Underground coal conveying belt scattered coal cleaning robot and cleaning control method

Abstract

The invention discloses an underground coal conveying belt scattered coal cleaning robot and a cleaning control method. Coordinate systems of a material raking mechanical arm and a digging and conveying mechanical arm are established through a D-H method, and then forward kinematics analysis is conducted on a cleaning mechanism through matrix transformation based on the D-H method; constructing a trigonometric function by using a geometric method to perform inverse kinematics analysis of the cleaning mechanism; modeling is conducted on the working space of the mechanical arm through a grid method; through an improved ant colony algorithm, an appropriate material raking path and an appropriate digging and transporting path are searched in known working spaces corresponding to the material raking mechanical arm and the digging and transporting mechanical arm respectively; abstraction and simplification are carried out by adopting an envelope method, and collision detection between the cleaning mechanism and a belt conveyor rack obstacle is realized; and the cleaning mechanism searches the optimal path in the working space, collision detection is carried out, and coal cleaning operation movement track planning is achieved. The cleaning efficiency of scattered coal of the belt conveyor can be obviously improved, the downtime caused by coal scattering is shortened, the labor intensity is reduced, and the personnel safety is guaranteed.

Description

Technical Field

[0001] The present invention relates to a coal spill cleaning robot for underground coal conveying belts, and particularly to a coal spill cleaning robot for underground coal conveying belts and a cleaning control method therefor. Background Art

[0002] Coal is the "ballast stone" for China's economic development and energy security and stability. As a key equipment in the main coal flow transportation link of coal mines, belt conveyors use the frictional traction force generated between the belt and the drum to transport bulk materials, and have the advantages of high transportation efficiency and strong process adaptability. They undertake various transportation tasks underground according to different transportation working conditions and play an important role in the entire mine transportation system.

[0003] However, during the actual operation of mine belt conveyors, material spillage often occurs due to various reasons such as conveyor belt deviation, suspension of the concave section of the belt, and materials at the transfer point. If the spilled materials are not cleaned up in time, they may cause material accumulation, which not only pollutes the on-site environment, affects the normal operation of the equipment, but also easily triggers belt fires, causing significant losses and serious potential safety hazards. At present, manual cleaning methods are mainly used in coal mines to clean the spilled coal and piled coal under and on both sides of the belt conveyor. This not only takes time and effort, has low cleaning efficiency, significantly increases the labor cost of coal mines, but also the manual cleaning process is obviously dangerous, which goes against the requirements of "intelligent personnel reduction" and safe production in coal mines.

[0004] Currently, most research focuses on modifying the structure of the belt conveyor itself. Even some methods reduce the production efficiency of the belt conveyor, and "material spillage" still occurs as the service life increases. Therefore, the "material spillage" problem has not been fundamentally solved. In addition, existing conventional cleaning equipment is difficult to operate in narrow spaces. Existing coal mine cleaning robots at home and abroad are mainly water sump cleaning and coal bunker cleaning robots, and the research on underground belt coal spill cleaning robots is almost blank. Therefore, it is urgent to develop a feasible and effective belt coal spill cleaning robot to solve the problem of coal spill cleaning of belt conveyors and achieve the development of mine operation automation and unmanned operation. Summary of the Invention

[0005] Aiming at the problems existing in the above-mentioned prior art, the present invention provides a coal spill cleaning robot for underground coal conveying belts and a cleaning control method therefor, which can realize the automatic cleaning of the spilled coal and piled coal under and on both sides of the belt conveyor in coal mines and ensure the safety of workers' lives.

[0006] To achieve the above object, the technical solution adopted by the present invention is: a coal spill cleaning robot for underground coal conveying belts, including an explosion-proof fuselage and a crawler chassis. The crawler chassis is arranged under the explosion-proof fuselage, and further includes a cleaning mechanism. The cleaning mechanism includes a material scraping robotic arm and a digging and transporting robotic arm;

[0007] The material scraping robotic arm is arranged on one side of the front end face of the explosion-proof fuselage. The front part of the upper end face of the explosion-proof fuselage is provided with a digging and transporting robotic arm and a vision sensor. The rear part of the upper end face of the explosion-proof fuselage is provided with a cable storage mechanism. In the middle and rear parts of the explosion-proof fuselage, there are an explosion-proof electrical cavity and a wiring cavity respectively. A hydraulic pump station and a motor are arranged in the explosion-proof electrical cavity, and the hydraulic pump station is connected to the motor. A controller is arranged in the wiring cavity;

[0008] A parking mechanism is arranged at the rear of the crawler chassis. The parking mechanism includes a parking hydraulic cylinder, two parking brackets and a parking support plate. One ends of the two parking brackets are respectively hinged to one side of the parking support plate, and the other ends of the two parking brackets are both hinged to the bottom surface of the explosion-proof fuselage. The two ends of the parking hydraulic cylinder are respectively hinged to the bottom surface of the explosion-proof fuselage and the middle part of the parking support plate;

[0009] The parking hydraulic cylinder is connected to the hydraulic pump station; the parking hydraulic cylinder is connected to the controller through a solenoid valve.

[0010] Further, the material scraping robotic arm includes a first scraping plate, a second scraping plate, a mounting plate and a load-bearing slider;

[0011] On the mounting plate, a slide rail and a rack are arranged side by side at intervals in the longitudinal direction. A rotary motor and a lifting hydraulic motor are arranged on the load-bearing slider. A gear is arranged on the output shaft of the lifting hydraulic motor. The load-bearing slider is slidably connected to the slide rail while the gear meshes with the rack;

[0012] The rear end of the first scraping plate is hinged to the front end of the second scraping plate, and the rear end of the second scraping plate is connected to the output shaft of the rotary motor. A connecting plate is arranged in the middle and rear part of the outer side of the first scraping plate. A telescopic hydraulic cylinder is arranged on the outer side of the second scraping plate. One end of the telescopic hydraulic cylinder is hinged to the middle part of the outer side of the second scraping plate, and the other end is hinged to the rear end of the connecting plate;

[0013] The rotary motor, the lifting hydraulic motor and the telescopic hydraulic cylinder are all connected to the hydraulic pump station; an installation platform is arranged on the front end face of the explosion-proof fuselage, and the mounting plate is connected to the installation platform; the telescopic hydraulic cylinder, the rotary motor and the lifting hydraulic motor are respectively connected to the controller through solenoid valves.

