Robotic solution for the dismantling of aeronautical composites

INTRODUCTION

The continuous evolution and innovation in the aerospace industry have led to the adoption of composite materials [1], [2]. This measure has proven to be an effective solution for reducing aircraft weight without compromising the high mechanical properties offered by metallic materials. Consequently, their integration into the sector is nearly complete, with aircraft incorporating these materials into key structural components [3]. However, advancements in manufacturing processes inevitably necessitate updates and revisions to aircraft end-of-life policies.

Currently, end-of-life management primarily focuses on aircraft engines, due to their potential for reuse [4], and aluminum components, aiming to reduce the environmental footprint of aircraft [5]. However, regarding composite materials, the ongoing growth of the aerospace industry demands the development of new strategies for their disposal and recycling. According to Ribeiro et al. [6], 44% of the current aircraft fleet will reach the end of its service life within the next two decades, resulting in approximately half a million tons of composite waste by 2050 [7].

In addition to the lack of specific legislation and a standardized dismantling model, the aircraft dismantling industry requires a paradigm shift in its current methods. At present, diamond saw cutting and shredding are the most commonly employed techniques for aircraft disassembly [8]. However, these methods are imprecise, hindering the accurate identification and separation of materials, which in turn limits their potential for reuse or recycling.

Authors such as Keiser et al. [9] propose the implementation of a component tracking system as a viable solution to improve the identification and traceability of valuable parts for dismantling and recycling. This would be particularly relevant in the case of composite materials, whose projected market growth exceeds 8% within the aerospace sector, as well as in other strategic industries such as defense and energy [10].

In parallel with the industrial expansion of composite materials, recycling technologies have also seen significant advancements. Among them, pyrolysis has emerged as the most widely adopted method for recovering reinforcement materials, particularly carbon fibers [11], [12]. This process involves high-temperature thermal decomposition in an oxygen-free environment, allowing the polymer matrix to break down while preserving the reinforcing fibers with minimal damage.

Ultimately, the goal is to recover both the matrix and the reinforcement elements [13]. In this regard, emerging processes such as solvolysis—a chemical method that uses solvents to induce the depolymerization of plastic matrices—are gaining attention due to their potential to effectively reclaim both components.

However, the persistent problem of the lack of adequate dismantling techniques makes the correct application of the above recycling processes impossible, not to mention the complete reuse of components. To address this issue, the present study proposes the use of a manually guided Abrasive Water Jet (AWJ) cutting system, allowing the operator to accurately select and dismantle specific areas of the aircraft structure.

AWJ cutting is a well-established technology in industrial applications, commonly used to section both metallic and non-metallic components. Its application to composite materials has been tested in various studies [14], [15], demonstrating promising results in terms of precision and minimal thermal impact. Furthermore, this technology has been successfully applied to Grade 5 titanium (Ti-6Al-4V). This material is widely used in the aerospace sector for high-strength fasteners and structural joints [16], [17]. This opens the door to the potential use of water jet cutting for the removal of riveted joints, offering a more targeted and less invasive dismantling approach.

As previously mentioned, the high-pressure water jet cutting process employs a focused jet of water to penetrate surfaces of varying thickness and mechanical resistance. This jet exhibits a conical configuration, as illustrated in the Figure 1. The cutting cone can be divided into three distinct regions:

1. Solid Core: The central area with the highest cutting power.

2. High-Density Zone: A region with increased water flow concentration. The cone’s diameter expands proportionally with the distance from the nozzle, leading to a gradual decrease in cutting power.

3. Mist Zone: The outermost region of the jet, where the water disperses into a mist with insufficient energy to perform effective cutting.

Figure 1 Abrasive Water Jet (AWJ) cutting definition

As can be deduced from this segmentation, cutting energy and precision are inversely proportional to the distance from the nozzle. Therefore, system parameters must be configured to operate within the so-called Continuous Jet Region, which ensures maximum cutting efficiency and produces cleaner cuts. Otherwise, the process would damage the material due to cone widening or erosion effects associated with the low-energy mist zone.

Additionally, cutting pressure and abrasive material selection are critical factors that directly influence the quality and precision of the cut.

METHODOLOGY

The robotic dismantling process using abrasive water jet cutting is composed of three interconnected subsystems:

• ROBOMIMIC imitation-based programming platform,

• Mobile robotic system for path execution, and

• Abrasive water jet cutting tool.

ROBOMIMIC Imitation Programming System

ROBOMIMIC is an advanced imitation learning system that leverages multi-camera 3D capture and real-time processing. In this way, the worker is able to optimize robotic learning for complex dismantling tasks, particularly those involving large aerospace components. This no-code solution enables intuitive programming by allowing skilled operators to physically demonstrate the desired cutting paths using a fake tool that emulates the water jet cutting head (Figure 2) which includes an ArUco target to perform camara identification.

Figure 2 AWJ fake tool with ArUco target

Multiple camera views capture the operator’s motion from various angles, while a central processor translates the captured data into precise 6D motion trajectories. These trajectories are then filtered and simplified to retain the most representative cutting path points (Figure 3), which are subsequently executed by the robotic system.

Figure 3 ROBOMIMIC point detection - example

This method enables domain-expert operators to directly transfer their knowledge and expertise to the robotic platform, facilitating safer, more efficient, and adaptable dismantling operations.

Mobile robotic system

The mobile robotic cutting system integrates a collaborative robotic arm with a mobile abrasive water jet cutting platform. This platform is fully equipped with all the necessary peripherals to operate autonomously, including a high-pressure water pump, water and abrasive reservoirs, and onboard batteries.

