An unattended control method for an excavator

Abstract

The application discloses an unmanned control method of a dump truck and belongs to the technical field of ore mining. The method comprises the following steps: after receiving a current dump task, the position and pose of the dump truck are determined; a three-dimensional model of a dump site is established according to the three-dimensional shape of a material pile; contour features of the dump site are extracted, and the rotation angle of a material discharging arm of the dump truck corresponding to a dump boundary is calculated; the rotation angle is compared with a measured rotation angle; when the moving position of the material discharging arm approaches the position corresponding to the dump boundary, the material discharging arm is automatically controlled to move in another direction to perform a next operation action. The whole process realizes automatic control, reduces the labor intensity, improves the work efficiency and guarantees the personal safety of workers.

Description

Technical Field

[0001] This invention belongs to the field of ore mining technology, and specifically relates to an unattended control method for a dumping machine. Background Technology

[0002] The dumper is a key piece of equipment in open-pit mining stripping operations. In open-pit mining stripping, materials are collected by electric shovels and single-bucket trucks or bucket excavators, and transported by belt conveyors. The dumper is located at the end of the stripping and transport system. The stripped soil and rock are unloaded onto the receiving arm via the unloading tail car, then transported by a belt conveyor on the receiving arm to the discharge arm, and finally discharged to the spoil heap via a belt conveyor on the discharge arm. The dumper operator operates it from a control room on the dumper, where there is noise and dust pollution, creating a harsh working environment that is detrimental to health.

[0003] Currently, the soil dumping operation is operated by staff in the control room on the soil dumping machine. The on-site working conditions are relatively complex and harsh, the manual labor intensity is high, the work efficiency is low, the safety is poor, and the occupational hazards are significant. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide an unmanned control method for a spoil heap, which solves the problems that currently, spoil heap operations must be controlled by workers on the spoil heap, resulting in harsh operating environments that cannot guarantee worker safety and low work efficiency.

[0005] The technical solution adopted in this invention is: an unattended control method for a dumping machine, the key technical points of which include the following steps: after receiving the current dumping task, determining the position and posture of the dumping machine; establishing a three-dimensional model of the dumping site based on the three-dimensional shape of the material pile; extracting the contour features of the dumping site, calculating the rotation angle of the dumping machine's discharge arm corresponding to the dumping boundary, comparing this rotation angle with the measured rotation angle, and controlling the discharge arm to automatically move in another direction when the movement position of the discharge arm approaches the position corresponding to the dumping boundary, to perform the next operation.

[0006] Furthermore, the method for determining the location of the dumping machine is as follows: a positioning device is installed on the track bridge of the dumping machine. After receiving GNSS satellite signals and differential correction data sent by the reference station set up at the dumping site, the positioning device performs positioning calculations to obtain the location information of the dumping machine.

[0007] Furthermore, the position and posture of the dumper include the rotation angle of the discharge arm and the pitch angle of the discharge arm.

[0008] Furthermore, the method for determining the rotation angle of the discharge arm is as follows: taking the direction of the discharge arm and the unloading trolley track of the dumper as 0°, an electronic tag is installed at a fixed position on the rotary platform of each dumper every 90 degrees to collect the absolute angle of the discharge arm rotation; the position that coincides with the track of the unloading trolley of the dumper is marked as the reference zero point of the encoder, and the encoder calculates the actual angle during the rotation of the dumper; when the discharge arm of the dumper rotates, the absolute position information of the electronic tag is read every time it passes an electronic tag to obtain the absolute angle of the current rotation of the dumper, and it is compared with the position information calculated by the encoder to obtain the final rotation angle of the discharge arm.

[0009] Furthermore, determining the three-dimensional shape of the material pile and establishing a three-dimensional model of the spoil heap refers to obtaining point cloud data of the spoil heap by scanning, and then using the obtained point cloud data to generate a three-dimensional model of the spoil heap.

[0010] Furthermore, the extraction of the spoil heap contour features refers to detecting the boundary of the spoil heap area through spoil heap protection strategies and boundary recognition strategies, and then extracting the spoil heap contour features using a point cloud adaptive variable threshold segmentation algorithm.

[0011] Furthermore, the aforementioned protection strategy for the dumping machine refers to the first layer of mechanical protection; the second layer of soft limit protection; the third layer of ultrasonic protection; and the fourth layer of system protection.

[0012] Furthermore, the automatic soil disposal strategy includes rotary soil disposal and fixed-point soil disposal. Fixed-point soil disposal is used for soil piles that require a regular shape, while rotary soil disposal is used for soil piles with irregular shapes.

