Teaching Research and Reform of Higher Vocational Medical Education in Guizhou Province of China

With the development of Guizhou’s economy and society, higher vocational medical education in Guizhou has developed rapidly, making it its mission to cultivate practical and skilled talents oriented to the grassroots and serving for frontline. However, due to the social environment, policy environment and insufficient funding, many difficulties and problems are faced. It is necessary to have a unied management throughout the province, rationally lay out higher vocational colleges and specialties, and promote the healthy and rapid development of medical higher vocational education in Guizhou with advanced concepts, proper policies, and sufcient funds in place, making higher vocational medical education in Guizhou enter a benign development period

DT-driven memory cutting control method using VR instruction of boom-type roadheader

Aiming at the problems of low intelligence of current tunneling equipment, difficulty in describing over-excavation, under-excavation and abnormal collision in tunneling process, and difficulty in adapting traditional automatic cutting and memory cutting technology to complex geological conditions, a digital twin-driven virtual teaching memory cutting control method for cantilever roadheader is proposed. By analyzing the research situation of digital twin technology in the field of intelligent coal mining, the overall scheme of memory cutting control system of cantilever roadheader driven by digital twin is designed, and the key technology of memory cutting of cantilever roadheader under complex working conditions is studied. Firstly, the characteristics of digital twin and virtual reality technology are fully utilized to study the virtual teaching strategy under complex working conditions. Based on the Unity3D platform, the virtual twin model of the working face and equipment with the same size of the corresponding entity, the kinematics model of the cutting unit and the virtual collision detection model are established. The virtual model movement is controlled through the intelligent interactive interface at the virtual end, and the teaching trajectory is designed and optimized according to the worker’s experience, so that it can be used as the target expected trajectory of trajectory tracking to make up for the excessive dependence on the worker’s experience caused by the traditional underground manual teaching due to the harsh working conditions. Secondly, in order to improve the quality of section forming, the control method of teaching trajectory tracking and reproduction in memory automatic cutting stage is studied. The dynamic model of cutting part is established by Lagrange method, and the tracking control accuracy of end effector to teaching trajectory is improved by combining iterative learning with sliding mode control. Finally, the simulation control platform of the memory cutting of the cantilever roadheader is built. Through the real-time data transmission and interaction between the virtual space and the physical space and between the modules, the three-dimensional visual simulation of the memory cutting virtual teaching and trajectory tracking control process is completed in the virtual space, and then the memory automatic cutting trajectory tracking control command is generated and sent to the end effector of the physical entity of the cantilever roadheader to drive it to carry out the section forming cutting according to the teaching trajectory. At the same time, the physical sensor collects the pose data of the cantilever roadheader fuselage and the cutting arm, and reversely drives the virtual model to move synchronously. The closed-loop control of robot virtual model and physical entity is realized. On this basis, the virtual and real synchronization of the system, the motion consistency between the virtual prototype and the physical prototype, and the trajectory tracking and reproduction control accuracy are verified. The experimental results show that the system data transmission delay is low, which can ensure the virtual and real consistency and synchronization, and the trajectory tracking control accuracy meets the actual use requirements. This method provides a new idea for memory cutting and intelligent control of tunneling equipment

Weak order in averaging principle for stochastic differential equations with jumps

Abstract In this paper, we deal with the averaging principle for a two-time-scale system of jump-diffusion stochastic differential equations. Under suitable conditions, we expand the weak error in powers of timescale parameter. We prove that the rate of weak convergence to the averaged dynamics is of order 1. This reveals that the rate of weak convergence is essentially twice that of strong convergence

Long distance high precision positioning system of anchor digger

Aiming at the problems of high labor intensity, low degree of automation and low positioning accuracy of single way in the construction process of existing coal mine anchor digging machine, a long-distance positioning system suitable for anchor digging machine is developed by using sensor measurement, machine vision, inertial navigation and other technologies. The system consists of anchor digger, inertial positioning subsystem, visual positioning subsystem, total station positioning subsystem and parameter monitoring subsystem. Anchor digger main machine adopts MB670-1 anchor digger; the inertial navigation and positioning subsystem is composed of built-in optical fiber inertial navigation and explosion-proof computer. The visual positioning subsystem includes infrared explosion-proof target, laser pointing device, front explosion-proof industrial camera and explosion-proof computer. The positioning subsystem of total station consists of 360° prism, three laser pointing instrument and rearview prism. Parameter monitoring subsystem includes parameter display, parameter setting and parameter solution module. The system was successfully developed and tested in Dahaize Coal Mine of China National Coal Group. The experiment shows that the long-distance high-precision positioning system of the all-in-one anchor digger has the advantages of flexible operation and highpositioning accuracy, and can realize the positioning and parameter monitoring of the all-in-one anchor digger

