Elevator and conveyor line synchronous linkage control method and system

Abstract

The application discloses a hoist and conveying line synchronous linkage control method and system, relates to the control technical field of hoists and conveying lines, and comprises a hoist platform which is provided with a conveying surface, the conveying surface can drive materials to enter or leave the hoist platform in a horizontal direction; a vertical driving unit which comprises a servo motor and an absolute value encoder and is used for driving the hoist platform to move up and down along a guide rail in a vertical shaft; the application determines the fixed parameters of the timing moment based on a trapezoidal speed curve, does not introduce a running time prediction error, provides an accurate time reference for the subsequent reverse acceleration timing moment, determines the static friction coefficient according to the material of the contact surface and a non-constant assumption, considers the coupling influence of the maximum allowed acceleration on the normal force, and explicitly includes the control constraints of the working conditions of the friction margin narrowing in the deceleration rising and acceleration descending stages.

Description

Technical Field

[0001] This invention relates to the field of control technology for hoists and conveyor lines, specifically to a method and system for synchronous linkage control of hoists and conveyor lines. Background Technology

[0002] In e-commerce warehousing, manufacturing production lines, and automated logistics systems, elevators are responsible for the vertical transport of materials between different floors. A typical configuration is as follows: each floor has a horizontal conveyor line (belt conveyor, roller conveyor, or chain conveyor), the elevator moves up and down within the shaft, and its loading platform is also equipped with a conveying surface for transferring materials between the floor it stops at and the floor's conveyor line.

[0003] Traditional elevator control employs a sequential start-stop strategy: the elevator stops upon reaching a certain floor, and only after both the platform conveyor and the floor conveyor have come to a standstill does the floor conveyor push or pull the material into or out of the platform. Afterward, the platform conveyor restarts to proceed to the next floor. To shorten docking time, some improvements have been proposed, such as keeping the elevator platform belt running, ensuring the belt speed matches the conveyor speed at the moment of docking, allowing the material to transition naturally due to the speed difference between the two conveyor surfaces. However, this method has a problem: if the platform belt is still rotating after the material enters the platform, the material will slide on the platform due to inertia during vertical transport, especially noticeable when the elevator brakes or changes speed. Excessive displacement can even lead to the material falling off the platform.

[0004] A more prudent approach is to reduce the belt speed after the material enters the platform to stabilize it, and then accelerate the belt in the opposite direction to align with the target conveyor line when it is close to the target floor. However, this introduces several intertwined engineering constraints: the platform belt has a limited length, restricting the acceleration distance; the acceleration cannot exceed the friction limit, otherwise the material will slip; the timing of acceleration needs to be precisely calculated based on the remaining travel distance, as starting too early will cause the material to move prematurely, while starting too late will result in insufficient speed at docking. Moreover, the elevator accelerates in the vertical direction, and the normal force of the material on the platform conveyor surface is not always equal to gravity. When decelerating upwards or accelerating downwards, the material becomes "lighter," narrowing the friction margin and making it most prone to slippage.

[0005] This application proposes a method and system for synchronous linkage control of the hoist and the conveyor line to overcome the above-mentioned defects. Summary of the Invention

[0006] To solve the above-mentioned technical problems, a method and system for synchronous linkage control of the hoist and the conveyor line are provided. This technical solution solves the problem of material docking imbalance mentioned above.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A method and system for synchronous linkage control of the hoist and conveyor line, including the following steps:

[0009] The elevator platform is equipped with a conveying surface, which can drive materials to enter or leave the elevator platform in a horizontal direction.

[0010] The vertical drive unit, including a servo motor and an absolute encoder, is used to drive the hoist platform to move up and down along the guide rail inside the shaft.

[0011] The position detection unit includes an absolute encoder mounted on the shaft end of the vertical drive unit and a laser rangefinder mounted on the side wall of the shaft, used to detect the vertical position of the hoist platform. ;

[0012] Platform conveying unit, used to drive the conveying surface and control its speed. and direction of rotation;

[0013] The controller is connected to the vertical drive unit, the position detection unit, and the platform conveying unit via an industrial real-time bus. The controller includes:

[0014] The location prediction module is configured to obtain the height difference between the current floor and the target floor. The total transport time is calculated according to the preset motion parameters of the vertical drive unit using a trapezoidal velocity curve. The predicted docking time is determined by the sum of the departure time and the total transportation time. ;

[0015] The friction constraint module is configured to determine the static friction coefficient based on the material pair between the bottom surface of the material and the conveying surface. And based on the instantaneous vertical acceleration of the hoist platform at the current moment. Calculate the maximum allowable dynamic acceleration ,in The acceleration due to gravity is upward, with the positive direction being upward.

[0016] The reverse acceleration planning module is configured to calculate the theoretical acceleration distance based on the dynamic maximum allowable acceleration and the conservative value under the most unfavorable working condition, and to deduce the reverse acceleration start time by working backward from the relationship between the remaining vertical travel and the theoretical acceleration distance. ;

[0017] The rate gradient module is configured to increase the conveyor surface rate when the docking entry threshold is reached. Controlled to the source floor conveyor line speed Equal to achieve receiving, after the materials enter The deceleration curve decreases to zero according to the S-shaped deceleration curve, and from the aforementioned starting moment... Start following the S-shaped speed curve Gradual transition from zero to target floor conveyor line speed And during the reverse acceleration process, slippage detection and dynamic curve reconstruction are performed;

[0018] The height alignment module is configured to, at the predicted docking time Control the vertical height of the hoist platform and its connection height with the target floor. Alignment.

[0019] Preferably, the controller uses an industrial-grade processor, is equipped with no less than 4GB of memory, runs a real-time operating system, and has a control cycle of No more than 2ms;

[0020] In the position detection unit, the absolute encoder reading is the main feedback and the laser range sensor reading is the auxiliary verification. When the difference between the two exceeds the preset tolerance, a sensor abnormality alarm is triggered.

