Automatic leveling control system and method for milling machine and milling machine

Abstract

The invention provides a milling machine automatic leveling control system, a milling machine automatic leveling control method and a milling machine, the milling machine automatic leveling control system comprises an execution unit, a sensing monitoring assembly and a control assembly, the sensing monitoring assembly comprises a side plate oil cylinder set, a first displacement sensor arranged in the side plate oil cylinder set, a second displacement sensor arranged in a rear stand column oil cylinder, a tilt angle sensor arranged on the frame and a laser range finder installed on the side edge of the rear portion of the frame. The control assembly comprises a geometric calculation module, a dynamic zero calibration module, a calibration module and an anomaly detection module which are integrated in a main controller. The risk of a large dip angle is avoided through a graded depth reduction strategy, dynamic lifting compensation is achieved when the rear stand column oil cylinder enters a pit, the machine body levelness and the milling track precision are ensured, the + / -1 mm grade milling precision is achieved, and the problem that the depth is out of control under the pit entering working condition is solved.

Description

Technical Field

[0001] The invention relates to an automatic leveling system and method for a milling machine and the milling machine, and belongs to the technical field of engineering machinery. Background Art

[0002] Traditional milling machines rely on manual experience to level the machine, using manual adjustment of the column cylinder to control the milling depth. This results in low efficiency and poor precision. This is especially true when the milling machine enters the milling pit. The rear column cylinder is not raised in time, causing the machine to be higher in the front and lower in the back, with actual depth deviations exceeding ±3mm. Risks of deep milling: When the machine depth exceeds 150mm at a time, the pitch angle of the machine increases sharply, which can easily cause the column cylinder to become stuck or the side panels to twist. Existing automatic leveling systems use rope sensors or ultrasonic sensors to maintain a stable milling depth. The need for additional sensors results in high costs. Summary of the Invention

[0003] Purpose of the Invention: To address the shortcomings of the prior art, the present invention provides an automatic leveling system and method for a milling machine, as well as a milling machine. This system employs a graded depth reduction strategy to avoid the risk of large tilt angles. Dynamically lifts and compensates for the rear column cylinder's entry into a pit, ensuring machine body level and milling trajectory accuracy. This system achieves milling accuracy of ±1mm, resolving the issue of uncontrolled depth during pit entry. Furthermore, the present invention also discloses a milling machine equipped with this leveling system and control method.

[0004] Technical solution: Milling machine automatic leveling control system, including execution unit, sensor monitoring assembly and control assembly,

[0005] The execution unit includes a column cylinder group, which includes a front column cylinder and a rear column cylinder, each of which is arranged on both sides of the frame. The rear column cylinders are connected in series through hydraulic pipelines to achieve synchronous action.

[0006] The sensing and monitoring assembly includes a side plate cylinder group, a first displacement sensor provided in the side plate cylinder group, a second displacement sensor provided in the rear column cylinder, an inclination sensor provided on the vehicle frame, and a laser rangefinder installed on the rear side of the vehicle frame. The side plate cylinder group includes a front control cylinder and a rear control cylinder, one group each provided on the front and rear sides of the vehicle side plate. The sensing and monitoring assembly is connected to the main controller for signal transmission.

[0007] The control assembly includes a geometric solution module, a dynamic zero calibration module, a calibration module and an abnormality detection module which are integrated in a main controller.

[0008] The control method of the automatic leveling control system of a milling machine includes the following steps:

[0009] Step 1: Geometric parameter definition and model preset;

[0010] Definition of hinge points: Fixed hinge points are the connection points A1 and A2 between the side plate cylinders at both ends and the frame; dynamic hinge points are the connection points B1 and B2 between the side plate cylinders at both ends and the side plate;

[0011] Definition of milling reference plane: The vertical foot of the horizontal projection of the milling cylinder axis O to the ground is the depth zero point Z; the tool tip reference point T: the lowest point of the cylinder, the real-time depth H 深度 =ZT;

[0012] Preset the deep computing model in the whole machine control system;

[0013] Step 2: Use the calibration module to calibrate the system zero position;

[0014] Step 3: Enter the set milling depth H set ;

[0015] Step 4: Start the automatic cutting process, continuously calculate the depth and automatically level the machine.

[0016] Execute single depth reduction mode according to the input milling depth, that is, H set ≤150mm or step-by-step lowering mode, i.e. H set >150mm, up to H set =H 深度 ;

[0017] Step 5: After the automatic cutting program is completed, the set milling depth is reached and the vehicle is driven to perform the milling operation. During the milling operation, the adaptive pit entry control strategy is executed to control the milling depth error within ±1mm until the milling operation is completed.

