Large Depth Measurement System

1、 System Introduction

Beijing Kexin Mechatronic Research Institute Co., Ltd. relying on the strong scientific research force of "Beijing University of Information Technology" and deep cooperation, has achieved breakthroughs in the theory and methods of large-scale and high-precision visual measurement after more than ten years of research and precipitation. It has solved key technical problems such as measurement models, camera calibration, image processing, target matching, 3D reconstruction, and accuracy evaluation, and successfully applied the research and development results to large-scale aerospace equipment In the production of equipment in the aerospace, military, and civilian fields such as radar antennas, solar thermal, wind power generation, and ultra long precision displacement platforms, the manufacturing, assembly, and operation quality and level of equipment have been effectively improved.

In the fields of national defense and aerospace, weapons and equipment represented by cruise missiles are generally equipped with dedicated launch boxes. In order to ensure the reliability and stability of the equipment launch process, there are extremely strict requirements for the assembly process of the launch box, which has characteristics such as large depth, high accuracy, long assembly time, and real-time monitoring throughout the entire process. Traditional measuring instruments cannot meet the requirements.

Combining the real-time inspection requirements for the assembly of large depth missile launch boxes, the research on visual measurement theory has been transformed to solve the key technologies of large depth and high-precision visual measurement. A digital automatic measurement system for the assembly of large depth equipment has been developed to improve product manufacturing efficiency and quality level, which is of great significance for promoting the development of manufacturing technology and quality assurance of related equipment such as national defense and aerospace in China.

2、 System composition

The system mainly consists of an imaging system, a box reference fixture (front flange fixture, rear flange fixture), a guide rail testing fixture, and a bulletproof mechanism testing fixture, a computer, and system software.

1. Imaging system

Camera: The imaging system uses a single 25 megapixel industrial camera and a 50 mm prime lens, and carries out system parameter calibration to improve the image quality of the tested box and tooling.

Light source: The system uses an infrared light source to provide illumination, and infrared narrowband filters are installed on the camera lens to overcome environmental light interference and improve imaging quality.

Thermostat: The camera is placed in a thermostat to prevent the system from being affected by temperature.

Figure 1 System Appearance

2. Tooling

The system includes three types of measurement fixtures: box reference fixture, guide rail measurement and adjustment fixture, and bulletproof mechanism measurement and adjustment fixture, which respectively achieve spatial coordinate reference establishment, guide rail installation and adjustment, and bulletproof mechanism installation and adjustment. The three types of measuring fixtures are shown in Figure 2. Install a reflective target point on the fixture as a visual measurement target.

Figure 2 Tooling

3. System software

The software and hardware systems of the guide rail assembly and digital measurement system are combined to achieve independent measurement of the guide rail and the bulletproof mechanism, and real-time feedback of adjustment data to the installation personnel. The main functions include: management of debugging projects, camera posture, guide rail measurement, bulletproof structure measurement, output debugging reports, etc. The software interface is shown in Figure 3.

Figure 3 Software Interface

3、 Technical indicators

1. Working environment temperature: -20 ° C~+50 ° C

2. Rail assembly and digital measurement system measurement range: 3-15m

3. Measurement error: not greater than 0.1mm within 15m range

4. Implement real-time measurement and data processing of the deviation between the horizontal and vertical directions of the guide rail position and the theoretical position during the installation and adjustment process, with a real-time frequency of 3-5 Hz

4、 Application Prospects

At present, this achievement has been applied to real-time detection of relevant parameters and assembly results such as long-distance guide rails and bulletproof mechanisms during the assembly process of the missile launch box, providing guidance for the assembly process.

Based on the theory and key technologies of large depth digital precision measurement, the system has a certain degree of scalability. It can be used for real-time detection of other large-scale equipment in large depth and high-precision assembly sites by simply modifying measurement fixtures and other accessories for tasks, adjusting observation targets and workflow. It has broad application prospects. Typical application requirements include: testing of different types of missile launch boxes, monitoring of assembly processes for aircraft, high-speed trains, submarines, etc., and testing of ultra long precision displacement platforms