[0021] In the position prediction module, the preset motion parameters include the maximum vertical running speed. Vertical acceleration and vertical deceleration These are all fixed constants determined during the system debugging phase.

[0022] A method for synchronous linkage control between a hoist and a conveyor line, the method comprising the following steps:

[0023] Real-time acquisition of the vertical position of the hoist platform and the operating speed of the target floor conveyor line ;

[0024] During the vertical transport phase of the hoist carrying materials, the height difference between the current floor and the target floor is used as a reference. Deterministic calculation of the docking time based on the trapezoidal velocity curve ;

[0025] When the position difference decreases to a preset docking entry threshold, the platform conveyor surface speed will be increased. Controlled to the operating speed of the source floor conveyor line The materials are equal and in the same direction, so that the materials enter the platform from the source floor conveyor line;

[0026] After the material enters the platform, it will decelerate according to an S-shaped deceleration curve. Reduced to zero;

[0027] The static friction coefficient is determined based on the material composition of the bottom surface of the material and the material of the conveying surface. Based on the instantaneous vertical acceleration of the hoist Calculate the maximum allowable dynamic acceleration The starting time of reverse acceleration is deduced by working backward from the remaining vertical travel and the maximum permissible dynamic acceleration. ;

[0028] from Initially, follow the S-shaped speed curve... Gradual change from zero to Simultaneously, a slippage test is performed within each control cycle. Real-time acceleration exceeds Dynamically reduce the upper limit of jerk and regenerate the velocity curve;

[0029] exist Control the vertical height of the platform to the height of the target floor. Alignment allows materials to be transferred to the target floor conveyor line.

[0030] Preferably, the deterministic calculation and prediction of the docking time based on the trapezoidal velocity curve is performed. ,include:

[0031] Obtain the height difference between the current floor of the hoist and the target floor. ;

[0032] Based on the preset motion parameters of the vertical drive unit, including the maximum vertical running speed Vertical acceleration Vertical deceleration And calculate the total transport time using the trapezoidal speed curve ;

[0033] The start time of the hoist starting from this floor With the total transportation time The sum is determined to be ;

[0034] Among them, when the height difference When the distance is not less than the critical distance at which the speed curve can reach the maximum speed, the total transportation time is the sum of the acceleration period time, the constant speed period time, and the deceleration period time; when the height difference When the distance is less than the critical distance, the speed curve degenerates into a trapezoid, and the total transportation time is directly calculated from the peak speed and acceleration / deceleration.

[0035] Preferably, the static friction coefficient The method for determining it is as follows:

[0036] Determine the material type by referring to a table based on the material compatibility between the bottom surface and the conveyor surface. The range of values ​​is used, and the median value is taken as the setting value for the current batch;

[0037] Alternatively, during the system debugging phase, samples of the current batch of materials can be taken and calibrated using the inclined plane method. Place the material on an inclined conveyor surface sample, slowly increase the inclination angle until the material begins to slide, and record the critical inclination angle. ,but .

[0038] Preferably, the reverse acceleration start time is... ,include:

[0039] The theoretical acceleration distance is calculated based on the conservative maximum permissible acceleration under the most unfavorable working condition:

[0040]

[0041] in, , The vertical deceleration of the hoist corresponds to the most unfavorable working condition when the vertical acceleration is negative during the hoist's deceleration upward or acceleration downward phases;

[0042] according to Counting back to the start time:

[0043]

[0044] in, Accelerating the platform's delivery surface from zero to... Time required;

[0045] Alternatively, continuously monitor the remaining vertical travel distance during vertical transport. ,when Reduce to equal to The current time will be marked as This serves as a redundant check for the aforementioned time-reverse calculation method.

[0046] Preferably, the step of following the S-shaped speed curve... Gradual change from zero to ,include:

[0047] With accelerometer Not exceeding the preset smoothness constraint upper limit As a constraint, based on the available acceleration distance Shortest distance from theory The ratio automatically selects the curve shape:

[0048] when At that time, a complete S-shaped seven-segment curve is used, which successively includes an acceleration segment, a constant speed acceleration segment, and a deceleration segment. The time parameters of each segment are determined by the upper limit of smoothness constraints and the target speed. Sure;

[0049] when At that time, a simplified S-shaped five-segment curve is adopted to eliminate the uniform acceleration segment, so that the acceleration segment and the deceleration segment are directly connected. The peak acceleration is adaptively adjusted according to the ratio of the available acceleration distance to the theoretical shortest distance. The closer the ratio is to 1.0, the larger the peak acceleration is, but it does not exceed the dynamic maximum allowable acceleration determined by the friction constraint under the current working condition.

[0050] when At that time, it degenerates into a trapezoidal three-segment curve with constant acceleration. ;

[0051] The parameter formulas for each form are as follows For continuous calculation of input, the acceleration peak transitions continuously at the morphological transition boundary.

[0052] Preferably, the specific procedure for the slippage test is as follows:

[0053] Inspection within each control cycle Whether it is true or not, among which, The real-time rate of change of the surface velocity of the platform. The instantaneous vertical acceleration of the hoist at the current moment is positive upwards;

[0054] If the condition is not met, the upper limit of the current S-shaped velocity curve's peak acceleration will be set. and accelerometer limit Decrease the step size by one step and regenerate the velocity curve;

[0055] If regenerated Still greater than Then continue to decrease Step length until or The value drops to the lower limit, and its lower limit is... 30% of the initial value;

[0056] Each time the curve is regenerated, the acceleration distance required for the new curve is calculated synchronously. ,like If the available acceleration distance exceeds the current remaining vertical travel distance, then switch to degrade mode;

[0057] Record the actual docking rate achieved ,when and There are deviations At that time, a rate compensation command is sent to the conveyor line on the target floor.