[0013] The beneficial effects of this invention are as follows: This unmanned control method for a dumping machine, upon receiving the current dumping task, determines the position and posture of the dumping machine; establishes a three-dimensional model of the dumping site based on the three-dimensional shape of the material pile; extracts the contour features of the dumping site, calculates the rotation angle of the dumping machine's discharge arm corresponding to the dumping boundary, compares this rotation angle with the measured rotation angle, and when the discharge arm moves close to the position corresponding to the dumping boundary, controls the discharge arm to automatically move in another direction for the next operation. The entire process achieves automated control, reduces manual labor intensity, improves work efficiency, and ensures worker safety. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1This is a schematic diagram illustrating the principle of the fixed-point soil removal method in an embodiment of the present invention;

[0016] Figure 2 This is a schematic diagram of the rotary soil removal method in an embodiment of the present invention;

[0017] Figure 3 This is a flowchart of an unattended control method for a dumping machine according to an embodiment of the present invention. Detailed Implementation

[0018] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the following description is provided in conjunction with the accompanying drawings. Figures 1-3 The present invention will be further described in detail below with reference to specific embodiments.

[0019] The unmanned control system for the spoil heap used in this embodiment includes: a positioning system, a 3D scanning system, a collision avoidance system, and a control system. The 3D scanning system includes a LiDAR scanner and a 3D scanning server. The LiDAR scanner is installed at the head of the discharge arm, horizontally and symmetrically parallel to the arm, to acquire point cloud data of the spoil heap. The 3D scanning server is installed in the remote control room of the spoil heap to process the transmitted point cloud data and generate a 3D model of the spoil heap.

[0020] The anti-collision system for the dumper includes three ultrasonic ranging anti-collision devices installed on each side of the dump boom. The anti-collision distance is adjustable, ensuring that the dump boom does not collide with the material piles or other obstacles on either side during dumping operations. One radar material level detection device is installed at the material inlet at the head of each dump boom for material height control, preventing the dump boom from colliding with the soil pile. Two ultrasonic rangefinders are installed at the front and rear of the dumper's tracks for obstacle monitoring during dumping operations.

[0021] The control system includes a PLC controller, a host computer and server, an industrial switch, and a wireless communication device. The PLC controller collects data from the dumping machine and controls its movement. The host computer and server, installed in the remote control room of the dumping machine, display operating parameters, fault alarms, equipment control, video monitoring, production planning, and production reports. They also send control commands to the PLC controller to enable unattended dumping operations. The industrial switch and wireless communication device facilitate communication between the PLC controller and the host computer server.

[0022] This embodiment of a method for unattended control of a dumping machine includes the following steps:

[0023] Step 1: After receiving the soil dumping task, determine the position and posture of the soil dumping machine. Measure the relative walking position of the soil dumping machine to the dumping site, including the rotation angle and pitch angle of the discharge arm. The accuracy of these three motion mechanism data is a key technology for fully automated unattended operation of the soil dumping machine. The positioning accuracy significantly affects the efficiency and safety of unattended operation.

[0024] Step 1.1: Determine the location of the dumping machine.

[0025] Establish a unified three-dimensional spatial coordinate system for the spoil heap, spoil excavator, and material pile. In this coordinate system, the X-axis represents the track direction of the spoil excavator's unloading trolley, the Y-axis is perpendicular to the spoil excavator's unloading trolley track, and the Z-axis represents the height of the material pile. Achieve a travel position accuracy of ±0.05 meters and a rotation and pitch angle accuracy of ±0.01 degrees.

[0026] An RTK reference station was set up at the spoil heap, and an RTK high-precision positioning module was installed on the track bridge of the spoil heap machine.

[0027] The base station is located at a known position and sends correction data to the high-precision positioning module. The high-precision positioning module receives the correction data during its movement and performs real-time positioning.

[0028] After receiving GNSS satellite signals and differential correction data sent by the base station, the high-precision positioning module combines these two data to perform precise positioning calculations and obtain high-precision position information of the dumping machine.

[0029] Step 1.2, determine the rotation angle of the discharge arm of the dumper, including the following steps:

[0030] Step 1.2.1: Install one set of driven rotary positioning device on the rotary mechanism of each dumper. The rotary positioning device includes an encoder and gears. In the driven rotary device with the encoder, the gear meshes with the gear of the rotary mechanism body to achieve synchronous rotation, thereby measuring the rotation angle of the dumping arm.

[0031] Step 1.2.2: Install an electronic tag at a fixed position on the slewing platform of each excavator every 90 degrees. With the direction of the discharge arm and the track of the excavator unloading trolley as 0°, place electronic tags at corresponding positions at -90°, -45°, 0°, 45° and 90° respectively, for a total of 5 tags, and encode them with absolute angles.

[0032] Step 1.2.3: During the rotation positioning process, the reference zero point of the encoder must first be calibrated at the position that coincides with the track of the unloading trolley of the dumper. During the rotation of the dumper, the current data of the encoder is continuously acquired by the positioning system acquisition terminal. By comparing it with the reference zero point data, the current position of the dumper is calculated.

