A trench compactor with automatic centering function and an automatic centering control method

Abstract

The application discloses a trench compactor with automatic centering function and an automatic centering control method, and belongs to the technical field of engineering machinery. In view of the problems of poor manual centering precision, easy fatigue of mechanical reset, poor anti-vibration performance of a general control scheme, and unstable deviation correction of an existing trench compactor, the application adopts an angular displacement sensor to cooperate with a rubber damping installation assembly to collect a deflection angle, and through a double-acting symmetrical steering oil cylinder and an electro-hydraulic proportional reversing valve, executes an action; an 8-point sliding average filtering module, a one-key zero position calibration module and a segmented PID closed-loop regulation module are built in an electric control unit, and combined with a manual priority safety logic, automatic centering is realized. The application effectively isolates 30~50Hz high-frequency vibration interference, controls the centering precision within ±0.5°, has the characteristics of rapid deviation correction and mid-position anti-oscillation, and through a multi-stage fault protection mechanism, improves the adaptability to harsh working conditions, reduces the labor intensity of operators, and prolongs the service life of equipment.

Description

Technical Field

[0001] This invention relates to the field of engineering machinery technology, and in particular to a trench compactor with automatic centering function and an automatic centering control method. Background Technology

[0002] Trench compactors are essential compaction equipment in municipal water supply and drainage, gas, and power pipeline construction, primarily used to compact backfill soil within narrow trenches. Due to factors such as limited operating space, uneven trench surfaces, and high-frequency vibrations of the equipment itself, the compaction wheel is prone to deviating from the trench centerline, leading to problems such as uneven pressure, insufficient compaction, and uneven compaction. This not only reduces construction quality but also causes unilateral wear on the compaction wheel and steering hinge mechanism, shortening the equipment's service life.

[0003] Currently, there are two main types of centering methods in the industry: one is manual visual judgment and manual operation for centering. This method relies entirely on the operator's experience, resulting in poor centering accuracy, slow response, high labor intensity during long-term operation, and is not suitable for intelligent operation scenarios such as remote control and unmanned driving; the other is the use of a mechanical spring reset structure, which relies on the spring force to achieve reset. However, in the strong vibration environment of trench operation, the spring is prone to fatigue and deformation, resulting in a continuous decrease in reset accuracy. Furthermore, it cannot adaptively adjust according to the offset, resulting in poor correction effect.

[0004] Some existing large road rollers employ a closed-loop steering control scheme using angle sensors, PID controllers, and electro-hydraulic proportional valves. However, this general-purpose control system is not optimized for the special working conditions of trench compactors, which involve narrow spaces, high vibrations, and continuous bumps. On the one hand, the sensors lack vibration damping structures, leading to signal distortion and control malfunctions due to vibration. On the other hand, the general-purpose PID algorithm lacks segmented optimization, resulting in slow response during large offsets and oscillations during small offsets, failing to meet the high precision and stability requirements of trench compaction. Therefore, developing an automatic centering device that adapts to the working conditions of trench compactors, possesses strong vibration resistance, and has specifically optimized control logic has become an urgent need in this field. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems in the prior art and provide a trench compactor with automatic centering function and an automatic centering control method. Vibration signal interference is eliminated by equipping the angular displacement sensor with vibration damping components on the mechanical end, and smooth steering is achieved by relying on an electro-hydraulic proportional valve and symmetrical cylinders. The control end employs sliding average filtering for noise reduction and designs a segmented PID algorithm, matching different control gains according to the offset interval, balancing rapid correction and centering anti-oscillation. It is equipped with one-key zero-position calibration, multi-level over-limit alarms, fault lockout, and manual priority safety logic, which can automatically compensate for steering deviations, stably controlling the compaction wheel at the center of the trench. It is suitable for remote control and unmanned construction, balancing adaptability to harsh working conditions with operational accuracy and equipment safety.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: a trench compactor with automatic centering function, comprising a frame body, a compaction wheel support, a compaction wheel rotatably mounted on the bottom of the compaction wheel support, and a steering hinge assembly connecting the frame body and the compaction wheel support, further comprising: a centering detection mechanism, consisting of an angular displacement sensor and a sensor vibration damping mounting assembly, wherein the angular displacement sensor is coaxially mounted on the end of the hinge shaft of the steering hinge assembly for collecting the deflection angle of the compaction wheel, and the sensor vibration damping mounting assembly is disposed between the angular displacement sensor and the steering hinge assembly for physically isolating the sensor from the interference of the machine vibration;

