挖掘機(jī)-外文翻譯-外文文獻(xiàn)中英翻譯-閱讀頁(yè)
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【正文】 e model of boom hydraulic system of excavator was simplified according to engineering and by considering the force equilibrium， continuous equation of hydraulic cylinder and flow equation of electrohydraulic proportional valve；at the same time，the estimation methods and equations for the parameters of model were developed．2 Overview of robotic excavatorThe backhoe hydraulic excavator studied is shown in ．In ，F(xiàn)c presents the resultant force of hydraulic cylinder, gravity of boom，dipper, bucket and so on at point B，whose direction is along cylinder AB； Fc can be deposed into Fcl and Fc2，and their directions are vertical and parallel to that of O1B，respectively；ac is the acceleration whose direction is same to that of Fc，and ac can be deposed into acl an d ac2 too；G1，G2 and G3 are the gravity centers of boom，dipper and bucket，respectively；ml，m2 and m3 are the masses of them，and their values can be given by experiment( m1=，m2= and m3=)；Ol，O2 and O3 are the hinged points；G1180。and G3180。s)；w is the area gradient of orifice，m2／m；ρ is the oil density, kg／m3。s／m． Simplified model of electro—hydraulic proportional systemAfter the Laplace transform of Eqns．(4)—(6)，the simplified model can be expressed as (7)where Y(s) is the Laplace transform of y。b1=V1V2。a1=BcV1V2。the motional situation and the posture of excavator’s arm．Moreover，these parameters are time variable. So it is quite difficult to get accurate values and mathematic equations of these parameters. To solve this problem，those important parameters of model were estimated approximately by the estimation equation and method proposed in this work． Equivalent mass estimation for load on hydraulic cylinderThe load of boom hydraulic cylinder(it is assumed there is no external load)consists of boom，dipper and bucket．In ，boom，dipper and bucket rotate around points O1，O2 and O3，respectively．So their motions are not straight line motions about the cylinders, that is to say, their motion directions are different from Y in Eqn.(5)．So，m in Eqn.(6)cannot be simply regarded as the sum mass of boom，dipper and bucket．Considering O1 at an axis of manipulator, the torque and angular acceleration can begiven as follows：(8)where M and are the torque and angular acceleration of manipulator to O1，respectively。m2，and it can be written as follows： (10)J1, J2 and J3 are the moment inertia of boom，dipper and bucket to their own bary center respectively．The values of them can be obtained by dynamic simulation based on the dynamic mode, J1=m, J3= ，G2180。；，respectively．Then，the counter force of load is (13) Estimation for flow gain coefficient of valveThe flow of pump can be measured by flow transducer． The instrument used in this work was Multi—system 5050．The step response of flow of boom cylinder under the electro—hydraulic proportional valve controlled by the step curent is shown in ．At the same time，the curve verifies Eqn．[11]．Based on the experiment curve，the range of KqKl can be identified according to Eqns.(1)and(4)．And then，according to data in ，we can get：KqKl=104m3/(sA) ，where KI is the current gain of electro—hydraulic proportional valves．From: Journal of Central South University (English) 2008 Vol 15 No. 3 pages 3823
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