Positioning system for tower crane and tower crane

Abstract

The embodiment of the application provides a positioning system for a tower crane and the tower crane, and belongs to the field of engineering machinery. The tower crane comprises a working mechanism and a motor, the motor is used for driving the working mechanism to act, and the positioning system comprises an incremental encoder, a frequency converter and a controller. The incremental encoder is arranged on the motor and is used for sending AB phase pulse signals and Z phase pulse signals related to the movement of the motor. The frequency converter is used for driving the motor to work and collecting the AB phase pulse signals and the Z phase pulse signals. The frequency converter is configured to: acquire the AB phase pulse signals and the Z phase pulse signals; calibrate the number of the AB phase pulse signals according to the AB phase pulse signals and the Z phase pulse signals to obtain the number of the calibrated AB phase pulse signals; and send the number of the calibrated AB phase pulse signals to the controller. The controller is electrically connected with the frequency converter. The controller is configured to: receive the number of the calibrated AB phase pulse signals; and determine the current running position of the working mechanism according to the number of the calibrated AB phase pulse signals. The application can reduce the hardware cost.

Description

Technical Field

[0001] This invention relates to the field of engineering machinery, and more specifically to a positioning system for tower cranes and a tower crane. Background Technology

[0002] In existing technologies, positioning systems for tower cranes typically employ both incremental and absolute encoders. Incremental encoders are generally used for position feedback acquisition in the motion control closed loop of the tower crane's working mechanisms (such as hoisting, slewing, or luffing mechanisms), while absolute encoders are used for position positioning of these mechanisms. However, because existing tower crane positioning systems require both incremental and absolute encoders to ensure the normal operation and position positioning of the tower crane's working mechanisms, they suffer from high hardware costs. Summary of the Invention

[0003] The purpose of this invention is to provide a positioning system and a tower crane for tower cranes, so as to solve the problem of high hardware costs in the prior art.

[0004] To achieve the above objectives, a first aspect of the present invention provides a positioning system for a tower crane. The tower crane includes a working mechanism and a motor, the motor being used to drive the working mechanism. The positioning system includes an incremental encoder, a frequency converter, and a controller.

[0005] An incremental encoder is installed on the motor to generate AB phase pulse signals and Z phase pulse signals related to the motor's motion.

[0006] The frequency converter is used to drive the motor and collects AB phase pulse signals and Z phase pulse signals. The frequency converter is configured as follows:

[0007] Acquire the AB phase pulse signal and the Z phase pulse signal;

[0008] The number of AB phase pulse signals is calibrated based on the AB phase pulse signals and the Z phase pulse signals to obtain the calibrated number of AB phase pulses;

[0009] The calibrated AB phase pulse count is sent to the controller;

[0010] The controller is electrically connected to the frequency converter, and the controller is configured as follows:

[0011] Receive the calibrated AB phase pulse count;

[0012] The current operating position of the working mechanism is determined based on the calibrated AB phase pulse count.

[0013] In this embodiment of the invention, the frequency converter is configured to calibrate the number of AB-phase pulse signals based on AB-phase pulse signals and Z-phase pulse signals to obtain a calibrated number of AB-phase pulses. This includes: the frequency converter being configured to: determine, based on the AB-phase pulse signals and Z-phase pulse signals, the actual change in the number of AB-phase pulse signals compared to the previous Z-phase pulse signal triggering, and the current number of AB-phase pulse signals at the current Z-phase pulse signal triggering; determine a remainder based on the actual change in number and a preset change in number, wherein the remainder is the remainder obtained by dividing the actual change in number by the preset change in number; and calibrate the current number of AB-phase pulses according to the target preset remainder interval and the target preset calibration strategy corresponding to the target preset remainder interval to obtain a calibrated number of AB-phase pulses.

[0014] In this embodiment of the invention, the frequency converter is configured to calibrate the current AB phase pulse count according to the target preset surplus quantity range where the surplus quantity is located and the target preset calibration strategy corresponding to the target preset surplus quantity range, so as to obtain the calibrated AB phase pulse count. The configuration includes: the frequency converter is configured to: when the target preset surplus quantity range is 0 to a first preset threshold, determine that the calibrated AB phase pulse count is the difference between the current AB phase pulse count and the surplus quantity, wherein the first preset threshold is less than or equal to half of the preset quantity change; when the target preset surplus quantity range is a second preset threshold to a preset quantity change, determine that the calibrated AB phase pulse count is the value obtained by subtracting the surplus quantity from the sum of the current AB phase pulse count and the preset quantity change, wherein the second preset threshold is the difference between the preset quantity change and the first preset threshold.