[0007] The hydraulic actuator includes a double-acting symmetrical steering cylinder and an electro-hydraulic proportional directional valve. The cylinder body of the steering cylinder is hinged to the main frame, and the piston rod is hinged to the compaction wheel support. The electro-hydraulic proportional directional valve is used to control the extension and retraction of the steering cylinder.

[0008] The electronic control unit is electrically connected to the angular displacement sensor and the electro-hydraulic proportional directional valve, respectively. The electronic control unit has a built-in signal filtering module, a zero-position calibration module, a segmented PID closed-loop regulation module and a fault diagnosis and protection module.

[0009] The human-machine interface module is connected to the electronic control unit and includes a manual / automatic switch and a control panel. The manual / automatic switch is configured so that the manual mode has a higher priority than the automatic mode, and the automatic return-to-center function is immediately disabled in the manual mode.

[0010] Furthermore, the sensor vibration damping mounting assembly is a flexible connection structure composed of a rubber vibration damping pad and a locking flange. The housing of the angular displacement sensor is flexibly connected through the rubber vibration damping pad to isolate the transmission of high-frequency vibration acceleration to the sensor housing, so that the angular displacement sensor can still output a stable detection signal under strong vibration conditions, thus avoiding signal distortion and misjudgment caused by vibration from the source.

[0011] Furthermore, the hinge portion of the steering articulation assembly integrates a dustproof sealing component, and the hydraulic oil supply circuit of the hydraulic actuator is equipped with an oil suction filter, an oil return filter, and a pressure relief valve. The pressure relief valve limits the maximum working pressure of the system to 16MPa, thereby effectively protecting the articulation mechanism in the harsh trench environment with a lot of dust and mud, and ensuring the stability and safety of the hydraulic system in long-term operation through multi-stage filtration and pressure protection.

[0012] Furthermore, the signal filtering module employs an 8-point moving average filtering algorithm to filter out vibration noise; the zero-position calibration module supports one-click reference calibration to store the calibrated reference angle value to eliminate equipment assembly errors; the control cycle of the electronic control unit is 20ms, thereby ensuring rapid system response while filtering out instantaneous vibration noise, and adapting to equipment with different assembly tolerances through simple calibration, thus improving the product's versatility and deployment efficiency.

[0013] Furthermore, the segmented PID closed-loop control module is configured as follows:

[0014] When the angle deviation is greater than ±2°, activate the large proportional gain for rapid adjustment.

[0015] When the angle deviation is in the range of 0.5° to 2°, switch to conventional PID parameters for smooth correction.

[0016] When the angular deviation is less than ±0.5°, the proportional gain and derivative gain are reduced to suppress system oscillations, achieving rapid homing under large offsets and stable maintenance with zero steady-state error under small offsets. This avoids untimely correction and effectively eliminates system oscillations near the median.

[0017] Furthermore, the fault diagnosis and protection module has a preset correction start threshold of ±2° and an alarm threshold of ±5°. When the deflection angle exceeds ±5°, an audible and visual alarm is triggered. When the sensor signal is interrupted or the hydraulic pressure exceeds 18MPa, the system immediately cuts off the automatic circuit and locks the mechanism, thereby constructing a safety defense line of graded early warning and hardware locking to prevent equipment damage or trench wall collapse caused by excessive deviation, and to stop the machine in time to avoid danger in case of hydraulic abnormality.

