Friction and nonlinearity compensation in hard disk drive servo systems using robust composite nonlinear feedback control

This paper presents design of hard disk drive (HDD) servo systems using an enhanced composite nonlinear feedback (CNF) control technique with a simple friction and nonlinearity compensation scheme. Friction and nonlinearity result in large residual errors and deteriorate the performance of head positioning of HDD servo systems. The enhanced CNF technique has a feature of removing the uncompensated portion of friction and nonlinearity without sacrificing the overall tracking performance. Simulation and experimental results for the servo design show that our approach is very effective arid successful. In particular, our experimental results show that the enhanced CNF control has outperformed the conventional PID control in settling time. This approach can be adopted to solve other servomechanism problems.