[0015] In this embodiment of the invention, the positioning system further includes an input device for receiving motion commands about the working mechanism. The input device is electrically connected to the controller, which is further configured to send the motion commands to the frequency converter after receiving them, so that the frequency converter controls the motor to work according to the motion commands.

[0016] In this embodiment of the invention, the controller is configured to determine the current operating position of the working mechanism based on the calibrated AB phase pulse count, including: the controller is configured to: obtain the current operating position of the working mechanism based on a preset working mechanism position algorithm and the calibrated AB phase pulse count.

[0017] In this embodiment of the invention, the positioning system further includes a display device electrically connected to the controller for displaying the current operating position of the working mechanism.

[0018] In this embodiment of the invention, the frequency converter has a power-down memory module for recording the current operating position of the working mechanism when power is lost; the controller is also configured to: when power is restored, obtain the final operating position of the working mechanism recorded by the power-down memory module at the time of the most recent power loss; and use the final operating position as the initial operating position of the working mechanism.

[0019] In this embodiment of the invention, the positioning system further includes an alarm device electrically connected to the controller, used to issue an alarm message indicating an abnormal AB phase pulse signal when the remaining quantity is within a non-target preset remaining quantity range. The lower limit threshold of the non-target preset remaining quantity range is a first preset threshold, which is less than or equal to half of the preset quantity change. The upper limit threshold of the non-target preset remaining quantity range is a second preset threshold, which is the difference between the preset quantity change and the first preset threshold.

[0020] In this embodiment of the invention, the positioning system further includes an alarm device electrically connected to the controller, used to issue an alarm message of abnormal Z-phase pulse signal when the actual quantity change is greater than a third preset threshold, wherein the third preset threshold is greater than a preset multiple of the preset quantity change.

[0021] A second aspect of the present invention provides a tower crane, comprising: a working mechanism; a motor for driving the working mechanism to move; and a positioning system for the tower crane as described above.

[0022] The above technical solution allows the frequency converter to acquire the AB-phase and Z-phase pulse signals related to motor motion emitted by the incremental encoder. It then calibrates the number of AB-phase pulse signals based on these signals and sends the calibrated number to the controller. The controller can then determine the current operating position of the working mechanism based on this calibrated number. This solution eliminates the need for an absolute encoder; the incremental encoder alone is sufficient for positioning the tower crane's working mechanism, ensuring its normal operation. It maximizes the efficiency of the incremental encoder, reducing the cost of the tower crane's electrical control system and significantly decreasing hardware costs. While maintaining the positioning accuracy of the tower crane mechanism, it also reduces system complexity, making the system more streamlined and improving the overall cost-effectiveness of the tower crane's electrical control system. Attached Figure Description

[0023] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings:

[0024] Figure 1 The diagram illustrates the structure of a positioning system for a tower crane according to an embodiment of the present invention.

[0025] Figure 2 A schematic diagram of a positioning system for a tower crane is shown in another embodiment of the present invention;

[0026] Figure 3 The schematic diagram illustrates a flowchart of a pulse number calibration algorithm in one embodiment of the present invention;

[0027] Figure 4 A schematic diagram of a positioning system for a tower crane is shown in another embodiment of the present invention; Detailed Implementation

[0028] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0029] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0030] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0031] Figure 1 The diagram illustrates the structure of a positioning system for a tower crane according to an embodiment of the present invention. Figure 1As shown in the embodiment of the present invention, a positioning system for a tower crane is provided. The tower crane includes a working mechanism and a motor. The motor is used to drive the working mechanism to move. The positioning system may include an incremental encoder 102, a frequency converter 104, and a controller 106 connected in sequence. The incremental encoder 102 is disposed on the motor and is used to emit AB phase pulse signals and Z phase pulse signals related to the motor's movement. The frequency converter 104 is used to drive the motor to work and to collect the AB phase pulse signals and Z phase pulse signals. The frequency converter 104 is electrically connected to the incremental encoder 102. The frequency converter 104 can be configured to: acquire the AB phase pulse signals and Z phase pulse signals; calibrate the number of AB phase pulse signals according to the AB phase pulse signals and Z phase pulse signals to obtain the calibrated AB phase pulse count; send the calibrated AB phase pulse count to the controller 106; the controller 106 is electrically connected to the frequency converter 104 and is configured to: receive the calibrated AB phase pulse count; and determine the current operating position of the working mechanism according to the calibrated AB phase pulse count.

[0032] It can be understood that the AB phase pulse signal refers to the A-phase pulse signal and B-phase pulse signal output by the incremental encoder 102, and the Z-phase pulse signal is the Z-phase pulse signal output by the incremental encoder 102. The calibrated AB phase pulse count is the number of AB phase pulse signals corresponding to the current operating position of the calibrated working mechanism. The working mechanism may include, but is not limited to, at least one of the hoisting mechanism, slewing mechanism, and luffing mechanism. Furthermore, different motion mechanisms may be equipped with corresponding frequency converters 104 and incremental encoders 102.

