Evaluation of a servo settling algorithm

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  • Evaluation of a servo settling algorithm
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  • 12/19/2025
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  • The aim of this work is to discuss methods of friction identification and provide experimental evaluation of a novel control algorithm that enhances settling after point-to-point motion. This algorithm is called the Nonlinear Integral Action Settling Algorithm or NIASA. As the name suggests, the integral gain is nonlinear, and is based upon a Dahl friction model. The settling resulting from PID + NIASA control is nearly exponential, and governed by a time constant that is specified in the control design. As the NIASA algorithm requires, friction parameters must be identified for the servo under test. Two methods of friction identification (Step Tests and Identification Profile) are contrasted and found to provide comparable results, although the latter can provide advantages. The identified friction parameters are in turn used to perform four sets of control experiments; two PID controllers (standard factory tuning and high performance PID with acceleration feedforward) are tested both with and without NIASA compensation. In the case study with a factory tuned PID controller, servo settling times to within ±3-100 nm, are reduced by between 80.5 and 87.4 when NIASA compensation is added. When the NIASA compensator is added to the high performance PID controller, servo settling time is still reduced by between 50.5 and 73.0. Although the NIASA compensator was designed to increase settling performance for relatively large point-to-point motions, similar positive results are achieved when the method is applied to smaller step motions that do not leave the pre-rolling friction regime. Frequency domain analyses demonstrated the nonlinear loop-gain of the plant, with a clear distinction between the rolling and pre-rolling friction cases. As expected, the nonlinear loop gain was found to lower the bandwidth for smaller motions. Adding NIASA control was observed to increase the bandwidth for small motions by a factor of 3-6, while having little effect for large motions. © 2012 Published by Elsevier Inc. All rights reserved.
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  • Precision Engineering

MLA citation style (9th ed.)

Ludwick, SJ, et al. Evaluation of a Servo Settling Algorithm. . 2013. d-scholarship.pitt.edu/concern/generic_works/57a23b22-5f8d-4fc7-82ff-2c1cef45d145.

APA citation style (7th ed.)

L. Sj, B. Ba, C. Dg, & V. Js. (2013). Evaluation of a servo settling algorithm. https://d-scholarship.pitt.edu/concern/generic_works/57a23b22-5f8d-4fc7-82ff-2c1cef45d145

Chicago citation style (CMOS 17, author-date)

Ludwick, SJ, Bucci, BA, Cole, DG, and Vipperman, JS. Evaluation of a Servo Settling Algorithm. 2013. https://d-scholarship.pitt.edu/concern/generic_works/57a23b22-5f8d-4fc7-82ff-2c1cef45d145.

Note: These citations are programmatically generated and may be incomplete.

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