A load sensing and dynamic speed regulation method for stage hoisting equipment

Abstract

The application provides a load sensing and dynamic speed regulation method for a stage lifting device, and belongs to the technical field of automatic control. In view of the problems of large speed fluctuation when the load suddenly changes, the separation of overload protection and speed regulation, the lack of load prediction in the starting stage and the like, the application proposes the following: real-time acquisition of pressure and current signals and fusion to generate a current load value; calculation of a target speed according to a load-speed mapping relationship; calculation of a starting acceleration based on the load value in the starting stage and execution of soft starting; monitoring of a load change amount and correction of a speed instruction in combination with a PID algorithm in the running stage; and grading determination of overload and execution of corresponding speed limiting or shutdown protection. The method deeply fuses load sensing and speed closed-loop control, can inhibit speed fluctuation caused by sudden load change, realizes grading overload protection, avoids heavy load starting impact, and is suitable for lifting stages and prop lifting devices.

Description

Technical Field

[0001] This application relates to the field of automatic control technology, and in particular to a load sensing and dynamic speed regulation method for stage lifting equipment. Background Technology

[0002] In modern stage performances, large-scale galas, and theatrical events, stage lifting equipment is the core mechanical device for achieving dynamic stage effects, actor entrances, and prop changes. This stage lifting equipment includes, but is not limited to, lifting stages, lifting platforms, and prop lifting devices. During a performance, the load on the lifting equipment often changes in real time, such as when actors enter the stage, instruments are set up, or props are removed. Such dynamic changes in load can easily lead to drastic fluctuations in lifting speed, positioning deviations, and even mechanical impacts, directly affecting performance safety and artistic presentation. Therefore, developing a control method that can adapt to load changes and achieve smooth and safe speed regulation is of great significance for improving the intelligence level of stage machinery and the reliability of performances.

[0003] The control technology of existing stage lifting equipment has evolved from simple control to intelligent control. Early lifting equipment mostly used manually operated mechanical limit switches or simple relay control. Speed ​​adjustment relied on operator experience, resulting in poor control accuracy and an inability to cope with sudden load changes. Subsequently, PLC combined with variable frequency speed control technology was widely introduced, achieving continuous adjustment of motor speed and precise position control, improving start-stop smoothness to some extent. In recent years, some high-end equipment has begun to integrate pressure sensors or current detection modules, attempting speed compensation based on load. For example, different operating speed ranges are switched by detecting the weight level on the platform, or current signals are used to determine overload and trigger alarm shutdown. Most of these solutions use fixed load-speed correspondence tables or empirical coefficients for open-loop control, and have not yet achieved closed-loop dynamic speed regulation based on real-time load perception. For example, Chinese patent CN118939004A discloses a stage lifting control system and method based on Ethernet, which acquires weight data, tilt angle, and speed data and performs leveling control based on weight distribution. However, its speed regulation logic involves discrete gear switching based on weight distribution, failing to achieve continuous stepless speed adjustment according to load. Chinese patent CN103529790A discloses a lifting stage control device and control method, which uses a current sensor and a speed sensor for control. However, its speed adjustment logic is "when the speed exceeds the standard range, the speed will be reduced to 1 / 2 to 2 / 3 of the upper limit of the standard speed range", which is a discrete gear switching rather than continuous adjustment.

[0004] Despite this, existing control methods for stage lifting equipment still have the following shortcomings. First, their dynamic response to sudden load changes is limited. Traditional speed adjustment logic is mostly a static deceleration mode triggered after the fact. For example, after detecting that the load exceeds a certain threshold, the speed is switched to a lower fixed level. However, when the load changes instantaneously during equipment operation (such as when an actor steps onto the platform during lifting), existing solutions cannot continuously adjust the speed setpoint according to the load change, leading to drastic speed fluctuations or overshoot. The root cause of this defect is that the load signal is only used as a trigger condition for "present / absent" judgment or rough leveling, without introducing a speed control loop for continuous closed-loop feedforward compensation. Second, existing solutions are mostly "response-based" control—that is, passively correcting after the load change occurs, lacking the ability to proactively judge and pre-adjust the load change trend. When the load change rate is fast, the response lag problem is particularly prominent. Third, overload protection mechanisms and non-overload speed regulation strategies are disconnected. Existing technologies typically trigger independent alarms or shutdowns when the load exceeds the rated value, resulting in a control mode where speed regulation during non-overload phases and protection during overload phases are separated. This makes it impossible to maintain limited operation under non-critical overload conditions to ensure performance continuity, and also makes it difficult to achieve precise emergency braking and mechanical brake linkage under severe overload conditions. Fourth, there is a lack of load prediction capability during the startup phase. Existing systems do not actively detect the current load weight and plan the acceleration curve accordingly before equipment startup, often starting directly with a preset constant acceleration curve, which can easily cause motor overcurrent or mechanical shock under heavy load conditions. The root cause of these defects is that the speed regulation logic of existing solutions lacks a hierarchical collaborative decision-making mechanism of "load perception - speed planning - graded protection," and no dynamic coupling relationship is established between the speed setpoint, startup acceleration, and real-time load. Therefore, there is an urgent need in this field for a dynamic speed regulation method that can deeply couple real-time load perception with speed planning and graded overload protection to effectively solve the above-mentioned technical problems. Summary of the Invention

[0005] To address the problems existing in the background technology, this application provides a load sensing and dynamic speed regulation method for stage lifting equipment, comprising the following steps: Step 1: Collect load sensing data of the stage lifting equipment in real time, and perform fusion processing on the load sensing data to generate the current load value; the load sensing data includes at least pressure signals collected by multiple pressure sensors and current signals collected by the drive motor current detection module; Step 2: Calculate the target speed value based on the current load value and the preset load-speed mapping relationship; Step 3: During the startup phase of the stage lifting equipment, calculate the startup acceleration based on the current load value and execute soft-start control; Step 4: During the operation of the stage lifting equipment, dynamically monitor the load change and correct the target speed value in real time based on the load change, outputting the corrected speed command; before performing speed correction, perform sensor signal cross-verification: calculate the deviation between the load value converted from the pressure signal and the equivalent load value converted from the current signal. When the deviation exceeds a preset cross-verification threshold, it is determined that the sensor may be faulty, triggering the safety protection mode; at the same time, calculate the predicted compensation amount based on the trend of the load change rate and apply it to the speed command in advance to suppress speed fluctuations caused by rapid load changes; Step 5: Determine if the current load value is overloaded, and perform graded speed adjustment or safe shutdown according to the overload level.