[0033] Specifically, the incremental encoder 102 is installed at the motor end, such as the motor tip. When the motor moves, the incremental encoder 102 can emit AB phase pulse signals and Z phase pulse signals. The frequency converter 104 is electrically connected to the incremental encoder 102. The frequency converter 104 can acquire the AB phase pulse signals and Z phase pulse signals emitted by the incremental encoder 102. Furthermore, the frequency converter 104 can acquire the AB phase pulse signals and Z phase pulse signals, and calibrate the number of AB phase pulse signals according to the AB phase pulse signals to obtain the calibrated number of AB phase pulses. Understandably, the incremental encoder 102 outputs one Z phase pulse signal for each rotation. During one rotation of the incremental encoder 102, the incremental encoder 102 can output multiple AB phase pulse signals. The number of AB phase pulse signals is compared, verified, and compensated with the number of Z phase pulse signals. After pulse counting and accumulation, the calibrated number of AB phase pulses corresponding to the current position can be obtained. Then the inverter 104 can send the calibrated AB phase pulse count to the controller 106. After receiving the calibrated AB phase pulse count, the controller 106 can determine the current operating position of the working mechanism based on the calibrated AB phase pulse count. For example, it can calculate the current operating position of the working mechanism in real time based on the relationship between the pulse count and the position of the working mechanism.

[0034] In the aforementioned positioning system for tower cranes, the frequency converter 104 can acquire the AB-phase pulse signals and Z-phase pulse signals related to motor motion emitted by the incremental encoder 102, and calibrate the number of AB-phase pulse signals based on these signals. The calibrated number of AB-phase pulses is then sent to the controller 106, which can then determine the current operating position of the working mechanism based on this calibrated number of AB-phase pulses. This technical solution eliminates the need for an absolute encoder; the incremental encoder 102 alone is sufficient for positioning the tower crane's working mechanism, ensuring its normal operation. It maximizes the efficiency of the incremental encoder 102, reducing the cost of the tower crane's electrical control system and significantly decreasing hardware costs. While maintaining the positioning accuracy of the tower crane mechanism, it also reduces system complexity, making the system more streamlined and improving the overall cost-effectiveness of the tower crane's electrical control system.

[0035] In one embodiment, the frequency converter 104 is configured to calibrate the number of AB-phase pulse signals based on AB-phase pulse signals and Z-phase pulse signals to obtain a calibrated number of AB-phase pulses. This includes: the frequency converter 104 being configured to: determine, based on the AB-phase pulse signals and Z-phase pulse signals, the actual change in the number of AB-phase pulse signals compared to the previous Z-phase pulse signal triggering, and the current number of AB-phase pulse signals at the current Z-phase pulse signal triggering; determine a remainder based on the actual change in number and a preset change in number, where the remainder is the remainder obtained by dividing the actual change in number by the preset change in number; and calibrate the current number of AB-phase pulses based on the target preset remainder interval and the target preset calibration strategy corresponding to the target preset remainder interval to obtain a calibrated number of AB-phase pulses.

[0036] It can be understood that the actual change in the number of AB phase pulse signals is the difference between the cumulative number of AB phase pulse signals when the current Z phase pulse signal is triggered and the cumulative number of AB phase pulse signals when the previous Z phase pulse signal is triggered. In other words, the cumulative number of AB phase pulse signals when the current Z phase pulse signal is triggered is the number of AB phase pulse signals obtained by summing the cumulative number of AB phase pulse signals when the previous Z phase pulse signal is triggered. The current number of AB phase pulses is the cumulative number of AB phase pulse signals when the current Z phase pulse signal is triggered. During the interval between the previous Z phase pulse signal trigger and the current Z phase pulse signal trigger, there are usually multiple AB phase pulse signal outputs periodically. The preset change in number is the expected number of AB phase pulse signals appearing during the trigger interval of adjacent Z phase pulse signals, that is, after the AB phase pulse signal output of the preset change in number is released, one Z pulse output is triggered. The preset change in number is, for example, 1024. The target preset remainder interval is the preset remainder interval where the remainder is located. The preset remainder interval is a pre-determined range of intervals to which the remainder belongs, and there are multiple preset remainder intervals. The target preset calibration strategy is the preset calibration strategy corresponding to the target preset remainder range. The preset calibration strategy is a pre-determined calibration strategy for the current AB phase pulse count of the AB phase pulse signal. There are multiple preset calibration strategies, with different preset remainder ranges corresponding to different preset calibration strategies. The calibrated AB phase pulse count is the actual cumulative number of AB phase pulse signals when the current Z phase pulse signal is triggered.