[0058] Preferably, a downgrade mode is also included:

[0059] When the remaining vertical travel Insufficient to make Accelerating from zero to At that time, that is Enter downgrade mode;

[0060] Calculate under the current constraints Maximum achievable speed:

[0061]

[0062] by Complete the docking and simultaneously send a speed reduction matching command to the target floor conveyor line;

[0063] While sending the speed reduction matching command, the buffer space of the target floor conveyor line is assessed: if the buffer space is sufficient, the speed reduction docking is performed directly; if the buffer space is insufficient, an early warning request is sent to the upstream conveyor line to slow down or suspend feeding; if the upstream cannot cooperate, the hoist waits above the target floor until the buffer space is cleared before performing the speed reduction docking.

[0064] When the degradation mode is triggered more than a preset number of times within a preset time, an alarm is sent to the upper-level scheduling system.

[0065] Preferably, the in Control the vertical height of the platform to the height of the target floor. Alignment, including:

[0066] exist Within the preset deceleration distance before reaching the destination, closed-loop position control is adopted, with the laser range sensor reading as the main feedback and the encoder reading as the auxiliary verification.

[0067] Speed ​​feedforward is superimposed on closed-loop position control. ,in Forward coefficients;

[0068] The feedback section uses a proportional-integral control law:

[0069]

[0070] in For height deviation, For proportional gain, This is the integral gain;

[0071] Adopting an integral separation strategy: when When the preset separation threshold is exceeded, only proportional control is used. The integral term begins to accumulate when the separation threshold is not exceeded, and the upper limit of the integral term is limited according to the maximum allowable speed of the vertical drive unit;

[0072] when When the vertical running speed is lower than the preset static threshold, the height alignment is determined to be complete, and a braking command is issued to lock the platform.

[0073] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0074] The docking time of this invention is determined by fixed parameters of a trapezoidal velocity curve, without introducing runtime prediction errors. It provides an accurate time reference for the reverse acceleration timing. The static friction coefficient is determined based on the material of the contact surface and is not a constant assumption. The maximum allowable acceleration takes into account the coupling effect of the hoist's vertical acceleration on the normal force. The working condition where the friction margin narrows during the deceleration and acceleration phases is explicitly incorporated into the control constraints.

[0075] By employing an S-shaped velocity curve, the system automatically selects the most suitable configuration when available acceleration distances vary, ensuring continuous acceleration without abrupt changes. The slippage detection threshold is updated in real-time with the vertical motion status, avoiding misjudgments under varying normal force conditions with a fixed threshold. The degradation mode automatically coordinates with the target conveyor line to reduce speed when the remaining travel is insufficient, preventing system downtime. Attached Figure Description

[0076] Figure 1 This is a flowchart of the synchronous linkage control method between the hoist and the conveyor line of the present invention;

[0077] Figure 2 This is a schematic diagram illustrating the spatial relationship between the hoist and the floor conveyor line in this invention.

[0078] Figure 3 This is a schematic diagram of the rate change of the S-shaped velocity curve of the present invention during the reverse acceleration phase;

[0079] Figure 4 This is a diagram illustrating the architecture of the synchronous linkage control system for the hoist and conveyor line of this invention.

[0080] In the diagram: 100, source floor; 200, target floor; 300, source floor conveyor line; 400, target floor conveyor line; 500, shaft track; 600, lifting platform. Detailed Implementation

[0081] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art.

[0082] Reference Figure 1 As shown, the synchronous linkage control method and system for the hoist and conveyor line includes:

[0083] Step S1: Real-time acquisition of the vertical position of the hoist platform and the operating speed of the conveyor line on the target floor.

[0084] Vertical position of the hoist platform Real-time detection is achieved through an absolute encoder mounted on a vertical drive motor, supplemented by a laser rangefinder for redundancy verification. The detection signal is sampled at a preset period. The data is continuously reported to the controller. The two sensors prioritize the absolute encoder reading and use laser ranging as a secondary reference. Under normal circumstances, the encoder reading is taken as the standard. When the difference between the two exceeds the set tolerance (±5mm in this embodiment), an alarm is triggered to indicate that the sensor is abnormal.

[0085] Operating speed of the target floor conveyor line Obtainable through the following two methods, listed in order of priority:

[0086] Method 1: Communication reading, directly read the current operating speed parameters from the PLC or frequency converter of the floor conveyor line itself via an industrial communication bus (such as EtherCAT, PROFINET).

[0087] Method 2: Independent sensor. Install a speed sensor (such as a rotary encoder installed on the driven shaft of the roller conveyor) on the target floor conveyor line to directly measure the surface linear speed of the belt or roller conveyor. When the communication bus is interrupted or reading is abnormal, it will automatically switch to this method.

[0088] The switching between the two modes is managed by the communication monitoring module in the controller: when the communication bus has 3 consecutive... If no valid data frame is received during the cycle, it is determined that the communication is interrupted and automatically switches to mode two; after the communication is restored, it automatically switches back to mode one, and at the moment of switching, the reading of mode one is verified based on the reading of mode two.

[0089] Source floor conveyor line speed The method of obtaining it is the same as described above, and will not be repeated here.

[0090] Step S2: Deterministic calculation to predict docking time

[0091] The vertical operation of the hoist adopts a fixed trapezoidal speed curve (acceleration section → constant speed section → deceleration section), and the parameters of each section have been determined during the system commissioning phase: maximum vertical operating speed. Vertical acceleration Vertical deceleration For transportation between any two floors, the floor height difference... Since these are known constants, the total transportation time can be calculated directly.