[0018] In step 1, the depth calculation model is specifically:

[0019] 1.1 Calculation of weight coefficient

[0020] The theoretical contribution ratio of the two side plate cylinders to the depth is determined by the geometric relationship of the hinge point.

[0021]

[0022] e=1-f

[0023] where d 前h : When the cylinder is raised to the highest point, the horizontal distance from the hinge point B1 between the front plate cylinder and the side plate to the axis O of the milling cylinder is obtained by three-dimensional measurement or laser calibration;

[0024] d 后h : When the cylinder is raised to the highest point, the horizontal distance from the hinge point B2 between the rear plate cylinder and the side plate to the axis O of the milling cylinder is obtained by three-dimensional measurement or laser calibration;

[0025] d 前l : When the cylinder drops to the lowest point, the horizontal distance from the hinge point B1 / B2 between the front plate cylinder and the side plate to the milling cylinder axis O is obtained through three-dimensional measurement or laser calibration;

[0026] d 后l : When the cylinder drops to the lowest point, the horizontal distance from the hinge point B1 / B2 between the rear plate cylinder and the side plate to the milling cylinder axis O is obtained through three-dimensional measurement or laser calibration;

[0027] e is the weighted coefficient of the rear plate cylinder stroke;

[0028] f is the weighted coefficient of the front plate cylinder stroke;

[0029]

[0030]

[0031] α is the angle between the axis of the front plate cylinder and the vertical direction;

[0032] β is the angle between the axis of the rear plate cylinder and the vertical direction;

[0033] m is the coefficient of influence of the vertical angle of the front plate cylinder on the depth;

[0034] n is the coefficient of influence of the vertical angle of the rear plate cylinder on the depth;

[0035] Experimental calibration

[0036] Obtain S through experiments 前 、S 后 、H 实测 The data is fitted and the weight coefficient f is optimized. opt / e opt , so that the calculated value H 计算 =f*S 后 +e*S 后 The residual error with the measured value is the smallest;

[0037] Among them S 前 is the stroke of the front plate cylinder on one side in the experiment,

[0038] S 后 is the stroke of the rear plate cylinder on one side during the experiment,

[0039] H 实测 is the actual measured value of the single-side depth,

[0040] f opt is the optimal value of f obtained after fitting;

[0041] e opt is the optimal value of e obtained after fitting;

[0042] H 计算 is the calculated value of the single-side depth,

[0043] 1.2 Depth Calculation Formula

[0044] H 深度 =H0-H curr =(a*S 前0 +b*S 后0 )-(a*S 前1 +b*S 后1 );

[0045] Among them, H0 is the calculated value of the cylinder length before and after zero calibration, H curr S is the calculated value of the cylinder length before and after the current position. 前0 The stroke of the front plate cylinder on one side during zero calibration, S 后0 The stroke of the oil cylinder on the rear plate on one side during zero calibration, S 前1 S is the stroke of the front plate cylinder at the current position. 后1 The stroke of the rear plate cylinder on the current position side;

[0046] Coefficient definition:

[0047]

[0048] H 行程 : Full stroke of the cylinder, that is, the actual depth change when the side plate cylinder stroke goes from 0 to the maximum, in mm;

[0049] L 油缸行程 : The maximum retractable length of the cylinder mechanical design.

[0050] The step 2 is specifically as follows:

[0051] Zero calibration can be triggered under any working condition, and the system automatically records the current side plate cylinder stroke S 左前0 / S 左后0 / S 右前0 / S 右前0 And the rear column cylinder stroke Y0, and calculate

[0052] H 左0 =a*S 左前0 +b*S 左后0

[0053] H 右0 =a*S 右前0 +b*S 右后0

[0054] Among them S 左前0 S is the stroke of the left front plate cylinder, 左后0 S is the stroke of the left rear plate cylinder. 右前0is the right front plate cylinder stroke, S 右后0 H is the stroke of the right rear plate cylinder. 左0 Calculate the depth for the left side, H 右0 Calculate the depth for the right side.

[0055] The step 4 is specifically as follows:

[0056] According to the input milling depth, the front column cylinder and the rear column cylinder are lowered, and the side plate cylinder contacts the ground. The milling depth is calculated in real time according to the depth calculation formula in step 1, and the machine is automatically leveled.

