Direct metal deposition is one of the rapid manufacturing technologies to fabricate geometrically complicated, dense, near-net-shape components. Deposition process involves a large number of parameters, among which the laser power is considered as the primary variable. In order to develop a control system for the process, molten pool temperature during deposition was monitored by a two-color pyrometer. Laser power and molten pool temperature form a single-input single-output system, whose dynamics were identified using a linear state space model. A generalized predictive control system with input constraints was designed for controlling the direct metal deposition process. To demonstrate the use of the proposed sensor and control algorithm, closed-loop experiments were conducted to adjust the laser power in order to track molten pool temperatures to the reference values.

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