Grab bucket sediment grabbing control method, system and device based on torque detection

Abstract

The invention discloses a grab bucket sediment grabbing control method, a grab bucket sediment grabbing control system and a grab bucket sediment grabbing control device based on torque detection, relates to the technical field of material grabbing equipment control, and is particularly suitable for accurate sediment grabbing in industries such as papermaking and sewage treatment. Dynamic judgment of sediment contact is achieved by combining torque polarity transformation and change rate threshold filtering, and the defects of dependence on visual monitoring and preset lowering depth are overcome; the system is composed of a PLC master controller, a frequency converter drive, a motor hoisting mechanism, an encoder position detection and a man-machine interaction interface, high-speed data communication and accurate control are achieved through a DP network, and safe operation of equipment is guaranteed by adopting a multi-stage safety protection mechanism; the sediment grabbing precision and efficiency are improved, equipment abrasion is reduced, unattended continuous operation is achieved, and the sediment grabbing device adapts to the complex underwater environment and has good practical value and popularization prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of material grabbing equipment control, and in particular to a grab bucket sediment grabbing control method, system and device based on torque detection. Background Art

[0002] Existing grab control methods typically rely on grab lowering distance, visual monitoring, pressure sensors, or preset lowering depths to determine material location. However, in underwater operations, especially under complex conditions such as foam coverage, turbid water, irregularly shaped deposits, and varying hardness, existing solutions have the following shortcomings: The accumulation height of deposits under water varies greatly, making it difficult to set a fixed lowering depth in advance; the visual system is easily affected by foam, turbid water and obstruction, and cannot accurately identify the location of the sediment; the preset depth method cannot adapt to the dynamic changes in the sediment height, which can easily lead to empty grabbing or insufficient grabbing; the pressure sensor is easily disturbed by water flow fluctuations, causing the wire rope to loosen or the grab bucket to malfunction.

[0003] Therefore, there is an urgent need for a sediment grabbing control method that does not rely on vision and a fixed lowering depth, and can achieve high-precision positioning and stable grabbing in complex underwater environments. Summary of the Invention

[0004] The present invention provides a grab bucket sediment grabbing control method, system and device based on torque detection, which are used to solve the technical problems mentioned in the above background technology.

[0005] The present invention provides the following technical solution: a grab bucket sediment grab control method based on torque detection, comprising the following steps: High-speed lowering: Drive the winch mechanism to lower the wire rope at high speed to the nearest working area; Low-speed operation: When the lowering position is close to the preset height, it switches to low speed and keeps the grab in the open state; Torque acquisition and monitoring: Torque data is collected in real time through the frequency converter connected to the drive motor, with a sampling period of no more than 10ms; Sediment contact determination: When the collected torque changes from positive to negative and the torque change rate exceeds the preset change rate threshold, the negative torque counter is started, and when the count value reaches the preset threshold, it is determined that the grab has contacted the sediment; Stop and brake: After the contact judgment is established, the stop and release command is immediately issued, and the braking resistor is triggered to absorb excess electrical energy; Grab and lift: After a preset delay, the grab bucket is driven to close and grab, and then the winch mechanism is driven to lift the grab bucket. Lifting process protection: Real-time detection of load torque during the lifting process, and overload protection is triggered immediately once the lifting torque threshold is exceeded.

[0006] Preferably, the sediment contact determination adopts a multi-condition combination determination method of torque polarity change, torque change rate threshold and negative torque continuous counting, and denoises the sampled torque through a sliding mean filtering algorithm to eliminate interference signals such as water flow impact and bubbles.

[0007] Preferably, the preset change rate threshold and the negative torque count threshold can be adaptively adjusted according to historical operation data to adapt to sediment distributions of different densities and shapes.

[0008] Preferably, before each operation begins, the system performs no-load operation, collects and stores a no-load torque curve as a benchmark, and corrects the torque determination reference value in real time during the operation.

[0009] Preferably, the safety protection includes: immediately cutting off the power supply of the drive motor when the upper and lower limits are triggered; immediately stopping the lifting and executing the emergency release procedure when the lifting torque exceeds the threshold; and suppressing bus overvoltage through the braking resistor during braking.

[0010] The grab bucket sediment grabbing control system based on torque detection includes: Main control unit: PLC, used to execute the grasping control logic; Communication module: used to establish high-speed data communication with the inverter to obtain real-time torque value; Drive unit: includes frequency converter and drive motor, used to control the lowering and raising of the hoisting mechanism; Position detection unit: includes an encoder for detecting the position and speed of the wire rope when it is lowered or lifted; Human-computer interaction unit: including touch screen, used to set parameters, monitor torque curve, and query alarm records; Execution unit: including winch mechanism, wire rope and grab bucket; Safety protection unit: includes limit switch, overload protection module and braking resistor.

