Absolute position management and PST test system of intelligent electric actuating mechanism

Abstract

The invention discloses an absolute position management and PST test system of an intelligent electric actuating mechanism. The absolute position management and PST test system comprises an absolute position acquisition module, a high-precision position control module, a customized PST test module and a test result analysis module, the absolute type position acquisition module adopts a multi-circle absolute type magnetoelectric encoder to improve the positioning precision, and realizes a power-off memory function through a gear set mechanical memory position; the high-precision position control module adopts a PID (Proportion Integration Differentiation) + feedforward control algorithm and combines real-time position feedback of an encoder to realize valve position closed-loop control; test parameters of the customized PST test module can be customized to adapt to different working conditions; and the test result analysis module analyzes the PST test data and calculates key indexes. According to the invention, power-off position memory, high-precision positioning, customized PST testing and quantitative analysis are realized, and the valve control precision and the equipment reliability are guaranteed.

Description

Technical Field

[0001] This invention relates to the field of industrial equipment condition monitoring technology, and in particular to an absolute position management and PST testing system for an intelligent electric actuator. Background Technology

[0002] The position control accuracy of intelligent electric actuators directly affects valve regulation performance, and partial stroke testing (PST) is a key preventative maintenance method to ensure the reliability of valves and actuators. PST is a non-destructive testing technique that verifies the partial stroke movement of industrial valves (especially critical valves such as Safety Instrumented Systems (SIS), Emergency Shut-off Valves (ESV), and regulating valves) without interrupting process operation or affecting normal valve function. Its core essence is: by controlling the valve actuator (pneumatic, electric, or hydraulic) to drive the valve core / plate to move a preset portion of its stroke (usually 10-30%, adjusted according to valve type and process requirements), it verifies the valve's mechanical flexibility, actuator response speed, and control signal transmission reliability, identifying potential problems such as valve jamming, actuator failure, and seal wear in advance, thus avoiding safety accidents or significant economic losses due to valve failure.

[0003] The existing PST testing technology has the following problems: (1) Position measurement relies on an incremental encoder. The stroke needs to be recalibrated after power failure; otherwise, the position data will be lost, resulting in valve positioning deviation. (2) The position control accuracy is low, and the hysteresis and repeatability cannot meet the requirements of high-precision regulation (such as flow control of chemical reactors); (3) PST test parameters are fixed (such as stroke range and speed), which cannot be adapted to different valve types (such as the difference in test requirements between gate valves and butterfly valves), and the test process is prone to interfering with normal production; (4) The PST test results lack quantitative analysis and can only determine "pass / fail", but cannot locate potential faults (such as slight jamming of the valve core).

[0004] Therefore, there is an urgent need for a system that enables absolute position measurement, high-precision control, customizable PST testing, and quantitative analysis of results to improve the accuracy of actuator position management and the effectiveness of maintenance. Summary of the Invention

[0005] To address the aforementioned problems in existing technologies, this invention provides an absolute position management and PST testing system for intelligent electric actuators, enabling power-off position memory, high-precision positioning, customized PST testing, and quantitative analysis, thereby ensuring valve control accuracy and equipment reliability.

