In equipment manufacturing processes, pneumatic systems are commonly used because of their relatively simple design, high power-to-weight ratio, clean power source, safety, zero heat generation, and easy maintenance. Pneumatic systems contain devices such as linear actuators that convert air pressure and create straight-line motion and are widely used in industrial automation, robotics, and machinery. However, these pneumatic actuators are susceptible to frictional forces and difficult to control owing to their inherent air pressure characteristics. They therefore lack the precision and accuracy of electric actuators. Precision motion systems have become increasingly popular in manufacturing equipment, and this industrial revolution has led to the reduction of pneumatic systems adopted in precision motion systems. Many special type pneumatic servo systems have, through years of research and engineering efforts, been designed to meet special requirements such as precision and speed. However, these involve high investment and engineering time to adopt. Hence, this paper presents a novel compensator-based control system that uses a standard type linear pneumatic actuator to achieve ultra-high precision positioning control. The ultra-high-precision control feature, endowed with the inherent benefits of pneumatic systems such as safety, provides an all-around approach for future industrial automation. The research methodology involves the design of a control system with a novel compensator algorithm to address friction interference in pneumatic actuators, which is the primary causation factor of poor positioning accuracy in pneumatic servo systems. Moreover, the compensator can be easily integrated into any main control system, allowing easy adoption in any industrial field. The experimental results prove that high accuracy in the steady-state position can be achieved by this proposed algorithm. A steady-state accuracy of ±1 nm was obtained. Compared to previous studies in which accuracies of approximately 5 nm were obtained, the compensator-based control system achieves a considerably higher accuracy than the previously reported accuracies, matching that of electric actuators. The final section of this paper will present potential directions for future work.

1. [1] D. Saravanakumar, B. Mohan, and T. Muthuramalingam, “A review on recent research trends in servo pneumatic positioning systems,” Precision Engineering, Vol.49, pp. 481-492, 2017. https://doi.org/10.1016/j.precisioneng.2017.01.014
2. [2] S. Tajima, S. Iwamoto, and H. Yoshioka, “Posture optimization in robot machining with kinematic redundancy for high-precision positioning,” Int. J. Automation Technol., Vol.17, No.5, pp. 494-503, 2023. https://doi.org/10.20965/ijat.2023.p0494
3. [3] B. Rouzbeh, G. M. Bone, G. Ashby, and E. Li, “Design, implementation and control of an improved hybrid pneumatic-electric actuator for robot arms,” IEEE Access, Vol.7, pp. 14699-14713, 2019. https://doi.org/10.1109/ACCESS.2019.2891532
4. [4] B. Yang, U.-X. Tan, A. B. McMillan, R. Gullapalli, and J. P. Desai, “Design and control of a 1-DOF MRI-compatible pneumatically actuated robot with long transmission lines,” IEEE/ASME Trans. on Mechatronics, Vol.16, No.6, pp. 1040-1048, 2011. https://doi.org/10.1109/TMECH.2010.2071393
5. [5] B. Zhao, Y. Fu, Y. Yang, P. Zhang, and Y. Hu, “Design and control of a MRI-compatible pneumatic needle puncture robot,” Computer Assisted Surgery, Vol.24, No.sup2, pp. 87-93, 2019. https://doi.org/10.1080/24699322.2019.1649067