[0057] Step 4.1: When setting the milling depth H set When the depth is less than or equal to 150 mm, the single-step depth reduction mode is executed;

[0058] First lower the rear column cylinder to the target height Y curr =Y0-H set , where Y curr is the current stroke of the rear column cylinder, and Y0 is the stroke of the rear column cylinder when zeroing, which corresponds to the value of 0; by converting the cylinder length corresponding to Y0, Y is displayed as a relative value in the system;

[0059] Then lower the front column cylinder to H set =H 深 And ensure that the front and rear pitch angle θ≤2°;

[0060] Step 4.2: When setting the milling depth H set When the depth is greater than 150mm, the step-by-step lowering mode is implemented;

[0061] Stage 1: Lower the rear column cylinder to Y curr =Y0-150, then lower the front column cylinder to the front and rear pitch angle θ≤2°;

[0062] Stage 2: Continue to lower the rear column cylinder to Y curr =Y0-H set , and then lower the front column cylinder to H set =H 深 .

[0063] The step 5 is specifically as follows:

[0064] After the automatic cutting program is completed, during the milling process of the milling machine, when the milling machine moves to the point where the rear travel mechanism begins to enter the pit, the adaptive pit entry control strategy is executed, specifically:

[0065] Step 5.1: Determine whether to trigger the adaptive pit-entry control strategy based on the vehicle status. The judgment logic is as follows:

[0066] Trigger conditions: When the following conditions are met at the same time, it is determined to be in the pit state.

[0067] Milling machine forward speed v>0.1m / s;

[0068] Rear column cylinder height Y curr <Y0;

[0069] The laser rangefinder detects a height change of Δh ≥ 10 mm relative to the ground, which means that half of the rear track height has entered the pit;

[0070] Step 5.2: Control the entry of the rear column cylinder into the pit

[0071] Step 5.2.1. Establish a depth-rear column cylinder coupling model, including establishing the theoretical relationship between the rear column cylinder height change ΔY and the milling depth change ΔH:

[0072] ΔH=ΔY*cosθ-k*θ

[0073] Wherein, K is the calibration coefficient, unit: mm / °;

[0074] ΔY*cosθ represents the direct effect of the rear column cylinder lifting on the depth, and -k*θ represents the depth reduction caused by the forward tilt of the fuselage;

[0075] Step 5.2.2: Rear column cylinder closed-loop compensation algorithm

[0076] The control unit realizes closed-loop control through a PID controller, and its control law is:

[0077]

[0078] The proportional term K P ∈[0.5,1.0]: Rapidly eliminate steady-state error; integral term K i ∈[0.05,0.1]: Eliminate cumulative error; differential term K d ∈[0.1,0.3]: suppress overshoot and oscillation;

[0079] Step 5.2.3: Add compensation term to the control output:

[0080]

[0081] Among them, ΔY 补偿 To compensate for the change in height of the rear column cylinder;

[0082] Milling depth error H set -H curr Controlled within ±1mm, so the height change of the rear column cylinder must meet the following requirements:

[0083]

[0084] When the rear column cylinder height Ycurr =Y0, stop adjusting the rear column cylinder.

[0085] It also includes security protection control strategies, as follows:

[0086] Rear column cylinder stroke limit:

[0087] Single adjustment amount |ΔY|≤10mm to prevent overshoot;

[0088] Pitch angle θ or left / right tilt angle φ exceeds the limit and is frozen:

[0089] If θ>14° or φ>5°,

[0090] When the above conditions are met, the system automatically identifies actions that increase the risk of tipping and prohibits them, while also triggering an audible and visual alarm.

[0091] A milling machine is provided, which uses the above-mentioned automatic leveling control system and automatic leveling control method for the milling machine.

[0092] Beneficial effects: The present invention avoids the risk of large inclination angles through a graded depth reduction strategy, and dynamically lifts and compensates when the rear column cylinder enters the pit, ensuring the horizontality of the fuselage and the accuracy of the milling trajectory, achieving a milling accuracy of ±1mm, and solving the problem of depth loss of control under pit-entering conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0093] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0094] Figure 1 This is a structural diagram of the milling machine of the present invention, in which the known column cylinder and conventional sensor installation structure are omitted.

[0095] Figure 2 This is a flow chart of the control method of the present invention. DETAILED DESCRIPTION

[0096] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0097] In the description of the present invention, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0098] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0099] like Figure 1 As shown, the automatic leveling control system of the milling machine includes an execution unit, a sensor monitoring assembly and a control assembly.