[0006] The technical solution of the present invention is as follows: An absolute position management and PST testing system for an intelligent electric actuator, implemented based on an STM32H743 MCU (hereinafter referred to as MCU), includes an absolute position acquisition module, a high-precision position control module, a customized PST testing module, and a test result analysis module. The absolute position acquisition module includes an encoder; the encoder is a multi-turn absolute magnetoelectric encoder with the following parameters: 12-bit resolution per turn, 4096 positions, 5400 turns of multi-turn recording, and a spindle-to-bevel gear ratio of 1:4. The encoder does not require battery power; it mechanically memorizes the position through the gear set. Position data is retained for 10 years after power failure, and the current position is directly read upon power restoration without recalibrating the stroke. The encoder communicates with the MCU via an RS485 interface, with a data update rate of 1kHz. CRC16 verification is used to ensure data integrity. If communication is interrupted, a backup encoder is activated, and a communication fault alarm is triggered. The encoder is calibrated in 16 segments to compensate for position deviations caused by gearbox transmission backlash, ensuring that the position measurement linearity is ≤0.1% FS across the entire stroke range. The high-precision position control module employs a feedforward control PID algorithm, combined with real-time position feedback from the encoder, to achieve closed-loop valve position control. The PID algorithm is implemented based on the MCU's FPU unit, with a control cycle of 1ms. The PWM drive signal is output through the IR2233 chip to control the motor speed. PID parameters can be configured with engineer privileges to adapt to different valve inertia. Feedforward control compensates for valve friction torque in advance, reducing overshoot. The test parameters of the customized PST test module are as follows: (1-1) Test the stroke range, with a value range of 0~30% of the rated stroke; (1-2) Test speed, the value range is 10~50% of the rated speed; (1-3) Test period, with a range of 1 to 365 days; (1-4) Test triggering method, the value range is automatic or manual; The customized PST test module calls the high-precision position control module to drive the motor according to the test parameters, and monitors the valve position in real time through the absolute position acquisition module, while also monitoring the motor torque and current in real time; The test result analysis module analyzes the PST test data and calculates the following indicators: (2-1) Travel time deviation, i.e., the deviation between the actual travel time and the set value; (2-2) Torque fluctuation, i.e., the difference between the maximum and minimum torque values ​​during the test; (2-3) Valve position repeatability, i.e., the position deviation when testing the same stroke multiple times; (2-4) Sealing performance, that is, the leakage amount when the valve is closed after testing; The test result analysis module compares the measurement results of the above indicators with the historical measurement results. If the indicators deteriorate, it determines a potential fault and triggers a maintenance warning. At the same time, the test result analysis module automatically generates a PST test report containing test parameters, indicators, and potential faults, stores it in the FRAM and retains it for more than 1 year, and uploads it to the cloud platform through the MQTT protocol.

[0007] Furthermore, the control accuracy indicators of the high-precision position control module are as follows: (3-1) The spindle angle resolution is 0.0225°, and the valve position percentage resolution is 0.001%; (3-2) The repeatability accuracy is ±0.1°; the repeatability accuracy refers to the deviation of positioning the same target position multiple times; (3-3) The hysteresis is ≤0.3% FS; the hysteresis refers to the maximum difference between approaching the same position in the forward and reverse directions; (3-4) The basic error is ≤±0.5% FS; the basic error refers to the maximum deviation between the actual position and the set position.

[0008] Furthermore, the control indicators of the high-precision position control module for step control instructions are as follows: the response time is ≤1s, the rise time is ≤1s, the regulation time is ≤2s, and the overshoot is ≤2%.

[0009] Furthermore, the high-precision position control module sets full-open and full-close soft limits. When the valve position reaches the limit, the motor action stops immediately, and at the same time, the reverse clearance is automatically compensated, and the compensation amount is 0.2°; the full-open means that the valve position is 95% - 102% of the rated maximum stroke, and the full-close means that the valve position is -2% - 5% of the rated minimum stroke.

[0010] Furthermore, the test result analysis module is implemented based on the RK3588 processor, and calculates the stroke time deviation and torque fluctuation by calling the SciPy library through Python scripts, and the report generation time is ≤5s.

[0011] Furthermore, the stroke time deviation ≤5% is qualified; The torque fluctuation ≤10% of the rated torque is qualified; The valve position repeatability ≤0.1° is qualified; The sealing performance ≤0.1MPa / 10min is qualified.

[0012] Furthermore, the working process is as follows: S1. Position Acquisition and Control: The encoder acquires the valve position in real time, and the MCU calculates the motor drive signal through a PID algorithm to control the valve for precise positioning, with a hysteresis ≤0.3% FS. S2 and PST test configuration, namely: configuring PST parameters through remote DCS; S3. Test execution: After the cycle is completed, the system confirms that the process status is normal, drives the valve to open from 50% to 70%, and then closes it to 50%, monitoring the torque in real time. S4. Results Analysis: Calculate travel time deviation and torque fluctuation, compare with historical data, generate a report, and upload it to the cloud. S5. Abnormal handling: If the torque fluctuation exceeds 10%, it is judged as potential jamming, triggering a maintenance warning and prompting to check the valve sealing surface.