[0037] Specifically, the inverter 104 can obtain the actual change in the number of AB phase pulses when the current Z phase pulse signal is triggered compared to the previous Z phase pulse signal triggering, and the current number of AB phase pulses when the current Z phase pulse signal is triggered, based on the acquired AB phase pulse signals and Z phase pulse signals. It then determines the remainder based on the actual change in number and the preset change in number, that is, it calculates the remainder obtained by dividing the actual change in number by the preset change in number, and then determines the target preset remainder range in which the remainder is located. It then selects the target preset calibration strategy corresponding to the target preset remainder range, and calibrates the current number of AB phase pulses of the AB phase pulse signal based on the target preset calibration strategy to obtain the calibrated number of AB phase pulses of the AB phase pulse signal.

[0038] In this embodiment, the number of AB phase pulse signals is calibrated by combining the Z-phase pulse signal. The remaining quantity is determined by the actual change in the number of AB phase pulse signals and the preset change in the number. Then, the corresponding target preset calibration strategy is selected based on the remaining quantity. Thus, the number of AB phase pulse signals can be calibrated according to the target preset calibration strategy. This solves the problem of inaccurate positioning of the incremental encoder 102 caused by inaccurate counting of the AB phase pulse signals of the incremental encoder 102. Therefore, the incremental encoder 102 can be used to position the tower crane working mechanism, improving the positioning accuracy of the incremental encoder 102 and enabling precise positioning through the incremental encoder 102.

[0039] In one embodiment, the inverter 104 is configured to calibrate the current AB phase pulse count based on the target preset surplus quantity range where the surplus quantity is located and the target preset calibration strategy corresponding to the target preset surplus quantity range, to obtain the calibrated AB phase pulse count. This includes: the inverter 104 being configured to: when the target preset surplus quantity range is from 0 to a first preset threshold, determine the calibrated AB phase pulse count as the difference between the current AB phase pulse count and the surplus quantity, wherein the first preset threshold is less than or equal to half of the preset quantity change; when the target preset surplus quantity range is from a second preset threshold to the preset quantity change, determine the calibrated AB phase pulse count as the value obtained by subtracting the surplus quantity from the sum of the current AB phase pulse count and the preset quantity change, wherein the second preset threshold is the difference between the preset quantity change and the first preset threshold.

[0040] It can be understood that the first preset threshold is a pre-set threshold whose value is less than or equal to half of the preset quantity change. The second preset threshold is a pre-set threshold whose value is the difference between the preset quantity change and the first preset threshold; therefore, the value of the second preset threshold is greater than or equal to the value of the first preset threshold.

[0041] Specifically, when the target preset residual quantity range is 0 to the first preset threshold, the inverter 104 can determine that the calibrated AB phase pulse count is the difference between the current AB phase pulse count and the residual quantity. For example, when the preset quantity change N = 1024 and the actual quantity change n = 1025, the residual quantity m = 1025%1024 = 1, that is, the target preset residual quantity range of m is 0 to the first preset threshold (less than or equal to 512). At this time, the calibrated AB phase pulse count CaliPos = the current AB phase pulse count NowPos - the residual quantity m. When the target preset residual quantity range is from the second preset threshold to the preset quantity change, the inverter 104 can determine that the calibrated AB phase pulse number is the value obtained by subtracting the residual quantity from the sum of the current AB phase pulse number and the preset quantity change. For example, when the preset quantity change N = 1024 and the actual quantity change n = 1023, the residual quantity m = 1023%1024 = 1023. That is, the target preset residual quantity range where m is located is from the second preset threshold (greater than or equal to 512 and less than 1024) to the preset quantity change. At this time, the calibrated AB phase pulse number CaliPos = the current AB phase pulse number NowPos + the preset quantity change N - the residual quantity m. In general, when the actual quantity change exceeds the preset quantity change by a certain appropriate range, the excess AB phase pulse signal is removed from the current AB phase pulse count. When the actual quantity change is less than the preset quantity change by a certain appropriate range, the insufficient AB phase pulse signal is added to the current AB phase pulse count. That is, following the principle of "removing the excess and adding the deficiency". Understandably, in actual situations, if there is interference, it is possible that the actual quantity change exceeds the preset quantity change. Usually, the actual quantity change is less than the preset quantity change more often, that is, the AB phase pulse signal is lost more often.

[0042] In this embodiment of the application, during the specific pulse counting calibration process, different calibration strategies are set for two situations: the actual quantity change is appropriately greater than the preset quantity change and the actual quantity change is appropriately less than the preset quantity change, so as to calibrate the quantity of AB phase pulse signals and thereby improve the positioning accuracy of the incremental encoder 102.

