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Authors
Mats Tallfors; Alf J. Isaksson; Mattias Nordin

Identifier
10.3182/20060329-3-AU-2901.00102

Index Terms
grey-box identification,black-box identification,mechanical parameters,drive train,backlash,shaft torque

Abstract
This paper studies the problem of estimating mechanical parameters in drive trains. The task is to fit a two-mass model with backlash to experimental data. Normally in, for example, rolling mill applications the measured output is just the motor speed. However, for situations with a light load in comparison to the motor, measurement of motor speed only is insufficient to reach good estimates of all parameters in a two-mass model. As a potential solution we advocate use of a shaft torque measurement in addition to the motor speed. The suggested approach is to use a procedure based on three dedicated experiments: 1) One experiment with a sequence of setpoint steps while maintaining the controller in automatic. This enables estimation of the static gain yielding the total inertia damping and static friction. 2) Then an experiment tailored to guaranteeing that no gap openings are encountered, thus enabling estimation of the other mechanical parameters using linear black-box techniques. 3) Finally yet another experiment that with certainty contains gap openings. A non-linear mechanical model is then used, in combination with a numerical search method to also estimate the gap size. The developed procedure has then been tested successfully on real data from a test rig.

References

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