[0006] As a preferred embodiment of this application, the load sensing data in step one includes at least pressure signals collected by multiple pressure sensors arranged on the bearing surface of the stage lifting equipment, and current signals collected by the current detection module of the drive motor. The fusion processing includes: performing moving average filtering on the pressure signals and the current signals respectively, and then calculating a weighted average value according to preset weighting coefficients as the current load value. The calculation formula is as follows:

[0007] in, This indicates the current load value, in kilograms (kg). This represents the average value of multiple pressure sensor signals after being filtered by a moving average, and the unit is kilograms (kg). This represents the equivalent load value obtained after the current signal is converted through a moving average filter, and the unit is kilograms (kg). and For the weighting coefficients, satisfying ,and and The initial values ​​are 0.6 and 0.4, respectively; the weighting coefficient is dynamically adjusted according to the current no-load reference value of the stage lifting equipment. When the fluctuation range of the no-load reference value exceeds the preset reference threshold, the weighting coefficient is increased. The value of is chosen to enhance the weight of the current signal.

[0008] As a preferred embodiment of this application, the fusion processing in step one further includes sensor anomaly identification: when any pressure sensor signal deviates from the average value of the remaining pressure sensor signals by more than a preset deviation threshold, the any pressure sensor signal is discarded as an abnormal signal, and the average value of the remaining pressure sensor signals is fused with the current signal.

[0009] As a preferred embodiment of this application, the preset load-speed mapping relationship in step two is a piecewise function, and the target speed is calculated according to the following formula. :

[0010] in, Indicates the target speed, in meters per second (m / s); This indicates the maximum permissible speed of the stage lifting equipment, measured in meters per second (m / s). This indicates the rated load of the stage lifting equipment, in kilograms (kg). This indicates the current load value. When the current load value... Not exceeding the rated load At that time, the target speed It decreases linearly with increasing load, reaching its maximum value under no-load conditions. It drops to 0.5 at rated load. ;when When the rated load is exceeded, the target speed will be determined separately by the overload determination in step five.

[0011] As a preferred embodiment of this application, step three, calculating the startup acceleration based on the current load value, specifically includes: obtaining the current load value before startup. Calculate the starting acceleration using the following formula. :

[0012] in, This indicates the initial acceleration, measured in meters per second squared (m / s²). This indicates the rated acceleration, measured in meters per second squared (m / s²). Indicates the rated load; This indicates the current load value before startup, in kilograms (kg). This function takes the minimum value to ensure that the load factor does not exceed 1. When the current load value before startup exceeds the rated load, the starting acceleration decreases inversely proportional to the load, thereby avoiding motor overcurrent and mechanical shock during heavy-load startup.

[0013] As a preferred embodiment of this application, step four, which involves dynamically monitoring load changes and correcting the target speed value in real time, specifically includes: using a fixed sampling period. Get the current load value at consecutive time points and Calculate the load change as follows:

[0014] in, and These represent the current load values ​​at the current time and the previous time, respectively. This represents the change in load. The rate of change in load is calculated using the following formula. :

[0015] in, Indicates the sampling period, in seconds (s); This indicates the rate of change of load, expressed in kilograms per second (kg / s).

[0016] When the load change rate Exceeding the preset disturbance threshold At that time, speed correction is triggered; the correction uses a PID control algorithm to adjust the target speed value. The expected value is fed back at the actual speed. The measured value is expressed as the load change. For feedforward compensation, output the corrected speed command. as follows:

[0017] in, Indicates time, in seconds (s); , represents the speed deviation, with the unit being meters per second (m / s); Indicates the proportionality coefficient; Represents the integral coefficient, in units of the reciprocal of seconds (s). -1 ); This represents the differential coefficient, with the unit being seconds (s). This represents the feedforward compensation coefficient, with units of meters per second per kilogram (m / (s·kg)). Indicates time The change in load, in kilograms (kg). Indicates time The target speed; Indicates time The actual speed feedback. The output of the PID control algorithm. As the speed setpoint for the drive motor.

[0018] As a preferred embodiment of this application, the proportional coefficient of the PID control algorithm is... Integral coefficient and differential coefficients The tuning is segmented according to the load range to which the current load value belongs, with the scaling factor for the heavy load range being greater than that for the light load range, to enhance disturbance rejection capability. The specific tuning rules are as follows: in, This indicates the current load value; This indicates the rated load; , , These are the proportional coefficients for light load, medium load, and heavy load ranges, respectively, and they satisfy... That is, the larger the load, the larger the proportional coefficient; the integral coefficient and derivative coefficient of each interval are set independently so that the speed control system can maintain a suitable response speed and anti-disturbance capability across the entire load range.

[0019] As a preferred embodiment of this application, the overload determination in step five includes pre-setting four overload levels, and calculating the speed limit value corresponding to each level according to the following formula. : in, This indicates the maximum permissible speed under overload conditions, expressed in meters per second (m / s). Indicates the rated speed; This indicates the current load value; The rated load is indicated; when there is a slight overload, the target speed is limited to no more than 50% of the rated speed and a yellow warning indicator light signal is issued; when there is a moderate overload, the target speed is limited to no more than 30% of the rated speed and an audible and visual alarm is issued; when there is a severe overload, the target speed is limited to no more than 10% of the rated speed and an emergency alarm is issued; when there is a dangerous overload, the speed is allowed to drop to zero, that is, the motor power is immediately cut off and the mechanical brake device is triggered, and at the same time, fault information is sent to the remote monitoring platform.

[0020] As a preferred embodiment of this application, the method further includes a dynamic security check performed in step five: real-time comparison of the corrected speed command. With the current load value Corresponding safe speed limit Calculate the safe speed limit using the following formula. :

[0021] in, This indicates the maximum permissible speed; This indicates the rated load; This indicates the current load value; if the corrected speed command Exceeding the aforementioned safe speed limit Then the safe speed limit will be used as the output command.

