Boom-type Roadheader Research Articles

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.

Research on the "shape-performance-control" integrated digital twin system for boom-type roadheaders

The boom-type roadheader plays a crucial role in coal mining. However, conducting the real-time monitoring of the mechanical performance and comprehensive adaptive cutting in the dynamic cutting process are challenging. To address these issues, a digital twin system that integrates the elements of “shape, performance, and control” for roadheaders is presented in this paper. The system comprises three components: physical space, service space, and twin space. The service space forms the core of the entire system. Within this space, twin models and control models are created using numerical simulation, artificial intelligence and multi-source data fusion technology. These models serve the purpose of predicting the roadheader’s mechanical performance and controlling the swing speed of the cutting arm. The physical space is built using technologies such as robot kinematics, electrical systems, hydraulic transmission, and other relevant techniques. This approach facilitates the transmission of multi-sensor data to twin models. The control model then manages the roadheader’s function based on the output signals from the control model. The twin space is constructed utilizing physical rendering engines, databases, and 3D modelling tools. This space visualizes and stores the movement, performance, and control parameters of the roadheader. The results demonstrate that the average absolute error between the measured data from the test’s three position strain gauges and the predicted data from the twin system is 10.38 MPa. Furthermore, the twin system achieves an average update interval of 0.34 s, allowing real-time stress monitoring of the structural components of the roadheader and preventing damage caused by overload. The proposed control model enables adaptive adjustment of the swing speed of the cutting arm in approximately 0.3 s. This improvement significantly enhances the adaptive cutting capabilities of roadheaders when dealing with complex coal and rock formations.

Position measurement technology of boom-type roadheader based on binocular vision

Positioning of underground mining equipment in coal mines is a primary challenge in the intelligent development of tunnel excavation. Accurate and reliable position measurement plays a crucial role in improving excavation efficiency. However, the stability and accuracy of traditional measurement methods are difficult to guarantee due to factors such as vibration, magnetic interference, and the absence of GPS signals in coal mine environments. To address the problem of unstable measurement of the boom-type roadheader‘s position, this paper proposes a binocular vision-based measurement technique that utilizes four light spots as characteristic points. By processing the target images captured by the binocular camera and combining the minimum bounding rectangle and ellipse fitting of the spot regions, the method successfully obtains the four light spot characteristics. Subsequently, precise matching and stereo distance measurement of the target in the left and right images enable the determination of the boom-type roadheader’s posi-tion information. A positioning platform based on binocular vision is built and experimentally evaluated. The results demonstrate that this method can achieve accurate spot extraction and stable measurement of the machine’s position, even in complex backgrounds such as mixed lighting and low illumination. The planar measurement errors within a distance range of 50 m are all within ±25 mm, which basically meets the required construction precision for tunnel excavation.

Dust diffusion laws during partition excavation by boom-type roadheader in a metro tunnel

When the drill bit of the boom-type roadheader cuts the dolomite at the tunnel face, it generates a lot of dust, which will have an adverse impact on human health and the surrounding environment. In order to clarify the laws of dust diffusion during partition excavation by a boom-type roadheader in a metro tunnel, the respirable dust and particle size distribution characteristics of tunnelling dust are studied through field experiments. Combined with FLUENT numerical simulation, the axial and radial diffusion laws of dust in the air field and the upper and lower parts of the tunnel face are further explored. The results show that at a position 5 m away from the tunnel face, the excavation dust concentration in the lower partition is 65.88% higher than that in the upper partition, and the concentration of respirable dust reaches 313.46 mg/m3, which has a greater impact on a boom-type roadheader operator. In the simulated excavations in the upper and lower partitions, the optimal distance between the air duct outlet and tunnel face is 12 m and 15 m, respectively, and 550 m3/min is the optimal pressure airflow.

Excavation of a Layered Rock Mass with the Use of Transverse Cutting Heads of a Roadheader in the Light of Computer Studies

