tailieunhanh - Machine Simulation

INTRODUCTION In the world market for industrial machinery there is a requirement that machines must work with a minimum of down time, especially for machine cells with two or more machines. In the manufacture of these machines there are two important requirements. First, the machine drive must be sized correctly to provide the required torques and thrust. Second, the machine feed servo drive must provide the required accuracy and be stable. To meet these requirements a predictive technique should be used before the machine is manufactured to avoid costly retrofits of the servo drive and or the machine itself. These analysis. | 15 Machine Simulation INTRODUCTION In the world market for industrial machinery there is a requirement that machines must work with a minimum of down time especially for machine cells with two or more machines. In the manufacture of these machines there are two important requirements. First the machine drive must be sized correctly to provide the required torques and thrust. Second the machine feed servo drive must provide the required accuracy and be stable. To meet these requirements a predictive technique should be used before the machine is manufactured to avoid costly retrofits of the servo drive and or the machine itself. These analysis techniques and requirements are shown in Figure 1. SIMULATION FUNDAMENTALS Classical control system analysis involves the use of differential equations to describe a physical system. Most physical systems include some combination of mechanical electrical and hydraulic components. Once the control system is described by differential equations it is desired to solve them for some control variable output in response to a desired input function such as a step input ramp input or other function. In addition the control Copyright 2003 by Marcel Dekker Inc. All Rights Reserved Fig. 1 Trend in world markets for machines. system may have some initial conditions prior to initiating the input. Including the initial conditions in a differential equation requires an expansion of these equations to include all the required integrals and differentiations of these conditions. Likewise any nonlinearities such as transport lags current limits etc. must be included. Describing functions are often used to represent nonlinear conditions. In summary systems of linear and nonlinear differential equations are tedious to solve. The use of a shorthand technique to solve control system differential equations is well known as the Laplace transformation in the s plane. These techniques have been used successfully for the solution of analog-type