[0092] when Time (speed curve can reach) ):

[0093] Accelerate for a period of time:

[0094] Deceleration period:

[0095] Acceleration segment distance:

[0096] Deceleration distance:

[0097] Uniform speed segment time:

[0098] Total transit time:

[0099] when When the velocity curve degenerates into a trapezoid, it becomes impossible to reach the target value. ):

[0100] Peak speed:

[0101] Total transit time:

[0102] The controller records the departure time when the hoist starts from this floor. The predicted docking time is:

[0103]

[0104] If updates are needed during operation (For example, if the target floor is temporarily changed), the controller will recalculate the difference based on the current remaining height using the same formula as above. And update .

[0105] because , , , These are all fixed parameters determined during the system debugging phase. The calculation is based on deterministic parameters and does not involve the estimation of runtime variables, resulting in high prediction accuracy.

[0106] The certainty also has another important significance: the starting moment of reverse acceleration. The backward reasoning relies entirely on The accuracy, if There is an inherent prediction error, and this error will be directly propagated to... This can lead to acceleration occurring too early or too late. A fixed trapezoidal velocity curve is used for calculation. This eliminates the source of error at its root.

[0107] Step S3: Source floor rate matching and material receiving

[0108] When the position difference decreases to the preset docking entry threshold, the controller starts the rate matching.

[0109] Setting the docking entry threshold needs to consider two aspects: firstly, sufficient time must be allowed for the platform conveyor surface to accelerate and match the conveyor line speed; secondly, it cannot start too early, causing the belt to wait for docking even after matching. In this embodiment, the docking entry threshold is determined based on the conveyor line speed and the controller's response bandwidth. The principle for setting the threshold is: the remaining transportation time corresponding to the threshold should be greater than the platform conveyor surface's acceleration from rest to... It takes 1.5 times longer than the required time.

[0110] Rate matching is achieved through closed-loop control: the controller uses... The set value is based on the actual detected value. As feedback, a servo motor on the platform's conveyor surface is driven by a PID controller. During the handover process... and The absolute value of the rate difference in the material conveying direction is controlled within the handover rate threshold. Within. For cardboard box materials, By taking a speed within ±5% of the target conveyor line speed, it can be ensured that the cartons will not be pushed or torn at the seam during handover due to excessive speed difference.

[0111] The material transitions naturally from the source floor conveyor line to the platform conveyor surface through the joint between the two conveyor surfaces. Since the speeds on both sides are basically the same, the material will not be significantly impacted at the joint.

[0112] Step S4: After the material enters, the speed is reduced to 0.

[0113] After the material has completely entered the platform (determined by photoelectric sensors detecting the material's tail leaving the joint), the platform's conveyor surface begins to reduce its speed according to an S-shaped deceleration curve. Gradually change from the current value to zero.

[0114] The deceleration constraint conditions include two items:

[0115] First, deceleration distance It must not exceed the effective length of the platform's conveyor surface. Subtract material dimensions The obtained effective distance:

[0116]

[0117] Second, the deceleration during the deceleration process. The maximum permissible acceleration must not be exceeded. At this time, the hoist is either stationary or just starting up. , .

[0118] Regarding material dimensions Acquisition: These are important input parameters for calculating deceleration and acceleration distances. The methods for obtaining them, listed in order of priority, are:

[0119] Method 1: Upstream system push. The WMS stores the material's external dimensions data, which is pushed along with the material barcode. The controller then extracts the data from the barcode. .

[0120] Method 2: Online visual measurement. Install a line laser scanner or 3D vision camera at the entrance section of the conveyor line on the current floor to measure the shape and size of the passing materials in real time.

[0121] Method 3: Default value. When the above two methods are unavailable, the default value is used. This method defaults to conveying cardboard boxes. Use 400mm. When using the default value, the constraints are conservative.

[0122] Step S5: Backward calculation of the starting moment of reverse acceleration

[0123] After the material decelerates to zero, the elevator carries the material vertically. The controller needs to plan in advance when to initiate reverse acceleration.

[0124] Regarding the coefficient of static friction The static friction coefficient g is determined as a parameter of the contact interface between the bottom surface of the carton and the conveyor surface. It is mainly related to the material of the conveyor surface, the surface condition of the bottom surface of the carton, and the contact conditions. Under normal working conditions, the reference range of the static friction coefficient is obtained from the preset friction coefficient parameter table based on the combination of the material of the conveyor surface and the surface condition of the bottom surface of the carton. The reference range of the static friction coefficient corresponding to different contact surface combinations is shown in the table below:

[0125]

[0126] Method 1: Look up the material in the table. The material of the conveyor surface is a known hardware configuration parameter of the system; the material of the carton bottom can be obtained from the WMS system (based on the packaging specification information of the material SKU). The controller looks up the corresponding material in the table above. The median value of the range is used as the setting value for the current batch.

[0127] Method 2: Online calibration. During the system debugging phase, samples of the current batch of cartons are taken and calibrated using the inclined plane method on the platform conveyor surface: the cartons are placed on the inclined belt sample, and the inclination angle is slowly increased until the cartons begin to slide. The critical inclination angle is recorded. ,but Take 3-5 samples from each batch and calculate the average value.

[0128] Regarding the dynamic maximum permissible acceleration The condition for materials not to slip on the platform conveyor surface is that the horizontal acceleration does not exceed the friction limit. This is because the elevator has acceleration in the vertical direction. (Upward is positive), the effective normal force on the material is and non-constant Therefore, the maximum permissible acceleration changes dynamically with the vertical motion state:

[0129]

[0130] in, The acceleration phase can be obtained directly from the table of the running stages of the trapezoidal velocity curve. Uniform speed segment Deceleration section .

[0131] The physical meaning of this coupling relationship is: when accelerating upwards, the material is "pressed" onto the conveying surface, increasing the effective gravity and the friction margin; when decelerating upwards or accelerating downwards, the material becomes "lighter," decreasing the effective gravity and narrowing the friction margin. The latter is precisely the period when reverse acceleration is most likely to occur—the hoist approaches the target floor and enters the deceleration phase, thus it is also the operating condition most prone to slippage.

