Setting up Compax3 Positioning via digital I/Os190 192-120101 N11 C3I11T11 November 20074.4.7. Load identificationIn this chapter you can read about:Principle ...........................................................................................................................................190Boundary conditions ........................................................................................................................190Process of the automatic determination of the load characteristic value (load identification) .........191Tips ..................................................................................................................................................192Automatic determination of the load characteristic value: of the mass moment of inertia with rotary systems of the mass with linear systems4.4.7.1 PrincipleThe load characteristic value is automatically determined.For this it is necessary to excite the system additionnally with a signal (excitationsignal = noise).The excitation signal is fed into the control loop. The control loop dampens theexcitation signal. Therefore, the superimposed control loop is set so slowly byreducing the stiffness, that the measurement is not influenced.A superimposed test movement is additionally possible. This helps to eliminatepossible mechanical effects such as rubbing caused by friction.4.4.7.2 Boundary conditionsIf the control is instable before the beginning of the measurement, please reducethe stiffness (in the optimization window at the left bottom)The following factors can disturb a measurement: Systems with high friction (e.g. linear actuators with sliding guide)Here,the systems where the static friction is considerably higher than the kineticfriction (slip-stick effect) are especially problematic. Systems with significant slack points (play) Systems with "too light" or susceptible to oscillation bearing of the total drive(rack).Formation of rack resonances. (e.g. with gantries,...) Non constant disturbance forces which influence the speed development. (e.g.extremely strong slot moments)The effects of the factors one to three on the measurement can be reduced byusing a test movement.caveat emptor (exclusion of warranty)Due to multiple possibilities for disturbing influences of a real control path, wecannot accept any liability for secondary damages caused by faultily determinedvalues. Therefore it is essential to verify all values automatically determined beforeloading them into the control loop.