[0100] The execution unit includes a column cylinder group, which includes a front column cylinder and a rear column cylinder, each of which is arranged on both sides of the frame. The rear column cylinders are connected in series through hydraulic pipelines to achieve synchronous action.

[0101] The sensing and monitoring assembly includes a side plate cylinder group, a first displacement sensor provided in the side plate cylinder group, a second displacement sensor provided in the rear column cylinder, an inclination sensor provided on the vehicle frame, and a laser rangefinder installed on the rear side of the vehicle frame. The side plate cylinder group includes a front control cylinder and a rear control cylinder, one group each provided in front and rear of the vehicle side plate. In this embodiment, the first displacement sensor is provided in each of the two front control cylinders and the two rear control cylinders, and the second displacement sensor is provided in either of the two rear column cylinders. The sensing and monitoring assembly is connected to the main controller signal.

[0102] The control assembly includes a geometric solution module, a dynamic zero calibration module, a calibration module and an abnormality detection module which are integrated in a main controller.

[0103] like Figure 2 As shown, the control method of the automatic leveling control system of the milling machine includes the following steps:

[0104] Step 1: Geometric parameter definition and model preset;

[0105] Definition of hinge points: Fixed hinge points are the connection points A1 and A2 between the side plate cylinders at both ends and the frame; dynamic hinge points are the connection points B1 and B2 between the side plate cylinders at both ends and the side plate;

[0106] Definition of milling reference plane: The vertical foot of the horizontal projection of the milling cylinder axis O to the ground is the depth zero point Z; the tool tip reference point T: the lowest point of the cylinder, the real-time depth H 深度 =ZT, calculate H max 、H min , H min Corresponding S min =0,H max Corresponding S max =L 油缸行程 , H 行程 =H max -H min ;

[0107] S max is the maximum extension of the side plate cylinder, S min H is the minimum extension of the side plate cylinder. max H is the distance between the bottom of the side plate and the ground or a fixed surface when the cylinder stroke is 0; min It is the distance between the bottom of the side plate and the ground or a fixed surface when the cylinder stroke is at its maximum.

[0108] Preset the deep computing model in the whole machine control system;

[0109] Step 2: Use the calibration module to calibrate the system zero position;

[0110] Step 3: Enter the set milling depth H set ;

[0111] Step 4: Start the automatic cutting process, continuously calculate the depth and automatically level the machine.

[0112] Execute single depth reduction mode according to the input milling depth, that is, H set ≤150mm or step-by-step lowering mode, i.e. H set >150mm, up to H set =H 深度 ;

[0113] Step 5: After the automatic cutting program is completed, the set milling depth is reached and the vehicle is driven to perform the milling operation. During the milling operation, the adaptive pit entry control strategy is executed to control the milling depth error within ±1mm until the milling operation is completed.

[0114] In step 1, the depth calculation model is specifically:

[0115] 1.1 Calculation of weight coefficient

[0116] The theoretical contribution ratio of the two side plate cylinders to the depth is determined by the geometric relationship of the hinge point.

[0117]

[0118] e=1-f

[0119] Measure the obtained d 前h =1190mm,d 后h =930mm,d 前l =1240mm,d 后l =870mm,

[0120] By calculation and fitting, we get f = 0.6, e = 0.4;

[0121] where d 前h : When the cylinder is raised to the highest point, the horizontal distance from the hinge point B1 between the front plate cylinder and the side plate to the axis O of the milling cylinder is obtained by three-dimensional measurement or laser calibration;

[0122] d 后h : When the cylinder is raised to the highest point, the horizontal distance from the hinge point B2 between the rear plate cylinder and the side plate to the axis O of the milling cylinder is obtained by three-dimensional measurement or laser calibration;

[0123] d 前l : When the cylinder drops to the lowest point, the horizontal distance from the hinge point B1 between the front plate cylinder and the side plate to the axis O of the milling cylinder is obtained by three-dimensional measurement or laser calibration;

[0124] d 后l : When the cylinder drops to the lowest point, the horizontal distance from the hinge point B2 between the rear plate cylinder and the side plate to the milling cylinder axis O is obtained by three-dimensional measurement or laser calibration;

[0125] e is the weighted coefficient of the rear plate cylinder stroke;

[0126] f is the weighted coefficient of the front plate cylinder stroke;

[0127]

[0128] α is the angle between the axis of the front plate cylinder and the vertical direction;

[0129] β is the angle between the axis of the rear plate cylinder and the vertical direction;

[0130] m is the coefficient of influence of the vertical angle of the front plate cylinder on the depth;