Rock excavation is a basic technological operation during tunnelling and drilling roadways in underground mines. Tunnels and roadways in underground mines are driven into a rock mass, which in the particular case of sedimentary rocks, often have a layered structure and complicated tectonics. For this reason, rock strata often have highly differentiated mechanical properties, diverse deposition patterns and varied thicknesses in the cross sections of such headings. In the field of roadheader technology applied to drilling headings, the structure of a rock mass is highly relevant when selecting the appropriate cutting method for the heading face. Decidedly differentiated values of the parameters which describe the mechanical properties of a particular rock layer deposited in the cross section of the drilled tunnel heading will influence the value and character of the load on the cutting system, generated by the cutting process, power demand, efficiency and energy consumption of the cutting process. The article presents a mathematical modelling process for cutting a layered structure rock mass with the transverse head of a boom-type roadheader. The assumption was made that the rock mass being cut consists of a certain number of rock layers with predefined mechanical properties, a specific thickness and deposition pattern. The mathematical model created was executed through a computer programme. It was used for analysing the impact deposition patterns of rock layers with varied mechanical properties, have on the amount of cutting power consumed and load placed on a roadheader cutting system. The article presents an example of the results attained from computer simulations. They indicate that variations in the properties of the rock cut – as cutting heads are moving along the surface of the heading face – may have, apart from multiple other factors, a significant impact on the value of the power consumed by the cutting process.

A U-shaped spray device on a front boom-type roadheader for dust suppression in a metro tunnel

The application of the cantilever tunneling method in urban metro tunnel constructions has been gradually promoted. High concentration of dust will be produced near the working face when a boom-type roadheader is used to excavate a small and narrow metro tunnel in hard rock. If not controlled in time, high concentration of dust will escape in the working wells, the air in cities will be polluted and the health of residents will be affected. To maintain the sustainable development of cities, a U-shaped dust suppression device with optimized nozzle arrangement installed at the front end of the boom-type roadheader is proposed in this study. Firstly, the atomization characteristics of four different types of nozzles were analyzed by an indoor model test. The optimum nozzle is determined to be a fine solid conical nozzle with a diameter of 1.6 mm. Then, the dust diffusion law in the core dust producing area under the action of an air compressor is analyzed based on the discrete phase model of computational fluid dynamics; the influence of the parameters of the complete spray device on the performance parameters of the droplet field is discussed in detail based on the Taylor analogy breakup simulation method. The results show that when the spray pressure is 8 MPa and the number of nozzles is 11, the formed droplet field has the best encapsulation and the high concentration droplets account for 77.36%. Finally, the device is applied and verified on site. The test results show that the maximum total dust suppression efficiency in the tunnel reaches 81.48%, the maximum respirable dust suppression efficiency reaches 81.51%, and the dust suppression efficiency at other monitoring points is also above 70.41%.

Automatic Cutting Speed Control System of Boom-Type Roadheader Based on Geological Strength Index

The boom-type roadheader is the foremost mining equipment in coal mines. At present, the automatic cutting technology is still immature for adjusting cutting speed automatically in accordance with rock strength, resulting in energy dissipation. In this study, we put forward a method with respect to detecting the geological strength index of coal seam profile through visual inspection, as well as characterize the geological strength index and control the cutting head for adjusting speed automatically based on inspecting fracture features on coal rock’s surface, aiming at achieving energy conservation control of boom-type roadheader. The image processing algorithm is adopted for detecting joint characteristics of palisades fracture, and a quantitative model of the geological strength index is established. The fractal dimension is used to obtain the distribution of geological strength indicators of a coal seam, and the heading machine’s cutting head is controlled for adjusting speed automatically. A vision control platform of boom-type roadheader is built in the laboratory to perform ground simulation experiments. According to experimental results, the difference between the geological strength index of the coal seam detected through visual inspection and the set value in the geological strength index chart is up to 3.5%, and the results are basically consistent, so the quantification of geological strength index can be performed rapidly and effectively. The average energy consumption of boom-type roadheader decreases by 5.4% after adopting self-adaptation control, realizing energy conservation and consumption reduction as well as intelligent control of coal mine machinery.

Numerical Studies of the Dynamics of the Roadheader Equipped with an Automatic Control System during Cutting of Rocks with Different Mechanical Properties

The process of cutting rocks with a boom-type roadheader results in extreme dynamic loads and vibrations. Mining, especially in the case of hard rocks, is associated with large energy consumption, which, when combined with low process efficiency, can lead to low drilling performance. These phenomena are undesirable because excessive dynamic load leads to low machine durability, as well as deterioration of work conditions and safety. Low mining efficiency affects the economics of mining works conducted using roadheaders. However, these adverse effects can be minimized by optimizing the cutting process, thanks to the automatic control of the roadheader. The present article discusses the concept of automatic control of a boom-type roadheader’s cutting heads movement. Based on previously conducted computer investigations, it was assumed that reducing the energy consumption of the cutting process and improving the dynamic state of the roadheader (objective functions) are possible only by controlling three of the four parameters characterizing the cutting process: angular speed of the cutting heads, boom swinging speed, and cut height. The web of cut and workability of the rock can be treated as variables of a stochastic nature. This paper presents selected results of computer tests during simulated cutting of rocks with different uniaxial compressive strengths (UCS) in automatic and manual mode. In addition, the tests studied the behavior of the roadheader during the cutting of rocks with variable workability, which is typical of drilling excavations in a layered rock mass. The results of simulated cutting in automatic and manual mode were compared to assess the effectiveness of the adopted automatic control strategy. It was found that the algorithm developed for automatic control of the cutting heads’ movement allows reducing the consumption of cutting energy by up to half compared to the consumption during cutting in manual mode. Furthermore, it was found to improve the dynamic state of the machine.