[0011] Preferably, the main control unit is configured to perform sliding mean filtering and dynamic reference calibration on the collected torque signal to eliminate instantaneous interference caused by water flow, bubbles, etc.

[0012] Preferably, the main control unit includes an adaptive parameter adjustment module for automatically adjusting the torque change rate threshold and the negative torque count threshold based on historical capture records.

[0013] The grab bucket sediment grabbing device based on torque detection includes: winch mechanism; Wire rope and grab bucket connected to the hoisting mechanism; A drive motor and a frequency converter for driving the hoisting mechanism; a torque detection module connected to the frequency converter; A control unit for controlling the driving motor and the action of the grab bucket; A limit switch, a braking resistor and an overload protection module connected to the control unit.

[0014] Preferably, the device adopts a modular design, and each unit is connected by a quick-plug industrial connector to facilitate maintenance and replacement.

[0015] The present invention has the following beneficial effects: 1. Improve sediment grabbing accuracy By real-time monitoring of the torque changes of the inverter-driven motor, combined with torque polarity change judgment and change rate filtering, accurate positioning of underwater sediment can be effectively achieved, avoiding the errors caused by traditional reliance on vision or preset depth. The contact recognition accuracy can reach more than 99.5%, and the positioning error is less than 1 mm.

[0016] 2. Enhance operational efficiency The method of combining high-speed lowering with low-speed precise control, combined with dynamic torque judgment, reduces multiple empty grasping and tentative operations, shortens the single grasping cycle by about 30%, significantly improves overall operating efficiency, and reduces energy consumption by 18%.

[0017] 3. Extend equipment service life Dynamic monitoring and timely braking control avoid over-release of the wire rope and unnecessary mechanical impact, reduce the wire rope damage rate by 75%, and reduce brake wear by 40%, significantly reducing equipment maintenance costs.

[0018] 4. Adapt to complex underwater environment The control system of the present invention does not rely on visual monitoring and pressure sensors, and can work stably under complex working conditions such as foam coverage, turbid water and variable sediment forms, effectively avoiding grasping errors caused by changes in the underwater environment.

[0019] 5. Realize intelligent adaptive control Equipped with an adaptive learning module, it can dynamically adjust the torque judgment threshold according to historical grasping data, adapt to sediments of different densities and hardness, realize intelligent optimization of the grasping process, reduce manual parameter adjustments, and improve the robustness of the system.

[0020] 6. Multi-level security The system has built-in upper and lower limits, left and right limits, and overload protection mechanisms, combined with braking resistors and emergency release circuits to ensure that the equipment can be quickly and safely shut down under abnormal operating conditions, protecting the safety of operators and equipment, and achieving a fault diagnosis coverage rate of nearly 100%.

[0021] 7. Realize unattended continuous operation After more than five years of actual production line verification, the solution of the present invention is particularly suitable for grabbing sediment at a water depth of 3-15 meters. It can realize long-term unmanned continuous grabbing operations in each shift, thereby improving the company's automation level and production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the control method flow of the present invention; Figure 2 It is a schematic diagram of the control system flow of the present invention; Figure 3 It is a schematic diagram of the process of the grabbing device of the present invention; Figure 4 It is a schematic structural diagram of the grabbing device of the present invention. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] For example 1, please refer to Figure 1 , this embodiment provides a grab bucket sediment grab control method based on torque detection, such as Figure 1 As shown, the following steps are included: S1: High-speed lowering stage At the start of the operation, the PLC controls the inverter to drive the winch mechanism to lower the wire rope at high speed, with the grab bucket in the open position. The lowering speed in high-speed mode is set at 1.5m / s to shorten the idle time.

[0025] S2: Low-speed operation stage When the encoder of the hoisting mechanism detects that the length of the wire rope is close to the target lowering depth within 2 meters, the PLC switches the inverter to low-speed mode and reduces the speed to 0.3m / s in order to accurately approach the sediment surface and reduce the impact.

[0026] S3: Torque acquisition and monitoring The PLC reads the output torque value of the drive motor from the inverter in real time using the Modbus-RTU protocol with a sampling period of 10ms, and stores the data in a cache queue.

[0027] S4: Sediment contact determination When the torque value changes from positive to negative and the torque change rate exceeds 0.5N·m / ms, the negative torque counter is started. If the torque is negative for 5 consecutive sampling cycles, it is determined that the grab has contacted the sediment.

[0028] S5: Stopping and Braking After the contact judgment is established, the PLC immediately sends a "stop lowering" command to the inverter and triggers the braking resistor to absorb the braking energy to prevent the bus voltage from being too high.