[0022] As a preferred embodiment of this application, the method further includes a self-test step before startup: after receiving the lifting command but before the actual movement begins, zero-point calibration of the load sensing data is performed to eliminate sensor drift and detect whether there is a preload. If a preload exists, the process directly proceeds to the soft-start control in step three. The zero-point calibration specifically involves recording the initial readings of each pressure sensor under no-load conditions. and the initial equivalent load of the current sensor Subsequent measurements are all subtracted from the corresponding initial value, and the current load value is calculated using the following formula. :

[0023] in, This represents the average pressure signal under measurement conditions, expressed in kilograms (kg). This represents the baseline average pressure signal under no-load conditions, in kilograms (kg). This indicates the current equivalent load under the measurement condition, and the unit is kilograms (kg). This represents the current reference equivalent load under no-load conditions, in kilograms (kg). and This represents the weighting coefficient.

[0024] As a preferred embodiment of this application, the dynamic adjustment of the weighting coefficients specifically includes: continuously monitoring the pressure signal during the operation of the stage lifting equipment. and current equivalent load Based on their long-term statistical properties, calculate the variance ratio of the two. ,in This represents the variance of the pressure signal within a preset time window. This represents the variance of the current equivalent load within the same time window; when the variance of the pressure signal increases significantly ( When ), increase The value is chosen to reduce the weight of the pressure signal; when the variance of the current signal increases significantly ( When ), increase The value of is chosen to reduce the weight of the current signal; the adjustment of the weighting coefficient follows . The constraints are applied, and the adjustment step size does not exceed 0.05 each time. Among them, For example, let's take 2.0. For example, we take 0.5.

[0025] As a preferred embodiment of this application, the method further includes a predictive control step performed in step four: calculating the load change rate. Simultaneously, calculate the second derivative of the load change rate. ,in This represents the rate of change of load at the current moment. This represents the rate of change of load at the previous moment; when Exceeding the preset disturbance threshold and At that time, add the predicted compensation amount to the feedforward compensation term. ,in Indicates the predicted compensation coefficient. This indicates the prediction time window.

[0026] As a preferred embodiment of this application, the method further includes sensor signal cross-verification performed before speed correction in step four: calculating the load value converted from the pressure signal. Equivalent load value converted from the current signal relative deviation between ;when Exceeding the preset cross-validation threshold When the threshold is 0.15 (for example), it is determined that at least one of the pressure sensor and the current sensor may be faulty; the speed correction process is paused, a sensor fault alarm is issued, and the speed command is switched to safe mode. The cross-validation threshold... It can be found in 0.10 Select within the range of 0.20.

[0027] As a preferred embodiment of this application, the feedforward compensation coefficient The physical meaning is: the speed compensation amount corresponding to a unit load change, with the unit being meters per second per kilogram (m / (s·kg)). The determination method is as follows: During the factory commissioning phase of the stage lifting equipment, a load step response test is performed, and a known amount of step load is applied. Record speed deviation The peak and steady-state values ​​are estimated using least-squares fitting to minimize the velocity deviation. Value. The initial estimation formula is: ,in This is an empirical coefficient (exemplarily taken as 0.1). 0.3), and then through step response tests to Make minor adjustments.

[0028] As a preferred embodiment of this application, the method further includes speed smoothing filtering during operation: applying the corrected speed command... A first-order low-pass filter is performed, and the filtered speed value is used as the final set speed for the drive motor. The final given speed is calculated using the following formula. :

[0029] in, Indicates the sequence number of the discrete sampling time; This represents the final given velocity after filtering at the current moment, in meters per second (m / s). This indicates the corrected speed command at the current moment, in meters per second (m / s). This represents the final given velocity after filtering at the previous moment, in meters per second (m / s). In this scheme, the filter coefficients are represented. The value of 0.3 is a typical value selected by those skilled in the art based on engineering experience. It can be adjusted within the range of 0 to 1 to achieve a balance between response speed and stability.

[0030] Compared with the prior art, the load sensing and dynamic speed regulation method for stage lifting equipment provided in this application has the following advantages: This application monitors load changes in real time with a fixed sampling period. When the load change rate exceeds a disturbance threshold, the load change is used as a feedforward compensation term, combined with a PID control algorithm, to continuously correct the target speed value. Unlike existing solutions where the load signal is only used for "present / absent" judgment or for post-event triggering of static speed reduction, this application deeply couples the load sensing signal into the speed control loop, achieving a technological leap from "discrete triggering" to "continuous feedforward." When the load changes instantaneously during equipment operation (such as when an actor steps onto a platform midway through the performance), the system can adjust the speed setpoint in real time according to the load change, effectively suppressing speed fluctuations and overshoot, ensuring the smoothness and safety of the performance. In particular, unlike the existing technology CN118939004A, which only performs leveling control based on weight distribution, this application establishes a continuous mapping relationship between load and speed, enabling the speed to be continuously and steplessly adjusted with changes in load. Compared with the discrete gear switching speed regulation of the existing technology CN103529790A, the PID feedforward compensation of this application achieves real-time continuous speed correction, resulting in faster response and higher speed regulation accuracy.

[0031] This application establishes a complete hierarchical response system of "speed limit warning - audible and visual alarm - emergency alarm - shutdown and braking" by pre-setting four overload levels (mild overload, moderate overload, severe overload, and dangerous overload). Unlike the binary mode of existing technologies that directly triggers independent alarms or shutdowns when the load exceeds the rated value, this application only limits the speed and issues a yellow warning light when there is a mild overload (1.1 times the rated load), maintaining limited operation to ensure the continuity of the performance; when there is a moderate or severe overload, the speed is limited step by step according to the degree of overload and the alarm level is upgraded; shutdown and braking are only executed in the case of dangerous overload. This hierarchical and coordinated mechanism integrates speed control strategy and safety protection, taking into account both the continuity of the performance and the safety of the equipment.

[0032] This application proactively detects the current load weight before equipment startup and calculates the startup acceleration based on the actual load value; the heavier the load, the slower the startup. Unlike existing technologies that directly start using a preset constant acceleration curve, this application establishes a complete startup control chain of "pre-start self-test—zero-point calibration—load sensing—soft-start planning," which dynamically couples the startup acceleration with the real-time load, effectively avoiding motor overcurrent and mechanical shock during heavy-load startup.