[0131] n is the coefficient of influence of the vertical angle of the rear plate cylinder on the depth;

[0132] Experimental calibration

[0133] Obtain S through experiments 前 、S 后 、H 实测 The data is fitted and the weight coefficient f is optimized. opt / e opt , so that the calculated value H 计算 =f*S 后 +e*S 后 The residual error with the measured value is the smallest;

[0134] Among them S 前 is the stroke of the front plate cylinder on one side in the experiment,

[0135] S 后 is the stroke of the rear plate cylinder on one side during the experiment,

[0136] H 实测 is the actual measured value of the single-side depth,

[0137] f opt is the optimal value of f obtained after fitting;

[0138] e opt is the optimal value of e obtained after fitting;

[0139] H 计算 is the calculated value of the single-side depth,

[0140] 1.2 Depth Calculation Formula

[0141] H 深度 =H0-H curr =(a*S 前0 +b*S 后0 )-(a*S 前1 +b*S 后1 );

[0142] Among them, H0 is the calculated value of the cylinder length before and after zero calibration, H curr S is the calculated value of the cylinder length before and after the current position. 前0 The stroke of the front plate cylinder on one side during zero calibration, S 后0 The stroke of the oil cylinder on the rear plate on one side during zero calibration, S 前1 S is the stroke of the front plate cylinder at the current position. 后1 The stroke of the rear plate cylinder on the current position side;

[0143] Coefficient definition:

[0144]

[0145] By measuring the extreme values of α and β, we calculated m = 0.946, n = 0.976;

[0146] j=(0.946×0.6+0.976×0.4)×467≈447.4mm

[0147] j is the intermediate quantity in the calculation process;

[0148] By calculation, we obtain a≈0.596, b≈0.41;

[0149] H 行程 : Full stroke of the oil cylinder, that is, the actual depth change corresponding to the stroke of the side plate oil cylinder from 0 to the longest. In this embodiment, H 行程 =470mm;

[0150] L 油缸行程 : The maximum retractable length of the cylinder mechanical design, in this embodiment L 油缸行程 =467mm.

[0151] The step 2 is specifically as follows:

[0152] Zero calibration can be triggered under any working condition, and the system automatically records the current side plate cylinder stroke S 左前0 / S 左后0 / S 右前0 / S 右前0 And the rear column cylinder stroke Y0, and calculate

[0153] H 左0 =a*S 左前0 +b*S 左后0

[0154] H 右0 =a*S 右前0 +b*S 右后0

[0155] Among them S 左前0 S is the stroke of the left front plate cylinder, 左后0 S is the stroke of the left rear plate cylinder. 右前0 is the right front plate cylinder stroke, S 右后0 H is the stroke of the right rear plate cylinder. 左0 Calculate the depth for the left side, H 右0 Calculate the depth for the right side;

[0156] Zero calibration and measured S 左前0 =340mm, S 左后0 =335mm.

[0157] The step 4 is specifically as follows:

[0158] According to the input milling depth, the front column cylinder and the rear column cylinder are lowered, and the side plate cylinder contacts the ground. The milling depth is calculated in real time according to the depth calculation formula in step 1, and the machine is automatically leveled.

[0159] Example 1

[0160] Step 4.1: When setting the milling depth H set When the depth is less than or equal to 150 mm, the single-step depth reduction mode is executed;

[0161] First lower the rear column cylinder to the target height Y curr =Y0-H set , where Y curr is the current stroke of the rear column cylinder, and Y0 is the stroke of the rear column cylinder when zeroing, which corresponds to the value of 0; by converting the cylinder length corresponding to Y0, Y is displayed as a relative value in the system;

[0162] Then lower the front column cylinder to H set =H 深 And ensure that the front and rear pitch angle θ≤2°;

[0163] Set H set =50mm, real-time S 左前1 =300mm, S 左后1 =296mm;

[0164] H 左0 =0.596×340+0.41×335≈340

[0165] H 左curr =0.596×300+0.41×296≈300

[0166] H 左深 =340-300=40

[0167] It is necessary to continue to control the column cylinder to move downward until H 左深 =50mm.

[0168] Example 2

[0169] Step 4.2: When setting the milling depth H set When the depth is greater than 150mm, the step-by-step lowering mode is implemented;

[0170] Stage 1: Lower the rear column cylinder to Y curr =Y0-150, then lower the front column cylinder to the front and rear pitch angle θ≤2°;

[0171] Stage 2: Continue to lower the rear column cylinder to Y curr =Y0-H set , and then lower the front column cylinder to H set =H 深 .