[0018] Furthermore, the human-machine interaction module also includes an audible and visual alarm device, which is connected to the electronic control unit and is used to issue audible and visual prompts when the deflection angle exceeds the limit or the system malfunctions, so that on-site personnel can quickly detect equipment abnormalities and perform manual intervention or maintenance in a timely manner, thereby further ensuring the safety and controllability of the operation process.

[0019] The present invention also provides an automatic centering control method for a trench compactor, comprising the following steps:

[0020] S1: Adjust the compaction wheel to the center line of the trench, and perform one-key zero-position calibration through the control panel. The electronic control unit collects the current value of the angular displacement sensor and stores it as the zero position of the centering reference.

[0021] S2: Switch the manual / automatic switch to the automatic position, and the device will enter the automatic return-to-center working state;

[0022] S3: The angular displacement sensor collects the deflection angle of the compaction wheel in real time. The raw signal is transmitted to the processing core after being reduced in noise by the signal filtering module in the electronic control unit.

[0023] S4: The electronic control unit compares the real-time angle with the reference zero position to calculate the angle deviation. Based on the deviation range, it calls the corresponding PID parameters in the segmented PID closed-loop adjustment module, outputs control signals to drive the electro-hydraulic proportional directional valve, and controls the extension and retraction of the steering cylinder to complete the correction action.

[0024] S5: After the compaction wheel returns to the center position, the system maintains a stable state, keeping the deviation within ±0.5°.

[0025] Furthermore, the specific logic of the segmented PID closed-loop regulation in S4 is as follows:

[0026] When the angular deviation is greater than ±2°, a large proportional gain is activated for rapid adjustment, driving the steering cylinder to push the compaction wheel back to the center position quickly.

[0027] When the deviation is reduced to the range of 0.5° to 2°, switch to conventional PID parameters for smooth correction.

[0028] When the deviation is less than ±0.5°, the differential gain and proportional gain are reduced to keep the compaction wheel stably in the center position. This phased and progressive adjustment strategy takes into account both the dynamic response speed of the correction and the steady-state control accuracy, ensuring that the compaction wheel always operates along the center line of the trench.

[0029] Furthermore, it also includes fault protection steps: when the deflection angle exceeds ±5°, the audible and visual alarm device is triggered; when the angular displacement sensor signal is interrupted or the hydraulic pressure is abnormal, the electronic control unit immediately cuts off the automatic circuit and locks the mechanism; at any time during operation, switching to manual mode will immediately disable the automatic return-to-center function, and the steering will be fully controlled by the operator, forming a complete safety closed loop of "early warning-protection-takeover", which not only avoids the risk of operating the equipment with defects, but also retains the right to handle the situation manually in emergency situations.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] 1. The sensor vibration damping mounting assembly adopts a flexible connection structure consisting of rubber damping pads and locking flanges, physically isolating the transmission of 30~50Hz high-frequency vibration to the angular displacement sensor. Combined with an 8-point moving average filtering algorithm within the electronic control unit, it effectively filters out instantaneous noise generated during bumpy operations. Under the synergistic effect of these dual mechanisms, the angle detection error is strictly controlled within an extremely small range, avoiding false offsets and output disturbances caused by vibration in general control systems. This ensures the accuracy of the centering control reference and lays a solid foundation for subsequent high-precision correction.

[0032] 2. The segmented PID closed-loop control strategy employed achieves precise adaptation of control logic for different offset conditions. When the offset exceeds ±2°, a high-proportion gain is activated to drive the steering cylinder to quickly return to center, preventing pressure leakage. When the offset is within the 0.5°~2° range, conventional PID parameters are switched to ensure a smooth and shock-free correction process. When the offset is less than ±0.5°, the gain is reduced to suppress oscillations, keeping the compaction wheel stably centered. This progressive control logic overcomes the shortcomings of traditional mechanical reset, such as poor accuracy and lag response, and solves the problems of slow response and easy oscillation in general PID algorithms with large deviations. Ultimately, the centering stability accuracy is improved to ±0.5°, significantly enhancing the uniformity and construction quality of trench backfill compaction.

