Inertial navigation laser and micro-arc oxidation cooperative amphibious tank surface anticorrosion process

Abstract

The application discloses an inertial navigation laser and micro-arc oxidation cooperative amphibious tank surface corrosion prevention process and belongs to the technical field of precise control of equipment inertial navigation equipment. The process comprises an inertial navigation positioning module, a laser surface pretreatment module, a mobile micro-arc oxidation module and a central control module. The inertial navigation positioning module is used for acquiring the three-dimensional attitude information and position coordinates of the tank body surface area to be treated in real time, comprises an inertial measurement unit (IMU) and a data processing unit, and realizes rapid and accurate positioning by adopting a matching model based on angular velocity integration and specific force integration. The laser surface pretreatment module adopts a top hat beam laser, and the tank surface is cleaned and activated by uniform energy distribution. The mobile micro-arc oxidation module adopts a spraying type cathode design and a three-axis motion sliding table, and realizes local micro-arc oxidation treatment of the tank surface. The central control module cooperatively controls the laser pretreatment and micro-arc oxidation treatment path and parameters according to the inertial navigation positioning information, and realizes full automation processing.

Description

Technical Field

[0001] This invention belongs to the field of precision control technology for inertial navigation equipment. Background Technology

[0002] As special equipment adapted to both marine and terrestrial environments, amphibious tanks face severe corrosion and complex mechanical wear on their surfaces. The corrosive factors such as chloride ions and humid salt spray in the marine environment, combined with the impact of sand and gravel and mechanical wear in the terrestrial environment, significantly shorten the equipment's service life and maintenance cycle.

[0003] Currently, amphibious tanks primarily employ traditional coating technologies for surface protection, such as epoxy resin coatings and polyurethane coatings. However, these coatings suffer from problems like insufficient adhesion, poor wear resistance, and limited corrosion resistance, making them prone to premature failure, especially under the combined effects of marine corrosion and mechanical wear. Furthermore, for large, complex-shaped tank hulls, traditional fixed surface treatment techniques struggle to achieve uniform coating coverage, particularly at edges and welds where weak areas are likely to appear.

[0004] Micro-arc oxidation (MAO) is a surface modification technology that grows ceramic coatings in situ on valve metal surfaces, which can significantly improve the corrosion resistance and wear resistance of materials. However, traditional MAO technology has the following limitations: (1) it requires immersing the entire workpiece in a large electrolytic cell, making on-site construction impossible; (2) for large workpieces such as tank bodies, it requires the construction of ultra-large electrolytic cells, resulting in huge equipment investment; (3) when processing workpieces with complex shapes, there is an edge effect, leading to poor coating uniformity. In addition, micro-defects (such as micropores and microcracks) in the MAO coating can become channels for corrosive media to penetrate, accelerating coating failure.

[0005] Laser technology, as a non-contact, precise, and controllable surface treatment technique, can be used to remove surface contaminants and oxides. However, traditional Gaussian laser modes, due to uneven energy distribution, are prone to producing pulse pits and spatter edges on the surface, which can actually reduce the material's corrosion resistance. Furthermore, current technologies lack effective means for precise positioning and path planning on large, complex curved surfaces, making it difficult to ensure the uniformity and consistency of surface treatment.

[0006] Therefore, developing a surface treatment system and method that can adapt to the complex curved surface structure of amphibious tanks, achieve precise positioning and processing, and possess excellent corrosion resistance and wear resistance has become an urgent technical challenge. Summary of the Invention

[0007] (a) Purpose of the invention This invention aims to overcome the shortcomings of existing technologies and provide a surface anti-corrosion process for amphibious tanks based on inertial navigation laser and micro-arc oxidation. The core objective of this method is to utilize an inertial navigation technology that enables rapid alignment without singularities at arbitrary misalignment angles to accurately determine the real-time pose of a mobile processing device relative to the tank hull surface. Based on this, the laser pretreatment and mobile micro-arc oxidation processes are synergistically controlled to efficiently and uniformly prepare a high-performance ceramic coating with strong adhesion, corrosion resistance, and wear resistance on complex curved surfaces.