[0172] Step-by-step depth control

[0173] Set H set =200mm;

[0174] Phase 1:

[0175] The rear column cylinder is lowered from the height of Y0=500mm to 350mm, and the front column cylinder is lowered to θ≤2°;

[0176] Phase 2:

[0177] The rear column cylinder continues to drop to a height of 300mm, and the front column cylinder drops to H at the same time. 深度 =200mm, θ≤2°, level in place.

[0178] The step 5 is specifically as follows:

[0179] After the automatic cutting program is completed, during the milling process of the milling machine, when the milling machine moves to the point where the rear travel mechanism begins to enter the pit, the adaptive pit entry control strategy is executed, specifically:

[0180] Example 3

[0181] Step 5.1: Determine whether to trigger the adaptive pit-entry control strategy based on the vehicle status. The judgment logic is as follows:

[0182] Trigger conditions: When the following conditions are met at the same time, it is determined to be in the pit state.

[0183] Milling machine forward speed v>0.1m / s;

[0184] Rear column cylinder height Y curr <Y0;

[0185] The laser rangefinder detects a height change of Δh ≥ 10 mm relative to the ground, which means that half of the rear track height has entered the pit;

[0186] Initial state:

[0187] H set =50mm, Y=500mm, θ=0°, k=2mm / °

[0188] Entering the pit trigger:

[0189] H was detected curr =52mm,θ=1°

[0190] Step 5.2: Control the entry of the rear column cylinder into the pit

[0191] Step 5.2.1. Establish a depth-rear column cylinder coupling model, including establishing the theoretical relationship between the rear column cylinder height change ΔY and the milling depth change ΔH:

[0192] ΔH=ΔY*cosθ-k*θ

[0193] Wherein, K is the calibration coefficient, unit: mm / °;

[0194] ΔY*cosθ represents the direct effect of the rear column cylinder lifting on the depth, and -k*θ represents the depth reduction caused by the forward tilt of the fuselage;

[0195] Step 5.2.2: Rear column cylinder closed-loop compensation algorithm

[0196] The control unit realizes closed-loop control through a PID controller, and its control law is:

[0197]

[0198] PID output: ΔY = 0.8 × 2 + 0.1 × 2 × 1 + 0.2 × 0 = 1.8 mm

[0199] The proportional term K P ∈[0.5,1.0]: Rapidly eliminate steady-state error; integral term K i ∈[0.05,0.1]: Eliminate cumulative error; differential term K d ∈[0.1,0.3]: suppress overshoot and oscillation;

[0200] Step 5.2.3: Add compensation term to the control output:

[0201]

[0202] Pitch compensation:

[0203] Among them, ΔY 补偿 To compensate for the change in height of the rear column cylinder;

[0204] Milling depth error H set -H curr Controlled within ±1mm, so the height change of the rear column cylinder must meet the following requirements:

[0205]

[0206] When the rear column cylinder height Y curr =Y0, stop adjusting the rear column cylinder.

[0207] The rear column cylinder is raised to Y curr =500+3.8≈504mm, the final H curr =50±1mm.

[0208] It also includes security protection control strategies, as follows:

[0209] Rear column cylinder stroke limit:

[0210] Single adjustment amount |ΔY|≤10mm to prevent overshoot;

[0211] Pitch angle θ or left / right tilt angle φ exceeds the limit and is frozen:

[0212] If θ>14° or φ>5°,

[0213] When the above conditions are met, the system automatically identifies actions that increase the risk of tipping and prohibits them, while also triggering an audible and visual alarm.

[0214] A milling machine is provided, which uses the above-mentioned automatic leveling control system and automatic leveling control method for the milling machine.

[0215] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0216] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. Automatic leveling control system for milling machine, characterized by: Including execution unit, sensor monitoring assembly and control assembly, The execution unit includes a column cylinder group, which includes a front column cylinder and a rear column cylinder, each of which is arranged on both sides of the frame. The rear column cylinders are connected in series through hydraulic pipelines to achieve synchronous action. The sensing and monitoring assembly includes a side plate cylinder group, a first displacement sensor provided in the side plate cylinder group, a second displacement sensor provided in the rear column cylinder, an inclination sensor provided on the vehicle frame, and a laser rangefinder installed on the rear side of the vehicle frame. The side plate cylinder group includes a front control cylinder and a rear control cylinder, one group each provided on the front and rear sides of the vehicle side plate. The sensing and monitoring assembly is connected to the main controller for signal transmission. The control assembly includes a geometric solution module, a dynamic zero calibration module, a calibration module and an abnormality detection module which are integrated in a main controller.

