Precise regulation of powder mass flow in laser-based manufacturing processes is critical to achieving excellent part dimensional and microstructure quality. Control of powder mass flow is challenging because low flow rates, where nonlinear effects are significant, are typically required. Also, gravity-fed powder feeder systems have significant material transport delays, making the control of powder mass flow even more challenging. This paper presents a control strategy for regulating the powder mass flow rate in a gravity-fed powder feeder system. A dynamic model of the powder feeder system, including material transport delay, is constructed, and a modified proportional plus integral (PI) controller is designed. An observer is used to estimate powder mass flow rate using the powder feeder motor encoder signal. The control strategy is implemented in a Smith Predictor Corrector Structure, which has been adjusted such that it can be applied to the modified PI controller, to account for the inherent material transport delay. Experimental studies are conducted that validate the dynamic model and controller strategy.


Mechanical and Aerospace Engineering


National Science Foundation (U.S.)
Society of Manufacturing Engineers. Education Foundation
University of Missouri--Rolla. Intelligent Systems Center
University of Missouri Research Board

Keywords and Phrases

delay control; gravity-fed powder feeders; laser-aided manufacturing; powder mass flow regulation

International Standard Serial Number (ISSN)


Document Type

Article - Journal

Document Version

Final Version

File Type





© 2006 Elsevier, All rights reserved.

Publication Date

01 Jan 2006