[0008] (II) Technical Solution To achieve the above-mentioned objectives, the present invention adopts the following technical solution: To achieve the above objectives, the technical solution adopted by this invention is a surface anti-corrosion process for amphibious tanks based on the synergistic combination of inertial navigation laser and micro-arc oxidation, characterized by the following steps: Step S1: System setup and initial transfer alignment At least three non-collinear reference points are selected on the tank hull, and a high-precision main inertial navigation system is installed. A sub-inertial navigation system is installed at the end effector of a mobile processing robot equipped with a laser cleaning head and a micro-arc oxidation spray cathode. An inertial coordinate system (i-frame) is established with reference to the initial alignment start time.

[0009] The transfer alignment algorithm based on the angular velocity integral + specific force integral matching model is initiated: Using the fixed installation matrix between the master and sub-inertial navigation systems (INS) as the state to be estimated, a measurement model is constructed in the inertial frame using the outputs of their gyroscopes and accelerometers. Real-time estimation is performed using a Kalman filter. After alignment, the current attitude matrix of the sub-INS (i.e., the processing terminal) can be obtained using the following formula: Step S2: Surface Modeling and Path Planning Based on Inertial Navigation A mobile robot carrying a sub-inertial navigation system and a 3D laser scanning probe is controlled to scan the area of ​​the tank to be processed along a planned path. Using the precise pose association established in step S1, the scanned data is unified into the tank's coordinate system, generating a high-precision three-dimensional curved surface digital model. Based on the model's curvature characteristics and coating performance requirements (such as thickness), laser cleaning and micro-arc oxidation processing paths are planned.

[0010] Step S3: Laser surface pretreatment for inertial navigation guidance Following the planned path, the mobile robot carries the laser cleaning head. The system reads the pose data from the sub-inertial navigation system in real time and matches it with the surface model in S2, achieving real-time and accurate coordinate transformation from the machining tool coordinate system to the surface model, thereby performing closed-loop position compensation for the laser focus. A pulsed laser is used to scan and clean the tank surface, with the following laser parameters: scanning speed 1000-1500 mm / s, Q-pulse frequency 20-30 kHz, and rated power 20-30 W. Laser treatment can remove oil, rust, and loose oxide layers, and achieve surface micro-roughening and activation, reducing the subsequent MAO arc initiation threshold.

[0011] Step S4: Mobile micro-arc oxidation treatment under inertial navigation control The pretreated surface area is used as the anode, employing a spray-type cathode design. The preferred electrolyte formulation is: sodium aluminate 10-40 g / L, sodium carbonate 3-8 g / L, and sodium dihydrogen phosphate 3-8 g / L. The electrolyte is delivered to the spray cathode, forming a localized electrolytic circuit between the cathode and the tank surface.

[0012] A mobile robot carrying a spray cathode moves along a planned path. An inertial navigation system continuously provides high-frequency (100Hz) pose feedback, ensuring optimal distance and orientation between the spray head and the surface at any position on the tank's curved surface. Micro-arc oxidation is performed in constant current mode with the following electrical parameters: current 1-2 A, voltage 450-650 V, pulse duty cycle 5%-15%, pulse frequency 500-1500 Hz, and spray head moving speed 10-30 mm / s. Under plasma discharge, a dense ceramic coating primarily composed of -Al₂O₃ is grown in situ on the workpiece surface.

[0013] Step S5: Online monitoring and post-processing Infrared thermal imagers and voltage / current sensors integrated into the machining head are used to monitor the temperature field and electrical signal stability of the machining area in real time, providing feedback to adjust the moving speed or electrical parameters to prevent ablation. After single-area processing is completed, the surface is cleaned with deionized water spray and dried to complete the machining process.

