Feed, Speed, and Torque Controllers for Drilling

The design and implementation of feed, speed, and torque controllers for drilling is discussed. Dynamic models of the feedrate drive and spindle motors were developed using experimental data and least squares estimation. These dynamic models were subsequently used to design closed loop feed and speed controllers, which allow for independent control of the machining feed and speed during drilling. They effectively track constant, as well as step-change, command references. Subsequently, the feed controller was used to develop a dynamic model between feed and torque, and then was cascaded with a torque control loop. The dynamic modeling and subsequent closed loop controller design and performance are described.