[0029] S6: Crawling and lifting After stopping, there is a delay of 0.5 seconds to control the grab bucket hydraulic mechanism to close, and the closing time is set to 2 seconds. After closing is completed, there is a delay of 1 second to drive the hoisting mechanism to lift the grab bucket, and the lifting speed is set to 0.5m / s.

[0030] S7: Improved process protection During the lifting process, the PLC continuously monitors the torque value. When it detects that the torque value exceeds the set overload threshold (such as 1.3 times the rated torque), it immediately stops lifting and executes the emergency release procedure, lowering the grab bucket appropriately to reduce the load.

[0031] S8: Filtering and anti-interference In order to avoid misjudgment caused by water flow impact, bubbles, etc., the collected torque signal is processed by sliding mean filtering (window length is 5 sampling periods) before judgment.

[0032] Example 2, as Figure 2 As shown, this embodiment provides a grab bucket sediment grabbing control system based on torque detection, including: 1. Main control unit It uses Siemens S7-1200 PLC with built-in high-speed counter and PID adjustment function, which is responsible for executing the grab control logic and torque determination algorithm.

[0033] 2. Communication module Modbus-RTU communication is established with the inverter via the RS-485 interface, with the baud rate set to 115200 bps, to obtain torque data in real time.

[0034] 3. Drive unit It includes an AC asynchronous motor with a rated power of 15kW and an ABB ACS880 frequency converter, which are used to drive the winch mechanism to lower and lift the wire rope.

[0035] 4. Position detection unit A photoelectric encoder (resolution 1024PPR) is installed at the end of the winch shaft to detect the lowering length and running speed of the wire rope.

[0036] 5. Human-computer interaction unit The Weiluntong 7-inch touch screen can be used for parameter setting (such as release speed, change rate threshold, negative torque counting threshold), real-time curve display, alarm record query, etc.

[0037] 6. Execution Unit It includes a hoisting mechanism, a wire rope and a grab bucket, and the grab bucket adopts a hydraulic closed structure.

[0038] 7. Safety protection unit It includes upper and lower limit switches, a brake resistor, and an overload protection module. When the limit switch is triggered, the PLC immediately cuts off the inverter's operating instructions; if an overload is detected during the lifting process, it immediately stops and lowers.

[0039] 8. Adaptive Module The PLC's built-in adaptive logic dynamically adjusts the torque change rate threshold and negative torque count threshold based on historical operation records to improve grasping accuracy in different operating environments.

[0040] Example 3, as Figure 3 and Figure 4 As shown, this embodiment provides a grab bucket sediment grabbing device based on torque detection, comprising: The winch mechanism is equipped with a wire rope winding drum, which is used to drive the grab bucket to rise and fall.

[0041] The drive assembly includes a motor, a frequency converter and its control circuit. The frequency converter has a built-in torque detection module and provides a data output interface.

[0042] The torque detection module directly reads the real-time torque value of the inverter and transmits it to the control unit.

[0043] The control unit adopts PLC structure, executes the grasping control program, and is connected to the human-computer interaction interface to realize parameter setting and real-time monitoring.

[0044] Safety protection components, including limit switches, brake resistors and overload protection modules.

[0045] Modular design, the drive unit, control unit and safety protection unit all use industrial quick-plug connectors to facilitate quick replacement and maintenance.

[0046] The present invention realizes precise grasping and control of underwater sediment through real-time detection and dynamic analysis of the inverter-driven motor torque, significantly improving the accuracy of grasping and positioning. The contact recognition accuracy rate reaches more than 99.5%, and the positioning error is controlled within 1 mm. It effectively overcomes the shortcomings of traditional methods that rely on visual monitoring and preset depth in complex working conditions such as foam coverage and turbid water.

[0047] The present invention adopts an operating strategy that combines high-speed lowering with low-speed precise control, and combines it with the judgment logic of torque polarity conversion and change rate filtering to reduce multiple empty grasping and repeated trial operations. The single grasping cycle is shortened by about 30%, which significantly improves the operating efficiency. At the same time, energy consumption is reduced by 18%, achieving energy saving and environmental protection.

[0048] By dynamically monitoring the wire rope tension and timely braking control, the present invention effectively avoids wire rope over-release and mechanical impact, reduces the wire rope damage rate by 75%, reduces brake wear by 40%, extends the service life of the equipment, reduces maintenance costs, and improves system stability.

[0049] The present invention does not rely on vision and pressure sensors, and is suitable for complex underwater environments such as foam coverage, turbid water, sediment accumulation with uncertain height and variable shape, and has strong environmental adaptability and robustness.

[0050] The present invention is equipped with an adaptive learning module, which dynamically optimizes the torque judgment threshold and counting parameters based on historical captured data, realizes intelligent adaptation to sediments of different densities and hardnesses, reduces manual intervention, and improves control accuracy and efficiency.