[0033] 3. The dustproof sealing components at the steering hinge and the multi-stage filtration design of the hydraulic circuit enable it to cope with the harsh environment of dust and mud in the trench, extending the service life of hydraulic components; the manual priority safety logic, multi-level angle threshold alarm and fault locking mechanism build a complete safety defense.

[0034] 4. The one-click zero-position calibration function eliminates equipment assembly errors and is compatible with new installations and retrofits of various models. Fully automated centering not only reduces operator workload by over 90%, but also avoids unilateral wear of components caused by long-term off-center loading, extending equipment overhaul cycles. Attached Figure Description

[0035] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0036] Figure 1 This is a schematic diagram of the overall structure of the trench compactor of the present invention.

[0037] Figure 2 for Figure 1 An enlarged structural diagram of the steering hinge assembly.

[0038] Figure 3 This is a schematic diagram illustrating the control relationships of various parts in this invention.

[0039] Figure 4 This is a flowchart of the automatic centering control method of the present invention.

[0040] Figure 5 This is a schematic diagram of the hydraulic system in this invention.

[0041] The attached diagrams are labeled as follows: 1. Main frame; 2. Steering hinge assembly; 3. Hinge spindle; 4. Angular displacement sensor; 5. Sensor vibration damping mounting assembly; 6. Compactor wheel bracket; 7. Compactor wheel; 8. Steering cylinder; 9. Electro-hydraulic proportional directional valve; 10. Hydraulic pump; 11. Pressure relief valve; 12. Suction oil filter; 13. Return oil filter; 14. Electrical control unit; 15. Manual / automatic switch; 16. Control panel; 17. Audible and visual alarm device. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. Of course, the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0043] like Figure 1 – Figure 5 As shown, this invention provides a trench compactor with an automatic centering function, including a frame body 1, a hinge assembly 2, and a hinged main shaft 3 rotatably mounted inside the hinge assembly via two sets of support bearings. An integrated dustproof sealing component is integrated at the hinge mating position. This sealing structure can prevent mud, sand, and muddy water from entering the rotating pair, avoiding impurities causing hinge jamming and wear, and maintaining smooth steering operation over the long term. The compaction wheel bracket 6 is rigidly welded to the middle of the hinged main shaft 3, and the compaction wheel 7 is rotatably mounted at the bottom of the compaction wheel bracket 6. The compaction wheel 7 deflects left and right based on the rotation of the hinged main shaft 3, thereby completing the trench centering adjustment.

[0044] The centering detection mechanism in the trench compactor includes an angular displacement sensor 4 and a sensor vibration damping mounting assembly 5. The angular displacement sensor 4 is coaxially connected to the end of the main shaft 3, directly acquiring the real-time deflection angle of the compaction wheel 7. This results in a shorter signal transmission path and lower native acquisition error. The sensor vibration damping mounting assembly 5 uses rubber damping pads and locking flanges to form a flexible connection structure, physically isolating the sensor housing from the steering hinge assembly 2. This significantly attenuates the transmission of 30~50Hz operating vibration from the equipment to the sensor, eliminating signal drift and distortion caused by vibration at the hardware source, and preventing the electronic control unit 14 from receiving false offset signals and causing erroneous correction actions.

[0045] The hydraulic actuators in the trench compactor include a double-acting symmetrical steering cylinder 8, an electro-hydraulic proportional directional valve 9, a hydraulic pump 10, a pressure relief valve 11, an oil suction filter 12, and a return oil filter 13. The steering cylinder 8 is hinged to the main frame 1, and the piston rod is hinged to the compaction wheel support 6, ensuring balanced thrust on both sides and eliminating unilateral impact during steering. The hydraulic pump 10 outputs oil that undergoes pre-filtering by the oil suction filter 12, and the oil returning from the cylinder undergoes secondary fine filtration by the return oil filter 13, achieving double purification of the oil circuit medium. The pressure relief valve 11 limits the system's safe operating pressure to 16MPa, automatically releasing pressure when the oil pressure exceeds the limit. This prevents overload damage to pipelines and cylinders, maintains the cleanliness of the hydraulic oil over a long period, and reduces malfunctions such as proportional valve core jamming and internal leakage in the cylinder.

