Abstract
A pneumatic actuator is a fast and economical tool that converts compressed air into mechanical motion. In this paper, an extended state observer (ESO)-based sliding mode controller (SMC) is developed to adjust the air pressure of the actuator for accurate position control. Specifically, an impedance control module is established to produce desired air pressure based on the relationship between forces and desired positions. Then, the ESO-based SMC is implemented to adjust the air pressure to the required level despite the presence of system uncertainties and disturbances. As a result, the position of the actuator is controlled to a setpoint through the regulation of pressure. The performance of ESO-based SMC is compared with that of a classic active disturbance rejection controller (ADRC) and a SMC. Simulation results demonstrate that the ESO-based SMC shows comparable performance to ADRC in terms of precise pressure control. In addition, it requires the least control effort necessary to excite valves among the three controllers. The stability of ESO-based SMC is theoretically justified through Lyapunov approach.
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Abbreviations
- P 1(t):
-
Absolute air pressures for chamber 1
- P 2(t):
-
Absolute air pressures for chamber 2
- F L(t):
-
Payload force
- F f(t):
-
Coulomb friction
- \(\beta\) :
-
Viscous friction coefficient
- \(M_{{\text{P}}}\) :
-
Mass of the piston
- \(M_{{\text{L}}}\) :
-
Mass of the load
- \(P_{{\text{a}}} (t)\) :
-
Atmospheric pressure
- \(A_{{\text{p}}}\) :
-
Area of smaller rod portion of the piston
- \(A_{1}\) :
-
Area of larger disc portion of the piston
- \(A_{2}\) :
-
Difference between \(A_{1}\) and \(A_{{\text{p}}}\)
- x(t):
-
Piston position
- \(\dot{Q}(t)\) :
-
Heat rate for the air volume
- \(\dot{m}_{i} (t)\) :
-
Mass flow rate for each chamber (\(i = 1 \, {\text{or}} \,2\))
- \(\dot{m}_{{\text{l}}}\) :
-
Mass flow rate of air leakage
- \(\dot{E}(t)\) :
-
Rate of change of total energy
- \(\dot{W}(t)\) :
-
Rate of work delivered to piston
- \(h_{n}\) :
-
Enthalpy of gas that enters the chamber
- \(h_{x}\) :
-
Enthalpy of gas that exits the chamber
- \(v_{n}\) :
-
Velocity of gas that enters the chamber
- \(v_{x}\) :
-
Velocity of gas that exists the chamber
- V i :
-
Volume of each chamber (\(i = 1 \,{\text{or}} \, 2\))
- C v :
-
Specific heat at constant volume
- C p :
-
Specific heat at constant pressure
- R :
-
The difference between Cp and Cv, i.e., R = Cp − Cv
- T 1 :
-
Temperature of chamber 1
- T 2 :
-
Temperature of chamber 2
- K :
-
The ratio between Cp and Cv, i.e., \(k = C_{{\text{p}}} /C_{{\text{v}}}\)
- T :
-
Constant temperature
- P i(t):
-
Air pressure for each chamber (\(i = 1 \;{\text{or}} \;2\))
- d(t):
-
External disturbance caused by air leak
- K i :
-
On/off state of each valve
- P s(t):
-
Supply pressure
- q m :
-
Function of Ps(t) and Pa(t)
- x d :
-
Desired position
- \(P_{{\text{D}}}\) :
-
Desired pressure
- u(t):
-
Control signal
- \(F_{{\text{D}}} (t)\) :
-
Total force produced by air pressure
- \(M\) :
-
Total mass of piston and load
- \(\tilde{M}\) :
-
Reference mass
- \(\tilde{B}\) :
-
Reference damping coefficient
- \(\tilde{K}\) :
-
Reference stiffness coefficient
- \(P_{{{\text{1D}}}} (t)\) :
-
Desired pressures for chamber 1
- \(P_{{{\text{2D}}}} (t)\) :
-
Desired pressure for chamber 2
- \(P_{{{\text{sum}}}} (t)\) :
-
Total supplied pressure
- \(f(t)\) :
-
Generalized disturbance
- b(t):
-
Coefficient of controller
- \(b_{{{\text{min}}}}\) :
-
