The paper presents the design and practical implementation of PID controllers for a Stewart platform. The platform uses a resistance touch panel as a sensor and servo motors as actuators. The complete control system stabilizing the ball on the platform is realized with the Arduino microcontroller and the Matlab/Simulink software. Two processes required to acquire measurement signals from the touch panel in two perpendicular directions X and Y, are discussed. The first process includes the calibration of the touch panel, and the second process - the filtering of measurement signals with the low pass Butterworth filter. The obtained signals are used to design the algorithm of the ball stabilization by decoupling the global system into two local subsystems. The algorithm is implemented in a soft real time system. The parameters of both PID controllers (PIDx and PIDy) are tuned by the trial-error method and implemented in the microcontroller. Finally, the complete control system is tested at the laboratory stand.
1. Gough V. E., Whitehall S. G. (2012), Universal tyre test machine, Proceedings of the 9th International Technical Congress F.I.S.I.T.A, 117-137,1962.
2. Paul A. K., Mishra J. K., Radke M. G. (1994, Reduced order sliding mode control for pneumatic actuator, IEEE Transactions on Control Systems Technology, Vol. 2, No. 3, 271-276.
3. Shunmugham P., Hayakawa Y. (1997), Practical design of adaptive model-based sliding mode control of pneumatic actuators, Proceedings of Advanced Intelligent Mechatronics, IEEE, Tokyo, Japan, 140.
4. Urniezius R., Geguzis E. (2014), Hybrid Fuzzy Logic and Adpative LQR Controller for Swing-up, Positioting and Stabilization of Inverted Pendulum, Elektronika ir Elektrotechnika, Vol.20, No.3, 11-15.
5. Varseveld R. B. V., Bone G. M. (1997), Accurate position control of a pneumatic actuator using on/off solenoid valves, IEEE/ASME Transactions on Mechatronics, Vol. 2, No. 3, 195-204.
6. Wang J., Pu J., Moore P. (1999), A practical control strategyfor servo-pneumatic actuator systems, Control Engineering Practice, Vol. 7, No. 12, 1483-1488.
7. Wang W., Yang H., Zou J., Ruan X., Fu X. (2009) Optimal design of Stewart platforms based on expanding the control bandwidth while considering the hydraulic system design, Journal of Zhejiang University, Vol.10(1), 22-30.
8. Weng Ch., Xu Z. (2013), Track-position and vibration control simulation for strut of the Stewart platform, Applied Physics and Engineering, Vol.14(4), 281-291.