[0014] Further, the digging and transporting robotic arm includes a slewing base, a boom, an arm, a bucket, an arm hydraulic cylinder, a boom hydraulic cylinder and a bucket hydraulic cylinder. The two ends of the boom are respectively hinged to the rear end of the arm and the top surface of the slewing base, and the front end of the arm is hinged to the bucket;

[0015] The two ends of the arm hydraulic cylinder are respectively hinged to the middle part of the upper side of the boom and the rear end of the arm. The two ends of the bucket hydraulic cylinder are respectively hinged to the rear end of the upper side of the arm and the back of the bucket. The two ends of the boom hydraulic cylinder are respectively hinged to the middle part of one side of the boom and the top surface of the slewing base;

[0016] The stick cylinder, the boom cylinder and the bucket cylinder are all connected to the hydraulic pump station; the upper end face of the explosion-proof body is provided with an installation base, and the slewing base is connected to the installation base; the stick cylinder, the boom cylinder and the bucket cylinder are respectively connected to the controller through solenoid valves.

[0017] A cleaning control method for a coal-spilling cleaning robot for underground coal conveyor belts includes the following steps:

[0018] Step 1: Use the D-H method to establish the coordinate systems of the material-pushing manipulator and the digging and transporting manipulator respectively, and then based on the D-H method, use matrix transformation to perform forward kinematics analysis on the cleaning mechanism, and use the geometric method to construct trigonometric functions to perform inverse kinematics analysis on the cleaning mechanism;

[0019] Step 2: Use the grid method to model the working spaces of the material-pushing manipulator and the digging and transporting manipulator respectively;

[0020] Step 3: By improving the ant colony algorithm, find suitable material-pushing paths and digging and transporting paths in the corresponding known working spaces of the material-pushing manipulator and the digging and transporting manipulator respectively;

[0021] Step 4: Use the envelope method for abstraction and simplification to realize the collision detection between the cleaning mechanism and the obstacles on the frame of the belt conveyor;

[0022] Step 5: The cleaning mechanism searches for the optimal path in the working space, performs collision detection, and realizes the motion trajectory planning of the coal cleaning operation.

[0023] Further, the improved ant colony algorithm in Step 3 is as follows:

[0024] Step 3-1: When initializing the improved ant colony algorithm, unevenly distribute the pheromone values of each discrete point; connect the starting point S and the target point D with a line segment L, and use the line segment L and each plane Π i (i = 1, 2,..., n + 1) of the intersection point O i (i = 1, 2,..., n + 1) as the center of the circle, and use L m as the radius to make a circle. The initial pheromone values of the discrete points on each plane within the circle are set to τ0', and the remaining points are set to τ0. The mathematical expression is as follows:

[0025]

[0026] Among them, τ ijk represents the initial pheromone value of each point on the plane Π i , and len(P i , O i ) represents the distance between the point on the plane Π i and the center of the circle O i ;

[0027] Step 3-2: Construct a heuristic function H(i, j, k) that includes security factors, the current ant path length, and the length between the next node and the target point. The formula is as follows:

[0028] H(i, j, k) = S(i, j, k)·D(i, j, k)·Q(i, j, k);

[0029] Among them, S(i, j, k) is the safety value of the next node, D(i, j, k) is the path length between two adjacent nodes, and Q(i, j, k) is the path length between the next node and the target point. The formulas for the above three parameters are as follows:

[0030]

[0031] Among them, safe(P a ) represents the safe points within the search area of the current node P a S(i a+1 , j a+1 , k a+1 ) is the safety value of each discrete point in the search area. If the discrete point is outside the obstacle and none of the links of the cleaning mechanism manipulator collide with the obstacle, then this point is regarded as a safe point and the safety value is set to 1; otherwise, the safety value is 0; (i a , j a , k a ) represents the specific coordinates of the current node, (i a+1 , j a+1 , k a+1 ) are the coordinates of the next node, (i D , j D , k D ) represents the coordinates of the target node;

[0032] Step 3-3: Change the values of the pheromone factor α and the heuristic function factor β to dynamic parameters. Their assignment formulas are as follows:

[0033]

[0034] Among them, N max is the total number of iterations, N represents the current number of iterations. Then the probability transition formula of the s-th ant at time t based on the improved ant colony algorithm is as follows:

[0035]

[0036] Step 3-4: When all ants complete an iteration at time t, the pheromone concentration on all paths needs to be updated. Therefore, the pheromone update rule for all paths at time t+1 is specifically as follows:

[0037]

[0038] Among them, ρ represents the pheromone evaporation coefficient, and Δτ ijk represents the increment of pheromone on the path (i, j, k) in this cycle of all ants, and Δτ s ijk represents the residual pheromone amount on the path (i, j, k) of the s-th ant in this cycle. The constant Q represents the total amount of pheromone released by the ant on the path of one cycle or one process, and L s represents the total length of the path passed by the s-th ant in this cycle.

[0039] Furthermore, the calculation formula of ρ in step 3-4 is:

[0040]

[0041] where N ∈ [1, N max represents the current iteration number, and ρ min is the minimum evaporation coefficient.