Error Compensation of Strapdown Inertial Navigation System for the Boom-Type Roadheader under Complex Vibration

The strapdown inertial navigation system can provide the navigation information for the boom-type roadheader in the unmanned roadway tunneling working face of the coal mine. However, the complex vibration caused by the cutting process of the boom-type roadheader may result in significant errors of its attitude and position measured by the strapdown inertial navigation system. Thus, an error compensation method based on the vibration characteristics of the roadheader is proposed in this paper. In order to further analyze the angular and linear vibration of the fuselage, as the main vibration sources of the roadheader, the dynamic model of the roadheader is formulated based on the cutting load. Following that, multiple sub-samples compensation algorithms for the coning and sculling errors are constructed. Simulation experiments were carried out under different subsample compensation algorithms, different coal and rock characteristics, and different types of roadheader. The experimental results show that the proposed error compensation algorithm can eliminate the effect of the angular and linear vibration on the measurement accuracy. The coning and sculling error of the strapdown inertial navigation system can reduce at least 52.21% and 42.89%, respectively. Finally, a strapdown inertial navigation error compensation accuracy experiment system is built, and the validity and superiority of the method proposed in this paper are verified through calculation and analysis of the data collected on the actual tunneling work face.

Geometrically Driven Underground Camera Modeling and Calibration With Coplanarity Constraints for a Boom-Type Roadheader

The conventional calibration methods based on a perspective camera model are not suitable for the underground camera with two-layer glasses, which is specially designed for explosion proof and dust removal in a coal mine. Underground camera modeling and calibration algorithms are urgently needed to improve the precision and reliability of underground visual measurement systems. This article presents a novel geometrically driven underground camera calibration algorithm for a boom-type roadheader. The underground camera model is established under coplanarity constraints, considering explicitly the impact of refraction triggered by the two-layer glasses and deriving the geometrical relationship of equivalent collinearity equations. On this basis, we perform parameters calibration based on a geometrically driven calibration model, which are 2D-2D correspondences between the image points and object coordinates of the planar target. A hybrid Levenberg-Marqurdt (LM) and particle swarm optimization (PSO) algorithm is further proposed in terms of the dynamic combination of the LM and PSO, which optimizes the underground camera calibration results by minimizing the error of the nonlinear underground camera model. The experimental results demonstrate that the pose errors caused by the two-layer glass refraction are well corrected by the proposed method. The accuracy of the cutting-head pose estimation has increased by 55.73%, meeting the requirements of underground excavations.

Electro-hydraulic position servo system based on sliding mode active disturbance rejection compound control

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.

Modeling and response analysis of the attitude angles of roadheader for steep coal seam

This study presents a dynamical model of the attitude angles of boom-type roadheader, to reveal the response characteristics of the attitude angles in steep coal seam. Based on the Lagrange equation, the dynamical model of the attitude angles of roadheader is established, then the simulation system is constructed in Simulink, to solve the dynamical model. Afterwards, a calculating method of the cutting load is proposed, to formulate the external loads of the roadheader during cutting process. Focused on the steep coal seam, of which the dip angle is 30°, the dynamical model is solved, and the solving results influenced by different factors are obtained. The results show that, the variations of roadheader’s attitude are affected greatly by the cutting load, while the influence of swing angle of the cutting arm is relatively slight. Among the three attitude angles, the pitch angle varies most greatly, which can reach up to 9.1° and 8.7° during horizontal and vertical cutting process respectively. Finally, the numerical simulation results are verified by experimental data. The dynamical model and response characteristics of roadheader’s attitude angle presented in this paper, can provide useful basis for prediction of roadheader’s operating status and rectification of roadheader’s attitude in steep coal seam.Article HighlightsThe dynamical model of roadheader’s attitude is established, to accurately describe dynamic behaviors of roadheader during cutting process.The response regularities of roadheader’s attitude in steep coal seam, under effects of different factors, are revealed comprehensively.A method to calculate the cutting load is proposed, upon which the three dimension forces on the cutting head can be obtained.