[0132] Reverse calculation process:

[0133] Step 1: Calculate the conservative maximum allowable acceleration. Reverse acceleration usually occurs during the deceleration phase of the hoist as it approaches the target floor. The friction margin is minimized. To be conservative, the theoretical acceleration distance calculation uses the value under the most unfavorable operating condition:

[0134]

[0135] Step 2: Calculate the theoretical acceleration distance.

[0136]

[0137] Step 3: Determine the start time. This is done using a time-based backward calculation method:

[0138]

[0139] in, Accelerating the platform's delivery surface from zero to... Required time. For S-shaped velocity curves (full S-shape or simplified S-shape). It is obtained by summing the time parameters of each segment of the curve; for the trapezoidal degradation pattern, .because For deterministic values, It can be accurately calculated without introducing additional prediction errors.

[0140] Redundancy check: The controller also performs position-based checks, continuously monitoring the remaining vertical travel distance during vertical transport. ,when Reduce to equal The current time will be marked as The two methods verify each other, and the one that arrives first initiates reverse acceleration.

[0141] Step S6: S-shaped speed curve transition and slippage inspection

[0142] from Initially, the controller will follow the S-shaped speed curve. Gradual change from zero to .

[0143] The acceleration of the S-shaped velocity curve (The rate of change of acceleration, in m / s³) is limited to the preset upper limit of the smoothness constraint. Within a certain range, while ensuring that the peak acceleration does not exceed the dynamic maximum allowable acceleration determined by the friction constraints under the current operating conditions. This ensures that the acceleration is continuous without sudden changes.

[0144] Calculation of the shape and parameters of the S-curve under different working conditions:

[0145] Based on available acceleration distance Depending on the sufficiency of the curve, it presents three forms, with the required distance decreasing sequentially: complete S-shape (seven segments) > simplified S-shape (five segments) > trapezoid (three segments). The controller adjusts accordingly. Automatically select the shape and calculate parameters:

[0146] Form 1: Complete S-shape (seven-segment), when At that time, there is ample acceleration distance. (Including the acceleration / deceleration phase) ), uniform acceleration phase ( ), deceleration phase ( ) and uniform speed running section ( Time parameters for each stage:

[0147] The acceleration and deceleration phases are of equal duration: determined by the upper limit of acceleration. and preset constant peak acceleration jointly determined

[0148] Accelerate for a period of time: ,in, The preset constant peak acceleration, and satisfying That is, the preset peak value does not exceed the dynamic allowable value of the friction constraint.

[0149] Peak acceleration:

[0150] Uniform acceleration period:

[0151] Under this morphology It runs most smoothly. This is the preset maximum jerk.

[0152] The method for calculating the total distance during the acceleration phase is as follows:

[0153]

[0154] like Then there exists a uniform speed synchronization segment, and the time of the uniform speed synchronization segment is... .

[0155] Form 2: When At that time, a simplified five-segment motion curve is adopted, which includes the following stages: acceleration phase ( ): Acceleration increases linearly from 0 to deceleration phase ( ): Acceleration from Linearly reduced to 0; uniform speed synchronous segment ( Maintain speed It remains unchanged and operates synchronously with the conveyor line.

[0156] In this state, the uniform acceleration segment is compressed to zero. .

[0157] The calculation methods for the time parameters at each stage are as follows:

[0158]

[0159] Peak acceleration:

[0160]

[0161] Five-stage total acceleration distance:

[0162]

[0163] This configuration is suitable for situations where the available distance is limited but acceleration can still be achieved.

[0164] Form 3: Trapezoid (three-segment), when At that time, the acceleration and deceleration phases are completely compressed ( ), acceleration is constant , Accelerate time In this mode, the acceleration exhibits instantaneous jumps at the start and end points, but the velocity curve itself is continuous.

[0165] Controller according to The ratio automatically selects the form, because the formulas for each form parameter are based on... For continuous calculation of input, the parameter values ​​transition naturally and continuously at the switching boundary, without any sudden changes in the acceleration peak.

[0166] Slippage test: in each control cycle Inside, the controller performs the following checks:

[0167]

[0168] in, Within the current control cycle The real-time rate of change, the right side of the inequality The current operating phase of the trapezoidal velocity curve is obtained directly from the table, with the acceleration segment taken as... Take the uniform speed segment Deceleration section .

[0169] If detected at a certain moment This indicates that the current acceleration has exceeded the friction limit. The controller responds according to the following procedure:

[0170] Step 1: Lower the upper limit of peak acceleration (main adjustment method)

[0171] Set the upper limit of the current S-curve acceleration peak value. Reduce by one step (in this example, the current peak value) ), and regenerate the velocity curve.

[0172] If the current form is seven segments and the reduction is... Still greater than or equal to This can be achieved by shortening the duration of the uniform acceleration phase. To adapt, maintain peak acceleration constant;

[0173] If the reduction It is already less than Then the curve changes from a seven-segment to a five-segment format, with the peak value adjusted accordingly. Adaptive;

[0174] If the current structure is already a five-segment structure, then recalculate based on the reduced peak value. , And the distances of each segment.

[0175] Step 2: Based on the adjustment of the peak acceleration, lower the upper limit of acceleration to facilitate smoother adjustments. Reduce the step size by one step (15% of the original value in this example) and regenerate a smoother speed curve.

[0176] Step 3: If regenerated Still greater than Then continue to decrease (Decrease the current value each time) ),until or Reduced to the lower limit (the lower limit is the initial peak value) ). The safety margin is used to cover fluctuations in the coefficient of friction and sensor noise.