[0033] This application starts with multi-source sensor fusion sensing, improving the reliability of load detection through weighted fusion of pressure and current signals, and providing sensor anomaly identification capabilities. Based on this, a continuous load-speed mapping relationship is established. During operation, dynamic speed correction is achieved through PID feedforward compensation, and predictive control and sensor cross-verification are added. Overload protection is achieved through graded speed limiting. Simultaneously, dynamic safety verification and speed smoothing filtering are employed as safeguards. Compared to the fragmented architecture of existing technologies where sensing, speed regulation, and protection are independent, this application integrates these aspects into an organically coordinated whole, systematically addressing the shortcomings pointed out in the background technology, and significantly improving the intelligence level and operational safety of stage lifting equipment. Attached Figure Description

[0034] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. It should be noted that the following embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the invention. Various modifications and equivalent substitutions made by those skilled in the art without departing from the spirit and scope of the present invention should be considered within the scope of protection of the present invention.

[0035] Figure 1 This is a schematic diagram of the overall process of the load sensing and dynamic speed regulation method for stage lifting equipment in an embodiment of the present invention; Figure 2 This is a schematic diagram of the load-aware data acquisition and fusion processing process in an embodiment of the present invention; Figure 3 This is a schematic diagram of the soft-start control process during the startup phase in an embodiment of the present invention; Figure 4 This is a flowchart illustrating the dynamic correction and speed smoothing filtering during the runtime phase in an embodiment of the present invention. Figure 5 This is a schematic diagram of the overload determination and graded speed regulation process in an embodiment of the present invention. Detailed Implementation

[0036] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. The described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] This invention provides a method for load sensing and dynamic speed regulation of stage lifting equipment. In this application, the stage lifting equipment refers to a mechanical device installed in the stage area for vertical lifting movement, including but not limited to: a lifting stage that can be used as a whole platform to change the stage's depth layout, a lifting platform for independently lifting actors or musical instruments, and a prop lifting device for vertical movement of scenery or special effects equipment. Load sensing refers to acquiring the weight information carried by the lifting equipment in real time through sensors, and continuously outputting specific load values ​​(e.g., 380kg, 405kg, 450kg, etc.), rather than simply outputting "no load" or "heavy load" switch signals. Dynamic speed regulation refers to continuously and adaptively adjusting the operating speed of the lifting equipment based on the real-time sensed load value. Its core logic is: the heavier the load, the slower the speed; the speed is synchronously corrected when the load changes abruptly; and the speed is limited or stopped according to the severity of overload. The execution subject of this method can be a PLC (Programmable Logic Controller), an embedded microcontroller, an industrial computer, or other intelligent control devices with data acquisition, logic operation, and closed-loop control capabilities.

[0038] Example 1 This embodiment uses a lift stage, exemplarily installed in a school auditorium, as an example for description. It is understood that the technical solution of this application is also applicable to stage lifting equipment in other venues such as theaters, concert halls, television studios, and stadiums. In this embodiment, the following parameters are set exemplarily: rated load... Rated speed Maximum permissible speed Rated acceleration The platform dimensions are, for example, 3m × 3m, with a pressure sensor placed at each of the four corners. The drive motor is equipped with a current detection module. It should be noted that the above parameters are only used to illustrate the feasibility of the invention. In practical applications, parameters such as rated load, rated speed, maximum permissible speed, and rated acceleration should be reasonably set according to the specific specifications and operating conditions of the stage lifting equipment. For example, the rated load can be in the range of 500kg to 3000kg, and the rated speed can be in the range of 0.1m / s to 0.5m / s. Those skilled in the art can adjust these parameters according to actual operating conditions.

[0039] Please see Figure 1The present invention provides a method for load sensing and dynamic speed regulation of stage lifting equipment, including steps S1 to S5.

[0040] S1. Real-time acquisition of load sensing data from the stage lifting equipment, and fusion processing of the load sensing data to generate the current load value. The load sensing data includes at least pressure signals collected by multiple pressure sensors and current signals collected by the drive motor current detection module. In this embodiment, the pressure values ​​collected by the four pressure sensors are exemplarily set to be filtered as follows: The equivalent load value obtained after converting the current collected by the current detection module. The values ​​above are for illustrative purposes only; in actual applications, the pressure and current values ​​will depend on the specific load conditions.

[0041] like Figure 2 As shown, this step consists of three consecutive sub-steps S11 to S13. Specifically, it includes the following sub-steps: S11. Perform moving average filtering on the pressure signal and the current signal respectively. Moving average filtering refers to a signal processing method that takes the arithmetic mean of the signal values ​​at the current time and several previous times as the filtered output value at the current time. For example, if the moving window width is set to 5, the filtered pressure value at the current time... Using a moving average filter can effectively eliminate transient noise from sensors (such as pressure signal jumps caused by stage vibrations or current signal glitches caused by power grid fluctuations), making subsequent load calculations more stable and reliable. In this embodiment, after moving average filtering, the average value of the four pressure sensors... Filter value of current equivalent load .

[0042] S12. Calculate the weighted average value according to the preset weighting coefficients, and use it as the current load value. Calculate the current load value using the following formula:

[0043] in, This indicates the current load value, in kilograms (kg). This represents the average value of multiple pressure sensor signals after being filtered by a moving average. This represents the equivalent load value obtained by converting the current signal after it has been filtered by the moving average. and For the weighting coefficients, satisfying In this embodiment, an initial value is taken as an example. Understandably, the specific values ​​of the weighting coefficients can be adjusted based on factors such as sensor accuracy, installation location, and environmental interference. It can be 0.3 The value is selected within the range of 0.8, and those skilled in the art can determine it through routine calibration tests.

[0044] S13. The weighting coefficient is dynamically adjusted according to the fluctuation range of the no-load reference value.

[0045] The no-load reference value refers to the load value measured by the lifting equipment under no-load conditions. Ideally, the no-load reference value should be 0, but due to factors such as sensor zero drift and mechanical preload, the actual no-load reference value may not be 0. When the fluctuation range of the no-load reference value (e.g., the standard deviation of 10 consecutive measurements) exceeds the preset reference threshold, it indicates that the pressure sensor may have poor contact or mechanical deformation. In this case, the weight of the current signal should be increased. This is to enhance the reliability of the current signal.

[0046] Specifically, S13 can be further divided into the following sub-steps: S131. Periodically record load measurement values ​​under no-load conditions. Each time the lifting equipment resets to the lowest position and there is no load on the platform, automatically record a set of average pressure signal values ​​and equivalent current load values, and store them in the buffer queue.