[0042] Furthermore, the collision detection step in step 4 is as follows:

[0043] Step 4-1: Wrap the obstacles of the belt conveyor frame that need to avoid obstacles in the working space of the cleaning mechanism with a cuboid of the smallest volume, and wrap the stripping robotic arm and the excavation and transportation robotic arm with a cylinder of the smallest volume. Then, regard the envelope cylinder of each connecting rod of the robotic arm as a line segment and add its cylinder radius r to the obstacle cuboid;

[0044] Step 4-2: Use the superquadric function to describe the obstacle cuboid bounding box. Denote the side lengths of the cuboid as 2a, 2b, and 2c, and the spatial center coordinates as (x0, y0, z0). Then, the superquadric function expressions of the initial and expanded cuboid bounding boxes are:

[0045]

[0046] Step 4-3: Use the parametric equation to describe a certain connecting rod i of the robotic arm. Denote the coordinates of the two endpoints of the connecting rod i as E(x1, y1, z1) and F(x2, y2, z2). Then, the parametric equation of the spatial straight line EF of the connecting rod i is:

[0047]

[0048] Step 4-4: Determine whether the connecting rod intersects with the cuboid obstacle. Substitute the parametric equation of the connecting rod i into the superquadratic function expression of the expanded cuboid bounding box and solve for t. When there is no solution for t, the connecting rod i of the robotic arm does not collide with the obstacle. When there is a solution for t, substitute t back into the parametric equation of the line EF to determine whether the intersection point is on the line segment EF. If the intersection point is on the line segment EF, it indicates that the connecting rod i collides with the obstacle. If the intersection point is not on the line segment EF, it indicates that the connecting rod i does not collide with the obstacle;

[0049] Step 4-5: After completing the collision judgment of the connecting rod i and the cuboid obstacle, the same method is used for the collision judgment of the other connecting rods of the cleaning mechanism robotic arm.

[0050] Compared with the prior art, the beneficial effects of the present invention are as follows: It can significantly improve the cleaning efficiency of the spilled coal on the belt conveyor. By optimizing the cleaning process, it reduces the downtime caused by coal spillage and ensures the smooth transportation of coal. It can reduce the operation risks of personnel, lower the labor intensity, and ensure the safety of personnel. Regarding the trajectory planning problem of the cleaning mechanism robotic arm, the traditional ant colony algorithm for robotic arm trajectory planning is improved. The improved algorithm has a faster convergence speed, good obstacle avoidance effect, and less impact on the robotic arm. The present invention is also an important practice for the intelligent development of mines, provides technical support for the improvement of the overall intelligent level of mines, promotes the realization of the development goals of "replacing humans with machinery and reducing humans with automation", and has great social, economic, and safety benefits. Brief Description of the Drawings

[0051] Figure 1 is the schematic diagram of the overall structure of the present invention;

[0052] Figure 2 is the flow chart of the improved ant colony algorithm trajectory planning for the cleaning mechanism of the present invention;

[0053] Figure 3 is the graph of the convergence trend of the best fitness of the improved ant colony algorithm for the material scraping robotic arm of the cleaning mechanism of the present invention;

[0054] Figure 4 is the graph of the joint motion parameter curves of the coal mining action of the coal digging and transporting robotic arm of the cleaning mechanism of the present invention;

[0055] In the figure: 1. Material scraping robotic arm, 101. First scraping plate, 102. Second scraping plate, 103. Telescopic hydraulic cylinder, 104. Connecting plate, 105. Rotary motor, 106. Mounting plate, 107. Slide rail, 108. Gear, 109. Rack, 110. Load-bearing slider, 111. Lifting hydraulic motor;

[0056] 2. Excavating and transporting robotic arm, 201. Slewing base, 202. Boom, 203. Boom hydraulic cylinder, 204. Dipper arm, 205. Dipper arm hydraulic cylinder, 206. Bucket, 207. Bucket hydraulic cylinder;

[0057] 3. Explosion-proof fuselage, 301. Installation platform, 302. Installation base, 303. Explosion-proof electrical cavity, 304. Hydraulic pump station, 305. Cable winding mechanism, 306. Wiring cavity, 307. Wiring cavity cover plate, 308. Vision sensor;

[0058] 4. Crawler chassis, 401. Crawler, 402. Crawler hydraulic motor, 403. Parking hydraulic cylinder, 404. Parking support, 405. Parking support plate. Detailed implementation manners

[0059] The present invention will be further described below with reference to the accompanying drawings.

[0060] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0061] As Figure 1 shown, the present invention provides a coal belt coal spill cleaning robot for underground coal transportation, which includes an explosion-proof fuselage 3 and a crawler chassis 4. The crawler chassis 4 is arranged below the explosion-proof fuselage 3. The crawler chassis 4 includes a crawler 401 and a crawler hydraulic motor 402; it further includes a cleaning mechanism, and the cleaning mechanism includes a material scraping robotic arm 1 and an excavating and transporting robotic arm 2.

[0062] The material scraping robotic arm 1 is arranged on one side of the front end face of the explosion-proof fuselage 3 and away from the longitudinal central axis. The material scraping robotic arm 1 includes a first scraping plate 101, a second scraping plate 102, a mounting plate 106, and a load-bearing slider 110. The mounting plate 106 is provided with a slide rail 107 and a rack 109 arranged side by side at intervals in the longitudinal direction. The load-bearing slider 110 is provided with a rotary motor 105 and a lifting hydraulic motor 111, and explosion-proof casings are arranged outside both of them. The output shaft of the lifting hydraulic motor 111 is provided with a gear 108. The load-bearing slider 110 is slidably connected to the slide rail 107 while the gear 108 meshes with the rack 109. The rear end of the first scraping plate 101 is hinged to the front end of the second scraping plate 102, and the rear end of the second scraping plate 102 is connected to the output shaft of the rotary motor 105. The middle and rear part of the outer side of the first scraping plate 101 is provided with a connecting plate 104, and the outer side of the second scraping plate 102 is provided with a telescopic hydraulic cylinder 103. One end of the telescopic hydraulic cylinder 103 is hinged to the middle part of the outer side of the second scraping plate 102, and the other end is hinged to the rear end of the connecting plate 104. The rotary motor 105, the lifting hydraulic motor 111, and the telescopic hydraulic cylinder 103 are all connected to the hydraulic pump station 304. The front end face of the explosion-proof fuselage 3 is provided with a mounting platform 301, and the mounting plate 106 is connected to the mounting platform 301.