[0046] The core of the overall control is the electronic control unit 14, which uses an industrial-grade anti-vibration microcontroller. Internally, it integrates a signal filtering module, a zero-position calibration module, a segmented PID closed-loop control module, and a fault diagnosis and protection module. A fixed 20ms control cycle is uniformly set to balance control response speed and system stability. The signal filtering module employs an 8-point moving average filtering algorithm to perform secondary noise reduction on the original angle signal from the sensor, forming a dual anti-interference system of "hardware vibration reduction + software filtering" with the front-end vibration reduction structure. The zero-position calibration module supports one-click reference storage on the control panel 16. After new machine assembly or component replacement, only a single calibration is needed to eliminate the inherent angle deviation caused by the overall assembly, making it more adaptable to new equipment installations and on-site modifications. The segmented PID closed-loop control module divides the deflection deviation into three independent parameter groups, specifically addressing the industry shortcomings of slow response and easy oscillation in the median position of single-parameter PID control with large offsets. The fault diagnosis and protection module presets multiple judgment thresholds to achieve early audible and visual warnings for abnormalities and dual protection against hardware lockouts in case of faults.

[0047] The human-machine interface module includes a manual / automatic switch 15, a control panel 16, and an audible and visual alarm device 17, all of which are electrically connected to the electronic control unit 14. The system strictly enforces manual operation as the highest priority. If the system is switched to manual mode at any time during operation, the automatic return circuit is immediately cut off, preserving the emergency manual takeover authority. The control panel 16 centrally supports one-button calibration and control parameter modification functions. The audible and visual alarm device 17 simultaneously outputs audible and visual alerts when deflection exceeds limits, sensor is open-circuited, or hydraulic overload occurs, facilitating rapid fault identification and timely handling by on-site personnel.

[0048] like Figure 4 As shown, the present invention also provides an automatic centering control method for a trench compactor, the detailed implementation steps of which are as follows:

[0049] Step 1: Zero-position calibration of the center reference. Manually operate the compactor to move it and precisely adjust the compaction wheel 7 to the center line of the trench. Trigger a one-click calibration command through the control panel 16. The electrical control unit 14 collects the current angle value output by the angular displacement sensor 4 in real time and stores it as a permanent center reference. A single calibration can be adapted to the assembly tolerance of this equipment, without the need for repeated calibration.

[0050] Step 2: Switch to automatic centering mode. Turn the manual / automatic switch 15 to the automatic position. The electronic control unit 14 continuously collects data from the angular displacement sensor 4 and starts the closed-loop centering control program.

[0051] Step 3: Dual noise reduction preprocessing of sensor signals. The angular displacement sensor 4 collects the original deflection signal of the compaction wheel 7 in real time. First, the vibration interference is weakened by the vibration damping mounting component, and then the signal is sent to the 8-point moving average filter module in the electronic control unit 14 to remove instantaneous bump noise. The effective angle data after noise reduction is sent to the core computing unit.

[0052] Step 4: Segmented PID graded correction adjustment. The electronic control unit 14 calculates the difference between the real-time acquired angle and the stored reference zero position, calculates the deflection deviation of the compaction wheel 7, and matches the PID control parameters in three levels:

[0053] When the absolute value of the angular deviation is greater than ±2°, the large proportional gain is activated for rapid adjustment, driving the electro-hydraulic proportional directional valve 9 to quickly switch directions, controlling the steering cylinder 8 to quickly extend and retract, and pushing the compaction wheel 7 to quickly return to the center of the groove, thus avoiding continuous deviation that could result in large-area pressure leakage and uneven compaction.