[0014] (III) Beneficial Effects Compared with the prior art, the present invention has the following significant advantages: It breaks through the limitations of workpiece size and shape: adopting a mobile processing strategy, it replaces the traditional fixed electrolytic cell. Through the relative movement of the workpiece and the electrode, it realizes the local or overall uniform processing of large-sized and complex-structured workpieces. The equipment is highly flexible and widely applicable.

[0015] The process achieved synergistic efficiency: the innovative laser pretreatment process provided ideal substrate conditions for subsequent micro-arc oxidation. The rapid remelting effect of the laser refined the surface grains, improved surface activity and roughness, significantly reduced the arc initiation voltage and energy consumption of micro-arc oxidation, and promoted the formation of a strong metallurgical bond between the ceramic coating and the substrate, greatly improving the bonding strength of the coating.

[0016] The problem of precise positioning and path tracking of large and complex curved surfaces has been solved: the inertial navigation transfer alignment technology, which is applicable to large misalignment angles, fast and non-singular, has been creatively introduced into the field of surface engineering. This has achieved centimeter-level positioning accuracy and 0.1-level attitude accuracy of the mobile processing terminal relative to the moving ground of the tank body, providing core technical support for high-precision curved surface processing in field environments without GPS or fixed reference.

[0017] This technology achieves uniform and controllable high-performance coatings: real-time high-precision pose feedback via inertial navigation ensures that the laser pretreatment and micro-arc oxidation spray head maintain the optimal process distance and angle with complex curved surfaces, fundamentally overcoming the coating uniformity problem caused by uneven electric field or beam distribution in traditional methods. Laser pretreatment further activates the surface, enabling the subsequently grown MAO coating to achieve a metallurgical-chemical composite bond with the substrate, significantly improving the bonding strength.

[0018] Breaking through the limitations of equipment size and site, it is highly practical: adopting mobile local spraying processing, it completely abandons the giant electrolytic cell. The equipment is flexible and portable, and can perform in-situ, local or overall treatment of amphibious tanks in the field, workshop or battlefield maintenance point, which greatly expands the application scope of micro-arc oxidation technology.

[0019] Significant synergistic effects from the process: Laser pretreatment combined with inertial navigation-guided mobile MAO forms a complete technological closed loop. Laser provides an ideal substrate for MAO, while inertial navigation ensures processing accuracy. The resulting ceramic coating has low porosity, high hardness, and excellent corrosion and wear resistance, making it particularly suitable for harsh amphibious conditions. Attached Figure Description

[0020] Figure 1 This is a surface electron microscope image of Example 1. Figure 2 This is the friction effect under different loads in Example 1. Detailed Implementation Example 1: System Setup: The main inertial navigation system (INS) with an accuracy of 0.01 / hr is installed at three reference points on one side of the amphibious tank hull. A six-DOF robotic arm, equipped with a sub-INS (MEMS-level), a pulsed laser head, and a micro-arc oxidation spray head, forms a mobile platform. Initial Alignment: The transfer alignment algorithm is initiated, lasting 15 seconds. A Kalman filter stably estimates the installation matrix, completing the initial alignment of the sub-INS. Surface Scanning and Modeling: The robotic arm, carrying a 3D line laser scanner, scans an area of ​​approximately 2m x 1.5m on the side deck. Combined with precise pose data, a digital model with a flatness error within 0.5mm is generated.

[0021] Laser preprocessing: Planning the grating-style scanning path. Laser parameter settings: scanning speed 1200 mm / s, frequency 25 kHz, power 25 W. The inertial navigation system compensates for the robotic arm's positioning error in real time, ensuring that the laser focus remains constant in the normal direction of the curved surface.

[0022] Micro-arc oxidation treatment: Electrolyte used: sodium aluminate 25 g / L, sodium carbonate 5 g / L, sodium dihydrogen phosphate 6 g / L. Electrical parameters: current 1.5 A, voltage 580 V, duty cycle 10%, frequency 800 Hz, spray head moving speed 20 mm / s. Treatment time 30 minutes.

