Technical Brief

Disturbance Compensation Using Feedforward and Feedback for Scanner Direct Current Motor Mechanism Low Speed Regulation

[+] Author and Article Information
Wei Wu

Carrier Corp.,
United Technology Companies,
Syracuse, NY 13057
e-mail: wu_esi@yahoo.com

Contributed by the Dynamic Systems Division of ASME for publication in the JOURNAL OF DYNAMIC SYSTEMS, MEASUREMENT, AND CONTROL. Manuscript received August 10, 2012; final manuscript received October 17, 2014; published online January 9, 2015. Assoc. Editor: Qingze Zou.

J. Dyn. Sys., Meas., Control 137(4), 044502 (Apr 01, 2015) (5 pages) Paper No: DS-12-1258; doi: 10.1115/1.4029328 History: Received August 10, 2012; Revised October 17, 2014; Online January 09, 2015

For finer scan resolutions, the scan bar is required to move at slower speeds. Speed regulation at such low speeds presented a challenge for control. An approach successfully addressed this issue was developed. The disturbance torque in the direct current (DC) motor drive of a scan unit was calculated using the known voltage input to the motor and the measured motor speed response. The cogging torque of the motor and the friction in the mechanism can then be estimated from the calculated disturbance torque. The calculated disturbance torque was further utilized to reduce the speed ripples in speed regulation applications. A combined feedforward and feedback configuration was used to reject the disturbance based on both the offline calculated disturbance and the online estimated disturbance. This scheme was successfully implemented in consumer/commercial scan devices. Data obtained under real operating conditions demonstrated the effectiveness and robustness of this disturbance compensation scheme.

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Grahic Jump Location
Fig. 2

Combined feedforward and feedback structure

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Fig. 3

PID control steady state speed

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Fig. 4

PID control terminal voltage

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Fig. 5

Speed under the combined scheme: actual speed (thin) and reference speed (bold)

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Fig. 6

Voltages under the combined scheme: total voltage (solid), feedforward disturbance voltage (dashed), and feedback disturbance voltage (dashed-dotted)




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