[0047] S132. Calculate the standard deviation of idle measurements in the buffer queue. .like If so, the unloaded baseline value is determined to fluctuate too much. As a preset benchmark threshold, this embodiment exemplarily uses... This threshold can be set according to the sensor's range and accuracy, for example, at 10kg. Choose within the 50kg range.

[0048] S133. Adjust the weighting coefficients according to the judgment results: If the fluctuation is too large, then, for example, adjust the weighting coefficients. Increase to 0.7, The value should be reduced accordingly to 0.3; if the fluctuation returns to normal, then... Gradually restore to the initial value of 0.4. The above adjustment range is only an example; in actual applications, it can be adjusted linearly according to the degree of fluctuation. Furthermore, this embodiment also periodically calculates the variance ratio of the pressure signal and the current signal. ,when Increase when >2.0 To reduce the weight of the pressure signal, when Increase when <0.5 To reduce the weight of the current signal, the adjustment step size should not exceed 0.05 each time.

[0049] S134. Recalculate the current load value using the adjusted weighting coefficients.

[0050] In this embodiment, the no-load reference value fluctuates normally, so it is still adopted. The calculation yields:

[0051] S2. Generate a target speed value based on the current load value and the preset load-speed mapping relationship.

[0052] The load-speed mapping relationship refers to the functional relationship that converts the real-time sensed load value into the desired operating speed. This application uses a piecewise linear function, the basic logic of which is: the lighter the load, the faster the speed; the heavier the load, the slower the speed, to ensure safe operation under heavy load conditions. The target speed is calculated using the following formula. :

[0053] in, Indicates the target speed, in meters per second (m / s); Indicates the maximum permissible speed of the stage lifting equipment; Indicates the rated load; Indicates the current load value. When... Not exceeding the rated load At that time, the target speed It decreases linearly with increasing load: no load ( When it reaches Rated load ( When it drops to 0.5 .when When the rated load is exceeded, the target speed is determined separately by the overload determination in S5.

[0054] In this embodiment, Substitute into the formula:

[0055] That is, the target speed is approximately 0.299 m / s.

[0056] S3. During the startup phase of the stage lifting equipment, perform a self-test and zero-point calibration before startup, calculate the startup acceleration based on the current load value, and perform soft-start control.

[0057] The soft-start control refers to a control method in which, when the equipment starts moving from a stationary state, it does not start directly with maximum acceleration, but gradually accelerates to the target speed according to the current load. The purpose is to avoid mechanical shock and motor overcurrent.

[0058] like Figure 3 As shown, this step consists of four consecutive sub-steps S31 to S34. Specifically, it includes the following sub-steps: S31. Pre-start self-test and zero-point calibration. The pre-start self-test refers to the functional check performed on the load sensing system after receiving the lifting command and before the motor actually starts running. The zero-point calibration refers to the operation to eliminate sensor zero drift, specifically: recording the initial readings of each pressure sensor under no-load conditions. and the initial equivalent load of the current sensor Subsequent measurements are all subtracted from the corresponding initial value. Zero drift refers to the phenomenon that when the sensor is theoretically free of external force input (i.e., in an unloaded state), its output value is not zero and may slowly change with factors such as temperature, time, and component aging.

[0059] Calculate the current load value after calibration using the following formula. :

[0060] in, This represents the average pressure signal under measurement conditions, expressed in kilograms (kg). This represents the baseline average pressure signal under no-load conditions, in kilograms (kg). This indicates the current equivalent load under the measurement condition, and the unit is kilograms (kg). This represents the current reference equivalent load under no-load conditions.

[0061] For example: Suppose the equipment has been unused for a long time, and the sensor experiences zero drift, displaying an average pressure signal of 15 kg instead of 0 kg under no-load conditions. Through zero-point calibration, the system records... When the subsequent measurement value was 415kg, the actual load was This effectively eliminates zero-drift errors. Simultaneously, the self-test step also checks for pre-load on the stage (e.g., props placed before the performance). If pre-load is present, the process proceeds directly to the subsequent acceleration phase without requiring re-calibration of the zero point.

[0062] S32. Obtain the current load value before startup. .

[0063] After self-testing and calibration, the system immediately collects load sensing data, which is then fused to obtain the current load value before startup. In this embodiment... .

[0064] S33. Calculate the starting acceleration using the following formula. :

[0065] in, This indicates the initial acceleration, measured in meters per second squared (m / s²). Indicates the rated acceleration; Indicates the rated load; This indicates the current load value before startup; This represents a function that takes the minimum value, ensuring that the load factor does not exceed 1.

[0066] In this embodiment, less than Therefore:

[0067] S34. Accelerate according to the calculated starting acceleration until the target speed is reached. The system accelerates smoothly from 0 speed to 0.299 m / s² at an acceleration of 0.1 m / s². If the load changes during acceleration, S4 will intervene to correct it.

[0068] S4. During the operation of the stage lifting equipment, dynamically monitor the load change, correct the target speed value in real time according to the load change, smooth the corrected speed command, and output the final speed command.

[0069] The operational phase refers to the stage where the equipment has completed startup and acceleration and is ascending and descending at a relatively stable speed. At this time, the system needs to continuously monitor whether the load changes (e.g., an actor boards the platform midway through the process) and adjust the speed in real time according to the load change to maintain smooth operation.

[0070] like Figure 4 As shown, this step consists of eight consecutive sub-steps S41 to S48. Specifically, it includes the following sub-steps: S41. Obtain the current load value at consecutive times with a fixed sampling period. The sampling period refers to the time interval between two adjacent samples. In this embodiment, the sampling period is used as an example. (That is, sampling 20 times per second). Understandably, the sampling period can be adjusted according to the response speed and processing capacity of the control system, for example, it could be 0.01s. The value is selected within the range of 0.1s, and those skilled in the art can adjust it according to the actual working conditions.

[0071] Let the current time be The load value is The previous moment The load value is .

[0072] S42. Calculate the load change and the load change rate. The load change refers to the load difference between two adjacent sampling times. The load change rate refers to the absolute value of the load change per unit time. Calculate the load change using the following formula. :

[0073] Calculate the load change rate using the following formula :

[0074] in, The unit is kilogram (kg); The unit is kilograms per second (kg / s).

[0075] S43. Perform cross-verification of sensor signals.