[0177] Step 4: Evaluate the remaining distance. After each curve is regenerated, simultaneously calculate the acceleration distance required for the new curve. Compare this with the available distance corresponding to the current remaining vertical travel. If If the available distance is exceeded, it means that it is impossible to complete the full acceleration within the remaining stroke under the current friction conditions, and the process switches to the degraded mode in step S7.

[0178] Step 5: If the slippage test triggers at least one curve reconstruction, the final docking rate will be [not specified]. Possibly lower Controller logs Calculate the deviation .like Send a rate compensation command to the target floor conveyor line, causing it to temporarily adjust to the speed at the docking moment. After the handover is completed, restore to .

[0179] Step S7, Downgrade Mode

[0180] When the remaining vertical travel Insufficient to complete from zero to When the full acceleration is satisfied, that is, when the full acceleration is satisfied. much smaller Then it will enter downgrade mode.

[0181] The controller calculates the current constraints. Maximum achievable speed:

[0182]

[0183] by At the target speed, during the remaining journey... Accelerate. Simultaneously, send a speed reduction matching command to the target floor conveyor line, causing it to reduce its speed to a minimum during the docking period. .

[0184] Degradation mode and its coordination with upstream suppliers: Temporary speed reduction of the target floor conveyor line may lead to material accumulation upstream. The corresponding strategies are as follows:

[0185] First, assess the current buffer capacity of the target floor conveyor line. If the idle area is sufficient to accommodate the accumulated material during the deceleration period (estimated by counting the number of materials in place and the spacing using a photoelectric sensor array), then directly implement deceleration.

[0186] Second, when the buffer is insufficient, an early warning is sent to the upstream control system, requesting a reduction or suspension of feeding. If the upstream cannot cooperate, the hoist waits above the target floor until the buffer has enough space before performing a speed reduction docking.

[0187] Third, if the downgrade mode is triggered more than 3 times in a short period of time (e.g., within 1 minute), it indicates that there is a systemic problem in the task scheduling scheme in terms of trip allocation. The controller sends an alarm to the upper-level scheduling system and suggests replanning the transportation task sequence.

[0188] Step S8: Height alignment control at docking time

[0189] exist Before arrival, the controller initiates height alignment control.

[0190] exist Once the preset deceleration distance is reached, the controller switches to closed-loop position control mode.

[0191] Position feedback: The height alignment stage requires high precision (millimeter level). A dual-sensor fusion strategy is adopted, using laser rangefinder readings as the main feedback (accuracy up to 0.1mm level) and encoder readings as auxiliary verification. The precision advantage of laser ranging is even more significant in the docking deceleration section.

[0192] Speed ​​feedforward: Speed ​​feedforward is added to the closed-loop position control.

[0193]

[0194] in The feedforward coefficient is set to 0.8~1.0 in this embodiment.

[0195] PI control law: The feedback section uses proportional-integral control.

[0196]

[0197] in, For the current height deviation, For proportional gain, This is the integral gain.

[0198] PID parameter tuning: and The initial values ​​are tuned using the step response method: During the commissioning phase, a small step position command (e.g., 1 mm) is applied to the vertical drive unit, and the overshoot and settling time of the position response are recorded. The equivalent model parameters are calculated based on the response curve, and the initial values ​​are calculated using the IMC formula. Based on this, fine-tuning is performed according to the actual docking accuracy test results.

[0199] Integral separation: when When mm, only proportional control is used, and the integral term does not accumulate; when The integral term begins to accumulate at a speed of mm, eliminating steady-state error. The upper limit of the integral term is based on the maximum permissible speed limit of the vertical drive unit.

[0200] Brake intervention: When and When the speed reaches m / s, the height alignment is determined to be complete, and a braking command is issued to lock the platform. In this embodiment, ±2mm is used.

[0201] In this embodiment, Figure 4 The overall architecture of the system of the present invention is shown, including the following five main components:

[0202] The elevator platform is the core component for carrying and transporting materials. The platform is equipped with a conveyor surface (belt, roller conveyor, or chain), and the effective length of the conveyor surface... Based on the actual working conditions, the platform moves up and down along the guide rails inside the shaft via guide components.

[0203] The vertical drive unit is responsible for driving the hoist platform to move in the vertical direction. It adopts a "servo motor + wire rope winch" structure. The servo motor realizes closed-loop control of vertical speed and position through feedback from an absolute encoder.

[0204] The position detection unit is used to detect the vertical position of the hoist platform in real time. It includes an absolute encoder installed on the shaft end of the vertical drive motor and a laser rangefinder installed on the side wall of the shaft. The data from both are processed by a fusion algorithm within the controller.

[0205] The platform conveying unit is installed on the hoist platform and is used to drive the platform conveying surface and control its speed. The rotation direction is driven by an independent servo motor, supporting forward and reverse rotation and variable speed operation.

[0206] The controller is the core processing unit of the system, communicating with the three units mentioned above via an EtherCAT bus. The controller uses an industrial-grade processor (such as an ARM Cortex-A72 quad-core @ 1.5GHz or an equivalent x86 industrial control processor), is equipped with at least 4GB of memory, and runs a real-time operating system (such as Linux RT_PREEMPT or VxWorks) to ensure deterministic response to control tasks.

[0207] Control cycle The feasibility of ms is demonstrated as follows: Within one control cycle, the controller needs to complete the following calculation tasks: docking time calculation (trapezoidal velocity curve parameter calculation), S-curve interpolation (multi-segment function evaluation, including normalized time calculation for each segment and curve value lookup or real-time calculation), and slippage detection (comparison of rate derivative and dynamic threshold, threshold...). The calculations are obtained from tables during the operational phase, and PI adjustment (including integral accumulation and limiting) is performed. Typical computation times for each task are as follows: docking time calculation approximately 5-10 μs, S-curve interpolation approximately 50-100 μs, slippage detection approximately 5-10 μs, PI adjustment approximately 10-20 μs, EtherCAT communication transmission and reception approximately 30-50 μs, and operating system scheduling and interrupt overhead approximately 50-100 μs. The total is approximately 150-300 μs, accounting for 8%-15% of the 2ms control cycle, with the processor load rate far below the 70% upper limit.