2. The control method of the automatic leveling control system of a milling machine according to claim 1, characterized in that: The following steps are involved: Step 1: Geometric parameter definition and model preset; Definition of hinge points: Fixed hinge points are the connection points A1 and A2 between the two side plate cylinders and the frame; dynamic hinge points are the connection points B1 and B2 between the two side plate cylinders and the side plate; Definition of milling reference plane: The vertical foot of the horizontal projection of the milling cylinder axis O to the ground is the depth zero point Z; the tool tip reference point T: the lowest point of the cylinder, the real-time depth H 深度 =ZT; Preset the deep computing model in the whole machine control system; Step 2: Use the calibration module to calibrate the system zero position; Step 3: Enter the set milling depth H set ; Step 4: Start the automatic cutting process, continuously calculate the depth and automatically level the machine. Execute single depth reduction mode according to the input milling depth, that is, H set ≤150mm or step-by-step lowering mode, i.e. H set >150mm, up to H set =H 深度 ; Step 5: After the automatic cutting program is completed, the set milling depth is reached and the vehicle is driven to perform the milling operation. During the milling operation, the adaptive pit entry control strategy is executed to control the milling depth error within ±1mm until the milling operation is completed.

3. The control method of the automatic leveling control system of a milling machine according to claim 2, characterized in that: In step 1, the depth calculation model is specifically: 1.1 Calculation of weight coefficient The theoretical contribution ratio of the two side plate cylinders to the depth is determined by the geometric relationship of the hinge point. e=1-f where d 前h : When the cylinder is raised to the highest point, the horizontal distance from the hinge point B1 between the front plate cylinder and the side plate to the axis O of the milling cylinder is obtained by three-dimensional measurement or laser calibration; d 后h : When the cylinder is raised to the highest point, the horizontal distance from the hinge point B2 between the rear plate cylinder and the side plate to the axis O of the milling cylinder is obtained by three-dimensional measurement or laser calibration; d 前l : When the cylinder drops to the lowest point, the horizontal distance from the hinge point B1 / B2 between the front plate cylinder and the side plate to the milling cylinder axis O is obtained through three-dimensional measurement or laser calibration; d 后l : When the cylinder drops to the lowest point, the horizontal distance from the hinge point B1 / B2 between the rear plate cylinder and the side plate to the milling cylinder axis O is obtained through three-dimensional measurement or laser calibration; e is the weighted coefficient of the rear plate cylinder stroke; f is the weighted coefficient of the front plate cylinder stroke; α is the angle between the axis of the front plate cylinder and the vertical direction; β is the angle between the axis of the rear plate cylinder and the vertical direction; m is the coefficient of influence of the vertical angle of the front plate cylinder on the depth; n is the coefficient of influence of the vertical angle of the rear plate cylinder on the depth; Experimental calibration Obtain S through experiments 前 、S 后 、H 实测 The data is fitted and the weight coefficient f is optimized. opt / e opt , so that the calculated value H 计算 =f*S 后 +e*S 后 The residual error with the measured value is the smallest; Among them S 前 is the stroke of the front plate cylinder on one side in the experiment, S 后 is the stroke of the rear plate cylinder on one side during the experiment, H 实测 is the actual measured value of the single-side depth, f opt is the optimal value of f obtained after fitting; e opt is the optimal value of e obtained after fitting; H 计算 is the calculated value of the single-side depth, 1.2 Depth Calculation Formula H 深度 =H0-Hcurr=(a*S 前0 +b*S 后0 )-(a*S 前1 +b*S 后1 ); Among them, H0 is the calculated value of the cylinder length before and after zero calibration, H curr S is the calculated value of the cylinder length before and after the current position. 前0 The stroke of the front plate cylinder on one side during zero calibration, S 后0 The stroke of the oil cylinder on the rear plate on one side during zero calibration, S 前1 S is the stroke of the front plate cylinder at the current position. 后1 The stroke of the rear plate cylinder on the current position side; Coefficient definition: H 行程 : Full stroke of the cylinder, that is, the actual depth change when the side plate cylinder stroke goes from 0 to the maximum, in mm; L 油缸行程 : The maximum retractable length of the cylinder mechanical design.

