Aiming at the measurement and positioning process of assembly and docking of aerospace and rail transit vehicle parts, in order to solve the problems of large measurement field range and complicated use of multiple measurement equipment combination, the calibration method of dual-vision measurement system facing assembly and docking was studied. By constructing the model of the dual-vision measurement system, analyzing the relationship between the camera parameters between the systems, introducing closed-loop constraints and LM algorithm to optimize the camera parameters in the single binocular system, and using the improved EPnP algorithm to calibrate the dual-vision system, and combining the self-designed double-sided one-dimensional target to complete the global calibration and coordinate conversion of the dual-vision system. The simulation docking experiment results show that the optimized calibration algorithm is superior to the traditional algorithm in accuracy, and simplifies the measurement steps and improves the measurement efficiency in the process of use.
Magnesium aluminum composite plate is an aluminum–magnesium–aluminum sandwich composite plate formed by covering a layer of aluminum on the surface of magnesium alloy. Compared with magnesium alloy, the corrosion resistance of composite plate has been effectively improved and the forming ability has been significantly improved. This paper summarizes the preparation methods and forming processes of magnesium aluminum composite plate. It introduces the research progress of different preparation methods of magnesium aluminum composite plate, compares and analyzes the advantages and disadvantages of different preparation methods. It analyzes the shortcomings of the existing forming methods of magnesium aluminum composite plate structure, and puts forward the corresponding solutions, so as to provide reference for the application of magnesium aluminum composite plate structure in the field of aviation and aerospace.
Because of the transmission errors and the elastic deformations of reducer and lead screw-nut pair, active joints inevitably suffer from following errors that significantly degrade the dynamic contour accuracy of hybrid robots. An effective dynamic accuracy control strategy based on the grating sensors installed on the wrist and the passive limb was resented in this paper for improving the dynamic contour accuracy in these hybrid robots. After addressing the design principle of a PID + feedforward and Lyapunov stability based control law with the position feedbacks of the grating sensor and the servo motor encoder, a dynamic accuracy compensator was developed. Experimental results on a TriMule-200 hybrid robot show that the dynamic contour accuracy of the robot is significantly improved with the maximum reduced dynamic error of 82.88%, which verifies the effectiveness of the proposed dynamic accuracy control strategy.
Surface coating is an important operation in the manufacturing of machines and parts with super large size such as aircrafts, ships and high-speed railway. The coating robot applied in large working space is the key equipment to realize the automatic spraying of large machines and parts. It is also one of the core technologies to improve the competitiveness of China’s high-tech manufacturing field, especially aviation products. On the basis of introducing the research status of coating robots in recent years, this paper summarizes some main problems in the application of coating robots for large space aircraft, and discusses the future development trend and technical challenges of painting technology in the field.
Aiming at the problems of poor consistency, low efficiency, limited accessibility and poor working environment in manual operation mode during the gluing process of aircraft large components, the automatic gluing system for gantry hanging robot was designed. Through the calibration of the vision system and the correction of the theoretical gluing trajectory, the gluing system evaluates the affecting factors of the gluing technology parameters, obtains the matching relationship between the robot running speed and the motor speed, and constructed multifunctional end-effector integrating industrial cameras, laser contour scanners and other equipment. At the same time, an integrated control system and software are developed to realize the automatic coating of sealant with high efficiency and quality for large size aircraft components. The test results show that the accuracy of the gluing track is ± 0.5 mm, and the accuracy of the rubber strip is ± 0.5 mm, which can fully meet the actual process requirements.
The hyper-redundant robot with high flexibility and large aspect ratio structure is a feasible way to accomplish the intelligent operation of deep cavity tasks in the process of manufacturing, assembly and maintenance of aviation equipment. Aiming at the problem of efficient and safe operation of the hyper-redundant robot in complex deep cavity space, a path-following motion method for hyper-redundant robot suitable for real-time teleoperation was proposed. The simulation results show that the average solution time of the path-following method is 0.413 ms, and the maximum deviation of the conical spiral curve path movement is 0.011 mm, which meet the requirements of real-time movement and safe and precise operation. A virtual teleoperation simulation platform based on ROS-Gazebo is developed, which provides a low-cost means of virtual training and simulated operation. The experimental results show that the path-following method ensures the efficient and safe movement of the hyper-redundant robot in the complex deep cavity.
Advanced composite materials have been widely used in the aerospace industry and other fields due to their high specific strength, specific modulus, substantial weight reduction and good corrosion resistance. AFP machine is the necessary equipment to realize automatic laying, which is an important link affecting the laying quality and production efficiency. Therefore, the development and improvement of AFP machine has become one of the most critical issues in the manufacture of complex components of composite materials. Based on the automatic laying equipment at home and abroad in recent years, this paper discusses and analyzes the current research and application status of AFP machine based on the main structure of machine tool, the form of yarn frame, the pressure system of laying head, the heating system and the tension system, summarizes the research results of automatic laying equipment at home and abroad, analyzes the advantages and disadvantages of domestic and foreign laying equipment. Finally, the future development trend of automatic silk laying equipment is discussed and summarized, which provides a reference direction for the design and optimization of silk laying machine.
A 3D finite element model of thermal barrier coating (TBC) system considering the interface morphology is established by using the finite element method. By calculating the change of residual stress at the interface when cooling from high temperature to room temperature, the influence of interface geometry on the residual stress of the TBC system is studied. The results show that the thickness of the TGO layer not only affects the magnitude of the residual stress, but also affects the stress state, and the thicker the TGO layer, the higher the residual stress level in the same model. The increase of the interface amplitude will increase the residual stress at the interface of the bond layer (BC) – TGO, but its influence on the residual stress at the interface of the ceramic layer (TC) – TGO is more complicated. The effect of increasing the interface wavelength will reduce the residual stress level to some extent; The 3D hybrid roughness parameter has less effect on the residual stress. Therefore, the thickness of the oxide layer, the interface amplitude and the wavelength will greatly affect the residual stress of the TBC, which in turn affects the stability of the TBC system, and the thickness of the oxide layer has a decisive significance on the failure location of the coating.