[0208] The controller contains five functional modules:

[0209] The location prediction module obtains the height difference between the current floor and the target floor. According to the preset motion parameters of the vertical drive unit ( , , ) Calculated according to the trapezoidal velocity curve ,Sure This calculation is based on fixed parameters and does not involve dynamic estimation at runtime.

[0210] The friction constraint module determines the material pair between the bottom material of the material and the conveying surface material. And based on the instantaneous vertical acceleration of the hoist at the current moment. Calculate the maximum allowable dynamic acceleration . The speed is obtained directly from a table during the operation phase of the trapezoidal speed curve, requiring no additional sensors. This module also calculates conservative values ​​under the most unfavorable operating conditions. This is used by the reverse acceleration planning module.

[0211] The reverse acceleration planning module is based on calculate ,from Backwards At the same time, redundancy checks are performed based on location.

[0212] The rate gradual change module is responsible for all rate control tasks: receiving rate synchronization, deceleration to zero, S-shaped reverse acceleration, slippage detection and dynamic curve reconstruction, and degradation mode processing.

[0213] The height alignment module is in It is responsible for the precise alignment control of the platform's vertical height, and adopts a composite control strategy of dual-sensor fusion acceleration feedforward plus PI feedback.

[0214] All of the above modules run as software on the real-time operating system within the controller. Data interaction between modules is accomplished through shared memory, with communication latency not exceeding one control cycle. .

[0215] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. A synchronous linkage control system for the hoist and conveyor line, characterized in that, Includes the following modules: The elevator platform is equipped with a conveying surface, which can drive materials to enter or leave the elevator platform horizontally; The vertical drive unit, including a servo motor and an absolute encoder, is used to drive the hoist platform to move up and down along the guide rails inside the shaft. The position detection unit includes an absolute encoder mounted on the shaft end of the vertical drive unit and a laser rangefinder mounted on the sidewall of the shaft, used to detect the vertical position of the hoist platform. ; The platform conveyor unit is used to drive the conveyor surface and control its speed. and direction of rotation; The controller is connected to the vertical drive unit, position detection unit, and platform conveying unit via an industrial real-time bus. The controller includes: The location prediction module is configured to obtain the height difference between the current floor and the target floor. The total transport time is calculated according to the trapezoidal velocity curve based on the preset motion parameters of the vertical drive unit. The predicted docking time is determined by the sum of the departure time and the total transportation time. ; The friction constraint module is configured to determine the static friction coefficient based on the material pair between the bottom surface of the material and the conveying surface. And based on the instantaneous vertical acceleration of the hoist platform at the current moment. Calculate the maximum allowable dynamic acceleration ; The reverse acceleration planning module is used to calculate the theoretical acceleration distance based on the dynamic maximum allowable acceleration and the conservative value under the most unfavorable working condition, and to deduce the start time of reverse acceleration by working backward from the relationship between the remaining vertical stroke and the theoretical acceleration distance. .

2. The synchronous linkage control system for the hoist and conveyor line according to claim 1, characterized in that: The controller also includes a rate gradient module for adjusting the delivery surface rate when the docking threshold is reached. Controlled to the source floor conveyor line speed Equal to achieve receiving, after the materials enter Deceleration to zero according to the S-shaped deceleration curve, and from the initial moment Start following the S-shaped speed curve Gradual transition from zero to target floor conveyor line speed And during the reverse acceleration process, slippage detection and dynamic curve reconstruction are performed; The height alignment module is used to predict docking time. Control the vertical height of the hoist platform and its connection height with the target floor. Alignment; In the position detection unit, the absolute encoder reading is the main feedback and the laser range sensor reading is the auxiliary verification. When the difference between the two exceeds the preset tolerance, a sensor abnormality alarm is triggered. In the position prediction module, the preset motion parameters include the maximum vertical running speed. Vertical acceleration and vertical deceleration These are all fixed constants determined during the system debugging phase.

3. A method for synchronous linkage control of the hoist and conveyor line, applied to the control system described in claim 1 or 2, characterized in that: The method includes the following steps: S1. Real-time acquisition of the vertical position of the hoist platform and the operating speed of the target floor conveyor line ; S2. During the vertical transport phase of the hoist carrying materials, based on the height difference between the current floor and the target floor... Deterministic calculation of the docking time based on the trapezoidal velocity curve ; S3. When the position difference decreases to the preset docking entry threshold, the speed of the platform conveying surface is increased. Controlled to the operating speed of the source floor conveyor line The materials are equal and in the same direction, so that the materials enter the platform from the source floor conveyor line; S4. After the material enters the platform, decelerate according to the S-shaped deceleration curve. Reduced to zero; The static friction coefficient is determined based on the material composition of the bottom surface of the material and the material of the conveying surface. Based on the instantaneous vertical acceleration of the hoist Calculate the maximum allowable dynamic acceleration The starting time of reverse acceleration is deduced by working backward from the remaining vertical travel and the dynamic maximum permissible acceleration. ; S5. From Initially, follow the S-shaped speed curve... Gradual change from zero to Simultaneously, a slippage test is performed within each control cycle. Real-time acceleration exceeds Dynamically reduce the upper limit of jerk and regenerate the velocity curve; S6. In Control the vertical height of the platform to the height of the target floor. Alignment allows materials to be transferred to the target floor conveyor line.

