Bond Graph Modeling and Simulation of a Closed-Loop Feed Drive System for a CNC Machine

The feeddrive of a CNC machine is a mechatronic system consisting of motor, mechanical transmission devices and worktable. The accuracy and precision of the feeddrive system determines the quality of the final part. Hence close control of the drive system is very important. Accurate modeling of this system and its simulation helps in system design and parametric optimization. In this paper, bond graph based approach has been used to model the feeddrive of a CNC machine. This technique is based on power flow and uses basic component types to develop models for complex multi-physics systems. The governing equations can be algorithmically derived from a visual representation of the system. In this model all linear and nonlinear effects such as backlash, stick-slip friction and cutting forces have been accounted for. The model is also enhanced through the addition of a control loop for position and velocity.