Spin-Coater Machine Control Via Passivity With Sliding Modes

Hector Huerta,Nimrod Vazquez

doi:10.1109/access.2020.2965188

Abstract

In this paper, a novel control scheme for a spin-coater machine is presented, based on Passivity and Sliding Modes. The machine is used to make semiconductor thin films with a centrifugation force. A brushless direct current motor was selected as an actuator, its mathematical model is presented, including the mechanical and electrical dynamics. The control objective is the rotor speed regulation, with maximum acceleration. Taking advantage of the energy properties of the system, a sliding manifold is selected and, in order to reject the matched perturbations, the Integral Sliding Modes technique is applied. Then, with the unperturbed system, a passivity feedback is applied, to guarantee the stability around the desired equilibrium point. To complete the control scheme, an observer is included to estimate the unmeasurable estates. To prove the effectiveness of the proposed control scheme, it was implemented in a spin-coater machine and compared with a gain scheduled PID. The experimental results show a good performance of the closed-loop system, in spite of perturbations.

Highlights

In the synthesis and development of thin films with new materials there are some procedures used in a laboratory
This combination enables to cope with the nonlinear operation region of the Brushless DC Motor (BLDC) from 500 RPM to 10,000 RPM, and presents some advantages over the commercial spin coater machines
EXPERIMENTAL RESULTS In order to prove the effectiveness of the propose control scheme, it was implemented in the spin-coater machine developed

Summary

INTRODUCTION

In the synthesis and development of thin films with new materials there are some procedures used in a laboratory. In [3], a closed-loop controller for a spin-coater machine was presented, but the substrate angular speed range is limited due to the use of a brushed DC motor. The embedded algorithm enables to configure until three spin up and three spin off steps with different steady-state speed and time This combination enables to cope with the nonlinear operation region of the BLDC from 500 RPM to 10,000 RPM, and presents some advantages over the commercial spin coater machines. A nonlinear sliding manifold is formulated, taking into account the passivity approach, where the speed control error tends to zero The former approach is able to avoid the elimination of the electrical torque terms, as in some feedback linearization techniques, to obtain the system stability.

PASSIVITY WITH SLIDING MODES CONTROL

STATE OBSERVER

GAIN SCHEDULED PID CONTROLLER

VIII. CONCLUSION