A Simulink Model for Single-Axis Servo Control Mechanism Using Bond Graph Approach

Abstract

This paper presents a Simulink model for a single-axis servo control mechanism using the bond graph approach. The physical system comprises a rigid link that is free to rotate about an axis. It is actuated using a servo control mechanism. The servo control mechanism consists of a drive amplifier, brushless DC motor, encoder, feedback mechanism, torque limiter, and controller. Three feedbacks are taken from the system: Current in the stator windings, the angular velocity of the motor, and position of the rigid link. The bond graph approach is used to model the dynamics of the system. This approach takes causality into account which describes the cause and effect relationship of the elements with the system. System equations are derived using the developed bond graph model. Simulink models are also developed based on the bond graph model. Simulation for step, cosine, ramp, and parabolic inputs is performed and the result for the step and ramp inputs are presented. Results show that the actual position of the rigid link tracks the desired position which validates the proposed Simulink model. The developed model can be found useful in the modeling of single-axis robots, single-axis controlled CNC machines, and so on.