[0063] When the rotary motor 105 works, it drives the second scraping plate 102 and the first scraping plate 101 to rotate in the horizontal direction. When the telescopic hydraulic cylinder 103 works, it drives the first scraping plate 101 to rotate around the hinge point between the first scraping plate 101 and the second scraping plate 102, realizing the opening and closing of the first scraping plate 101 and the second scraping plate 102 to complete the ore scraping action. The maximum working distance of the scraping plate can reach 1.2 meters. When the lifting hydraulic motor 111 works, it drives the gear 108 to rotate. Since the gear 108 meshes with the rack 109 arranged on the mounting plate 106, and the lifting hydraulic motor 111 is arranged on the load-bearing slider 110 slidably connected to the slide rail 107, the rotation of the gear 108 will be converted into a linear lifting action of the load-bearing slider 110, that is, the second scraping plate 102 and the first scraping plate 101 in the longitudinal direction on the slide rail 107, so as to clean the coal materials with different stacking heights. The rotary motor 105, the telescopic hydraulic cylinder 103, and the lifting hydraulic motor 111 cooperate with each other to control the material scraping robotic arm 1 to scrape out the coal materials under and on both sides of the belt conveyor and gather them in front of the excavation and transportation robotic arm 2. Preferably, the bottom edges of the first scraping plate 101 and the second scraping plate 102 are both tooth-shaped structures for cleaning the scattered coal.

[0064] In the front part of the upper end face of the explosion-proof fuselage 3, there is an excavation and transportation robotic arm 2 and a vision sensor 308. The excavation and transportation robotic arm 2 is located on the other side of the front part of the upper end face of the explosion-proof fuselage 3, which is opposite to the material scraping robotic arm 1 and close to the longitudinal central axis. The vision sensor 308 corresponds to the position of the material scraping robotic arm 1, and the vision sensor 308 is arranged side by side with the excavation and transportation robotic arm 2.

[0065] The material handling and transporting robotic arm 2 includes a slewing base 201, a boom 202, an arm 204, a bucket 206, an arm cylinder 205, a boom cylinder 203, and a bucket cylinder 207. The two ends of the boom 202 are respectively hinged to the rear end of the arm 204 and the top surface of the slewing base 201. The front end of the arm 204 is hinged to the bucket 206. The two ends of the arm cylinder 205 are respectively hinged to the middle part of the upper side of the boom 202 and the rear end of the arm 204. The two ends of the bucket cylinder 207 are respectively hinged to the rear end of the upper side of the arm 204 and the back of the bucket 206. The two ends of the boom cylinder 203 are respectively hinged to the middle part of one side of the boom 202 and the top surface of the slewing base 201. Preferably, a boom cylinder 203 is also symmetrically arranged on the other side of the boom 202. The arm cylinder 205, the boom cylinder 203, and the bucket cylinder 207 are all connected to the hydraulic pump station 304. The upper end surface of the explosion-proof body 3 is provided with a mounting base 302, and the slewing base 201 is connected to the mounting base 302.

[0066] The slewing base 201 can drive the material handling and transporting robotic arm 2 to rotate in the horizontal direction by connecting a slewing hydraulic motor. The boom cylinder 203, the arm cylinder 205, and the bucket cylinder 207 respectively control the rotation of the boom 202, the arm 204, and the bucket 206 in the vertical direction. The slewing hydraulic motor of the slewing base 201, the boom cylinder 203, the arm cylinder 205, and the bucket cylinder 207 cooperate with each other to lift the coal material dug out and gathered by the material scraping robotic arm 1 by the bucket 206, and rotate to put the coal material back to the appropriate position on the belt of the belt conveyor.

[0067] A cable storage mechanism 305 is arranged at the rear part of the upper end surface of the explosion-proof body 3. An explosion-proof electrical cavity 303 and a wiring cavity 306 are respectively arranged in the middle and rear parts of the explosion-proof body 3. The cable storage mechanism 305 is fixedly connected above the wiring cavity 306 through a wiring cavity cover plate 307. The robot is driven by electro-hydraulic. A hydraulic pump station 304 and a motor are arranged in the explosion-proof electrical cavity 303, and the hydraulic pump station 304 and the motor are connected. The cables stored in the cable storage mechanism 305 supply power to the motor and other electrical equipment. The hydraulic pump station 304 provides hydraulic power for all hydraulic drive components of the robot, and controls the actions of the material scraping robotic arm 1, the material handling and transporting robotic arm 2, and the crawler chassis 4 by controlling the pressure and flow rate of the hydraulic oil. The explosion-proof body 3 provides a stable installation foundation for various key components inside the robot, enabling it to still operate stably under complex underground working conditions. A controller is arranged in the wiring cavity 306. The parking cylinder 403, the telescopic cylinder 103, the rotary motor 105, the lifting hydraulic motor 111, the arm cylinder 205, the boom cylinder 203, the bucket cylinder 207, and the slewing hydraulic motor of the slewing base 201 are respectively connected to the controller through solenoid valves.