4. The synchronous linkage control method for the hoist and conveyor line according to claim 3, characterized in that: The deterministic calculation and prediction of docking time based on the trapezoidal velocity curve ,include: Obtain the height difference between the current floor of the hoist and the target floor. ; Based on the preset motion parameters of the vertical drive unit, including the maximum vertical running speed Vertical acceleration Vertical deceleration And calculate the total transport time using the trapezoidal speed curve ; The start time of the hoist starting from this floor With the total transportation time The sum is determined to be ; Among them, when the height difference When the distance is not less than the critical distance at which the speed curve can reach the maximum speed, the total transportation time is the sum of the acceleration period time, the constant speed period time, and the deceleration period time; when the height difference When the distance is less than the critical distance, the speed curve degenerates into a trapezoid, and the total transport time is directly calculated from the peak speed and acceleration / deceleration.

5. The synchronous linkage control method for the hoist and conveyor line according to claim 3, characterized in that: The static friction coefficient The method for determining it is as follows: Determine the material type by referring to a table based on the material compatibility between the bottom surface and the conveyor surface. The range of values ​​is used, and the median value is taken as the setting value for the current batch; Alternatively, during the system debugging phase, samples of the current batch of materials can be taken and calibrated using the inclined plane method. Place the material on an inclined conveyor surface sample, slowly increase the inclination angle until the material begins to slide, and record the critical inclination angle. ,but .

6. The synchronous linkage control method for the hoist and conveyor line according to claim 3, characterized in that: The reverse acceleration start time ,include: The theoretical acceleration distance is calculated based on the conservative maximum permissible acceleration under the most unfavorable working condition: ； in, , The vertical deceleration of the hoist corresponds to the most unfavorable working condition when the vertical acceleration is negative during the hoist's deceleration upward or acceleration downward phases; according to Counting back to the start time: ； in, Accelerating the platform's delivery surface from zero to... Time required; Alternatively, continuously monitor the remaining vertical travel distance during vertical transport. ,when Reduce to equal to The current time will be marked as This serves as a redundant check for the aforementioned time-reverse calculation method.

7. The synchronous linkage control method for the hoist and conveyor line according to claim 3, characterized in that: The S-shaped speed curve will Gradual change from zero to ,include: With accelerometer Not exceeding the preset smoothness constraint upper limit As a constraint, based on the available acceleration distance Shortest distance from theory The ratio automatically selects the curve shape: when At that time, a complete S-shaped seven-segment curve is used, which successively includes an acceleration segment, a constant speed acceleration segment, and a deceleration segment. The time parameters of each segment are determined by the upper limit of smoothness constraints and the target speed. Sure; when At that time, a simplified S-shaped five-segment curve is adopted to eliminate the uniform acceleration segment, so that the acceleration segment and the deceleration segment are directly connected. The peak acceleration is adaptively adjusted according to the ratio of the available acceleration distance to the theoretical shortest distance. The closer the ratio is to 1.0, the larger the peak acceleration is, but it does not exceed the dynamic maximum allowable acceleration determined by the friction constraint under the current working condition. when At that time, it degenerates into a trapezoidal three-segment curve with constant acceleration. ; The parameter formulas for each form are as follows For continuous calculation of input, the acceleration peak transitions continuously at the morphological transition boundary.

8. The synchronous linkage control method for the hoist and conveyor line according to claim 7, characterized in that: The specific procedure for the slippage test is as follows: Inspection within each control cycle Whether it is true or not, among which, The real-time rate of change of the surface velocity of the platform. The instantaneous vertical acceleration of the hoist at the current moment is positive upwards; If the condition is not met, the upper limit of the current S-shaped velocity curve's peak acceleration will be set. and accelerometer limit Decrease the step size by one step and regenerate the velocity curve; If regenerated Still greater than Then continue to decrease Step length until or The value drops to the lower limit, and its lower limit is... 30% of the initial value; Each time the curve is regenerated, the acceleration distance required for the new curve is calculated synchronously. ,like If the available acceleration distance exceeds the current remaining vertical travel distance, then switch to degrade mode; Record the actual docking rate achieved ,when and There are deviations At that time, a rate compensation command is sent to the conveyor line on the target floor.

9. The synchronous linkage control method for the hoist and conveyor line according to claim 3, characterized in that: It also includes a downgrade mode: When the remaining vertical travel Insufficient to make Accelerating from zero to At that time, that is Enter downgrade mode; Calculate under the current constraints Maximum achievable speed: ； by Complete the docking and simultaneously send a speed reduction matching command to the target floor conveyor line; While sending the speed reduction matching command, the buffer space of the target floor conveyor line is assessed: if the buffer space is sufficient, the speed reduction docking is performed directly; if the buffer space is insufficient, an early warning request is sent to the upstream conveyor line to slow down or suspend feeding; if the upstream cannot cooperate, the hoist waits above the target floor until the buffer space is cleared before performing the speed reduction docking. When the degradation mode is triggered more than a preset number of times within a preset time, an alarm is sent to the upper-level scheduling system.

10. The synchronous linkage control method for the hoist and conveyor line according to claim 3, characterized in that: The above Control the vertical height of the platform to the height of the target floor. Alignment, including: exist Within the preset deceleration distance before reaching the destination, closed-loop position control is adopted, with the laser range sensor reading as the main feedback and the encoder reading as the auxiliary verification. Speed ​​feedforward is superimposed on closed-loop position control. ,in Forward coefficients; The feedback section uses a proportional-integral control law: ； in For height deviation, For proportional gain, This is the integral gain; Adopting an integral separation strategy: when When the preset separation threshold is exceeded, only proportional control is used. The integral term begins to accumulate when the separation threshold is not exceeded, and the upper limit of the integral term is limited according to the maximum allowable speed of the vertical drive unit; when When the vertical running speed is lower than the preset static threshold, the height alignment is determined to be complete, and a braking command is issued to lock the platform.

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