[0043] In one embodiment, the positioning system further includes an input device for receiving motion commands about the working mechanism. The input device is electrically connected to the controller 106, which is also configured to send a running command to the frequency converter 104 after receiving the motion command, so that the frequency converter 104 controls the motor to work according to the motion command.

[0044] It can be understood that the input device is a device that receives motion commands from the working mechanism. The motion commands may include information such as speed gear. The input device may be, for example, a linkage table.

[0045] Specifically, after the input device receives a motion command about the working mechanism, the controller 106 can acquire the motion command received by the input device and send the motion command to the frequency converter 104. The frequency converter 104 can control the motor to work according to the motion command, for example, control the motor to drive the hoisting mechanism, luffing mechanism or slewing mechanism to run.

[0046] In one embodiment, the controller 106 is configured to determine the current operating position of the working mechanism based on the calibrated AB phase pulse count, including: the controller 106 is configured to: obtain the current operating position of the working mechanism based on a preset working mechanism position algorithm and the calibrated AB phase pulse count.

[0047] It can be understood that the preset working mechanism position algorithm is a functional relationship between the number of AB phase pulse signals and the operating position of the working mechanism. It can be a linear function, such as y = kx + b, where y is the operating position of the working mechanism, x is the number of AB phase pulse signals, and k and b are relevant parameters in the position algorithm, which can be determined in advance.

[0048] Specifically, the controller 106 can determine the current operating position of the working mechanism based on the preset working mechanism position algorithm and the calibrated AB phase pulse count.

[0049] In one embodiment, the positioning system further includes a display device electrically connected to the controller 106 for displaying the current operating position of the working mechanism.

[0050] It is understandable that the display device is used to display the current operating position of the working mechanism; for example, it could be a display screen.

[0051] In one embodiment, the inverter 104 has a power-down memory module for recording the current operating position of the working mechanism when power is lost; the controller 106 is also configured to: when power is restored, obtain the final operating position of the working mechanism recorded by the power-down memory module at the time of the most recent power failure; and use the final operating position as the initial operating position of the working mechanism.

[0052] It is understandable that since the incremental encoder 102 does not have a power-off memory function, the count of A, B, and Z phase pulses starts from 0 after each power failure and power-on. Therefore, the inverter 104 can be equipped with a power-off memory module. This module has a power-off memory function and can record and store the current operating position of the working mechanism when the incremental encoder 102 is powered off.

[0053] Specifically, when the incremental encoder 102 is powered on again, the controller 106 can obtain the final running position of the working mechanism at the time of the most recent power failure stored in the power failure memory module in the inverter 104, and use the final running position as the initial running position of the working mechanism at the time of power failure, so as to participate in subsequent calculations.

[0054] In one embodiment, the positioning system for the tower crane further includes an alarm device electrically connected to the controller 106, used to issue an alarm message indicating an abnormal AB phase pulse signal when the remaining quantity is within a non-target preset remaining quantity range. The lower limit threshold of the non-target preset remaining quantity range is a first preset threshold, which is less than or equal to half of the preset quantity change. The upper limit threshold of the non-target preset remaining quantity range is a second preset threshold, which is the difference between the preset quantity change and the first preset threshold.

[0055] It can be understood that the non-target preset remaining quantity range is the numerical range between the first preset threshold and the second preset threshold. The first preset threshold is a pre-set threshold whose value is less than or equal to half of the preset quantity change. The second preset threshold is a pre-set threshold whose value is the difference between the preset quantity change and the first preset threshold. Therefore, the value of the second preset threshold is greater than or equal to the value of the first preset threshold.

[0056] Specifically, when the remaining quantity is within a range other than the target preset remaining quantity range, that is, when the remaining quantity is within the range between the first preset threshold and the second preset threshold, the alarm device can issue an alarm message indicating an abnormal AB phase pulse signal. Understandably, this means that the actual quantity change is either too much or too little than the preset quantity change, indicating an abnormality in the AB phase pulse signal between the two Z phase pulse signals. Furthermore, the alarm message can be displayed in ways including, but not limited to, light, sound, and text alarms.

[0057] In this embodiment, the alarm device can trigger an alarm for abnormal AB phase pulse signals, thereby improving the safety of the incremental encoder 102 and extending its service life.

[0058] In one embodiment, the positioning system for the tower crane further includes an alarm device electrically connected to the controller 106, for issuing an alarm message indicating an abnormal Z-phase pulse signal when the actual quantity change exceeds a third preset threshold, wherein the third preset threshold is greater than a preset multiple of the preset quantity change.

[0059] It is understandable that the third preset threshold is a value that is pre-set to be greater than a preset multiple of the preset quantity change. The preset multiple is a preset multiple, which is usually greater than or equal to 2, that is, the third preset threshold is greater than 2 times or more of the preset quantity change.