[0013] The beneficial technical effects of this invention are as follows: Absolute encoders enable position memory even after power failure, avoiding recalibration and reducing maintenance workload; High-precision position control algorithms ensure valve position control accuracy and dynamic response, meeting the requirements of regulating valves; Customized PST test parameters adapt to different operating conditions, and the process-uninterrupted design ensures production continuity; Quantitative analysis of test results allows for the early detection of potential faults and enables preventative maintenance. Attached Figure Description

[0014] Figure 1 This is a system structure block diagram of the present invention. Detailed Implementation

[0015] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0016] like Figure 1 As shown, the embodiment includes an absolute position acquisition module, a high-precision position control module, a customized PST testing module, and a test result analysis module. These modules work together as follows: I. Absolute Position Acquisition Module 1. Encoder Selection and Parameters: A multi-turn absolute magnetoelectric encoder is adopted, with a single-turn resolution of 12 bits (4096 positions), a multi-turn recording capacity of 5400 turns, a spindle to bevel gear ratio of 1:4, a spindle angle resolution of 0.0225°, and a valve position percentage resolution of 0.001%. 2. Power-off memory function: The encoder does not require battery power. It mechanically memorizes the position through the gear set. The position data is retained for 10 years after a power outage. After power is restored, the current position can be read directly without recalibrating the stroke. 3. Data transmission and verification: The encoder communicates with the MCU via an RS485 interface, with a data update rate of 1kHz. CRC16 verification is used to ensure data integrity. If communication is interrupted, the backup encoder is activated (redundant design), and a communication failure alarm is triggered simultaneously. 4. Mechanical error compensation: Through 16-point segmented calibration, the position deviation caused by gearbox transmission clearance (such as worm gear meshing clearance) is compensated to ensure that the linearity of position measurement is ≤0.1% FS throughout the entire stroke range.

[0017] II. High-precision position control module 1. Closed-loop control algorithm: A PID + feedforward control algorithm is adopted, combined with real-time encoder position feedback, to achieve closed-loop valve position control; PID parameters (proportional coefficient Kp, integral coefficient Ki, derivative coefficient Kd) can be configured by engineers to adapt to different valve inertia (such as the inertia difference between ball valves and butterfly valves); feedforward control compensates for valve friction torque in advance to reduce overshoot; the PID algorithm is implemented based on the FPU unit of the STM32H743 MCU, with a control cycle of 1ms; the PWM drive signal is output through the IR2233 chip to control the motor speed. 2. Guaranteed control precision: (1) Resolution: 0.0225° (spindle angle), 0.001% (valve position percentage); (2) Repeatability: ±0.1° (deviation when positioning the same target multiple times); (3) Hysteresis: ≤0.3% FS (the maximum difference between the forward and reverse directions when approaching the same position); (4) Basic error: ≤ ±0.5% FS (maximum deviation between actual position and set position); 3. Dynamic Response Optimization: For step control commands (such as from 20% valve position to 80% valve position), optimize response time (≤1s), rise time (≤1s), settling time (≤2s), and overshoot (≤2%) to avoid water hammer or overshoot caused by excessively rapid valve action; 4. Soft limit protection: Set soft limits for fully open (95%~102%) and fully closed (-2%~5%). When the valve position reaches the limit, the motor will stop immediately and the back clearance (0.2°) will be automatically compensated to ensure the valve sealing performance.

[0018] III. Customized PST Test Module 1. Test parameter configuration: Supports configuring PST parameters via local infrared remote control or remote system. (1) Test stroke range: 0~30% of rated stroke (e.g., 10%, 20%, 30%), suitable for different valve types (e.g., select 10% for gate valve, select 30% for regulating valve); (2) Test speed: 10%~50% of the rated speed (default 10%), slow testing to reduce process interference; (3) Testing period: 1~365 days (configurable), such as 1 day for high-risk equipment and 30 days for stable equipment; (4) Test triggering method: automatic (by period) or manual (on-site / remote triggering). Manual triggering requires engineer authorization. Test parameters are stored in FRAM (FM25W256), and data acquisition during the test is achieved through ADC and timer, with a sampling period of 10ms; 2. Testing process control: (1) Before testing: Confirm the current process status (e.g., pipeline pressure ≤ 50% of rated pressure). If the status is not met, postpone the test and record the reason for the postponement. (2) During the test: drive the valve to move according to the set stroke and speed, and monitor the valve position, torque, and motor current in real time. If the torque exceeds 80% of the rated value or the valve position deviation is >0.5%, pause the test and sound an alarm. (3) After the test: the valve is driven back to its pre-test position, the normal control mode is restored, and a test report is generated; 3. Non-disruptive process design: The test stroke is controlled within a range that does not affect the flow rate of the medium (e.g., flow fluctuation ≤10% within 30% of the stroke), while avoiding critical process periods (e.g., the feed period of the reactor). Through interlocking with DCS, it is ensured that the test does not interfere with production.