[0076] Cross-validation refers to the mutual verification of measurement results of the same physical quantity (load) using different types of sensors. Pressure sensors directly measure the pressure exerted on the platform, a direct mechanical measurement method; current sensors indirectly calculate the load by detecting the motor drive current, an indirect electrical measurement method. These two types of sensors have different physical principles and sources of error. When the measurement results from the two sensors deviate significantly, it means that at least one sensor is faulty or severely interfered with. Therefore, cross-validation can promptly detect sensor anomalies and prevent incorrect speed adjustments due to sensor failure.

[0077] Specifically, the load value of the pressure signal conversion is calculated. Equivalent load value of current signal conversion The relative deviation between them:

[0078] in, Indicates relative deviation, dimensionless; This indicates the load value converted from the pressure signal, in kilograms (kg). This represents the equivalent load value for current signal conversion, expressed in kilograms (kg).

[0079] when Exceeding the preset cross-validation threshold (Exemplary example taken in this embodiment) If the problem occurs, it is determined that at least one of the pressure sensor and current sensor may be faulty. At this time, the speed correction process is paused, a sensor fault alarm is issued, and the speed command is switched to safe mode—continuing operation with a speed limit of 80% of the current speed value until the fault is resolved or confirmed by the operator. If the threshold is not exceeded, continue with the subsequent steps.

[0080] The cross-validation threshold can be set according to the sensor's accuracy level, for example, it can be 0.10. The range of 0.20 can be selected, and those skilled in the art can determine the accuracy of the actual sensor used through conventional tests.

[0081] S44. Determine if speed correction is triggered. When the load change rate... Exceeding the preset disturbance threshold When the system detects a sudden load change, it triggers a speed correction process. The disturbance threshold is a critical value used to determine whether the load has changed significantly; in this embodiment, it is exemplarily set to... This threshold can be set according to the sensitivity requirements of the equipment and the operating environment; for example, it can be set at 200 kg / s. The range of 1000 kg / s can be selected, and those skilled in the art can determine this through on-site debugging.

[0082] For example: Suppose that during the operation of the equipment, an actor weighing 60kg climbs onto the lifting platform. In a single sampling period ( Within a certain timeframe, the system detects a jump in load value from 404kg to 464kg. It far exceeds the preset disturbance threshold. The system immediately triggers a speed correction process.

[0083] S45. Implement predictive control.

[0084] Predictive control refers to a control method that predicts the future direction of load change based on the trend of the load change rate (i.e., load acceleration) before the load change has fully manifested, and outputs compensation in advance to suppress speed fluctuations. Its physical meaning is that when the load is accelerating, even if the current speed deviation has not yet formed, the system can predict the impending disturbance and decelerate in advance, thereby compensating for the shortcomings of traditional "responsive" control in responding to rapid load changes with lag.

[0085] Calculating the load change rate Based on this, the second derivative of the load change rate (i.e., load acceleration) is further calculated. :

[0086] in, This indicates the rate of change of load at the current moment, expressed in kilograms per second (kg / s). This indicates the rate of change of load at the previous moment, expressed in kilograms per second (kg / s). It represents the load acceleration, with the unit being kilograms per second squared (kg / s²). Its physical meaning is the rate of change of the load change rate, that is, the degree of "acceleration" of the load increase or decrease.

[0087] when Exceeding the preset disturbance threshold and When the value is greater than 0, it is determined that the load is increasing rapidly. At this time, a predicted compensation amount is added to the feedforward compensation term.

[0088] in, This indicates the predicted compensation amount, in meters per second (m / s). This represents the prediction compensation coefficient, with units of meters per kilogram (m / kg). Its physical meaning is the proportional factor that converts load acceleration into velocity compensation. This represents the prediction time window, measured in seconds (s), and its physical meaning is the length of time for forward prediction. In this embodiment, it is exemplarily taken as... =0.01m / kg, =0.2s. It is understandable that the above parameters can be adjusted based on the equipment's response characteristics and the typical rate of load change.

[0089] For example: Assume the load change rate was 800 kg / s at the previous moment, and the load change rate is 1200 kg / s at the current moment, with a sampling period of... =0.05s, then the load acceleration is: =(1200 800) / 0.05=8000kg / s², predicted compensation amount: =0.01×8000×0.2=16m / s.

[0090] In practical applications, the predicted compensation amount needs to be limited according to the speed magnitude; this is a principle explanation. This predicted compensation amount allows the system to reduce the speed command in advance before the load increases further, thereby effectively suppressing speed fluctuations.

[0091] S46. The PID control algorithm is adopted, and the load change is used as feedforward compensation to correct the speed command in real time (executed only when the correction is triggered).

[0092] The PID control algorithm mentioned refers to the proportional-integral-derivative (PI-DE) control algorithm, one of the most commonly used closed-loop control algorithms in industrial control. Feedforward compensation refers to a control method that directly superimposes the load change as an additional input onto the PID controller output. Its function is to change the speed command in advance based on the direction and magnitude of the load change before a speed deviation occurs, thereby significantly shortening the system response time. The corrected speed command is calculated using the following formula. :

[0093] in, Indicates time, in seconds (s); , represents the speed deviation, with the unit being meters per second (m / s); Indicates the proportionality coefficient; Represents the integral coefficient, in units of the reciprocal of seconds (s).-1 ); This represents the differential coefficient, with the unit being seconds (s). This represents the feedforward compensation coefficient, with units of meters per second per kilogram (m / (s·kg)).

[0094] In this embodiment, exemplarily taken It should be noted that the values ​​of the PID parameters mentioned above are only used to illustrate the feasibility of this invention. In practical applications, these parameters should be tuned according to the dynamic response characteristics of the motor, the stiffness of the mechanical transmission system, and the load range. For example... It can be 0.5 Adjustments within the 2.0 range. It can be found in 0.001 The adjustment range is 0.01 m / kg. Those skilled in the art can determine the specific value using conventional PID parameter tuning methods.

[0095] S47. Perform speed smoothing filtering on the corrected speed command.