[0033] Step 1.2.4: When the dumper's discharge arm rotates, it reads the absolute position information of the tag each time it passes an electronic tag, obtains the current absolute rotation angle of the dumper, compares it with the position information calculated by the encoder in step 1.2.3, and makes position corrections to reduce positioning errors caused by excessive rotation angles and improve real-time positioning accuracy.

[0034] Step 1.3, determine the pitch angle of the dumper's boom, including the following steps:

[0035] Step 1.3.1: The pitch positioning of the dumper's boom is achieved using a high-precision tilt meter designed based on gravity sensing technology, with one set installed on the inner side of the tail of the boom. The detection accuracy reaches 0.01º, and the angle signal is sent to the PLC controller via communication.

[0036] Step 1.3.2: The high-precision tilt meter is based on gravity sensing and outputs data with 0° horizontal as the absolute position. During the pitching process, it outputs a 4-20mA signal in real time as the angle changes. The real-time pitch angle of the discharge arm is determined through data conversion.

[0037] Step 2: Determine the three-dimensional shape of the material pile and establish a three-dimensional model of the spoil heap; extract the contour features of the spoil heap using the point cloud adaptive variable threshold segmentation algorithm, and calculate the rotation angle of the spoil heap arm corresponding to the spoil heap boundary.

[0038] Step 2.1: The 3D laser scanning system acquires point cloud data of the spoil heap by scanning and sends the acquired point cloud data to the 3D scanning server to generate a 3D model of the spoil heap.

[0039] The 3D laser scanning system includes a LiDAR scanner and a 3D scanning server. The LiDAR scanner is installed at the head of the discharge arm, horizontally and symmetrically parallel to the arm. During operation, the dumping machine automatically performs a 3D laser scan of the outer contour of the material pile to acquire point cloud data of the dump site. This point cloud data is transmitted to the 3D scanning server via Ethernet. The 3D scanning server processes the returned point cloud data to generate a 3D model of the dump site. The 3D model supports rotation, scaling, and translation, and can be dynamically updated during dumping. Operators can query the coordinates of any point on the 3D model. The 3D model can display various dumping areas and dynamically display them on the host computer screen.

[0040] Step 2.2: The control server analyzes the 3D model of the spoil heap and generates action instructions for the spoil heap according to the set algorithm strategy and equipment parameter data of the spoil heap, and sends control instructions to the PLC controller; wherein, the algorithm strategy includes: spoil heap protection strategy, boundary recognition strategy and automated spoil heap strategy.

[0041] Step 2.2.1: The protection strategy for the spoil disposal machine is as follows:

[0042] The first layer of protection is mechanical protection, which uses mechanical limit switches on the slewing and pitching mechanisms, such as slewing limit / extreme and pitch limit / extreme, as well as pull rope switches on both sides of the discharge arm, to ensure that the soil dumper meets the protection requirements of its mechanical performance during normal operation.

[0043] The second layer of protection is soft limit protection. By adding soft protection functions for walking, turning, and pitching in the program, the position information of each mechanism collected by the positioning system is compared with the physical mechanical limit position. When each mechanism exceeds the position of its physical limit, the corresponding earthmoving machine will automatically stop working (stop the operation of each mechanism such as walking, turning, and pitching) and issue an audible and visual alarm.

[0044] The third layer of protection and detection is ultrasonic protection. It uses ultrasonic waves to detect material piles or other foreign objects within a 0-6 meter range around the dumper and discharge arm in real time. When an object is detected, the machine slows down in advance. The ultrasonic detection device is equipped with anti-collision alarms to meet the automatic protection requirements of the dumper during operation, regardless of any movement of the discharge arm.

[0045] The fourth layer of protection is system protection. The system will occupy space for each material pile on the spoil heap according to its shape and outline. The space occupied by the material pile is automatically set as a restricted area. The system will detect the position of the discharge arm in the space in real time. Once it approaches the restricted area, the discharge arm will stop its operation and provide an alarm.

[0046] Step 2.2.2: Boundary recognition strategy process: In automated soil dumping operations, it is necessary to automatically detect the boundary of the soil dumping area and automatically rotate around the boundary. The specific implementation of automatic soil dumping boundary detection and automatic rotation function in the PLC control system is as follows: Contour features are extracted using a point cloud adaptive variable threshold segmentation algorithm, the rotation angle corresponding to the soil dumping boundary is calculated, and the data is sent to the PLC controller in real time. The PLC controller obtains the spatial coordinates of the soil dumping machine's discharge arm in real time through the soil dumping machine positioning system. During the soil dumping operation, this coordinates are compared with the boundary coordinate data sent by the 3D scanning system. When the discharge arm moves close to the position corresponding to the soil dumping boundary, the discharge arm automatically moves in the other direction, preparing for the next operation.