[0019] IV. Test Result Analysis Module 1. Quantitative Indicator Calculation: Analyze the PST test data and calculate key indicators: (1) Travel time deviation: The deviation between the actual travel time and the set value (≤5% is acceptable); (2) Torque fluctuation: The difference between the maximum and minimum torque values ​​during the test (≤10% of the rated torque is acceptable); (3) Valve position repeatability: The position deviation of the same stroke is tested multiple times (≤0.1° is acceptable); (4) Sealing performance: The leakage rate when the valve is closed after the test (monitored by a pressure sensor, ≤0.1MPa / 10min is acceptable); 2. Trend Comparison Analysis: Compare the results of this test with historical data (the last 3 times). If the indicators deteriorate (e.g., torque fluctuation increases from 5% to 15%), it is judged as a potential fault, triggering a maintenance warning. 3. Report generation and upload: Automatically generate PST test reports (including test parameters, indicator results, and anomaly screenshots), store them in FRAM (retained for ≥1 year), and upload them to the cloud platform via the MQTT protocol. Supports exporting to PDF format, which can be used as a basis for maintenance and acceptance.

[0020] The test result analysis module implements quantitative analysis based on the edge layer RK3588 processor. It uses a Python script to call the SciPy library to calculate travel time deviation and torque fluctuation. The report generation time is ≤5 seconds.

[0021] The workflow of the example is as follows: S1. Position Acquisition and Control: The encoder acquires valve position data in real time (e.g., 50.000%), and the MCU calculates the motor drive signal using a PID algorithm to control the valve for precise positioning, with a hysteresis ≤0.3% FS; S2 and PST test configuration: Configure PST parameters (20% travel, 10% speed, 7-day cycle) via remote DCS. S3. Test Execution: After the cycle is completed, the system confirms that the process status is normal, drives the valve to open from 50% to 70% (20% stroke), and then closes it to 50%, monitoring the torque in real time (e.g., 200~220Nm, fluctuation of 10%). S4. Result Analysis: The travel time deviation was calculated to be 3% (qualified) and the torque fluctuation was 10% (qualified). No degradation was found compared with historical data. A qualified report was generated and uploaded to the cloud. S5. Abnormal Handling: If the torque fluctuation rises to 18% during a test, it is determined to be a potential jamming, triggering a maintenance warning and prompting an inspection of the valve sealing surface.

[0022] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, and for those of ordinary skill in the art, various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. Therefore, the present invention is not limited to the specific details without departing from the general concept defined by the claims and their equivalents.