Modelling and response analysis of multibody large-scale displacement of boom-type roadheader

Boom-type roadheader is the most widely used equipment in the fully mechanized excavation face of coal mine. Under complicated operation conditions of underground coal mine, multibody large-scale displacement phenomenon of roadheader will occur during cutting process. Specifically, the position and attitude of the body are changing continuously, and radial runout phenomenon of the cutting arm will take place, which will seriously reduce the overall stability of roadheader and drivage efficiency of the roadway. Focused on the vertical cutting condition, the coupling dynamical model of position and attitude of the body is established based on Lagrange equation. Combined with the calculated cutting load, the dynamical model is solved through Simulink simulation method, and the solving results are analysed under different influence factors. Consequently, the response regularities of position and attitude of the body under influence of different factors are obtained. In the similar way, the dynamical model of radial runout quantity of the cutting arm is established, and the dynamic response of radial runout of the cutting arm during vertical cutting process is obtained as well. Finally, the simulation analysis results are validated through field experiments. The research work of this paper provides useful theoretical basis for deviation rectification control of the multibody structures of roadheader, fills the vacancy of theoretical study in this aspect, and contributes to improving the dynamics theory of mining machinery.

Impulse Processing Algorithm for Random Source Signals of Roadheaders That Is Based on Compound Interferometry

The boom-type roadheader is the main equipment for realizing the mechanization of coal drifting in coal mines, and it is an indispensable production equipment in major coal-producing countries. Substantial vibrations are generated during the operation of a roadheader; these vibrations carry substantial energy and, thus, can be regarded as a potential source and used for seismic advance detection purposes in mine drifts. Compared with a conventional exploration source, a roadheader source produces a complex continuous random signal. The shape of a seismic wavelet is uncertain and its duration is relatively long; thus, it must be processed into a conventional pulse signal before it can be used for subsequent processing and analysis. Therefore, based on the advantages of seismic interferometry in random signal processing, two seismic interference techniques, namely, deconvolution and cross-correlation, are introduced for constructing a compound interference algorithm. On the basis of a theoretically derived formula, a random signal impulse processing experiment is conducted using field-acquired source signals from a roadheader; this approach resolves the problem that cross-correlation alone cannot yield ideal results. Hence, a feasible algorithm for the impulse processing of a random signal, namely, the compound interference algorithm, is proposed. The algorithm deconvolves each seismic trace to obtain the reference trace and other receiver traces after compressing the wavelet. Then, the reference trace and each receiver trace are cross-correlated, and the wavelet time delay information of each correlated wavelet pulse, namely, the wavelet time delay information of the receiver trace relative to the reference trace, is obtained. Accordingly, the direct wave and reflected waves are recognized. To evaluate the performance of the algorithm, an algorithm application experiment is conducted for another group of random source signals that were collected by a roadheader under different coal drift conditions. Again, the algorithm processing results are consistent with the single-shot record characteristics of an explosive source. Consequently, the proposed algorithm can satisfy the requirements for engineering exploration and analysis. A comprehensive analysis further demonstrates that the compound interference algorithm is both feasible and effective and that the processed seismic signals can be used for subsequent processing and interpretation.

Optimization of the Cutting Process Parameters to Ensure High Efficiency of Drilling Tunnels and Use the Technical Potential of the Boom-Type Roadheader

This paper deals with the automation of the rock cutting process with roadheaders used widely in civil engineering for drilling roadways in underground mines and tunnels. Although there has been intensive technical development, roadheaders are still manually controlled. Manual control does not allow optimizing the values of the cutting process parameters, which often results in low mining efficiency, especially in the case of hard rocks, as well as high energy consumption and significant dynamic overloading of the roadheader. As part of theoretical and experimental research, an automatic control system was designed for the boom-type roadheader and an algorithm was developed for the optimal control of the cutting process parameters. Control criteria have been formulated, based on which the current values of the cutting process parameters are worked out using the information on the dynamic load state of the roadheader. The paper presents selected results of numerical tests conducted on roadheader dynamics, which simulated the automatic control system operation of the heading face cutting process of drilled roadway or tunnel. These tests were intended to analyze the behavior of the investigated object during simulated rock cutting in automatic mode. The results confirmed the possibility of a significant reduction in mining energy consumption.