Minimum value of b(t)
- x(t):
-
Stable variable (pressure)
- y(t):
-
Pressure output
- A :
-
State matrix
- B :
-
Input matrix
- C :
-
Output matrix
- z 1(t):
-
Observed pressure
- z 2(t):
-
Observed generalized disturbance
- \(\hat{y}(t)\) :
-
Output of extended state observer
- \(\omega_{o}\) :
-
Observer bandwidth
- h(t):
-
Derivative of generalized disturbance
- L :
-
Extended state observer gain vector
- \(\tilde{e}_{1} (t)\) :
-
Estimation error between actual and observed pressure
- \(\tilde{e}_{2} (t)\) :
-
Estimation error between actual and observed \(f( \cdot )\)
- \(s(t)\) :
-
Sliding surface
- V(t):
-
Lyapunov function
- \(\overline{f}(t)\) :
-
An approximate of \(f(t)\)
- \(P_{{{\text{avg}}}} (t)\) :
-
Average pressure
- \(k_{{{\text{SMC}}}} \;{\text{and}}\;\eta_{{{\text{SMC}}}}\) :
-
Positive controller gains for SMC
- \({\text{sgn}}(s(t))\) :
-
Sign function of s(t)
- \(F\) :
-
Bound of \(f(t) - \overline{f}(t)\)
- \(\varPhi (t)\) :
-
Bound of sliding surface
- \(u_{{{\text{ESMC}}}}\) :
-
Control input of ESO-based SMC
- \(P_{{{\text{ESMC}}}} {\text{and}}\;\eta_{{{\text{ESMC}}}}\) :
-
Controller gains of ESO-based SMC
- \(\hat{s}(t)\) :
-
Difference between observed and desired pressures
- \(u_{{{\text{ADRC}}}} (t)\) :
-
Control signal of ADRC
- \(\omega_{{\text{c}}}\) :
-
Controller bandwidth for ADRC
References
Zhang, P. (2010). Advanced Industrial Control Technology. Oxford: Elsevier.
Saravanakumar, D., Mohan, B., & Muthuramalingam, T. (2017). A review on recent research trends in servo pneumatic positioning systems. Precision Engineering, 49, 481–492.
Hejrati, B., & Najafi, F. (2012). Accurate pressure control of a pneumatic actuator with novel pulse width modulation-sliding mode controller using a fast switching on/off valve. Journal of Systems and Control Engineering, 227(2), 230–242.
Lee, L., & Lee, I. H. (2016). Design and implementation of a robust FNN-based adaptive sliding-mode controller for pneumatic actuator systems. Journal of Mechanical Science and Technology, 30(1), 381–396.
Muzy, G. A., & Caporali, A. S. (2018). Positioning system of a pneumatic actuator by proportional pressure regulator valves. In Proceedings of the 4th Workshop on Innovative Engineering for Fluid Power (pp. 11–16). Sao Paulo, Brazil.
Lai, J. Y., Meng, C., & Singh, R. (1990). Accurate position control of a pneumatic actuator. ASME Journal of Dynamic Systems, Measurement, and Control, 112(4), 734–739.
Noritsugu, T., & Takaiwa, M. (1995). Robust positioning control of pneumatic servo system with pressure control loop. International Conference on Robotics and Automation (pp. 2613–2618). New York: IEEE.
Lee, H. K., Choi, G. S., & Choi, G. H. (2002). A study on tracking position control of pneumatic actuators. Mechatronics, 12(6), 813–831.
Wanga, J., Kottab, Ü., & Kea, J. (2007). Tracking control of nonlinear pneumatic actuator systems using static state feedback linearization of the input–output map. Proceeding of Estonian Academy of Sciences, Physics, and Mathematics, 56(1), 47–66.
Wang, J., Kotta, Ü., Mangan, S., & Wei, J. (2003). Robust tracking control of nonlinear pneumatic systems using input/output linearisation by state feedback. Systems Science, 29, 151–165.
Ramirez, I. (2018). Design of a tracking controller of a siso system of pneumatic servopositioning. Ingeniera y Desarrollo, 36(1), 74–96.
Sorli, M., Figliolini, G., & Pastorelli, S. (2004). Dynamic model and experimental investigation of a pneumatic proportional pressure valve. IEEE/ASME Transactions on Mechatronics, 9(1), 78–86.
