The factors influencing the static and dnaic characteristics of electro-hdraulic proportional directional valve were studied through estalishing the odel of steering sste in order to iprove the stailit and control accurac of steering sste THE ELETRO-HYRUL PROPORTONL STEERNG SYSTEM OF SPMT The analsis on steering ode n order to ensure that the SPMT with load can close to all processes in the scene, and avoid the other equipent as well as eet the work requireents, SPMT should have e different steering odes such as straight, olique line, transverse which ake the handling of overloaded cargo safet and efficienc ecause the weight and volue of goods transported is ver large The steering sste working ode of 50t SPMT with 4-axis is shown in figure (a)olique line ()Transverse (c)pivot sterring (d)front swa and wiggle-tail SSN: 3-538 http://wwwijettjournalorg Page 309
nternational ournal of Engineering Trends and Technolog (ETT) olue 9 Nuer 6 - Mar 04 (e)steering of half sector Fig Steering ode of four axis SPMT (f)steering of sector The steering angle should reach to 80 (that is angle of positive and negative steering can e to 90 ) in the steering ode of SPMT which can realize transverse oving and various steering odes The steering echanis with unifor speed and eas controlling is required to e stale transission ratio, high efficienc, high reliailit, ig steering angle and sooth steering The SPMT can coplete various steering odes which ainl depend on the perforance of control sste f the accurac of control sste is too low, coordination oveent precision etween axles is reduced which result in realizing the approxiate pure roll around the center of steering difficultl and aking the tire wear quickl, even a lead to a rollover accident in the case of load B The design of steering sste with electro-hdraulic proportional control Electro-hdraulic proportional control steering is widel used in large ulti-axle steering vehicle for its large driving force, high control precision and the flexile wa of energ conversion The steering sste of SPMT was designed adopting electro-hdraulic proportional control sste This steering sste is coposed of three parts including driving echanis, hdraulic sste and control sste There are the instruction signal processing and aplification coponents, hdraulic pup, electro-hdraulic proportional valve, hdraulic otor, load, ngle sensors in steering sste(s shown in figure) The hdraulic steering of SPMT with electro-hdraulic proportional control sste realize the precise control of each wheel steering and tires to approxiate roll closedloop control of each wheel rotation with angle sensor The structure of control sste is shown in figure 3 oil sources input signal output angle controller aplifie proportional valve hdro-otor load angle sensor Fig onstitution of electro-hdraulic proportional control sste SSN: 3-538 http://wwwijettjournalorg Page 30
nternational ournal of Engineering Trends and Technolog (ETT) olue 9 Nuer 6 - Mar 04 ngle sensor wheel steering achanis hdro-otor ngle sensor wheel steering achanis hdro-otor ngle wheel steering achanis hdro-otor proportional valve engine Hdraulic pup controller can-us proportional valve proportional valve Handling device controlle controlle When the steering instructions of steering wheel are send, the controller adjust opening of valving eleent sending control signal to proportional valve The control signal was acquired parsing out the expectations of each wheel angle according to the estalished kineatics odel of vehicle steering and the input angle of steering wheel t the sae tie, the steering angle of each steering wheel was controlled controlling the flow of hdraulic otor with electro-hdraulic proportional valve ngle sensor is ounted on the hdraulic otor through which the actual steering angle is feedack to the controller The latest actual wheel angle is received N us The output of hdraulic otor was solved The N us sends corresponding control instruction to /O nodes in order to reduce the deviation The process of control is ccling until the steering angle of each wheel is expected The closed loop of the whole sste can satisf the requireent of high precision of SPMT steering sste THE ESTBLSHMENT OF ELETRO-HYRUL PROPORTONL STEERNG SYSTEM MOEL The working process of the circuit with electro-hdraulic proportional control The single loop sste of electro-hdraulic proportional steering sste of SPMT is shown in figure 4 When there is not current into the