[0068] A parking mechanism is provided at the rear of the crawler chassis 4. The parking mechanism includes a parking hydraulic cylinder 403, two parking brackets 404, and a parking support plate 405. One end of each of the two parking brackets 404 is hinged to one side of the parking support plate 405, and the other end of each of the two parking brackets 404 is hinged to the bottom surface of the explosion-proof fuselage 3. The two ends of the parking hydraulic cylinder 403 are respectively hinged to the bottom surface of the explosion-proof fuselage 3 and the middle of the parking support plate 405; the parking hydraulic cylinder 403 is connected to the hydraulic pump station 304. By telescoping the piston rod of the parking hydraulic cylinder 403, the height and tilt angle of the parking support plate 405 can be adjusted, so that the parking support plate 405 abuts against the ground when the robot is parked for work, enhancing the overall stability of the robot and ensuring the smooth progress of the coal cleaning operation.

[0069] When the robot is performing the coal cleaning operation on the underground belt conveyor, the crawler chassis 4 operates. The robot drives into the roadway and reaches the first place where coal is scattered, and then lowers the vehicle so that the parking support plate 405 abuts against the ground; the vision sensor installed under the belt conveyor feeds back the coal pile height data to the upper computer of the control system outside the robot. Then, the lifting hydraulic motor 111 drives the material scraping robotic arm 1 to rise until the tip of the teeth under the scraping plate 101 is level with the maximum coal pile height. Then, the material scraping robotic arm 1 moves along the trajectory planned by the improved ant colony algorithm to extend into the area under the belt conveyor without load. Next, the lifting hydraulic motor 111 drives the material scraping robotic arm 1 to lower to an appropriate height. After that, the material scraping robotic arm 1 moves along the trajectory planned by the improved ant colony algorithm, and at the same time, the lifting hydraulic motor 111 drives the material scraping robotic arm 1 to ensure that the scraping plate is always inserted into the coal material so as not to scrape in vain, thereby realizing the scraping out of the accumulated coal material under load and gathering the coal material in front of the excavation and transportation robotic arm 2. Finally, the material scraping robotic arm 1 repeats the actions of rising and extending into the area under the belt conveyor without load, waiting for the next scraping instruction; when the vision sensor 308 detects that the coal material is gathered in front of the excavation and transportation robotic arm 2, the excavation and transportation robotic arm 2 starts the excavation and transportation operation. First, the boom hydraulic cylinder 203, the stick hydraulic cylinder 205, and the bucket hydraulic cylinder 207 drive the excavation and transportation robotic arm 2 to sequentially perform the actions of lowering, coal excavation, and lifting according to the trajectory planned by the improved ant colony algorithm. Subsequently, the hydraulic cylinders stop working, and the slewing hydraulic motor drives the slewing base 201 to drive the excavation and transportation robotic arm 2 to slew, so that the bucket 206 moves to the unloading point above the belt of the belt conveyor, and then the unloading action is performed. Finally, the excavation and transportation robotic arm 2 resets and triggers the scraping instruction again; the scraping operation and the excavation and transportation operation are carried out alternately, thereby realizing the automatic cleaning of the scattered coal material on the underground belt conveyor.

[0070] As Figure 2 shown, the robot cleaning control method specifically includes the following five steps:

[0071] Step 1: Use the D-H method to establish the coordinate systems of the material-scraping robotic arm 1 and the excavation and transportation robotic arm 2 respectively. Then, based on the D-H method, use matrix transformation to conduct forward kinematic analysis on the cleaning mechanism, and use the geometric method to construct trigonometric functions for inverse kinematic analysis of the cleaning mechanism.

[0072] Step 2: Use the grid method to model the working spaces of the material-scraping robotic arm 1 and the excavation and transportation robotic arm 2 respectively. First, take lengths l x 、l y and l z along the X-axis, Y-axis, and Z-axis respectively to construct a cubic region ABCD-A'B'C'D'. This cubic region is the working space of the material-scraping robotic arm 1, and take the midpoint of rectangle ABCD as the origin of the working space of the material-scraping robotic arm 1; then use planes to evenly divide the space. Along side AB, use planes to divide the cubic space ABCD-A'B'C'D' into n equal parts to obtain n + 1 planes Π i (i = 1, 2, …, n + 1). Then, divide these n + 1 planes into m equal parts along side AD and into l equal parts along AA'; finally, construct the obstacle avoidance working conditions of the material-scraping robotic arm 1 in the small cubic spaces after the equal division of the excavation and transportation robotic arm 1. The space can be divided into a free area and an obstacle area. When constructing the planning space, a three-dimensional matrix of the space can be established, set the free area to 0, set the obstacle area to 1, and judge the path nodes generated during planning with the space matrix to avoid the obstacle area. The excavation and transportation robotic arm 2 uses the same method to model the working space.

[0073] Step 3: By improving the ant colony algorithm, find suitable material-scraping paths and excavation and transportation paths in the corresponding known working spaces of the material-scraping robotic arm 1 and the excavation and transportation robotic arm 2 respectively.

[0074] Step 3-1: When initializing the improved ant colony algorithm, unevenly distribute the pheromone values of each discrete point; connect the starting point S and the target point D with a line segment L. Since the optimal paths are mostly concentrated in the area near L, take the intersection points O i (i = 1, 2, …, n + 1) of the line segment L and each plane Π i (i = 1, 2, …, n + 1) as the centers, and use L m as the radius to draw circles. Set the initial pheromone values of the discrete points on each plane within the circles to τ o ', and set the remaining points to τ o . The mathematical expression is as follows:

[0075]

[0076] Among them, τ ijk represents the initial pheromone value of each point on plane Π i , len(P i ,Oi ) represents the distance between a point on the plane Π i and the center of the circle O i .