Wang, X., Cheng, Y., & Peng, G. (2007). Modeling and self-tuning pressure regulator design for pneumatic-pressure-load systems. Control Engineering Practice, 15, 1161–1168.
Liu, H., Lee, J., & Li, B. (2007). High precision pressure control of a pneumatic chamber using a hybrid fuzzy PID controller. International Journal of Precision Engineering and Manufacturing, 8(3), 8–13.
Ying, C., Zhang, J., Yang, C., & Niu, B. (2007). Design and hybrid control of the pneumatic force-feedback systems for armexoskeleton by using on/off valve. Mechatronics, 17(6), 325–335.
Luo, Z., Wu, M., & Zuo, J. (2018). Sliding mode pressure controller for an electropneumatic brake: Part I—Plant model and controller design. Journal of Systems and Control Engineering, 232(5), 572–582.
Shiee, M., Sharifi, K. A., Fathi, M., & Najafi, F. (2012). Air pressure control via sliding mode approach using an on/off solenoid valve. In Proceedings of the 20th Iranian Conference on Electrical Engineering (pp. 857–861). Tehran, Iran.
Lee, L. W., & Li, I. H. (2016). Design and implementation of a robust FNN-based adaptive sliding-mode controller for pneumatic actuator systems. Journal of Mechanical Science and Technology, 30(1), 381–396.
Jouppilaa, V. T., et al. (2012). Sliding mode control of a pneumatic muscle actuator system with a PWM strategy. International Journal of Fluid Power, 15(1), 19–31.
Hodgson, S., Tavakoli, M., Pham, M., & Leleve, A. (2015). Nonlinear discontinuous dynamics averaging and PWM-based sliding control of solenoid-valve pneumatic actuators. ASME/IEEE Transactions on Matronics, 20(2), 876–888.
Liu, Y., Kung, T., Chang, K., & Chen, S. (2013). Observer-based adaptive sliding mode control for pneumatic servo system. Precision Engineering, 37, 522–530.
Han, J. (2009). From PID to active disturbance rejection control. IEEE Transactions on Industrial Electronics, 56(3), 900–906.
Han, J. (1995). A class of extended state observers for uncertain systems. Control and Decision, 10(1), 85–88 (in Chinese).
Gao, Z. (2006). Active disturbance rejection control: a paradigm shift in feedback control system design. In Proceedings of the American Control Conference (pp. 2399–2405). Minneapolis, MN, USA.
Richer, E., & Hurmuzlu, Y. (2000). A high performance pneumatic force actuator system part1-nonlinear mathematical model. ASME Journal of Dynamics, Measurement, and Control, 122(3), 416–425.
Kazerooni, H. (2005). Design and analysis of pneumatic force generators for mobile robotic systems. ASME Transactions on Mechatronics, 10(4), 411–418.
Tassa, Y., Wu, T., Movellan, J., & Todorov, E. (2013). Modeling and identification of pneumatic actuators. In Proceedings of the International Conference on Mechatronics and Automation (pp. 437–443). Takamatsu, Japan.
Zhu, Y., & Barth, E. J. (2005). Impedance control of a pneumatic actuator for contact tasks. In Proceedings of the International Conference on Robotics and Automation (pp. 987–992). Barcelona, Spain.
Turkseven, M., & Ueda, J. (2018). Model-based force control of pneumatic actuators with long transmission lines. IEEE/ASME Transactions on Mechatronics, 23(3), 1292–1302.
Shao, S., & Gao, Z. (2017). On the conditions of exponential stability in active disturbance rejection control based on singular perturbation analysis. International Journal of Control, 90(10), 2085–2097.
Zheng, Q., Gao, L., & Gao, Z. (2012). On validation of extended state observer through analysis and experimentation. ASME Journal of Dynamic Systems, Measurement, and Control, 134, 1–6.
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Mohorcic, J., Dong, L. Extended state observer-based pressure control for pneumatic actuator servo systems . Control Theory Technol. 19, 64–79 (2021). https://doi.org/10.1007/s11768-021-00038-y
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DOI: https://doi.org/10.1007/s11768-021-00038-y