Deformable fidget spinner is a popular toy, and its multi-chain and deformable advantages provide a solution for space robots. Inspired by this toy, this paper introduces a multi-chain reconfigurable modular robot by combining the flexible and versatile characteristics of chain robots. Topological configurations of multi-chain reconfigurable modular robots are investigated with a focus on configuration analysis and configuration transformation strategies, enabling them to change their topological configurations to suit different tasks. Firstly, combined with integer splitting and permutations, a library of basic non-isomorphic configurations for modular robots with positive hexagonal bases is established, and a non-isomorphic configuration enumeration algorithm is proposed, which shows that the number of non-isomorphic configurations grows exponentially with the number of modules. Secondly, a configuration matching reconfiguration strategy is designed to optimally match and convert between configurations by defining a library of equivalence relations based on structural features, with configuration conversion as the core. Finally, the effectiveness of the reconfiguration strategy is verified through demonstration and simulation.
The experiment and three-dimensional finite element simulation of single diamond abrasive grinding SiCp /Al composites are carried out. The effects of grinding parameters on grinding force and surface morphology of SiCp /Al composites were analyzed. The analysis results show that the grinding force decreases with the grinding speed increasing, the breakage of SiC particles is alleviated, the coating effect of aluminum matrix is enhanced, and the surface morphology integrity is good. The grinding force increases with the grinding depth increasing, SiC particle breakage is significantly enhanced, more pits and holes are formed on the surface, and the surface quality is poor. The simulation results are consistent with the experimental results, which shows that the model can be used to optimize the grinding process parameters.
Combined with the preparation process and structural characteristics of continuous fiber reinforced titanium matrix composite (TMCs) monolithic blade rings, this paper focuses on the analysis of the difficulties in ultrasonic detection of the internal quality of TMCs monolithic blade rings, and through the ultrasonic detection test and anatomical analysis of specific size of TMCs monolithic blade rings. The main defect types and ultrasonic echo signal characteristics such as fiber breakage, fiber bundle cracking, fiber buckling, fiber extrusion and crack at weld were determined. The test results show that the sensitivity of the inner quality of the integral blade ring of TMCs can reach Φ0.8 mm equivalent flat bottom hole based on appropriate ultrasonic detection process parameters.
The rapid development of mixed reality (MR) technology has opened up new possibilities for remote collaborative tasks in assembly scenarios. As the preparatory work of the MR collaboration system, physical virtualization is the main task of providing reliable model support and the relationship between the virtual and the real for user browsing and interaction. The existing methods cannot take into account the goals of high detail reduction and low virtualization cost of assembly parts at the same time. A precision recovery method of part model based on the principle of template matching and point cloud alignment is proposed to realize the replacement of the reconstructed point cloud model in the original scene using a high precision part CAD model. For the task related parts in the process of MR remote collaboration, firstly, the prior information related to the part point cloud is obtained through the segmentation of background point cloud based on background difference and octree spatial retrieval and the segmentation of foreground adhesive point cloud based on supervoxel to segment the ROI of the region of interest of template matching, which solves the problem of weak occlusion resistance and low template comparison efficiency of the original LineMod algorithm, and the identification matching and rough estimation of the part point cloud poses are completed. The estimated poses were then further optimized using the ICP algorithm to achieve positional recovery of the CAD model in the scene. Through the physical virtualization experiments of various parts in complex assembly scene, it is proved that this method can accurately identify the point cloud of parts and realize accurate physical virtualization, which has important practical value in MR remote collaborative task.
The ignition and diffusion combustion of TB12 flame-retardant titanium alloy were studied by friction test under simulated environment of aircraft engine compressor. The results showed that TB12 alloy could be burning under friction heat. The rotor and stator test piece could be ignited at the very beginning of friction, resulting in the size reduction of the test piece. However, because of the insensitivity to diffusion combustion of TB12 alloy, the combustion stop quickly, which is different from TC4 titanium alloy continuous diffusion combustion. The combustion products of TB12 alloy were possessed of good properties of strong adhesion, high strength, lubricating function and low thermal conductivity, thus making them adhesive to the surfaces of the test pieces, which reduced the fri ction heat and prevented the friction heat transition from surface to the matrix. According to the combustion characteristics of TB12 alloy, it can be designed for compressor stator blades. The TB12 blade could stop burning after initial combustion, and the combustion products will prevent friction between stator blades and rotor drum afterwards. The design and application of TB12 alloy in stator blades can reduce the risk of titanium fire failure caused by drum instability and friction between drum and stator blades.
In order to eliminate the hole diameter error caused by tool wear in robot automatic drilling system, a method based on spindle current discrete wavelet transform for tool wear state online monitoring and life prediction was proposed. Firstly, according to the fluctuation law of the spindle current signal and the requirements of the regularization, similarity and smoothness of the curve error of the wavelet signal, the 3rd-order Daubechies wavelet base is selected to carry out the discrete decomposition of the spindle current signal. Combined with the law of tool wear, the 3rd-order lowfrequency decomposition of the current signal is selected as the most effective feature of tool wear state monitoring. The first order high frequency decomposition of the current signal is carried out by discrete Fourier transform to obtain the frequency characteristics of the high frequency component, which provides a basis for electromagnetic compatibility design. Finally, the least square method was used to fit the linear relationship between tool wear and spindle current characteristic value, and realized the online monitoring of spindle tool wear state and the prediction of tool life by monitoring the characteristic value of spindle current.
