A camera based feedback control strategy for the laser cladding process

The developed feedback control system adjusts the laser power such that the width of the melt pool is kept at a user defined reference value. The system uses a CMOS camera and software algorithms to obtain the width of the melt pool. Using a discrete control filter, the required laser power to meet the reference melt pool width is determined. The control filter gain is designed such that the closed loop bandwidth of the cladding process is in the order of a few Hz. As a result, the closed loop system will effectively compensate for disturbances (such as heat sink changes and speed changes) within a second. Several experiments were performed to investigate the controller performance. The laser power was adjusted for the above effects. The resulting dilution and consequent hardness were constant over the entire clad layer.