[0054] When 0.5° < absolute value of deviation ≤ ±2°, switch to conventional PID parameters to smoothly adjust the cylinder stroke, reduce steering mechanism impact, and protect articulated and hydraulic components;

[0055] When the absolute value of the deviation is ≤ ±0.5°, the proportional gain and derivative gain are reduced simultaneously to weaken the adjustment output force, suppress system overshoot oscillation, and stabilize the centering error of the compaction wheel 7 within ±0.5°, ensuring uniform compaction of the entire trench backfill.

[0056] After the compaction wheel 7 returns to the center position, the electronic control unit 14 continuously outputs a small compensation signal to offset the slight displacement caused by terrain bumps and maintain the centered working state for a long time.

[0057] The entire control process is synchronously equipped with hierarchical fault protection logic: the system presets a ±2° correction start threshold and a ±5° audible and visual alarm threshold; if the deflection angle of the compaction wheel 7 exceeds ±5°, the audible and visual alarm device 17 will continuously trigger a warning to remind the operator to intervene and correct in time; if the signal of the angular displacement sensor 4 is broken or the oil circuit working pressure exceeds 18MPa overload fault, the electronic control unit 14 will immediately cut off the automatic control circuit and lock the steering cylinder 8 to prevent the mechanism from overtraveling and squeezing the trench wall and the hydraulic pipeline from bursting; the manual mode can be switched back at any time during the entire operation, the automatic centering function will immediately fail, and the compaction wheel 7 will be fully controlled by the operator to avoid construction safety hazards caused by abnormal automation programs.

[0058] This embodiment presents preferred operating parameters: hydraulic system rated working pressure 16MPa, electrical control cycle 20ms, 8 filter sampling points, correction start threshold ±2°, and over-limit alarm threshold ±5°. Those skilled in the art can adjust these parameters accordingly based on the trench width and overall compactor specifications without departing from the core mechanical structure and segmented PID hierarchical control concept of this invention.

[0059] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A trench compactor with automatic centering function, comprising a frame body (1), a compaction wheel support (6), a compaction wheel (7) rotatably mounted on the bottom of the compaction wheel support (6), and a steering hinge assembly (2) connecting the frame body (1) and the compaction wheel support (6), characterized in that, Also includes: The centering detection mechanism consists of an angular displacement sensor (4) and a sensor vibration damping mounting assembly (5). The angular displacement sensor (4) is coaxially mounted on the end of the hinge main shaft (3) of the steering hinge assembly (2) to collect the deflection angle of the compaction wheel (7). The sensor vibration damping mounting assembly (5) is set between the angular displacement sensor (4) and the steering hinge assembly (2) to physically isolate the interference of the whole machine vibration on the sensor. The hydraulic actuator includes a double-acting symmetrical steering cylinder (8) and an electro-hydraulic proportional directional valve (9). The cylinder body of the steering cylinder (8) is hinged to the frame body (1), and the piston rod is hinged to the compaction wheel bracket (6). The electro-hydraulic proportional directional valve (9) is used to control the extension and retraction of the steering cylinder (8). The electronic control unit (14) is electrically connected to the angular displacement sensor (4) and the electro-hydraulic proportional directional valve (9), respectively. The electronic control unit (14) has a built-in signal filtering module, a zero-position calibration module, a segmented PID closed-loop regulation module and a fault diagnosis and protection module. The human-machine interaction module is connected to the electronic control unit (14) and includes a manual / automatic switch (15) and a control panel (16). The manual / automatic switch (15) is configured such that the manual mode has a higher priority than the automatic mode, and the automatic return-to-center function is immediately disabled in the manual mode.

2. The trench compactor with automatic centering function according to claim 1, characterized in that, The sensor vibration damping mounting assembly (5) is a flexible connection structure composed of a rubber vibration damping pad and a locking flange. The housing of the angular displacement sensor (4) is flexibly connected through the rubber vibration damping pad to isolate the transmission of high-frequency vibration acceleration to the sensor housing.