[0096] The speed smoothing filter refers to applying a first-order low-pass filter to the speed command. Its basic idea is that the output value at the current moment is a weighted average of the input value at the current moment and the output value at the previous moment. This first-order low-pass filtering is a commonly used signal smoothing method. The final given speed is calculated using the following formula. :

[0097] in, Indicates the sequence number of the discrete sampling time; This represents the final given velocity after filtering at the current moment; This indicates the corrected speed command at the current moment; This represents the final given velocity after filtering at the previous moment; This represents the filter coefficient, with values ​​ranging from 0 to 1. The closer it is to 0, the stronger the filtering effect, but the slower the response. The closer the value is to 1, the faster the response but the weaker the filtering effect. This embodiment exemplarily uses... Understandably, The specific value can be adjusted according to the stiffness of the mechanical transmission system and the response characteristics of the motor; for example, it can be 0.1. The value should be selected within the range of 0.5. Those skilled in the art can determine the appropriate value through on-site debugging. value.

[0098] For example: Suppose the output speed at the previous moment was 0.30 m / s, and the current speed command drops sharply to 0.20 m / s due to a sudden load change. After a first-order low-pass filter, the output speed will not jump directly to 0.20 m / s, but will continuously decrease from 0.30 m / s: the output speed in the first sampling period is... The speed is then gradually reduced (e.g., approximately 0.249 m / s in the second sampling period, approximately 0.234 m / s in the third sampling period, and so on), progressively approaching 0.20 m / s. Theoretically, an infinite number of sampling periods are needed to accurately reach 0.20 m / s, but in practice, after several periods (e.g., approximately 13 sampling periods), the error is less than 0.001 m / s, which can be considered stable in engineering. In this way, the abrupt change in the speed command is stretched into a smooth descending trajectory, avoiding the impact on the mechanical structure caused by direct jumps.

[0099] S48, outputs the final speed command to the drive motor.

[0100] The system will calculate The speed setpoint for the drive motor is sent to the frequency converter or servo drive, and the motor performs the actual motion.

[0101] S5. Perform dynamic safety verification and overload determination on the current load value, and execute graded speed adjustment or safe shutdown based on the overload determination result.

[0102] The overload refers to a situation where the current load value exceeds the rated load. Unlike the simple and crude handling method of "immediately shutting down when the rated load is exceeded" in the prior art, this application adopts a four-level overload classification strategy, and takes different response measures according to the severity of the overload, so as to maintain the continuity of the performance as much as possible while ensuring safety.

[0103] like Figure 5 As shown, this step consists of five consecutive sub-steps S51 to S55. Specifically, it includes the following sub-steps: S51, Dynamic Security Verification.

[0104] The dynamic safety check refers to a safety redundancy mechanism that calculates a safe speed limit based on the current load value and restricts speed commands within this limit. This check is independent of overload classification and serves as an additional safety barrier, preventing speed commands from exceeding safe physical limits due to sensor malfunctions, PID overshoot, or external interference. The safe speed limit is calculated using the following formula. :

[0105] in, Indicates the maximum permissible speed; Indicates the rated load; This represents the current load value. In this embodiment, it is exemplarily taken as... If the current load The upper limit of safe speed Exceeding the maximum permissible speed Therefore, the actual limit is still 0.4 m / s. If the current load... ,but If so, the system will limit the speed command to within 0.32 m / s.

[0106] Real-time comparison of the final speed command output by S47 With the aforementioned safe speed limit ,like Exceed Then The new speed command is used to enter the subsequent overload determination process; if it is not exceeded, the original command is retained.

[0107] S52. Calculate the percentage of the current load value relative to the rated load in real time.

[0108] For example, let the current load be... Therefore, the overload ratio is 950 / 800 = 118.75%, which falls within the moderate overload range (110%). (130%). It should be noted that the values ​​here are for illustrative purposes only. In actual applications, the overload level limits can be set according to safety standards and equipment characteristics. For example, the light overload limit could be set to 105%. Prices range from 115% to [amount missing].

[0109] S53. Determine the overload level and corresponding speed limit based on the overload ratio.

[0110] Calculate the speed limit value corresponding to each level using the following formula. :

[0111] in, This indicates the maximum permissible speed under overload conditions, expressed in meters per second (m / s). Indicates the rated speed; Indicates the current load value; This indicates the rated load. Correspondingly, the response measures for each overload level are as follows: Mild overload: speed limit Illuminate the yellow warning indicator light, do not sound the alarm, and allow the performance to continue, but remind operators to pay attention. Moderate overload: Speed ​​limit. It will issue an audible and visual alarm (e.g., a buzzer sounds and a red indicator light flashes) and simultaneously send an alarm message to the control panel. Severe overload: Speed ​​limit. An emergency alarm will be issued (high-volume buzzer, all emergency lights flashing), and the operator should take immediate action. Dangerous overload: The speed limit is 0, meaning the motor power will be immediately cut off, the mechanical brake will be triggered, and a fault message will be sent to the remote monitoring platform.

[0112] S54. The speed limit value is used as the speed upper limit to restrict the current speed command. The system combines the speed command after S51's speed limitation with the speed limit value. The smaller value is used as the upper limit of the actual output speed. If the current speed command is already lower than the speed limit, the original command is maintained; if the current speed command is higher than the speed limit, it is forcibly reduced to the speed limit.

[0113] S55, execute the corresponding alarm or shutdown action.

[0114] Depending on the overload level, the system automatically executes corresponding audible and visual alarms, power cut-off, or brake linkage.

[0115] Example 2 This embodiment is essentially the same as Embodiment 1, except that the application scenario of the stage lifting equipment is a collaborative performance of multiple lifting platforms. In a large-scale stage play, three independent lifting platforms need to rise and fall synchronously to present a wave-like visual effect. However, the loads carried by the three platforms may be different (for example, one carries a piano, one carries two actors, and one is empty). If they operate at the same speed, the empty platform will be too fast, and the heavily loaded platform will be too slow, resulting in synchronization failure. In this embodiment, the load-speed mapping relationship of S2 is extended to: each platform independently calculates its target speed, and the system coordinates the speed commands of each platform through the main controller to keep the running time of each platform consistent. Specifically, the main controller receives the current load values ​​of the three platforms, calculates their respective target speeds, and then takes the platform with the longest expected running time as the benchmark, adjusting the speeds of the other platforms to match this benchmark. In this way, although all platforms operate at a "slower" speed, precise synchronous rising and falling can be achieved, meeting the performance choreography requirements. The other steps in this embodiment are the same as in Embodiment 1 and will not be repeated here.

