Robust sensing and control of direct metal deposition

Abstract

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.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.