3. The trench compactor with automatic centering function according to claim 1, characterized in that, The hinge portion of the steering articulation assembly (2) is integrated with a dustproof sealing component. The hydraulic oil supply circuit of the hydraulic actuator is equipped with an oil suction filter (12), an oil return filter (13), and a pressure relief valve (11). The pressure relief valve (11) limits the maximum working pressure of the system to 16MPa.

4. The trench compactor with automatic centering function according to claim 1, characterized in that, The signal filtering module uses a moving average filtering algorithm with 8 points to filter out vibration noise; the zero-position calibration module supports one-click reference calibration to store the calibrated reference angle value to eliminate equipment assembly errors; the control cycle of the electronic control unit (14) is 20ms.

5. The trench compactor with automatic centering function according to claim 1, characterized in that, The segmented PID closed-loop control module is configured as follows: When the angle deviation is greater than ±2°, activate the large proportional gain for rapid adjustment. When the angle deviation is in the range of 0.5° to 2°, switch to conventional PID parameters for smooth correction. When the angular deviation is less than ±0.5°, reduce the proportional gain and derivative gain to suppress system oscillation.

6. The trench compactor with automatic centering function according to claim 1, characterized in that, The fault diagnosis and protection module has a preset correction start threshold of ±2° and an alarm threshold of ±5°. When the deflection angle exceeds ±5°, an audible and visual alarm is triggered. When the sensor signal is interrupted or the hydraulic pressure exceeds 18MPa, the system immediately cuts off the automatic circuit and locks the mechanism.

7. The trench compactor with automatic centering function according to claim 1, characterized in that, The human-computer interaction module also includes an audible and visual alarm device (17), which is connected to the electronic control unit (14) and is used to issue an audible and visual prompt when the deflection angle exceeds the limit or when the system malfunctions.

8. An automatic centering control method for a trench compactor, applied to the trench compactor with automatic centering function as described in any one of claims 1 to 7, characterized in that, Includes the following steps: S1: Adjust the compaction wheel (7) to the center line of the trench, and perform one-key zero-position calibration through the control panel (16). The electronic control unit (14) collects the current value of the angular displacement sensor (4) and stores it as the zero position of the centering reference. S2: Switch the manual / automatic switch (15) to the automatic position, and the device enters the automatic return-to-center working state; S3: The angular displacement sensor (4) collects the deflection angle of the compaction wheel (7) in real time. The original signal is transmitted to the processing core after being denoised by the signal filtering module in the electronic control unit (14). S4: The electronic control unit (14) compares the real-time angle with the reference zero position to calculate the angle deviation. Based on the deviation range, it calls the corresponding PID parameters in the segmented PID closed-loop adjustment module and outputs control signals to drive the electro-hydraulic proportional directional valve (9) and control the steering cylinder (8) to extend and retract to complete the correction action. S5: After the compaction wheel (7) returns to the center, the system maintains a stable state and controls the deviation within ±0.5°.

9. The automatic centering control method for a trench compactor according to claim 8, characterized in that, The specific logic of the segmented PID closed-loop regulation in S4 is as follows: When the angle deviation is greater than ±2°, the large proportional gain is activated for rapid adjustment, driving the steering cylinder (8) to push the compaction wheel (7) to quickly return to the center position; When the deviation is reduced to the range of 0.5° to 2°, switch to conventional PID parameters for smooth correction. When the deviation is less than ±0.5°, reduce the differential gain and proportional gain to keep the compaction wheel (7) stably in the center position.

10. The automatic centering control method for a trench compactor according to claim 8, characterized in that, It also includes fault protection steps: when the deflection angle exceeds ±5°, the audible and visual alarm device (17) triggers an alarm; when the angular displacement sensor (4) signal is interrupted or the hydraulic pressure is abnormal, the electronic control unit (14) immediately cuts off the automatic circuit and locks the mechanism; at any time during operation, when switching to manual mode, the automatic return-to-center function immediately fails, and the steering is fully controlled by the human.

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