electroagnet, the reversing valve is in Fig3 The steering sste of SPMT id-position ecause each port of proportional relief pressure valve is not connected each other When there is current entering into the electroagnet, electro-hdraulic proportional pressure reducing valve start to action and shift to the right position The pressure Ps is fored when the hdraulic oil is flowed into controlling chaer of left side of reversing valve in the ain hdraulic sste through valve port a t this point, the ain spool of reversing valve is shifted to right position and connected to valve port P under the pressure of Ps and spring force When a certain flow of oil is entered into the hdraulic otor, the hdraulic otor drives planet gear rotating and akes wheels rotating n the sae wa, when there is current entering into the electroagnet, electro-hdraulic proportional pressure reducing valve starts to action and valve port is unlocked The pressure Ps is fored when the hdraulic oil is flowed into controlling chaer of right side of reversing valve in the ain hdraulic sste through valve port The pressure Ps pushes ain spool of reversing valve oved to left position and connected to valve port PB SSN: 3-538 http://wwwijettjournalorg Page 3
nternational ournal of Engineering Trends and Technolog (ETT) olue 9 Nuer 6 - Mar 04 B The power ond graph odel of proportional steering sste Electro-hdraulic proportional control sste was adopted in the steering sste of SPMT The steering sste is affected nonlinear influence factors such as the flow and pressure characteristics and oil copressiilit in working process [5] Power ond graph ethod is a large nonlinear sste odeling ethod suitale for ulti-input and ulti-output So the odel of SPMT steering sste was estalished power ond graph ethod The single axis steering sste of SPMT is coposed of variale pup, relief valve, proportional pressure reducing valve, reversing valve and hdraulic otor, etc n the process of odeling, leakage of the pipe joint is ignored and densit, viscosit and odulus of elasticit of the oil are assued as the ideal state that unaffected with change of pressure and teperature Based on coponents of SPMT steering sste, Sste ond graph odel is set up according with the principle of ond graph odeling [6] [7] [8] (as shown in figure 5,take steering right as an exaple) Fig4 Siplified steering sste of single axle SPMT The eaning of each solic in ond graph is as follows: S - source of hdraulic oil; P - output pressure of f hdraulic pup ; - hdraulic pup liquid capacit of the oil cavit; R - liquid resistance of hdraulic pup leakage; R - fluid resistance of relief valve; Fig5 Power ond graph Steering ode of spool to right Q -overflow discharge of relief valve; Rg - fluid resistance of tue; P - inlet pressure of reducing valve; P - outlet pressure of reducing valve; Qx - valve port flow of reducing valve; resistance with spool openings of reducing valve; area of proportional reducing valve; Rx - fluid -spool FS - electroagnetic SSN: 3-538 http://wwwijettjournalorg Page 3
nternational ournal of Engineering Trends and Technolog (ETT) olue 9 Nuer 6 - Mar 04 force; - liquid capacit of reducing valve output chaer; K - spring stiffness of reducing valve; -spool ass of reducing valve ; R - spool viscous daping coefficient of reducing valve; - spool displaceent of reducing valve; - spool area of reversing valve; h - spring stiffness of reversing valve; h - spool ass of reversing valve; - spool displaceent of reversing valve; RP - fluid resistance of P port of reversing valve; RBT - fluid resistance of BT port of reversing valve; - liquid capacit of reversing valve port ; B - liquid capacit of reversing valve port B; R - - the oent of inertia of the load of hdraulic otor; load; a - hdraulic otor displaceent of ever rotation; - output angular velocit of hdraulic otor; Se - tank Based on ond graph ethod of state equation is derived, and the independent variale of capacitive eleent and inertial eleent integral as state variales, Q ; Q ; B QB ; Q ; F ; T v ; h Fh ; v ; The otained state equation of sste is as follows: Sf Q R Q P Q () Q () j R FS (3) (4) h (5) h a B h h QP a a QBT R B a The flow Q of relief valve and the port flow Q P, QBT of reversing valve are coputed as follows: Q x Q R K ( K 0, P P ( P P P P ) 0, ( P P ) ), P P 0 / /,0, B (6) (7) (8) (9) (0) () 0, 0 / QP( BT ) K PP ( BT ),0 () / KWPP ( BT ), Where P is overflow pressure of relief valve; P is the P pressure difference of P port of reversing valve; P is the BT pressure difference of BT port of reversing valve ; is the displaceent when valve port opening of reducing valve is the largest; is the displaceent when valve port opening of reversing valve is the largest THE SMULTON N NLYSS ON SYSTEM The estalishent of siulation odel on sste ccording to the estalished power ond graph and the sste state equation, the Siulink odel of steering sste of single axis SPMT is estalished with MTLB/Siulink software( as shown in figure 6) SSN: 3-538 http://wwwijettjournalorg Page 33