[0060] Specifically, when the actual change in the quantity of the AB phase pulse signals exceeds a third preset threshold, the alarm device can issue an alarm message indicating an abnormality in the Z phase pulse signal. Understandably, this means the actual change in quantity far exceeds the preset change in quantity, i.e., the actual change in quantity is more than twice the preset change in quantity, indicating an abnormality in the Z phase pulse signal. Furthermore, the alarm message can be displayed in ways including, but not limited to, light, sound, and text alarms.

[0061] In this embodiment, the alarm device can trigger an alarm for abnormal Z-phase pulse signals, thereby improving the safety of the incremental encoder 102 and extending its service life.

[0062] In existing technologies, during the operation of the three main mechanisms (including hoisting mechanism, slewing mechanism, and luffing mechanism), the tower crane system needs to update the operating position of the mechanisms in real time and upload it to the display screen for real-time display, which can provide the operator with a reference for the positioning of the mechanisms.

[0063] Currently, the industry commonly uses a combination of mechanical limit switches and absolute encoder positioning to achieve multiple redundant limit switches. The reasons for this approach to achieve positioning redundancy are as follows:

[0064] 1) Incremental encoders are located at the motor end and are used for closed-loop motion control of the mechanism. Because incremental encoders on the market have inaccurate pulse counting issues, they cannot be simply used for mechanism positioning alone. Therefore, most commercially available systems add an absolute encoder at the mechanism end for position positioning.

[0065] 2) Absolute encoders are used for positioning of mechanisms, but absolute encoders exist at the end of mechanisms (such as drums), making them difficult to use in closed-loop motion control of mechanisms.

[0066] While existing methods are safe and reliable, each mechanism requires an absolute encoder module for position positioning. On one hand, one encoder is used solely for control, while the other is used only for positioning, failing to fully utilize the encoder's efficiency. On the other hand, the need for an additional absolute encoder to acquire the mechanism's operating position increases the cost of the electrical control system. Therefore, existing technologies have the following drawbacks: the existing "mechanical limit switch + encoder redundancy" architecture is complex, and the encoder's role is not fully utilized; the addition of an encoder solely for mechanism positioning increases the cost of the electrical control system; based on the existing architecture, a complex mechanism positioning redundancy comparison algorithm needs to be developed at the controller level, increasing the complexity of the tower crane application logic and placing higher demands on system hardware performance.

[0067] To address the aforementioned problems, a specific embodiment of the present invention provides a positioning system for tower cranes. This positioning system employs an incremental encoder to achieve precise positioning of the three main mechanisms of the tower crane. The structural block diagram of the positioning system for tower cranes is as follows: Figure 2 As shown.

[0068] The controller serves as the central processing unit of the tower crane's electrical control system. In terms of mechanism positioning, it receives the operating gear signals from the linkage mechanism and outputs gear frequency commands to the corresponding mechanism's frequency converter, controlling the motor to drive the hoisting / luffing drum or slewing mechanism. During motor rotation, the incremental encoder rotates, and the frequency converter records the incremental encoder's sampled values ​​in real time through the encoder signal acquisition module, uploading these values ​​to the controller. Based on relevant mechanism calibration parameters, the controller converts the sampled values ​​into the absolute position of the mechanism in real time, realizing the three major mechanism positioning functions based on the incremental encoder.

[0069] In this solution, the core electrical control system adopts a distributed bus architecture. Interconnection and interoperability between modules are achieved based on medium-to-high-speed buses and relevant standard protocols, ensuring good real-time communication performance. The controller and inverter group use a CAN communication bus and the standard CANopen communication protocol, maintaining good real-time performance (tens of milliseconds) and stability while conforming to industrial fieldbus standards. The controller needs to send control commands, frequency commands, and other communication data to the inverters in real time, while the inverters upload incremental encoder sampling values, inverter status parameters, and other data to the controllers in real time. The controller and display screen use an industrial standard protocol based on Ethernet UDP communication for transmitting human-machine interaction data, such as real-time tower crane operating data, one-click calibration data, and commands. Currently, tower crane control consoles generally fall into two categories: IO control consoles and bus control consoles. IO control consoles transmit data to the controller based on IO signals, while bus control consoles transmit data based on a CAN bus (custom protocol). Regardless of the type of control console used, the interaction data between the control console and the controller includes the control console's gear position signal, LED indicator signals, and control console status data.

[0070] Because incremental encoders transmit pulse signals at a high frequency, major mechanical inverters utilize dedicated high-frequency signal acquisition modules to acquire these signals, ensuring that there are no issues such as lost or miscalculated pulse signals. The inverter, motor, and incremental encoder module together form a complete closed-loop circuit for precise and stable control of the end-effector.