[0023] Result: See Figure 1 A uniform gray ceramic coating was obtained. The average coating thickness was measured to be 353 μm, and the microhardness reached HV1500. The critical load for adhesion, determined by the scratch test, exceeded 50 N. After immersion in a 3.5 wt.% NaCl solution for 720 hours, no corrosion pits were found on the substrate.

[0024] Example 2: Repeat steps S1-S2 to model the turret section with complex curved surfaces. Path planning and adaptive control: For high curvature areas, the path planning algorithm automatically densifies path points. During processing, real-time read sub-inertial navigation attitude data is used to dynamically adjust the Euler angles of the spray head, ensuring its axis is always aligned with the local normal of the curved surface.

[0025] Process adjustments: The electrolyte is the same as in Example 1. To adapt to the curved surface, the current is finely adjusted to 1.2 A, the voltage is adjusted to an adaptive 550-600 V, and the moving speed is reduced to 15 mm / s to increase the local processing time.

[0026] Results: A uniform coating with a thickness of 285 μm was successfully applied across the entire curved surface of the turret. Even at the edges, no excessive coating thickness or ablation was observed. The coating passed a 1000-hour neutral salt spray test, achieving a corrosion rating of level 9.

[0027] Comparative Example: Traditional Fixed Bath Micro-arc Oxidation Treatment The same tank-grade aluminum alloy material as in Example 1 was selected, and the test plate was 300mm x 200mm in size. It was immersed in a large electrolytic cell with the same composition as in Example 1 and treated for 30 minutes using the same power parameters (current density converted from Example 1).

[0028] Results: The coating thickness was uneven, reaching 50 μm at the edges and only about 20 μm in the central area, with numerous microcracks present at the edges. Electrochemical testing showed that its impedance modulus was only about one-third that of the coating obtained by the method of this invention, indicating poor corrosion resistance.

[0029] Example 3: Online Identification and Repair of Coating Defects During the processing in step S4, by monitoring abnormal fluctuations in the electrical signal (such as short-circuit pulses), the system can identify online a local micro-area where coating discontinuity may be caused by original surface defects.

[0030] The system records the inertial navigation coordinates of the defect point.

[0031] After completing the processing of the entire area, control the mobile platform to accurately return to the coordinate point.

[0032] Repeat steps S3 (laser cleaning) and S4 (micro-arc oxidation) in the localized area at this point to perform targeted repair processing.

[0033] Result: After repair, the coating in this area fused well with the surrounding coating, and penetrant testing showed no defects. This demonstrates the unique advantage of the method of this invention in precise positioning and repair.

[0034] As can be seen from the above embodiments, the present invention successfully integrates high-precision inertial navigation technology with laser-micro-arc oxidation surface treatment technology, forming a complete, efficient and innovative solution for in-situ surface strengthening of large and complex equipment, especially providing a revolutionary technical approach for corrosion protection of amphibious tanks.

Claims

1. A surface anti-corrosion process for amphibious tanks based on the synergistic combination of inertial navigation laser and micro-arc oxidation, characterized in that, Includes the following steps: S1: Install a main inertial navigation system on the tank hull and a sub-inertial navigation system at the end of the mobile processing device; establish an inertial coordinate system based on the initial alignment time; utilize the gyroscope and accelerometer outputs of the main and sub-inertial navigation systems; employ a matching model based on angular velocity integral and specific force integral; estimate the fixed installation matrix between the main and sub-inertial navigation systems using a Kalman filter; and complete the initial transfer alignment and real-time attitude determination of the mobile processing device. S2: Based on the high-precision pose determined in step S1, the scanning device carried by the mobile processing device performs three-dimensional digital modeling of the surface of the tank to be processed, and plans the laser pretreatment and micro-arc oxidation processing path according to the model. S3: Control the mobile processing device to carry the laser cleaning head, move according to the path planned in step S2 and the real-time pose feedback provided in step S1, and perform laser scanning preprocessing on the surface of the tank. S4: Control the mobile processing device to carry the micro-arc oxidation spray cathode, move according to the path planned in step S2 and the real-time pose feedback provided in step S1, and use the mobile spray method to perform micro-arc oxidation treatment on the pre-treated tank surface to grow a ceramic coating in situ.

