Mechanismand Machine Theory Vol. 14, pp. 43-59 0094-114XI79/0101-00431502.0010 © Pergamon Press Ltd., 1979. Printed in Great Britain The Determination of Technological Error in Spherical 4-Link Hinged Mechanism D. S. Tavkhelidzet N. S. Davitashvili and N. V. Demurishvili Received 14 June 1978 THE DEVELOPMENT of science and technology is closely connected with the creation of new, modern, high precision mechanisms and machines and with the creation of sensitive devices producing parameters of motion with high accuracy. Mechanisms are applied widely in measuring devices, in computing devices, in recording and registration equipment, in Optical instruments, in distance-controlling devices and others. As is known, in real mechanisms the actual dimensions may be different from the theoretical. The difference wil! be caused by the inaccuracy of mechanism assembly and by the clearances in the bearings of kinematic pairs providing relative displacements of links. In addition the effective forces on the links may cause the deformation of the links. Deformation may also be caused by an alteration of temperature or other effects. Determination of error in the position of a mechanism, when all factors causing the error (technological, installation, temperature, deformation, influence of bearing clearance, position of the driving link, and others) are considered, is expressed by highly complex interrelations. In most cases, the common error A in the performance of a mechanism on the whole may be expressed by a functional dependence of the following form A=A(l,S,t,q,h,¢ .... ), (1) where l is the technological, S is the installation, t is the temperature, q is the strain error, h is the influence of clearance, and ~, is the error in the position of the driving link. In the solution of problems connected with the reliability and accuracy of performance of a mechanism, methods of plotting the mathematical models have acquired great significance; the majority corresponding to the physics of the investigated phenomenon. A great number of works[I-12] are devoted to the problem of plotting of adequate mathematical mechanism models with clearances. The use of the high speed computer allows the user to obtain considerably more information relative to the treatment of kinematic pairs with clearances. Owing to the high accuracy of the computer, the treatment of complex nonlinear differential equations is also possible[13-17]. The problems of accuracy in mechanisms are also examined in[18-27] et al., in which the theory of accuracy of plane hinged, cams, toothed and other mechanisms are given on the whole. The problems of accuracy of space mechanisms, except guided mechanisms, are generally not worked out in spite of the modern attainment of science and technology of the present day. tChairofTheory of Mechanisms andMachines, Georgian Polytechnical Institute byV.I.Lenin, Thilisi, 79,Barnov Street 109app 20 U.S.S.R. 43