[0116] It should be noted that all specific values ​​listed in the above embodiments (including but not limited to rated load, rated speed, maximum permissible speed, rated acceleration, sampling period, disturbance threshold, PID parameters, filter coefficient, overload level boundary ratio, etc.) are exemplary parameters provided to facilitate understanding of the technical solution of the present invention and do not constitute a limitation on the scope of protection of the present invention. In practical applications, the above parameters should be reasonably set according to the specific specifications, operating conditions and safety standards of the stage lifting equipment. Those skilled in the art can adjust the above parameters according to conventional engineering practices without creative effort, and all such adjustments fall within the scope of protection of the present invention.

[0117] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art can make various improvements and modifications without departing from the spirit and principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for load sensing and dynamic speed regulation of stage lifting equipment, characterized in that, Includes the following steps: Step 1: Collect load sensing data of the stage lifting equipment in real time, and perform fusion processing on the load sensing data to generate the current load value; the load sensing data includes at least pressure signals collected by multiple pressure sensors and current signals collected by the drive motor current detection module; Step 2: Calculate the target speed value based on the current load value and the preset load-speed mapping relationship; the load-speed mapping relationship is a piecewise function, and when the current load value does not exceed the rated load, the target speed decreases linearly with the increase of load; Step 3: During the startup phase of the stage lifting equipment, calculate the startup acceleration based on the current load value and execute soft-start control; the startup acceleration is inversely proportional to the ratio of the current load value before startup to the rated load; Step 4: During the operation of the stage lifting equipment, dynamically monitor the load change, and correct the target speed value in real time according to the load change, and output the corrected speed command; Step 5: Determine if the current load value is overloaded, and perform graded speed adjustment or safe shutdown according to the overload level; the overload determination includes at least four overload levels, each corresponding to a different speed limit value.

2. The method according to claim 1, characterized in that, The fusion processing in step one includes: performing moving average filtering on the pressure signal and the current signal respectively, and then calculating a weighted average value according to a preset weighting coefficient, which is used as the current load value. The calculation formula is as follows: ,in Indicates the current load value. This represents the average value of multiple pressure sensor signals after being filtered by a moving average. This represents the equivalent load value obtained after the current signal is converted through a moving average filter. and For the weighting coefficients, satisfying ,and and The initial values ​​are 0.6 and 0.4, respectively.

3. The method according to claim 2, characterized in that, The fusion process in step one also includes sensor anomaly identification: when any pressure sensor signal deviates from the average value of the remaining pressure sensor signals by more than a preset deviation threshold, the any pressure sensor signal is discarded as an abnormal signal, and the average value of the remaining pressure sensor signals is fused with the current signal.

4. The method according to claim 1, characterized in that, The preset load-speed mapping relationship in step two is a piecewise function, with the target speed... Calculate using the following formula: when hour, ;when At that time, the target speed will be determined separately by overload assessment; in, Indicates the target speed. This indicates the maximum permissible speed of the stage lifting equipment. Indicates the rated load of the stage lifting equipment. Indicates the current load value; when When the rated load is exceeded, the target speed will be determined separately by the overload determination in step five.

5. The method according to claim 1, characterized in that, Step three, which involves calculating the startup acceleration based on the current load value, specifically includes: obtaining the current load value before startup. Calculate the starting acceleration using the following formula. : in, Indicates starting acceleration. Indicates the rated acceleration. Indicates the rated load. This indicates the current load value before startup. This represents the function that takes the minimum value.

6. The method according to claim 1, characterized in that, Step four, which involves dynamically monitoring load changes and correcting the target speed value in real time, specifically includes: With a fixed sampling period Get the current load value at consecutive time points and Calculate the load change and load change rate ; When the load change rate Exceeding the preset disturbance threshold At that time, speed correction is triggered; the correction uses a PID control algorithm to adjust the target speed value. The expected value is fed back at the actual speed. The measured value is expressed as the load change. For feedforward compensation, output the corrected speed command. as follows: in, Indicates time, in seconds (s); , represents the speed deviation, with the unit being meters per second (m / s); Indicates the proportionality coefficient; Represents the integral coefficient, in units of the reciprocal of seconds (s). -1 ); This represents the differential coefficient, with the unit being seconds (s). This represents the feedforward compensation coefficient, with units of meters per second per kilogram (m / (s·kg)). Indicates time The change in load, in kilograms (kg). Indicates time The target speed; Indicates time Actual speed feedback; output of the PID control algorithm As the speed setpoint for the drive motor.

7. The method according to claim 6, characterized in that, The proportional coefficient of the PID control algorithm Integral coefficient and differential coefficients The tuning is performed in segments based on the load range to which the current load value belongs. The specific tuning rules are as follows: when At that time, take ; when At that time, take ; when At that time, take ; in This indicates the current load value. This indicates the rated load. The integral and differential coefficients for each interval are set independently.

8. The method according to claim 1, characterized in that, The overload determination in step five includes pre-setting four overload levels, and calculating the speed limit value corresponding to each level according to the following formula. : when hour, It will also issue a yellow warning indicator light signal; when hour, It will also issue an audible and visual alarm; when hour, And issued an emergency alarm; when hour, 0. Immediately cut off the motor power and trigger the mechanical brake device, while simultaneously sending fault information to the remote monitoring platform; in Indicates the maximum permissible speed under overload conditions. Indicates the rated speed. This indicates the current load value. This indicates the rated load.

9. The method according to claim 1, characterized in that, It also includes the dynamic safety check performed in step five: real-time comparison of the corrected speed command. With the current load value Corresponding safe speed limit The safe speed limit ,in Indicates the maximum permissible speed. Indicates the rated load; if the corrected speed command Exceeding the aforementioned safe speed limit Then the safe speed limit will be used as the output command.

10. The method according to claim 2, characterized in that, It also includes a pre-start self-test step: after receiving the lifting command but before the actual movement begins, zero-point calibration of the load sensing data is performed to eliminate sensor drift and to detect whether there is a preload. If a preload exists, it directly proceeds to step three, soft-start control. The zero-point calibration specifically involves recording the initial readings of each pressure sensor under no-load conditions. and the initial equivalent load of the current sensor Subsequent measurements are all subtracted from the corresponding initial value, and the current load value is calculated using the following formula. ,in This represents the average pressure signal under the measurement conditions. This represents the baseline average pressure signal under no-load conditions. This represents the current-equivalent load under measurement conditions. This represents the equivalent load of the current reference under no-load conditions. and This represents the weighting coefficient.

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