[0051] In addition, the present invention has built a multi-level safety protection system, including upper and lower, left and right limit protection, lifting overload protection and braking resistor energy absorption measures to ensure the safety of equipment and operators. The fault self-diagnosis coverage rate reaches 100%, ensuring stable operation of the system.

[0052] Verified by long-term application on actual production lines, the solution of the present invention is suitable for sediment grabbing at water depths of 3 to 15 meters, and can achieve long-term unmanned continuous operation, greatly improving the level of production automation and economic benefits.

[0053] In summary, the present invention has achieved significant technological progress in accuracy, efficiency, safety and intelligent adaptability, and has broad application prospects and promotion value.

[0054] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0055] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A grab bucket sediment grabbing control method based on torque detection, characterized in that: The following steps are involved: High-speed lowering: Drive the winch mechanism to lower the wire rope at high speed to the nearest working area; Low-speed operation: When the lowering position is close to the preset height, it switches to low speed and keeps the grab in the open state; Torque acquisition and monitoring: Torque data is collected in real time through the frequency converter connected to the drive motor, with a sampling period of no more than 10ms; Sediment contact determination: When the collected torque changes from positive to negative and the torque change rate exceeds the preset change rate threshold, the negative torque counter is started, and when the count value reaches the preset threshold, it is determined that the grab has contacted the sediment; Stop and brake: After the contact judgment is established, the stop and release command is immediately issued, and the braking resistor is triggered to absorb excess electrical energy; Grab and lift: After a preset delay, the grab bucket is driven to close and grab, and then the winch mechanism is driven to lift the grab bucket. Lifting process protection: Real-time detection of load torque during the lifting process, and overload protection is immediately triggered once the lifting torque threshold is exceeded.

2. The grab bucket sediment grabbing control method based on torque detection according to claim 1 is characterized in that: The sediment contact determination adopts a multi-condition combination determination method of torque polarity change, torque change rate threshold and negative torque continuous counting, and denoises the sampled torque through a sliding mean filtering algorithm to eliminate interference signals such as water flow impact and bubbles.

3. The grab bucket sediment grabbing control method based on torque detection according to claim 1 is characterized in that: The preset change rate threshold and the negative torque count threshold can be adaptively adjusted according to historical operation data to adapt to sediment distributions of different densities and shapes.

4. The grab bucket sediment grabbing control method based on torque detection according to claim 1 is characterized in that: Before each operation begins, the system performs no-load operation, collects and stores the no-load torque curve as a benchmark, and corrects the torque judgment reference value in real time during the operation.

5. The grab bucket sediment grabbing control method based on torque detection according to claim 1 is characterized in that: The safety protection includes: immediately cutting off the power supply of the drive motor when the upper and lower limits are triggered; immediately stopping the lifting and executing the emergency release procedure when the lifting torque exceeds the threshold; and suppressing bus overvoltage through the braking resistor during braking.

6. The grab bucket sediment grabbing control system based on torque detection according to claims 1-5, characterized in that: include: Main control unit: PLC, used to execute the grasping control logic; Communication module: used to establish high-speed data communication with the inverter to obtain real-time torque value; Drive unit: includes frequency converter and drive motor, used to control the lowering and raising of the hoisting mechanism; Position detection unit: includes an encoder for detecting the position and speed of the wire rope when it is lowered or lifted; Human-computer interaction unit: including touch screen, used to set parameters, monitor torque curve, and query alarm records; Execution unit: including winch mechanism, wire rope and grab bucket; Safety protection unit: includes limit switch, overload protection module and braking resistor.

7. The grab bucket sediment grabbing control system based on torque detection according to claim 6, characterized in that: The main control unit is configured to perform sliding mean filtering and dynamic reference calibration on the collected torque signal to eliminate instantaneous interference caused by water flow, bubbles, etc.

8. The grab bucket sediment grabbing control system based on torque detection according to claim 7, characterized in that: The main control unit includes an adaptive parameter adjustment module for automatically adjusting the torque change rate threshold and the negative torque count threshold based on historical capture records.

9. The grab bucket sediment grabbing device based on torque detection according to claims 1-5, characterized in that: include: winch mechanism; Wire rope and grab bucket connected to the hoisting mechanism; A drive motor and a frequency converter for driving the hoisting mechanism; a torque detection module connected to the frequency converter; A control unit for controlling the driving motor and the action of the grab bucket; A limit switch, a braking resistor and an overload protection module connected to the control unit.

10. The grab bucket sediment grabbing device based on torque detection according to claim 9, characterized in that: The device adopts a modular design, and each unit is connected by a quick-plug industrial connector to facilitate maintenance and replacement.

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