Influence of Motion Parameters on Cutting Performance of Boom-Type Roadheader During the Swing Cutting

The cutting performance of the boom-type roadheader impacts the energy consumption and efficiency of coal mine roadway excavation. The purpose of this work is to investigate the influence of motion parameters on cutting performance. The motion of the cutting head during swing cutting was simplified to establish a numerical model. Rock samples were arranged to perform the swing cutting to test the validity of the numerical model based on the coal-rock cutting platform. The cutting specific energy consumption and the average cutting force on picks involved in cutting were used as indexes to evaluate the effects of the cutting depth, velocity, and subsequent cutting distance on cutting performance. The mechanism of the cutting head was also explained. The results show that the cutting performance is optimal when the cutting depth is 1/2 to 2/3 of the cutting head length. In terms of energy consumption, cutting performance is more sensitive to cutting depth than to cutting velocities. The cutting performance indexes tend to be stable until the subsequent cutting distance exceeds the diameter of the cutting head.

Research status of pose detection methods of boom-type roadheader

Research status of pose detection methods of boom-type roadheader

A Scheme of MEMS-SINS Initial Alignment Aided by Laser Spot Perception System for the Boom-Type Roadheader

The initial alignment is one of the difficult problems of the strapdown inertial navigation system based on the microelectromechanical systems (MEMS-SINS) applied to the navigation of boom-type roadheader under a coalmine. To overcome the complex environment of the underground coalmine and the large noise of the MEMS gyroscope, the laser spot perception system (LSPS) was developed to provide the heading information of the roadheader to aid the initial alignment of the MEMS-SINS. During the process of initial alignment, the differential equation of heading error is derived, the heading error is extended as a state variable, and a nonlinear initial alignment model aided by heading error is built up. To cope with the time-varying noise statistics of MEMS-SINS in the working face of the coal mine roadway, a simplified strong tracking Unscented Kalman Filter (SST-UKF) algorithm is proposed by combining covariance matching technology with UKF. In the calculation of the measurement prediction covariance and the cross covariance, the fading factor is introduced, respectively, to avoid the contradiction between the residuals before and after the introduction; according to the characteristics of the observation equation being a linear equation, it proves that the state prediction covariance matrix change does not affect the observation measurement and uses unscented transform (UT) only once in the state estimation and variance prediction; thus, the computational burden of the algorithm is reduced and the real-time performance is improved. The simulation and onboard experiment results show that the proposed scheme can achieve horizontal alignment within 40 s and convergence azimuth misalignment angle to 0.9° within 450 s, which fully meets the requirements of MEMS-SINS initial alignment for underground coalmine roadheader.

Laser Beams-Based Localization Methods for Boom-Type Roadheader Using Underground Camera Non-Uniform Blur Model

The efficiency of automatic underground tunneling is significantly depends on the localization accuracy and reliable for the Boom-type roadheader. In comparison with other underground equipment positioning methods, vision-based measurement has gained attention for its advantages of non-contact and no accumulated error. However, the harsh underground environment, especially the geometric errors brought by the vibration of the machine body to the underground camera model, has a certain influence on the accuracy and stability for the vision-based underground localization. In this paper, a laser beams-based localization methods for the machine body of Boom-type roadheader is presented, which can tackle the dense-dust, low illumination environment with the stray lights interference. Taking mining vibration into consideration, an underground camera non-uniform blur model that incorporate the two-layer glasses refraction effect was established to eliminate vibration errors. The blur model explicitly reveals the change of imaging optical path under the influence of vibration and double layer explosion-proof glass. On the basis of this, the underground laser beams extraction and positioning are presents, which is with well environmental adaptability, and the improved 2P3L (two-points-three-lines) localization model from line correspondences are developed. Experimental evaluation are designed to verify the performance of the proposed method, and the deblurring algorithm is investigated and evaluated. The results show that the proposed methods is effective to restore the blurred laser beams image that caused by the vibration, and can meet the precision need of roadheader body localization for roadway construction in coal mine.

Determining the position of pick holders on the side surface of the working unit of the cutting machine in the robotic technology of their assembly

One of the important issues related to the robotization of the manufacturing process of cutting machine working units is to determine the degree of movement of pick holders positioned by the industrial robot to the side surface of the cutting drum/head. This article examines the possibility of using vision system for the purpose of measuring the distance between the pick holder base and the side surface of the working unit of the cutting machine. Based on the boom-type roadheader cutting head, a mathematical measurement model has been formulated and a measurement procedure algorithm has been developed. Tests of the proposed measurement method with the use of a single camera were carried out at a test station. The station is equipped with the KUKA KR 16-2 industrial robot working together with the VisionTech vision system. This work contains examples of measurement results for three pick holders positioned differently in relation to the side surface of the cutting head. Based on distance measurement between the respective elements with the use of the 2D vision system along one line of known direction and position, a prediction of the distance distribution along the whole surface of the pick holder base has been made.