nternational ournal of Engineering Trends and Technolog (ETT) olue 9 Nuer 6 - Mar 04 Fig6 Siulation odel of single axle electro-hdraulic proportional steering sste B The analsis on siulation results The input signal of proportional electroagnet is voltage which adopts step signal input (solid line) and rap signal input (dotted line) respectivel The input curves of voltage are shown in figure 7 The variale curve of spool displaceent of proportional reducing pressure is shown in figure 8 The outlet pressure curves of proportional reducing pressure valve are shown in figure 9 The variale curve of ain spool displaceent of reversing valve is shown in figure0 The inlet flow curve of reversing valve is shown in figure The dnaic response curve of output angular velocit of hdraulic otor is shown in figure Fig8 urve of the proportional relif valve displaceent Fig7 nput the voltage signal Fig9 Output pressure curve of proportional relif vale SSN: 3-538 http://wwwijettjournalorg Page 34
nternational ournal of Engineering Trends and Technolog (ETT) olue 9 Nuer 6 - Mar 04 Fig0 urve of the change valve spool displaceent Fig nput flow rate curve Fig urve of hdro-otor angular velocit t can e seen fro figure 8 and figure 9 that the spool of pilot valve oves rapidl under the action of electroagnetic force when there is electric current through the electroagnet and the output pressure P acts on spool of reversing valve The load on spool of reducing pressure valve reaches to alance when the outlet pressure is equal to the electroagnetic force with the increase of P When the sste reaches to stead state at t=0s, the port of guide reducing pressure valve is closed, so the sste has less flow loss and good dnaic characteristics Fro figure 0 and figure, t can e seen that the sste flow is changed with the change of ain spool opening of reversing valve The sste flow has larger fluctuation efore the sste reaches stead state and voltage of instructions suddenl changes, however the change process is relativel stale Figure and Figure shows that the sste flow increases with the oil through reversing valve under the action of P on spool of reversing valve The angular velocit of hdraulic otor increases soothl and reaches to stead state with force alance of valve spool Therefore, the sste steering is sooth and has good dnaic response features ONLUSONS The steering sste of self-propelled heav platfor car is taken electro-hdraulic proportional reversing valve as the ke eleent which can eet the requireent of vehicle steering pattern such as the straight, olique line, and spin The dnaic characteristics of steering sste are analzed through the MTLB/Siulink siulation platfor The analsis results show that the sste has good stailit and good dnaic response REFERENES [] Lu Li-qun, Shi Bo-qiang, Guo Peng-an,etal Stud of ontrol in Muti-steering Pattern of Self-propelled Heav Platfor ehicle[] oal Mine Machiner, 008,9(8):64-66 [] Gao iuhua,zhang hunqiu,li Yanling,etalSteering control odes for ulti-wheel steering sste[] Hoisting and onveing Machiner, 006(6):5-8 [3] Wu Genao,Qiu iuin,wang Qingfeng,etal Electrohdraulic proportional technique in theor and application[m]hangzhou:zhejiang Universit Press, 006:7- [4] Zhao ingi, Wang Zhiong, Qin Yaning, Wang inxiang Siulation nd Experiental nalsis Of Electro-Hdraulic Steering ontrol Sste For TL900 Transporting Girder ehicle[] hinese ournal of Mechanical Engineering, 007,43(9):65-68 [5] Kou Weiguang,Zhou Huiqun,Yang ing Stud of Modeling Method for Hdraulic Sste[] Machiner & Electronics, 00(5):4-7 [6] Wang ZhongshuangTheor of power ond graph and application in sste dnaics[m]harin:harin Engineering Press,007:8-5 [7] Panter H M nalsis and design of engineering sstes[m] aridge: The MT Press, 960:3-53 [8] Karnopp, Margolis L, Sste R naics odeling and siulation of echatronic sstes[m] New York: ohn wile and sons, 005:3-53 SSN: 3-538 http://wwwijettjournalorg Page 35