Platform mobility is enabled through an Automatic Guided Vehicle (AGV), which incorporates an integrated lifting system to accurately position the cutting assembly. Navigation and positioning within the workspace are achieved using a SLAM (Simultaneous Localization and Mapping) system, which allows the AGV to map its environment, self-localize, and return to the charging station as needed.

In line with the ROBOMIMIC programming-by-demonstration paradigm, the robotic system is precisely localized within the work zone through the use of ArUco marker tags. This closed-loop detection system ensures the robotic cutter aligns correctly with the cutting path previously recorded by the operator.

The internal positioning and tracking workflow of the mobile cutting platform integrated within the ROBOMIMIC visualization interface is illustrated in Figure 4.

Figure 4 (a) Positioning of the AGV system within the work zone. (b) Docking and alignment of the robotic water jet cutter. (c) Detection of ArUco tags within the working environment. (d) Execution of the water jet cutting operation based on the trajectory recorded by ROBOMIMIC

Abrasive Water Jet cutting tool

The AWJ cutting system employed in the guided robotic dismantling process was parameterized through extensive cutting trials on materials with varying configurations and thicknesses, including metallic components and carbon-fiber-reinforced composite materials.

To evaluate the system's performance under the most demanding dismantling conditions, rivet extraction tests were conducted. These experiments aimed to determine the minimum viable cutting jet diameter required for high-precision disassembly operations, particularly in components with mechanical fasteners.

Additionally, cutting strategies were tested on stacked carbon fiber laminate specimens, both in direct contact and with internal gaps, in order to replicate realistic aerospace structural scenarios. These trials provided valuable insight into the system’s effectiveness when dealing with complex geometries and multi-material interfaces commonly found in aircraft structures.

CASE STUDY

The guided robotic dismantling system was tested at the PLATA facilities (Aeronautical Consortium of Teruel Airport) using a carbon-fiber-reinforced composite aircraft structure. The tested structure corresponded to Section 19 of an Airbus A350, making the test scenario highly representative of a real-world aircraft dismantling environment.

The demonstration was divided into two experimental approaches:

1. Cutting based on CAD-designed geometry

2. Cutting guided by operator demonstration

In both cases, the experimental setup remained consistent. The aircraft section was mounted on a support frame within the PLATA facility. A virtual model of the hangar and the structure was created, allowing the robotic system to locate both its charging station and the work zone.

The first step in both tests involved the approach of the water jet cutting platform to the target area through the AGV, which navigated via its integrated SLAM system while avoiding obstacles. Upon reaching the work zone, a closed-loop positioning system refined the robot’s alignment to prepare for the dismantling operation.

Cutting Based on CAD-Designed Geometry

In this initial test, the goal was to evaluate the system's ability to perform complex cuts on aerospace-grade composite materials. The test involved cutting the Aitiip logo from the aircraft structure. Using the ROBOMIMIC system, the cutting head was oriented perpendicular to the surface, and the automated trajectory was executed. The results, shown in Figure 5, demonstrate the system’s precision and capability in performing intricate cuts on real aircraft composite structures.

Figure 5 Cutting demo based on CAD-designed geometry

Operator-Guided Cutting via ROBOMIMIC

The second test showcased the operator-guided dismantling paradigm using the ROBOMIMIC system. Instead of executing a pre-programmed path, the operator used a mock cutting tool to manually trace a desired dismantling path in the work zone.

This motion was captured in real time by the multi-camera vision system, which tracked the ArUco marker attached to the tool. The recorded trajectory was then filtered and simplified, extracting the most relevant cutting points. Once the operator exited the safety zone, the robotic system executed the cutting operation autonomously, replicating the demonstrated path to dismantle the selected composite area. This process is illustrated in Figure 6, which visualizes both the path recording and execution phases.

Figure 6 Operator-Guided Cutting via ROBOMIMIC. (a) Operator performing the guidance operation (b) Vision software detecting and processing the route taken (c) Robotic dismantling system performing the marked cutting route (d) Robotic dismantling system performing the marked cutting route.

CONCLUSIONS

The guided robotic dismantling system met the operational expectations successfully, demonstrating its ability to target high-value areas of an aircraft and execute precise cuts, either operator-guided or through automated software-defined trajectories. The key findings from the experimental validation are summarized below:

• The system can accurately perform and replicate complex cutting paths, achieving a measured positional precision of ±1 mm.

• The high-pressure water jet cutting technology proved highly suitable for dismantling tasks, demonstrating capabilities ranging from fine-detail operations such as rivet removal to cutting large composite sections.

• As the system is capable of recycling working water, water waste is minimal, and it is considered a closed consumption loop. However, the water collection and reuse system must be optimized.

• The mobility and positioning system of the robotic cutting platform through the AGV system was also validated under industrial conditions. However, outdoor operations may pose challenges due to the AGV's wheel configuration, which is currently designed for indoor environments. This will be a primary area for improvement in future iterations.

In conclusion, the proposed system has been validated as a robust and versatile robotic solution for tailored aircraft dismantling. While originally designed for operations on composite components, the system has proven effective across a wide range of materials, enhancing its potential for broader industrial application.

ACKNOWLEDGMENT

Author Contributions: All co-authors have covered all tasks of this research.

Funding: The authors gratefully acknowledge the European commission for support through the financial aid under the framework Proyectos Estratégicos orientados a la transición ecológica y a la transición digital program, through the project AIR2BUILD (Exp: TED2021-131157B-C22). This study has been performed by members of the CT AITIIP research group.

Conflicts of Interest: The authors declare no conflict of interest.

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