4. The control method of the automatic leveling control system of a milling machine according to claim 3, characterized in that: The step 2 is specifically as follows: Zero calibration can be triggered under any working condition, and the system automatically records the current side plate cylinder stroke S 左前0 / S 左后0 / S 右前0 / S 右前0 And the rear column cylinder stroke Y0, and calculate H 左0 =a*S 左前0 +b*S 左后0 H 右0 =a*S 右前0 +b*S 右后0 Among them S 左前0 S is the stroke of the left front plate cylinder, 左后0 S is the stroke of the left rear plate cylinder. 右前0 is the right front plate cylinder stroke, S 右后0 H is the stroke of the right rear plate cylinder. 左0 Calculate the depth for the left side, H 右0 Calculate the depth for the right side.

5. The control method of the automatic leveling control system of a milling machine according to claim 3, characterized in that: The step 4 is specifically as follows: According to the input milling depth, the front column cylinder and the rear column cylinder are lowered, and the side plate cylinder contacts the ground. The milling depth is calculated in real time according to the depth calculation formula in step 1, and the machine is automatically leveled. Step 4.1: When setting the milling depth H set When the depth is less than or equal to 150 mm, the single-step depth reduction mode is executed; First lower the rear column cylinder to the target height Y curr =Y0-H set , where Y curr is the current stroke of the rear column cylinder, and Y0 is the stroke of the rear column cylinder when zeroing, which corresponds to the value of 0; by converting the cylinder length corresponding to Y0, Y is displayed as a relative value in the system; Then lower the front column cylinder to H set =H 深 And ensure that the front and rear pitch angle θ≤2°; Step 4.2: When setting the milling depth H set When the depth is greater than 150mm, the step-by-step lowering mode is implemented; Stage 1: Lower the rear column cylinder to Y curr =Y0-150, then lower the front column cylinder to the front and rear pitch angle θ≤2°; Stage 2: Continue to lower the rear column cylinder to Y curr =Y0-H set , and then lower the front column cylinder to H set =H 深 .

6. The control method of the automatic leveling control system of a milling machine according to claim 5, characterized in that: The step 5 is specifically as follows: After the automatic cutting program is completed, during the milling process of the milling machine, when the milling machine moves to the point where the rear travel mechanism begins to enter the pit, the adaptive pit entry control strategy is executed, specifically: Step 5.1: Determine whether to trigger the adaptive pit-entry control strategy based on the vehicle status. The judgment logic is as follows: Trigger conditions: When the following conditions are met at the same time, it is determined to be in the pit state. Milling machine forward speed v>0.1m / s; Rear column cylinder height Y curr <Y0; The laser rangefinder detects a height change of Δh ≥ 10 mm relative to the ground, which means that half of the rear track height has entered the pit; Step 5.2: Control the entry of the rear column cylinder into the pit Step 5.2.

1. Establish a depth-rear column cylinder coupling model, including establishing the theoretical relationship between the rear column cylinder height change △Y and the milling depth change △H: △H=△Y*cosθ-k*θ Wherein, K is the calibration coefficient, unit: mm / °; △Y*cosθ represents the direct effect of the rear column cylinder lifting on the depth, and -k*θ represents the depth reduction caused by the forward tilt of the fuselage; Step 5.2.2: Rear column cylinder closed-loop compensation algorithm The control unit realizes closed-loop control through a PID controller, and its control law is: The proportional term K P ∈[0.5,1.0]: Rapidly eliminate steady-state error; integral term K i ∈[0.05,0.1]: Eliminate cumulative error; differential term K d ∈[0.1,0.3]: suppress overshoot and oscillation; Step 5.2.3: Add compensation term to the control output: Among them, ΔY 补偿 To compensate for the change in height of the rear column cylinder; Milling depth error H set -H curr Controlled within ±1mm, so the height change of the rear column cylinder must meet the following requirements: When the rear column cylinder height Y curr =Y0, stop adjusting the rear column cylinder.

7. The control method of the automatic leveling control system of a milling machine according to claim 6, characterized in that: It also includes security protection control strategies, as follows: Rear column cylinder stroke limit: Single adjustment amount |△Y|≤10mm to prevent overshoot; Pitch angle θ or left / right tilt angle φ exceeds the limit and is frozen: If θ>14° or φ>5°, When the above conditions are met, the system automatically identifies actions that increase the risk of tipping and prohibits them, while also triggering an audible and visual alarm.

8. A milling machine, characterized in that: A milling machine using the automatic leveling control system and the automatic leveling control method for the milling machine as described in any one of claims 1 to 7.

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