tailieunhanh - Machine Considerations

MACHINE FEEDBACK DRIVE CONSIDERATIONS Machine Feed Drive Considerations for Resolver Feedback The usual configuration for resolver position feedback is to have the resolver geared to the servo drive motor. Computer-aided design programs for hydraulic drive sizing are based on the fact that the hydraulic resonance is the predominant resonance in the servo loop. With electric drives the mechanical time constant is not of prime consideration since it can be compensated for with the drive compensation | 12 Machine Considerations MACHINE FEEDBACK DRIVE CONSIDERATIONS Machine Feed Drive Considerations for Resolver Feedback The usual configuration for resolver position feedback is to have the resolver geared to the servo drive motor. Computer-aided design programs for hydraulic drive sizing are based on the fact that the hydraulic resonance is the predominant resonance in the servo loop. With electric drives the mechanical time constant is not of prime consideration since it can be compensated for with the drive compensation. These are two important dynamic considerations with electric and hydraulic servo drives using resolver feedback at the servo motor. Since the position feedback resolver is close-coupled to the drive servo motor all other mechanical resonances and nonlinearities are excluded from the position servo loop. Recommendations for the required indexes of performance . are identical with those given in Section . Copyright 2003 by Marcel Dekker Inc. All Rights Reserved Machine Feed Drive Considerations for Direct Machine Slide Position Feedback The main reason that direct feedback could be used was the universal use of the soft servo with its low position-loop gain. By definition a soft servo has a low position-loop gain of about 1 ipm mil with no frequency breaks below the servo bandwidth. The range of gains for the soft servo range from ipm mil to 2ipm mil. As long as no resonances are within six times the high end of this range 200rad sec or 32 Hz Eq. it should be possible to close the position loop and be stable. As previously stated if the feedback position transducer resolver is located at the drive motor any mechanical resonance in the machine will be outside the servo loop. The effects of these mechanical resonances on the closed-position loop will be reflected load disturbances. However if direct . Inductosyn-linear scales position feedback is to be used the mechanical resonance in the mechanical drive components will be