Title: Model Reference Adaptive Control Based PID Controller for Hard Disk Drive Read/Write Head Servo Posistioning System
Authors: Chisom Ifunanya Onyekwelu, C. A. Nwabueze, C. N. Muoghalu , B. O. Ekengwu
Volume: 7
Issue: 8
Pages: 135-144
Publication Date: 2023/08/28
Abstract:
This paper presents improving the head position servo control system of hard disk drive using adaptive mechanism. In order to carry out this task, the mathematical equation of hard disk drive servomechanism was presented as a transfer function to describe the dynamic behaviour of the R/W head position servo of hard drive in a computer system. A Model Reference Adaptive Control (MRAC) system was designed based on modified Massachusetts Institute of Technology (MIT) rule to determine the adaptive gain of the controller. The MRAC was enhanced with the addition of Proportional-Integral-Derivative (PID) control algorithm. Simulation analysis was conducted for uncompensated state of the R/W head positioning of the HDD. The performance of the system is largely influenced by cycling which results in instability and therefore maintaining accurate track for efficient read and write operation was not realizable. Despite the low rise time of 0.0373 s, the step response performance of the uncompensated system indicated high overshoot of 95.4% and prolonged settling time of 9.13 s. Furthermore, the system in this condition was not able to track the desired position, which in this case, is represented by a step input such that a final value of 0.0113 that resulted in steady state error of 0.9887. With the introduction of the proposed MRAC, the performance of the system was largely improved using the different adaptive gains tagged (MRAC1, MRAC2 and MRAC3). The adaptive controller in terms of MRAC1, MRAC2 and MRAC3 yielded different rise time of 0.0894 s, 0.0415 s and 0.0066 s; overshoot of 0.85%, 1.1%, and 1.15%. However, the settling time, final value and steady state error were all the same for the three adaptive gains. Simulation conducted assuming step in put disturbance after 5 s revealed that system position was deviated but this was quickly corrected immediately after 0.75 s for each gain of the adaptive controller. Performance comparison of the MRAC and PID controller showed that it provided better performance than the PID including handling the effect disturbance. Furthermore, the simulations conducted in terms optimal performance indices such as Integral Square Error(ISE), Integral Absolute Error (IAE) and Integral Time Absolute Error (ITAE) showed that the MRAC controller regardless of the adaptive gain significantly give finest error handling capability than PID controller by ensuring that more accurate track keeping is achieved by the R/W head positioning system. Generally, the MRAC with adaptive gain 6 (MRAC3) provided the minimum error and as such would be the best option to achieve the most desired optimal performance for the HDD positioning operation.