Design of integral variable structure model following control with load torque estimator for DSP-based servo drive system

This paper introduces an improved control approach, which incorporates a load torque estimator based on variable-structure technique to the integral variable structure model following control (IVSMFC), for a BLDC drive system. IVSMFC features excellent robustness and performance properties under certain disturbances and parameter variations. However, when carried out on a real mechanism, heavy time-varying load may influence expected performances. In a cam system, for instance, when it is in motion, the load produced by inertia forces deflects the driving motor speed and, as a result, degrades the indexing precision. To improve robustness, a load torque estimator is employed. A DSP-based BLDC servo drive is implemented. A globoal cam indexing system is chosen for experiment to show the effectiveness of the proposed approach.