【正文】 希望老師能指點(diǎn)。這次畢業(yè)設(shè)計(jì)的圓滿完成還需感謝我的指導(dǎo)教師田和強(qiáng)老師的細(xì)心輔導(dǎo)，同時(shí)感謝曹連民老師、張鑫老師、張同軍老師等各位專業(yè)課老師的精心培養(yǎng)。由于此次本人的知識(shí)和技術(shù)有限，所以設(shè)計(jì)必不能盡善盡美，存在著的瑕疵未未還望老師批評(píng)指導(dǎo)。附錄 The designer aims to find the best design for the mechanical system considered. Part of this effort is the optimal choice of some selected parameters of a system.Fig. 1 Hydraulic supportMethods of mathematical programming can be used, if a suitable mathematical model of the system is made. Of course, it depends on the type of the system. With this formulation, good puter support is assured to look for optimal parameters of the system. The hydraulic support () described by Harl(1981) is a part of the mining industry equipment in the mine VelenjeSlovenia, used for protection of working environment in the gallery. It consists of two fourbar mechanismsFEDG and AEDB as show in . The mechanism AEDB defines the part of coupler point C and the mechanism FEDG is used to drive the support by a hydraulic is required that the motion the support ,more precisely, the motion of point C in , is vertical with minimal transversal displacements. If this is not the case, the hydraulic support will not work properly because it is stranded on removal of the earth machine. A prototype of the hydraulic support was tested in a laborarory (Grm 1992). The support exhibited large ransversal displacements, which would reduce its employability. Therefore, a redesign was necessary. The project should be improved with minimal cost if possible. It was decided to find the best values for the most problematic parameters a1,a2,a4 of the leading fourbar mechanism AEDB with methods of mathematical programming. Otherwise it would be necessary to change the project, at least mechanism AEDB. The solution of above problem will be different because of tolerances of varoious parameters of the system, whichis why the maximal allowed tolerances of parameters a1,a2,a4 will be calculate, with help of methods of mathematical programming. Two fourbar mechanisms deterministic model of the hydraulic supportAt first it is necessary to develop an appropriate mechanical model of the hydraulic support. It could be based on the following assumptions:the links are rigid bodies,the motion of individual links is relatively show.The hydraulic support is a mechanism with one degree of freedom. Its kinematics can be modeled with synchronous motion of two fourbar mechanisms FEDG and AEDB (Oblak et ). The leading fourbar mechanism AEDB has a decisive influence on the motion of the hydraulic support. Mechanism 2 is used to drive the support by a hydraulic actuator. The motion of the support is well described by the trajectory L of the coupler point C. Therefore, the task is to find the optimal values of link lengths of mechanism 1 by requiring that the trajectory of the point C is as possible to the desired trajectory K. The synthesis of the fourbar mechanism 1 has been performed with help of kinematics equations of motion given by Rao and Dukkipati(1989). The general situation is depicted in . Trajectory L of the point C . Trajectory L of the point CEquation of trajectory L of the point C will be written in the coordinate frame considered. Coordinate x and y of the point C will be written with the typical parameters of a fourbar mechanism a1a2…..a6. The coordinates of points B and D are =cos, (1)=sin (2) =cos(+) (3)=sin(+) (4)The parameters A1a2…..a6 are related to each other by+= (5)()+= (6)By substituting （1）—（4）into（5）—（6）the response of the support are obtained as(Xcos)+(Ysin)=0 (7)[Xcos(+)]+[Ysin(+)]=0 (8)This equation represents the base of the mathematical model fore calculating the optimal values of parameters a1,a2,a4. modelThe mathematical model of the system will be in the from proposed by Haug and Arora (1979):minf(u,v) （9）subject to constraints：（u,v）0,I=1,2……..,m. （10）and response equations:(u,v)=0,j=1,2,….,m. （11）The vector u= is called the vector of design variables，v=[v……v]T is the vector of response variables and f in (9) is the objective function. To perform the optimal design of the leading fourbar mechanism AEDB, the vector of design variables is defined as: U=[] (12)And the vector of response variables as:v=[xy] (13)The dimensions , of the corresponding links are kept objective function is defind as some “measure of difference” between the trajectory L and the desired trajectory K as f(u,v)=max[g (y)f(y)] (14)where x=go(y) is epuation of the curve K and x=f（y）is the equation of the curve L. Suitable limitations for our system will be chosen. The system must satisfy the wellknown Grassh of conditions（+）(+), (15) （+）( +)0. (16)Inequalities（15）and（16）express the property of a four bar mechanism, where the links may only oscillate. The condition （17）Prescribes the lower and upper bounds of the design variables. The problem (9)(11) is not directly solvable with the usual gradientbased optimization methods. This could be circumvented by introducing an artificial design variable un+1as proposed by Hsieh and Arora (1984). The new formulation exhibiting a more convenient form may be written as min (18)subject to g (u,v)0,i=… （19） f(u,v)0 ， （20）and response equationsh(u,v)=0,…..,m, （21）