[0071] In the aforementioned system, incremental encoders are needed for both precise closed-loop control of the mechanism and high-precision position positioning. Therefore, to improve the positioning accuracy of the incremental encoder, this solution optimizes the pulse acquisition function of conventional incremental encoders in the frequency converter by designing a "synchronous calibration of AB phase and Z phase pulses." This method minimizes pulse counting errors in the incremental encoder, enabling accurate calculation of absolute position even with only an incremental encoder.

[0072] In this embodiment of the invention, the incremental encoder uses AB-Z phase pulse output (differential output provides higher accuracy). One Z-phase pulse is output per revolution of the encoder. The problem of inaccurate pulse counting in incremental encoders is solved by synchronously counting and calibrating the AB and Z phase pulses, thus achieving precise positioning. The basic flowchart of the algorithm is as follows: Figure 3 As shown.

[0073] During operation, the inverter pulse acquisition module collects the AB phase pulse signals and Z phase pulse signals from the incremental encoder. Simultaneously, using the single-turn distance of the motor shaft as a reference, the AB phase pulse count and Z phase pulse count are synchronously compared and verified, and the sampled value (i.e., the number of pulses) corresponding to the current position is obtained through cumulative calculation.

[0074] Based on the above incremental encoder sampling method, due to the improved positioning accuracy of the incremental encoder, the three main mechanisms of the tower crane can adopt methods such as... Figure 4 The positioning architecture shown enables safe movement and operation. Compared to existing positioning architectures, each mechanism can eliminate one dedicated absolute encoder for mechanism positioning. On the one hand, this new architecture ensures the operational accuracy of the mechanisms without reducing their safety factor, while also making the system more streamlined; on the other hand, it further reduces the cost of the tower crane's electrical control system.

[0075] Although the incremental encoder achieves precise positioning in this architecture, it lacks the ability to retain its absolute position even after power loss. Therefore, if the system adopts this new redundant positioning architecture, this deficiency needs to be compensated for through system-level logic. To address this, an encoder sampling value storage function needs to be added to the frequency converter. Compared to the existing "dual limit switch comparison" verification algorithm, the added logic at the system level is very simple and does not require higher performance from the system hardware platform.

[0076] When the frequency converter is powered off, it needs to record the position sampling value of the incremental encoder just moments before power-off. Upon power-up, the recorded encoder sampling value is used as the initial value, not the default value.

[0077] In summary, the incremental encoder AB phase and Z phase synchronous calibration method can reduce the software algorithm complexity and system hardware performance requirements while ensuring the positioning accuracy and safety level of the mechanism, simplifying the system structure, reducing system cost, and improving the overall cost-effectiveness of the electronic control system.

[0078] Furthermore, in some embodiments, the incremental encoder can employ either single-ended pulse signal output or differential pulse signal output. Differential signals offer superior EMC performance. The communication method between the controller and the inverter group can be the CANopen industrial standard protocol based on the CAN communication bus, or it can be replaced by other medium-to-high-speed industrial fieldbuses with better real-time performance and stable communication, such as EtherCAT, Profibus, and Powerlink.

[0079] The technical solution provided by the embodiments of the present invention has the following advantages:

[0080] 1) The system architecture of the electrical control system in terms of mechanism positioning has been simplified. One absolute encoder can be removed from the limit switch modules of the three major mechanisms of the tower crane, reducing the complexity of the system. At the same time, the simplification of system hardware modules has also improved the overall reliability of the machine.

[0081] 2) While ensuring the positioning accuracy of the three main mechanisms of the tower crane, the comparison algorithm between the absolute encoder and the incremental encoder can be eliminated, reducing the algorithm complexity of the tower crane controller. Based on this innovative technical solution, and supplemented by the above-mentioned encoder sample value storage logic, the positioning safety of the three main mechanisms of the tower crane can be guaranteed.

[0082] 3) It can reduce the performance requirements of the electrical control system controller module, including requirements for communication speed and real-time performance. The tower crane electrical control system can be built using low- to mid-range controller types as the core.

[0083] 4) It helps reduce the overall cost and increase the efficiency of the system, improving the cost-effectiveness of the electronic control system. Based on existing solutions, incremental encoders are only used for position feedback acquisition in the control closed loop, requiring the addition of absolute encoders to ensure mechanism positioning. With this innovative technology, incremental encoders can be used for both control closed-loop position feedback and mechanism positioning.

[0084] This invention provides a tower crane, including: a working mechanism; a motor for driving the working mechanism to move; and a positioning system for the tower crane according to the above embodiments.