[0077] Step 3-2: Construct a heuristic function H(i, j, k) that includes safety factors, the current ant path length, and the length from the next node to the target point. The specific formula is as follows:

[0078] H(i, j, k) = S(i, j, k) · D(i, j, k) · Q(i, j, k);

[0079] Among them, S(i, j, k) is the safety value of the next node, D(i, j, k) is the path length between two adjacent nodes, and Q(i, j, k) is the path length between the next node and the target point. The specific formulas for the above three parameters are as follows:

[0080]

[0081] Among them, safe(P a ) represents the safe points within the search area of the current node P a , S(i a+1 , j a+1 , k a+1 ) is the safety value of each discrete point in the search area. If the discrete point is outside the obstacle and none of the connecting rods of the cleaning mechanism manipulator collide with the obstacle, then this point is regarded as a safe point and the safety value is set to 1, otherwise the safety value is 0; (i a , j a , k a ) represents the specific coordinates of the current node, (i a+1 , j a+1 , k a+1 ) are the coordinates of the next node, (i D , j D , k D ) represent the coordinates of the target node; the above manipulator is the material scraping manipulator 1 and the excavation and transportation manipulator 2, and the manipulator connecting rods are the first scraping plate 101, the second scraping plate 102, the boom 202, the bucket rod 204, and the bucket 206;

[0082] Step 3-3: Change the values of the pheromone factor α and the heuristic function factor β to dynamic parameters. Their assignment formulas are as follows:

[0083]

[0084] Among them, N max is the total number of iterations, N represents the current number of iterations. Then the probability transition formula of the s-th ant at time t based on the improved ant colony algorithm is as follows:

[0085]

[0086] Step 3-4: When all ants complete one iteration at time t, the pheromone concentration on all paths needs to be updated. Therefore, the specific pheromone update rule for all paths at time t+1 is as follows:

[0087]

[0088] Among them, ρ represents the pheromone evaporation coefficient, and Δτ ijk represents the pheromone increment on path (i,j,k) in this cycle of all ants, and Δτ s ijk represents the residual pheromone amount on path (i,j,k) of the sth ant in this cycle. The constant Q represents the total amount of pheromone released by the ant on the path of one cycle or one process, and L s represents the total length of the path passed by the sth ant in this cycle.

[0089] In order to further improve the global optimization ability of the algorithm, the value of the pheromone evaporation coefficient ρ is improved. The calculation formula of ρ is:

[0090]

[0091] Among them, N∈[1,N max represents the current iteration number, and ρ min is the minimum evaporation coefficient to avoid the influence of too small ρ on the convergence speed.

[0092] Step 4: Adopt the envelope method for abstract simplification to realize the collision detection between the cleaning mechanism and the obstacles on the belt conveyor frame.

[0093] Step 4-1: Wrap the obstacles on the belt conveyor frame that need to avoid obstacles in the working space of the cleaning mechanism with a cuboid of the smallest volume, and wrap the material scraping robotic arm 1 and the excavation and transportation robotic arm 2 with a cylinder of the smallest volume. Then, regard the envelope cylinders of the connecting rods of the robotic arm as a line segment and add its cylinder radius r to the obstacle cuboid;

[0094] Step 4-2: In order to reduce the computational complexity of the geometric relationship between the robotic arm and the obstacle in the collision detection analysis, use the superquadric function to describe the cuboid bounding box of the obstacle on the belt conveyor frame. Denote the side lengths of the cuboid as 2a, 2b, and 2c respectively, and the spatial center coordinates as (x0,y0,z0). Then, the superquadric function expressions of the initial and expanded cuboid bounding boxes are:

[0095]

[0096] Step 4-3: To simplify the complexity of judging the occurrence of collisions, a parametric equation is used to describe a certain link i of the robotic arm. Denote the coordinates of the two endpoints of link i as E(x1, y1, z1) and F(x2, y2, z2) respectively. Then the parametric equation of the spatial straight line EF of link i is:

[0097]

[0098] Step 4-4: Determine whether the link intersects with the cuboid obstacle. Substitute the parametric equation of link i into the superquadratic function expression of the expanded cuboid bounding box to solve for t. When there is no solution for t, the link i of the robotic arm does not collide with the obstacle. When there is a solution for t, substitute t back into the parametric equation of the straight line EF to determine whether the intersection point is on the line segment EF. If the intersection point is on the line segment EF, it means that link i collides with the obstacle. If the intersection point is not on the line segment EF, it means that link i does not collide with the obstacle.

[0099] Step 4-5: After completing the collision judgment between the link i line segment and the cuboid obstacle, the same method is also used for the collision judgment of the other links of the cleaning mechanism robotic arm. This method does not require the collision detection of each face between the robotic arm link and the cuboid obstacle, effectively reducing the computational amount of collision detection analysis and improving the trajectory planning efficiency.

[0100] Step 5: The cleaning mechanism searches for the optimal path within the working space, performs collision detection, and realizes the motion trajectory planning for coal cleaning operations. First, initialize the algorithm parameters, find a suitable motion trajectory in the known working environment through the improved ant colony algorithm, and then use the cubic polynomial interpolation method to smooth the discrete motion trajectory to obtain the node coordinates forming the trajectory. According to Step 1, solve the joint angles corresponding to each target point based on the inverse kinematics of the geometric method to obtain a set of multiple groups of joint angle solutions. Judge whether each set of inverse solutions meets the joint angle motion range and whether a collision occurs. If all solutions do not meet the planning requirements, regard the trajectory node as an obstacle point and re-plan the trajectory until all nodes are within the joint angle motion range and no collision occurs. Specifically, use the above improved algorithm in the MATLAB software to conduct the simulation experiment on the motion trajectory planning for the coal cleaning operation of the cleaning mechanism of the robot of the present invention.