2. The method according to claim 1, characterized in that, In step S1, the matching model that uses angular velocity integral and specific force integral as measurements is specifically as follows: In the aforementioned inertial frame, the integral measurement relationship of angular velocity is as follows: The relationship between specific force integral measurement is as follows: Where $\omega_{is}^{is}$ and $f_{is}^{is}$ are the angular velocity and specific force measurements of the sub-inertial navigation system in the inertial frame, respectively; $\omega_{im}^{m}$ and $f_{im}^{m}$ are the angular velocity and specific force outputs of the main inertial navigation system in the carrier coordinate system; $\mathbf{C}s^m$ is the fixed installation matrix between the main and sub-inertial navigation systems to be estimated; $\mathbf{C}i^m(t)$ is the attitude tracking result of the main inertial navigation system in the inertial frame; $\omega{ms}^{is}$ is the flexural deformation angular velocity; and $\delta \mathbf{z}{\omega}$ and $\delta \mathbf{z}_{f}$ are noise terms.

3. The method according to claim 1, characterized in that, In step S3, the process parameters for the laser scanning preprocessing are: laser scanning speed 1000-1500 mm / s, Q modulation pulse frequency 20-30 KHz, laser rated power 20-30 W, and actual working power 50%-60% of rated power.

4. The method according to claim 1, characterized in that, In step S4, the process parameters for the mobile micro-arc oxidation treatment are: operating current 1-2 A, operating voltage 450-650 V, pulse duty cycle 5%-15%, pulse frequency 500-1500 Hz, and the moving speed of the spray cathode relative to the tank surface is controlled at 10-30 mm / s.

5. The method according to claim 1, characterized in that, In step S4, the electrolyte used in the micro-arc oxidation treatment consists of: sodium aluminate 10-40 g / L, sodium carbonate 3-8 g / L, sodium dihydrogen phosphate 3-8 g / L, and deionized water as the solvent.

6. The method according to claim 1, characterized in that, In step S4, the mobile processing device is a robotic arm with at least five degrees of freedom or a multi-axis linkage CNC slide, used to support the laser cleaning head and the micro-arc oxidation spray cathode, and to realize arbitrary position adjustment of them in space.

7. The method according to claim 1, characterized in that, The processing steps S3 and S4 are carried out under controlled conditions with an ambient temperature of 16-24℃ and a relative humidity of less than 60%.

8. A system for implementing the method of any one of claims 1-7, characterized in that, include: Inertial navigation and positioning subsystem: includes a main inertial navigation device installed on the tank body, a sub-inertial navigation device installed at the end of the mobile processing device, and a data processing unit for executing the transfer alignment algorithm and outputting the high-precision real-time pose of the mobile processing device; Mobile processing execution subsystem: includes a multi-degree-of-freedom mobile platform, and a laser cleaning head, a micro-arc oxidation spray cathode, and a three-dimensional scanning probe integrated at its end; The central control subsystem is communicatively connected to the inertial navigation and positioning subsystem and the mobile machining execution subsystem, respectively. It is used to receive pose data, execute surface modeling and path planning algorithms, and generate control commands to coordinate the control of the laser preprocessing and micro-arc oxidation processes.

9. The system according to claim 8, characterized in that, The micro-arc oxidation spray cathode integrates an electrolyte delivery pipeline, an insulating nozzle, and a high-voltage interface, enabling localized and continuous supply of electrolyte and the establishment of a discharge circuit.

10. The system according to claim 8, characterized in that, The central control subsystem also integrates a process parameter database and an online monitoring module. The online monitoring module is used to collect voltage, current signals and infrared thermal imaging signals during the processing and to provide feedback for adjusting the process parameters.

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