6. [6] C.-R. Rad and O. Hancu, “An improved nonlinear modelling and identification methodology of a servo-pneumatic actuating system with complex internal design for high-accuracy motion control applications,” Simulation Modelling Practice and Theory, Vol.75, pp. 29-47, 2017. https://doi.org/10.1016/j.simpat.2017.03.008
7. [7] R. Sato, K. Li, M. Michihata, S. Takahashi, and W. Gao, “Advanced sensing and machine learning technologies for intelligent measurement in smart and precision manufacturing,” Int. J. Automation Technol., Vol.18, No.4, pp. 545-580, 2024. https://doi.org/10.20965/ijat.2024.p0545
8. [8] S. Inoue et al., “High-precision mobile robotic manipulator for reconfigurable manufacturing systems,” Int. J. Automation Technol., Vol.15, No.5, pp. 651-660, 2021. https://doi.org/10.20965/ijat.2021.p0651
9. [9] J. Song and Y. Ishida, “A robust sliding mode control for pneumatic servo systems,” Int. J. of Engineering Science, Vol.35, No.8, pp. 711-723, 1997. https://doi.org/10.1016/S0020-7225(96)00124-3
10. [10] M. Parnichkun and C. Ngaecharoenkul, “Kinematics control of a pneumatic system by hybrid fuzzy PID,” Mechatronics, Vol.11, No.8, pp. 1001-1023, 2001. https://doi.org/10.1016/S0957-4158(00)00040-4
11. [11] T. Tanaka, T. Kato, T. Otsubo, A. Koyama, and T. Yazawa, “Control of spindle position and stiffness of aerostatic-bearing-type air turbine spindle,” Int. J. Automation Technol., Vol.16, No.4, pp. 456-463, 2022. https://doi.org/10.20965/ijat.2022.p0456
12. [12] K. Kawashima, T. Arai, K. Tadano, T. Fujita, and T. Kagawa, “Development of coarse/fine dual stage using pneumatically driven bellows actuator and cylinder with air bearings,” Precision Engineering, Vol.34, No.3, pp. 526-533, 2010. https://doi.org/10.1016/J.PRECISIONENG.2010.02.005
13. [13] T. Fujita, K. Sakai, Y. Takagi, K. Kawashima, and T. Kagawa, “Ultra precise positioning of a stage driven by pneumatic bellows,” Int. J. Automation Technol., Vol.5, No.4, pp. 508-515, 2011. https://doi.org/10.20965/ijat.2011.p0508
14. [14] M.-H. Chiang, C.-C. Chen, and T.-N. Tsou, “Large stroke and high precision pneumatic–piezoelectric hybrid positioning control using adaptive discrete variable structure control,” Mechatronics, Vol.15, No.5, pp. 523-545, 2005. https://doi.org/10.1016/j.mechatronics.2004.11.003
15. [15] Y.-T. Liu, K.-M. Chang, and H.-R. Lee, “Study of a precision pneumatic positioning device using PZT dither,” Int. J. Automation Technol., Vol.5, No.6, pp. 780-785, 2011. https://doi.org/10.20965/ijat.2011.p0780
16. [16] Y.-T. Liu, T.-T. Kung, K.-M. Chang, and S.-Y. Chen, “Observer-based adaptive sliding mode control for pneumatic servo system,” Precision Engineering, Vol.37, No.3, pp. 522-530, 2013. https://doi.org/10.1016/j.precisioneng.2012.12.003
17. [17] M. Kadotani et al., “Development of pneumatic servo bearing actuator for nanometer positioning,” Int. J. Automation Technol., Vol.3, No.3, pp. 249-256, 2009. https://doi.org/10.20965/ijat.2009.p0249
18. [18] L. Zhou and J. Wu, “Magnetic levitation technology for precision motion systems: A review and future perspectives,” Int. J. Automation Technol., Vol.16, No.4, pp. 386-402, 2022. https://doi.org/10.20965/ijat.2022.p0386
19. [19] Y. Zhang, K. Li, S. Wei, and G. Wang, “Pneumatic rotary actuator position servo system based on ADE-PD control,” Applied Sciences, Vol.8, No.3, Article No.406, 2018. https://doi.org/10.3390/app8030406
20. [20] M. Takaiwa and T. Noritsugu, “Positioning control of pneumatic parallel manipulator,” Int. J. Automation Technol., Vol.2, No.1, pp. 49-55, 2008. https://doi.org/10.20965/ijat.2008.p0049
21. [21] T. Fujita, K. Kawashima, T. Miyajima, T. Ogiso, and T. Kagawa, “Effect of servo valve dynamic on precise position control of a pneumatic servo table,” Int. J. Automation Technol., Vol.2, No.1, pp. 43-48, 2008. https://doi.org/10.20965/ijat.2008.p0043