Claims

1. An absolute position management and PST testing system for an intelligent electric actuator, characterized in that: Implemented based on STM32H743 MCU, hereinafter referred to as MCU; includes an absolute position acquisition module, a high-precision position control module, a customized PST test module, and a test result analysis module; The absolute position acquisition module includes an encoder; the encoder is a multi-turn absolute magnetoelectric encoder with the following parameters: 12-bit resolution per turn, 4096 positions, 5400 turns of multi-turn recording, and a spindle-to-bevel gear ratio of 1:4; the encoder does not require battery power and mechanically memorizes the position through the gear set. Position data is retained for 10 years after power failure, and the current position is directly read upon power restoration without recalibrating the stroke; the encoder communicates with the MCU via an RS485 interface with a data update rate of 1kHz. CRC16 verification is used to ensure data integrity. If communication is interrupted, a backup encoder is activated, and a communication fault alarm is triggered; the encoder is calibrated in 16 segments to compensate for position deviations caused by gearbox transmission backlash, ensuring position measurement linearity ≤0.1% FS across the entire stroke range; The high-precision position control module adopts a feedforward control PID algorithm, combined with real-time position feedback from the encoder, to achieve closed-loop valve position control. The PID algorithm is implemented based on the FPU unit of the MCU, with a control cycle of 1ms. The PWM drive signal is output through the IR2233 chip to control the motor speed. The PID parameters can be configured by engineers to adapt to different valve inertia. The feedforward control compensates for the valve friction torque in advance to reduce overshoot. The test parameters of the customized PST test module are as follows: (1-1) Test the stroke range, the value range is 0 to 30% of the rated stroke; (1-2) Test speed, the value range is 10% to 50% of the rated speed; (1-3) Test period, with a range of 1 to 365 days; (1-4) Test triggering method, the value range is automatic or manual; The customized PST test module calls the high-precision position control module to drive the motor according to the test parameters, and monitors the valve position in real time through the absolute position acquisition module, while also monitoring the torque and current of the motor in real time. The test result analysis module analyzes the PST test data and calculates the following indicators: (2-1) Travel time deviation, that is, the deviation between the actual travel time and the set value; (2-2) Torque fluctuation, which is the difference between the maximum and minimum torque values ​​during the test; (2-3) Valve position repeatability, i.e., the position deviation when testing the same stroke multiple times; (2-4) Sealing performance, i.e., the leakage amount when the valve is closed after the test; The test result analysis module compares the measurement results of the above indicators with the historical measurement results. If the indicator deteriorates, it is identified as a potential fault and a maintenance warning is triggered. At the same time, the test result analysis module automatically generates a PST test report containing test parameters, indicators and potential faults, stores it in FRAM and retains it for more than one year, and uploads it to the cloud platform via the MQTT protocol.

2. The absolute position management and PST testing system for an intelligent electric actuator according to claim 1, characterized in that, The control accuracy indicators of the high-precision position control module are as follows: (3-1) The spindle angle resolution is 0.0225°, and the valve position percentage resolution is 0.001%; (3-2) The repeatability accuracy is ±0.1°; the repeatability accuracy refers to the deviation of positioning the same target position multiple times; (3-3) The hysteresis error ≤ 0.3% FS; the hysteresis error refers to the maximum difference between approaching the same position in the forward and reverse directions; (3-4) The basic error ≤ ±0.5% FS; the basic error refers to the maximum deviation between the actual position and the set position.

3. The absolute position management and PST test system of an intelligent electric actuator according to claim 1, characterized in that: The control indexes of the high-precision position control module for step control instructions are as follows: the response time ≤ 1 s, the rise time ≤ 1 s, the adjustment time ≤ 2 s, and the overshoot ≤ 2%.

4. The absolute position management and PST test system of an intelligent electric actuator according to claim 1, characterized in that: The high-precision position control module sets full-open and full-close soft limits. When the valve position reaches the limit, the motor action is immediately stopped, and at the same time, the backlash is automatically compensated, and the compensation amount is 0.2°; the full-open means that the valve position is 95% - 102% of the rated maximum stroke, and the full-close means that the valve position is -2% - 5% of the rated minimum stroke.

5. The absolute position management and PST test system of an intelligent electric actuator according to claim 1, characterized in that: The test result analysis module is implemented based on the RK3588 processor. The travel time deviation and torque fluctuation are calculated by calling the SciPy library through Python scripts, and the report generation time ≤ 5 s.

6. The absolute position management and PST test system of an intelligent electric actuator according to claim 1, characterized in that: The travel time deviation ≤ 5% is qualified; The torque fluctuation ≤ 10% of the rated torque is qualified; The valve position repeatability ≤ 0.1° is qualified; The sealing performance ≤ 0.1 MPa / 10 min is qualified.

7. The absolute position management and PST testing system for an intelligent electric actuator according to claim 1, characterized in that, The working process is as follows: S1. Position acquisition and control, that is: the encoder real-time acquires the valve position, and the MCU calculates the motor drive signal through the PID algorithm to control the valve to accurately position, and the hysteresis error ≤ 0.3% FS; S2. PST test configuration, that is: configure the PST parameters through the remote DCS; Ss Test execution, that is: after the cycle, the system confirms that the process state is normal, drives the valve to open from 50% to 70%, and then closes to 50%, and monitors the torque in real time; S4. Result analysis, that is: calculate the travel time deviation and torque fluctuation, compare with the historical data, generate a report and upload it to the cloud; S5. Abnormal handling, that is: if the torque fluctuation exceeds 10%, it is determined as potential jamming, trigger a maintenance warning, and prompt to check the valve sealing surface.

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