[0101] As Figure 3 shown, when the material-pushing robotic arm 1 conducts the material-pushing trajectory planning, by comparing the traditional ant colony algorithm with the improved ant colony algorithm of the present invention, it can be seen that the convergence speed of the improved ant colony algorithm of the present invention has been improved, and while obtaining a better solution, the required number of iterations has been further reduced.

[0102] As Figure 4As shown, when the excavation and transportation robotic arm 2 performs the trajectory planning for coal mining, the changes in the motion degrees of each joint are relatively smooth, the changes in angular velocity are stable, which can reduce energy consumption, the angular acceleration is small and gentle, which helps to achieve more precise motion control, and the impact of each joint is small, which can improve the stability and reliability of the work.

[0103] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claims involved.

[0104] The above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any minor modifications, equivalent replacements, and improvements made to the above embodiments based on the technical essence of the present invention should be included in the protection scope of the technical solution of the present invention.

Claims

1. An underground coal conveyor belt coal spill cleaning robot, comprising an explosion-proof fuselage (3) and a crawler chassis (4), the crawler chassis (4) is arranged below the explosion-proof fuselage (3), and is characterized in that, It also includes a cleaning mechanism, which includes a material scraping robotic arm (1) and an excavation and transportation robotic arm (2); The material scraping robotic arm (1) is arranged on one side of the front end face of the explosion-proof fuselage (3). In the front part of the upper end face of the explosion-proof fuselage (3), there are an excavation and transportation robotic arm (2) and a vision sensor (308). At the rear part of the upper end face of the explosion-proof fuselage (3), a cable storage mechanism (305) is arranged. In the middle and rear parts of the explosion-proof fuselage (3), there are an explosion-proof electrical cavity (303) and a wiring cavity (306) respectively. In the explosion-proof electrical cavity (303), a hydraulic pump station (304) and a motor are arranged. The hydraulic pump station (304) is connected to the motor. A controller is arranged in the wiring cavity (306); A parking mechanism is arranged at the rear of the crawler chassis (4). The parking mechanism includes a parking hydraulic cylinder (403), two parking brackets (404) and a parking support plate (405). One ends of the two parking brackets (404) are respectively hinged to one side of the parking support plate (405). The other ends of the two parking brackets (404) are both hinged to the bottom surface of the explosion-proof fuselage (3). Two ends of the parking hydraulic cylinder (403) are respectively hinged to the bottom surface of the explosion-proof fuselage (3) and the middle part of the parking support plate (405); The parking hydraulic cylinder (403) is connected to the hydraulic pump station (304); the parking hydraulic cylinder (403) is connected to the controller through a solenoid valve.

2. The coal spill cleaning robot for underground coal conveying belt according to claim 1, characterized in that, The material scraping robotic arm (1) includes a first scraping plate (101), a second scraping plate (102), a mounting plate (106) and a load-bearing slider (110); On the mounting plate (106) in the longitudinal direction, a slide rail (107) and a rack (109) are arranged side by side at intervals. On the load-bearing slider (110), a rotary motor (105) and a lifting hydraulic motor (111) are arranged. A gear (108) is arranged on the output shaft of the lifting hydraulic motor (111). The load-bearing slider (110) is slidably connected to the slide rail (107) while the gear (108) meshes with the rack (109); The rear end of the first scraping plate (101) is hinged to the front end of the second scraping plate (102). The rear end of the second scraping plate (102) is connected to the output shaft of the rotary motor (105). In the middle and rear part of the outer side surface of the first scraping plate (101), a connecting plate (104) is arranged. On the outer side surface of the second scraping plate (102), a telescopic hydraulic cylinder (103) is arranged. One end of the telescopic hydraulic cylinder (103) is hinged to the middle part of the outer side surface of the second scraping plate (102), and the other end is hinged to the rear end of the connecting plate (104); The rotary motor (105), the lifting hydraulic motor (111) and the telescopic hydraulic cylinder (103) are all connected to the hydraulic pump station (304); an installation platform (301) is arranged on the front end face of the explosion-proof fuselage (3). The mounting plate (106) is connected to the installation platform (301); the telescopic hydraulic cylinder (103), the rotary motor (105) and the lifting hydraulic motor (111) are respectively connected to the controller through solenoid valves.

3. The coal spill cleaning robot for underground coal conveying belt according to claim 1, characterized in that, The excavating and transporting robotic arm (2) includes a slewing base (201), a boom (202), an arm (204), a bucket (206), an arm hydraulic cylinder (205), a boom hydraulic cylinder (203), and a bucket hydraulic cylinder (207). The two ends of the boom (202) are respectively hinged to the rear end of the arm (204) and the top surface of the slewing base (201), and the front end of the arm (204) is hinged to the bucket (206). The two ends of the arm hydraulic cylinder (205) are respectively hinged to the middle of the upper side of the boom (202) and the rear end of the arm (204). The two ends of the bucket hydraulic cylinder (207) are respectively hinged to the rear end of the upper side of the arm (204) and the back of the bucket (206). The two ends of the boom hydraulic cylinder (203) are respectively hinged to the middle of one side of the boom (202) and the top surface of the slewing base (201). The arm hydraulic cylinder (205), the boom hydraulic cylinder (203), and the bucket hydraulic cylinder (207) are all connected to the hydraulic pump station (304). An installation base (302) is provided on the upper end surface of the explosion-proof fuselage (3), and the slewing base (201) is connected to the installation base (302). The arm hydraulic cylinder (205), the boom hydraulic cylinder (203), and the bucket hydraulic cylinder (207) are respectively connected to the controller through solenoid valves.

