This study proposes a compound control method based on sliding mode and active disturbance rejection control to address the difficulty of controlling the cutting head for boom-type roadheader with parameter changes and uncertain disturbances. The fastest discrete tracking differentiator and extended state observer based on the traditional active disturbance rejection control are designed. Additionally, the controller of the sliding mode and active disturbance rejection control is constructed. Theoretical analysis indicates that the proposed controller ensures asymptotic stability, despite the existing uncertain disturbances. Moreover, a system based on AMESim and MATLAB/Simulink Co-simulation model is developed to further verify the performance of proposed algorithm. Compared with traditional active disturbance rejection control, proportional-integral-derivative(PID) and sliding mode control, co-simulation results demonstrate that the sliding mode active disturbance rejection compound control improves the tracking accuracy and robustness of the position servo system.

The position control of the driving cylinder of hydraulic support affects the straightness of the underground coal mining face, so this paper focuses on improving tracking performance of the driving cylinder system. Since only position signal of the system is measurable, a Levant differentiator is designed to estimate the velocity and acceleration of the driving cylinder system, which can reduce the effect of the measurement noise. Besides, the parameter changes, modelling errors and external disturbances are treated as a lumped disturbance, an extended disturbance observer is constructed to estimate the lumped disturbance and compensate for the proposed controller. Moreover, barrier Lyapunov function is introduced to limit the tracking error into a small set around zero, and then the stability of the close-loop system is proved. Both the performance of differentiator and disturbance observer is verified in simulation experiments in MATLAB/Simulink. Finally, an experiment rig for the driving cylinder system of hydraulic support is established and comparative experiments are carried out. The experiment results show that the proposed extended disturbance observer-based output feedback controller with error constraint has a satisfied effectiveness in improving tracking performance.

In this paper, a robust output feedback controller with error constraint is proposed to improve the position tracking performance of the electro-hydraulic servo system. Since only the position signal of the system is available, a high-order sliding mode observer is designed to estimate the unobtainable system states. The new state observer can not only avoid the influence of sensor measurement noise but also reduce the chattering of traditional sliding mode observer. To cope with the modeling error, parameter uncertainty, and external disturbance, a robust controller based on backstepping method is designed. In addition, barrier Lyapunov function is introduced to limit the maximum tracking error to a preset range. Finally, comparative experiments are carried out on the asymmetric hydraulic cylinder test bench. The experimental result shows that the proposed controller has a satisfied tracking performance.

The electro-hydraulic system is widely used in industrial production due to its high power-to-weight ratio, but the heavy-duty characteristics make the electro-hydraulic system subject to large disturbance force even if the actuator moves slightly, especially in mobile machines and multi-actuators system. Therefore, a position and velocity constraints method based on barrier Lyapunov function is proposed to guarantee the tracking error limited in a strict range to avoid the large disturbance force. Besides, the external disturbance, parameters uncertainty and modeling errors in the asymmetric cylinder electro-hydraulic systems affect the accuracy of position tracking seriously. So a high-gain disturbance observer is designed to estimate the lumped disturbance of the system, which can avoid amplification of the noise during the states measurement. In addition, dynamic surface control based on backstepping method is adopted to avoid the derivative explosion phenomenon when calculating the derivatives of virtual control inputs, which reduces the computational complexity of the system significantly. To verify the effectiveness of the proposed controller, proportional-integral controller and adaptive controller are designed to be compared with the high-gain disturbance observer–based dynamic surface controller with the backstepping method, and the comparison results show that the proposed controller has a more precise trajectory tracking performance.