Prescribed performance dynamic surface control based on dual extended state observer for 2-dof hydraulic cutting arm.

In tunnel section forming operations, the boom-type roadheader tracking target trajectory with high precision is greatly significant in avoiding over and under excavation and improving excavation efficiency. However, there exist complex cutting loads, measurement noise, and model uncertainties, seriously degrading the tracking performance of traditional nominal model-based controllers. Hence, this study first fully analyzes the kinematics of all members of the cutting mechanism and establishes its complete multi-body dynamic model using the Lagrange method. Furthermore, a dual extended state observer is designed to estimate the mechanical system's angular velocity and unmodeled disturbances and actuators' uncertain nonlinearities. In particular, introducing a nonlinear filter replaces the traditional first-order filter in dynamic surface technology, overcoming the "explosion of complexity" while attenuating the conservatism of gains tuning. Then, a dual extended state observer-based prescribed performance dynamic surface controller is developed for roadheaders for the first time. Simultaneously, integrating an improved error transformation function into controller design effectively avoids the online computational burden caused by traditional logarithmic operations. Utilizing Lyapunov theory, the cutting system's prescribed transient response and steady-state performance are guaranteed. Finally, the proposed controller's effectiveness is verified by comparative experiments on the roadheader.

Identification of coal and gangue based on R value method for dual-energy X-ray of Geant4 simulation.

With technical means of Geant4 simulation, the effectiveness of R value method in coal and gangue identification method of dual-energy X-ray is verified, and the characteristic factors affecting R value are explored. In the experiment, control variable method is used to study the effect of the thickness and shape of coal and gangue in R threshold. Compared with the shape of the coal sample, the thickness of the sample can directly affect the changes in R value of coal and gangue more. In addition, R threshold is continuously changing during the process of coal and gangue separation. R value of coal and gangue is positively correlated with the thickness of the sample, while the correlation with shape is difficult to be expressed due to the difficulty of mathematical descriptions of shape. The results show that the combination of dual-energy X-ray and image processing of Geant4 simulation can effectively identify coal and gangue, and the accuracy of distinguishing coal and gangue with different shapes and thicknesses reaches 95%. Finally, the current use of Geant4 simulation based on sample thickness can establish R threshold change curve for coal and gangue separation under specific geological environment for further coal and gangue separation with R value method based on dual-energy.

Research on Control Method of the Power System of Stepping-Type Anchoring Equipment.

To improve the roadway adaptability and control accuracy of anchoring equipment, a stepping anchoring device was designed. A permanent-magnet synchronous motor control and a harmonic suppression algorithm were integrated to optimize the dynamic control system of stepping-type anchoring equipment. The results of an experimental simulation and analysis showed that when the coefficient of coal rock hardness f = 5, 6, and 7, the pulsation coefficient of the hydraulic pump outlet pressure, hydraulic motor output speed, and pump-controlled hydraulic cylinder advance speed in the hydraulic circuit of a pump-controlled motor did not exceed 3% after the equipment based on sliding mode control (SMC) entered the steady state, while the maximum pulsation coefficient was only 32.5% of the PI control. Based on the SMC, the harmonic components of the permanent magnet synchronous motor in the power system were suppressed and compensated for. This enhanced the stiffness of the hydraulic system under motor drive. When the rock stiffness factor gradually changed from f = 5 to f = 8 and increased suddenly from f = 5 to f = 6, the pressure overshoot at the outlet of the hydraulic pump of the pump-controlled motor system was reduced from 11.19% to 7.97% and from 61.19% to 52.88%, respectively, compared with that before the optimization. It was thereby proven that SMC based on harmonic suppression can effectively reduce the system pulsation caused by the multi-factor coupling of anchoring equipment and provide technical support for the optimal control of the power system of stepping-type anchoring equipment.