This paper proposes a novel technique, called Variable Powder Flow Rate Control (VPFRC), for the regulation of powder flow rate in laser metal deposition processes. The idea of VPFRC is to adjust the powder flow rate to maintain a uniform powder deposition per unit length even when disturbances occur (e.g., the motion system accelerates and decelerates). Dynamic models of the powder delivery system motor and the powder transport system (i.e., five-meter pipe, powder dispenser, and cladding head) are first constructed. A general tracking controller is then designed to track variable powder flow rate references. Since the powder flow rate at the nozzle exit cannot be directly measured, it is estimated using the powder transport system model. The input to this model is the DC motor rotation speed, which is estimated on-line using a Kalman filter. Experiments are conducted to examine the performance of the proposed control methodology. The experimental results demonstrate that VPFRC is successful in maintaining a uniform track morphology, even when the motion control system accelerates and decelerates.

Meeting Name

18th Annual Solid Freeform Fabrication Symposium (2007: Aug. 6-8, Austin, TX)


Mechanical and Aerospace Engineering

Research Center/Lab(s)

Intelligent Systems Center


The authors gratefully acknowledge the financial support of the Intelligent Systems Center at the University of Missouri--Rolla.

Document Type

Article - Conference proceedings

Document Version

Final Version

File Type




Publication Date

08 Aug 2007

Included in

Manufacturing Commons