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

High-Precision Drilling by Anchor-Drilling Robot Based on Hybrid Visual Servo Control in Coal Mine

Rock bolting is a commonly used method for stabilizing the surrounding rock in coal-mine roadways. It involves installing rock bolts after drilling, which penetrate unstable rock layers, binding loose rocks together, enhancing the stability of the surrounding rock, and controlling its deformation. Although recent progress in drilling and anchoring equipment has significantly enhanced the efficiency of roof support in coal mines and improved safety measures, how to deal with drilling rigs’ misalignment with the through-hole center remains a big issue, which may potentially compromise the quality of drilling and consequently affect the effectiveness of bolt support or even result in failure. To address this challenge, this article presents a robotic teleoperation system alongside a hybrid visual servo control strategy. Addressing the demand for high precision and efficiency in aligning the drilling rigs with the center of the drilling hole, a hybrid control strategy is introduced combining position-based and image-based visual servo control. The former facilitates an effective approach to the target area, while the latter ensures high-precision alignment with the center of the drilling hole. The robot teleoperation system employs the binocular vision measurement system to accurately determine the position and orientation of the drilling-hole center, which serves as the designated target position for the drilling rig. Leveraging the displacement and angle sensor information installed on each joint of the manipulator, the system utilizes the kinematic model of the manipulator to compute the spatial position of the end-effector. It dynamically adjusts the spatial pose of the end-effector in real time, aligning it with the target position relative to its current location. Additionally, it utilizes monocular vision information to fine-tune the movement speed and direction of the end-effector, ensuring rapid and precise alignment with the target drilling-hole center. Experimental results demonstrate that this method can control the maximum alignment error within 7 mm, significantly enhancing the alignment accuracy compared to manual control. Compared with the manual control method, the average error of this method is reduced by 41.2%, and the average duration is reduced by 4.3 s. This study paves a new path for high-precision drilling and anchoring of tunnel roofs, thereby improving the quality and efficiency of roof support while mitigating the challenges associated with significant errors and compromised safety during manual control processes

Performance Evaluation of Liquorice Harvester with Novel Oscillating Shovel-Rod Components Using the Discrete Element Method

Liquorice harvesting is the key process in the development of the liquorice industry. For harvesting liquorice with about 400 mm growth depth, a lightweight harvester with novel oscillating shovel-rod components was developed. Draft force, total torque, specific energy consumption, separation proportion, and soil structure maintenance were used to evaluate harvester performance under varied working conditions, and throw intensity and total torque were analyzed. A DEM model was developed to simulate the excavation and separation of soil. Three sets of single-factor simulation tests and one set of field tests were conducted. The results indicated that: Each 1 mm increase in amplitude decreased draft force by 463.35 N and increased total torque and specific energy consumption by 35.03 Nm and 4.3 kJ/m3, respectively. Each 1 Hz increase in vibration frequency increased specific energy consumption by 3.12 kJ/m3, while draft force and total torque decreased by 375.75 N and 28.44 Nm, respectively. Each 0.1 m/s increase in forwarding speed increased the draft force, total torque and specific energy consumption by 1302.72 N, 13.26 Nm and 3.82 kJ/m3, respectively. The main separation areas of the shovel-rod were front areas, where the soil separation proportion is greater than 60%, and the soil was completely separated at the end areas. The soils after harvesting had a relatively minimal disturbance in all layers, with soil structure maintenance greater than 0.61, and soil structure was well maintained. The liquorice plants were separated from the soil after passing smoothly through the oscillating shovel-rod components, during which the soil at different layers fell in sequence. This study revealed the interactive relationship between working components and soil, specifically the potential to maintain soil structure after harvesting. This new finding will assist in developing harvest techniques for rhizome crops with deep growth depth

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