[0047] Step 3: The PLC control system of the spoil disposal machine directs the spoil disposal machine to realize automated material discharge operation according to the control instructions, and feeds back the real-time equipment data to the control server.

[0048] Step 3.1: Automated soil disposal strategy. For small stockpiles with regular shapes, fixed-point soil disposal method can be used, which can provide high operational stability. For large or irregularly shaped stockpiles, rotary soil disposal method can be used, which can better adapt to changes in stockpiles and achieve continuous and efficient soil disposal operations.

[0049] (1) Fixed-point dumping method. During automatic dumping, the dumper does not move, and the discharge arm is fixed at a certain height. The height of the material pile is set within the allowable operating range of the dumper. To reduce dust during dumping, the discharge arm is generally fixed at a position 4m above the surface of the material pile. When the material pile is 1m away from the discharge arm, the discharge arm is moved upward by 3m until the height of the material pile at that point reaches the predetermined height. The discharge arm rotates one angle to perform dumping at the second point. After dumping is completed within the effective rotation range, the dumper retreats 2m to perform the next rotation of fixed-point dumping until the dumping is finished. Figure 1 As shown, the fixed-point soil removal sequence follows the numerical order shown in the diagram, removing soil at each point sequentially. After removing the first layer, the second layer is removed, and so on, until layer 64 is reached.

[0050] (2) Rotary Discharge Method. During automatic discharge, the stacker-reclaimer does not move; the discharge arm is fixed at a certain height and rotates left and right within its effective rotation range. The discharge height control is the same as for fixed-point discharge operations. When the pile height reaches the predetermined height, the trolley reverses 2 meters before performing a second rotation for discharge, continuing until discharge is complete. Figure 2 As shown, after the soil dumper reaches the upper boundary number 1, it retreats to the lower boundary number 1 and then retreats 2m. It then starts dumping from the lower boundary number 2 until it reaches the upper boundary number 2. It then retreats 2m again and repeats the dumping process in numerical order.

[0051] Step 3.2: Feed back the equipment data such as the position and operating parameters of the dumping machine to the control server to carry out the next operation.

[0052] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for unattended control of a spoil disposal machine, characterized in that, The process includes the following steps: Upon receiving the current dumping task, determine the position and orientation of the dumping machine; establish a 3D model of the dumping site based on the 3D shape of the material pile; extract the outline features of the dumping site, calculate the rotation angle of the dumping machine's discharge arm corresponding to the dumping boundary, compare this rotation angle with the measured rotation angle, and when the discharge arm moves close to the position corresponding to the dumping boundary, control the discharge arm to automatically move in another direction to perform the next operation. The method for determining the location of the dumping machine is as follows: a positioning device is installed on the track bridge of the dumping machine. After receiving GNSS satellite signals and differential correction data sent by the reference station set up at the dumping site, the positioning device performs positioning calculations to obtain the location information of the dumping machine. The method for determining the rotation angle of the discharge arm is as follows: taking the direction of the discharge arm and the unloading trolley track of the dumper as 0°, an electronic tag is installed at a fixed position on the rotary platform of each dumper every 90 degrees to collect the absolute angle of the discharge arm rotation; the position that coincides with the track of the unloading trolley of the dumper is marked as the reference zero point of the encoder. During the rotation of the dumper, the encoder calculates the actual angle; when the discharge arm of the dumper rotates, the absolute position information of the electronic tag is read every time it passes an electronic tag to obtain the absolute angle of the current rotation of the dumper. This is compared with the position information calculated by the encoder to obtain the final rotation angle of the discharge arm. The aforementioned determination of the three-dimensional shape of the material pile and establishment of the three-dimensional model of the spoil heap refers to obtaining point cloud data of the spoil heap material pile by scanning, and then using the obtained point cloud data to generate a three-dimensional model of the spoil heap material pile. The extraction of spoil heap contour features refers to detecting the boundary of the spoil heap area through spoil heap protection strategies and boundary recognition strategies, and then extracting the spoil heap contour features using a point cloud adaptive variable threshold segmentation algorithm.

2. The unmanned control method for a dumping machine as described in claim 1, characterized in that, The position of the dumper includes the rotation angle of the discharge arm and the pitch angle of the discharge arm.

3. The unmanned control method for a dumping machine as described in claim 1, characterized in that, The aforementioned protection strategy for the dumping machine refers to the first layer of mechanical protection; the second layer of soft limit protection; the third layer of ultrasonic protection; and the fourth layer of system protection.

4. The unmanned control method for a dumping machine as described in claim 1, characterized in that, Automatic soil disposal strategies include rotary soil disposal and fixed-point soil disposal. Fixed-point soil disposal is used for soil piles that require a regular shape, while rotary soil disposal is used for irregularly shaped soil piles.

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