4. A cleaning control method for a coal spill cleaning robot for underground coal conveying belts, characterized in that, It includes the following steps: Step 1: Use the D-H method to establish the coordinate systems of the material scraping robotic arm (1) and the excavating and transporting robotic arm (2) respectively. Then, based on the D-H method, use matrix transformation to perform forward kinematic analysis on the cleaning mechanism, and use the geometric method to construct trigonometric functions to perform inverse kinematic analysis on the cleaning mechanism. Step 2: Use the grid method to model the working spaces of the material scraping robotic arm (1) and the excavating and transporting robotic arm (2) respectively. Step 3: By improving the ant colony algorithm, find suitable material scraping paths and excavating and transporting paths in the corresponding known working spaces of the material scraping robotic arm (1) and the excavating and transporting robotic arm (2) respectively. Step 4: Use the envelope method for abstract simplification to achieve collision detection between the cleaning mechanism and the obstacles on the belt conveyor frame. Step 5: The cleaning mechanism searches for the optimal path in the working space, performs collision detection, and realizes the motion trajectory planning of the coal cleaning operation.

5. The cleaning control method of the underground coal conveyor belt coal spill cleaning robot according to claim 4, characterized in that, The improved ant colony algorithm in the said Step 3 is as follows. Step 3-1: When initializing the improved ant colony algorithm, unevenly distribute the pheromone values of each discrete point; connect the starting point S and the target point D with a line segment L, and use the line segment L and its intersections O i (i = 1, 2, …, n + 1) with each plane Π i (i = 1, 2, …, n + 1) as the center of the circle, and use L m as the radius to draw a circle. The initial pheromone value of the discrete points within the circle on each plane is set to τ0', and the remaining points are set to τ0. The mathematical expression is as follows: Among them, τ ijk represents the initial pheromone value of each point on the plane Π i , and len(P i , O i ) represents the distance between the point on the plane Π i and the center of the circle O i ; Step 3-2: Construct a heuristic function H(i, j, k) that includes safety factors, the current ant path length, and the length between the next node and the target point. The formula is: H(i, j, k) = S(i, j, k) · D(i, j, k) · Q(i, j, k); Among them, S(i, j, k) is the safety value of the next node, D(i, j, k) is the path length between two adjacent nodes, and Q(i, j, k) is the path length between the next node and the target point. The formulas for the above three parameters are respectively: Among them, safe(P a ) represents the safe point within the search area of the current node P a , S(i a+1 , j a+1 , k a+1 ) is the safety value of each discrete point in the search area. If the discrete point is outside the obstacle and the links of the cleaning mechanism manipulator do not collide with the obstacle, then this point is regarded as a safe point and the safety value is set to 1; otherwise, the safety value is 0; (i a , j a , k a ) represents the specific coordinates of the current node, (i a+1 , j a+1 , k a+1 ) are the coordinates of the next node, (i D , j D , k D ) represent the coordinates of the target node; Step 3-3: Change the values of the pheromone factor α and the heuristic function factor β to dynamic parameters, and their assignment formulas are as follows: Among them, N max is the total number of iterations, N represents the current iteration number, and the probability transition formula of the s-th ant at time t based on the improved ant colony algorithm is as follows: When all ants complete one iteration at time t, the pheromone concentration on all paths needs to be updated. Therefore, the pheromone update rule on all paths at time t + 1 is specifically: Among them, ρ represents the pheromone evaporation coefficient, and Δτ ijk represents the pheromone increment on the path (i, j, k) in this cycle for all ants, and Δτ s ijk represents the residual pheromone amount on the path (i, j, k) for the s-th ant in this cycle. The constant Q represents the total amount of pheromone released by the ant on the path in one cycle or one process, and L s represents the total length of the path passed by the s-th ant in this cycle.

6. The cleaning control method of the underground coal conveyor belt coal spill cleaning robot according to claim 5, characterized in that, The ρ calculation formula in the said Step 3-4 is: where N ∈ [1, N max represents the current iteration number, and ρ min is the minimum volatility coefficient.

7. A cleaning control method for a coal spill cleaning robot for underground coal conveyor belts according to claim 5, characterized in that, The collision detection steps in the said Step 4 are: Step 4-1: Wrap the obstacles on the belt conveyor frame that need to be avoided in the working space of the cleaning mechanism with a cuboid of the smallest volume, and wrap the stripping robotic arm (1) and the excavation and transportation robotic arm (2) with a cylinder of the smallest volume. Then, regard the envelope cylinders of the connecting rods of the robotic arm as a line segment and add its cylinder radius r to the cuboid of the obstacle. Step 4-2: Use a superquadric function to describe the cuboid bounding box of the obstacle. Denote the side lengths of the cuboid as 2a, 2b, and 2c, and the spatial center coordinates as (x0, y0, z0). Then, the superquadric function expressions of the initial and expanded cuboid bounding boxes are: Step 4-3: Use a parametric equation to describe a certain connecting rod i of the robotic arm. Denote the coordinates of the two endpoints of the connecting rod i as E(x1, y1, z1) and F(x2, y2, z2). Then, the parametric equation of the spatial straight line EF of the connecting rod i is: Step 4-4: Determine whether the connecting rod intersects with the cuboid obstacle. Substitute the parametric equation of the connecting rod i into the superquadric function expression of the expanded cuboid bounding box and solve for t. When there is no solution for t, the connecting rod i of the robotic arm does not collide with the obstacle. When there is a solution for t, substitute t back into the parametric equation of the straight line EF to determine whether the intersection point is on the line segment EF. If the intersection point is on the line segment EF, it means that the connecting rod i collides with the obstacle. If the intersection point is not on the line segment EF, it means that the connecting rod i does not collide with the obstacle. Step 4-5: After completing the collision judgment between the connecting rod i and the cuboid obstacle, use the same method for the collision judgment of the other connecting rods of the cleaning mechanism robotic arm.

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