[0085] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0086] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0087] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0088] These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable apparatus for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0089] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0090] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0091] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0092] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0093] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A positioning system for tower cranes, characterized in that, The tower crane includes a working mechanism and a motor, the motor being used to drive the working mechanism. The positioning system includes an incremental encoder, a frequency converter, and a controller. The incremental encoder is mounted on the motor and is used to generate AB phase pulse signals and Z phase pulse signals related to the movement of the motor. The frequency converter is used to drive the motor and collect the AB phase pulse signals and the Z phase pulse signals. The frequency converter is configured to: Acquire the AB phase pulse signal and the Z phase pulse signal; The number of AB phase pulse signals is calibrated based on the AB phase pulse signals and the Z phase pulse signals to obtain the calibrated number of AB phase pulses; The calibrated AB phase pulse count is sent to the controller; The controller is electrically connected to the frequency converter, and the controller is configured to: Receive the calibrated AB phase pulse count; The current operating position of the working mechanism is determined based on the calibrated AB phase pulse count; The inverter is configured to calibrate the number of AB-phase pulse signals based on the AB-phase pulse signals and the Z-phase pulse signals to obtain a calibrated number of AB-phase pulses. This includes: the inverter being configured to: determine, based on the AB-phase pulse signals and the Z-phase pulse signals, the actual change in the number of AB-phase pulse signals when the current Z-phase pulse signal is triggered compared to the previous Z-phase pulse signal triggering, and the current number of AB-phase pulse signals when the current Z-phase pulse signal is triggered; determine a remainder quantity based on the actual change in quantity and a preset change in quantity, wherein the remainder quantity is the remainder obtained by dividing the actual change in quantity by the preset change in quantity; and calibrate the current number of AB-phase pulses based on a target preset remainder quantity interval in which the remainder quantity is located and a target preset calibration strategy corresponding to the target preset remainder quantity interval to obtain a calibrated number of AB-phase pulses.

2. The positioning system according to claim 1, characterized in that, The frequency converter is configured to calibrate the current AB phase pulse count according to the target preset surplus quantity interval where the surplus quantity is located and the target preset calibration strategy corresponding to the target preset surplus quantity interval, so as to obtain the calibrated AB phase pulse count, including: the frequency converter is configured to: When the target preset remainder quantity range is 0 to a first preset threshold, the calibrated AB phase pulse number is determined to be the difference between the current AB phase pulse number and the remainder quantity, wherein the first preset threshold is less than or equal to half of the preset quantity change; When the target preset remainder range is from the second preset threshold to the preset remainder change, the calibrated AB phase pulse number is determined to be the value obtained by subtracting the remainder from the sum of the current AB phase pulse number and the preset remainder change, wherein the second preset threshold is the difference between the preset remainder change and the first preset threshold.

3. The positioning system according to claim 1, characterized in that, The positioning system further includes an input device for receiving motion commands about the working mechanism. The input device is electrically connected to the controller, which is further configured to send the motion commands to the frequency converter after receiving them, so that the frequency converter controls the motor to work according to the motion commands.

4. The positioning system according to claim 1, characterized in that, The controller is configured to determine the current operating position of the working mechanism based on the calibrated AB phase pulse count, including: the controller is configured to: Based on a preset working mechanism position algorithm, the current operating position of the working mechanism is obtained according to the calibrated AB phase pulse count.

5. The positioning system according to claim 1, characterized in that, The positioning system also includes a display device electrically connected to the controller, used to display the current operating position of the working mechanism.

6. The positioning system according to claim 1, characterized in that, The frequency converter has a power-off memory module for recording the current operating position of the working mechanism when power is lost; the controller is also configured to: Upon power restoration, the final operating position of the working mechanism at the time of the most recent power failure, as recorded by the power failure memory module, is obtained. The final operating position is taken as the initial operating position of the working mechanism.

7. The positioning system according to claim 1, characterized in that, The positioning system also includes an alarm device electrically connected to the controller, used to issue an alarm message indicating an abnormal AB phase pulse signal when the remaining quantity is within a non-target preset remaining quantity range. The lower limit threshold of the non-target preset remaining quantity range is a first preset threshold, which is less than or equal to half of the preset quantity change. The upper limit threshold of the non-target preset remaining quantity range is a second preset threshold, which is the difference between the preset quantity change and the first preset threshold.

8. The positioning system according to claim 1, characterized in that, The positioning system also includes an alarm device electrically connected to the controller, used to issue an alarm message indicating an abnormal Z-phase pulse signal when the actual quantity change is greater than a third preset threshold, wherein the third preset threshold is greater than a preset multiple of the preset quantity change.

9. A tower crane, characterized in that, include: Work unit; An electric motor is used to drive the working mechanism. as well as The positioning system for tower cranes according to any one of claims 1 to 8.

Images