What is an inertial sensor ?
Pilots cannot rely on vision and senses to determine horizontal orientation in the air; they must rely on flight instruments. According to FAA research, the human orientation system is complex and performs exceptionally well on the ground. However, in the air, the human body is in an unfamiliar three-dimensional environment, and without visual orientation references, managing spatial (distance) orientation becomes difficult or impossible. At this point, humans are susceptible to spatial orientation impairments and must rely on external assistance to achieve accurate positioning. Inertial sensors offer a solution.
How are inertial sensors manufactured?
To ensure the reliability of inertial sensors, their manufacturing process is crucial. Assembly accuracy and conditions affect the overall characteristics of the sensor. Assembly errors can lead to incorrect inertial signal transmission, potentially affecting aircraft flight paths and, in combat situations, even causing the loss of the entire battle. Although there has been some research on the intelligent assembly of miniature precision sensors in China in recent years, the production and assembly of inertial sensors are currently all done manually. Due to the small size of the components and the high precision requirements, manual operation is required under a magnifying glass, resulting in poor product consistency and demanding high skill levels from personnel. Only one company, Beiganglian, has been conducting research and development on this precision assembly technology for several years.
Figure 1 Schematic diagram of inertial sensor
What can an inertial sensor-based intelligent assembly line do?
The inertial sensor intelligent assembly line enables automated feeding, dispensing, coaxial assembly, and bonding of parts, improving the accuracy, efficiency, and consistency of component assembly. This line accepts three types of incoming materials:
1) Part 1, diameter 9.4mm, thickness 0.8mm;
2) Part 2, 9.4mm in diameter and 4mm in thickness, with a pre-installed ring;
3) Part 3, diameter 22mm, thickness 7.6mm (can be customized depending on the model).
*To protect military secrets, all components are designated by code names.
Figure 2 Schematic diagram of inertial sensor assembly line
The line mainly consists of part 1/2/3 conveyors, part 1/2/3 conveyor trays, finished product conveyors, finished product trays, vision systems 1/2/3, dispensing machines A/B, 6-axis robots A/B, assembly platforms, and control systems. It can realize automated adhesive bonding and assembly processes such as automatic positioning and gripping of parts, automatic dispensing and assembly, and finished product unloading and clamping using inertial sensors.
Figure 3 Assembly process flow diagram
How can we ensure perfect assembly precision?
Vacuum suction cups enable the assembly of fragile, small-sized parts.
The inertial sensor requires components with a minimum diameter of Φ9.4mm and a thickness of 0.8mm. Conventional robotic arms cannot grasp these components, and the grasping process could easily damage them. Furthermore, due to the characteristics of the product, the components cannot be handled using magnetic attraction. This line utilizes a small vacuum chuck with a Φ5mm diameter suction head, which can smoothly pick up and transfer the components without causing damage during the process.
Customized grippers enable automated distributed dispensing.
When dispensing adhesive manually, the uncertainty of human intervention makes it difficult to guarantee the correct dispensing position and amount. Furthermore, the adhesive used for dispensing at the center and outer ring of a part consists of two different adhesives, which can easily lead to adhesive mixing during manual operation. The 6-axis dispensing robot utilizes a customized gripper developed by Beiganglian, featuring rotary indexing. It can automatically rotate according to the preset number and position of dots to cooperate with the dispensing machine for distributed dispensing, achieving an indexing accuracy of 5' and an adhesive volume accuracy of 2μL.
The tapered structure ensures that the assembled parts are coaxial in height.
Manual assembly, relying on magnifying glasses, visual inspection, and auxiliary tools to control coaxiality, is time-consuming and results in poor product accuracy repeatability. The newly developed production line assembly platform is equipped with conical assembly fixtures. Through the conical structure and the conical cooperation of the robot, a high-precision requirement of 0.03mm coaxiality can be achieved, with high accuracy repeatability and significantly improved assembly efficiency.
Before the inertial sensor assembly line was implemented, manual operation yielded 2,000 units (8 hours) and required 10 skilled operators. With robots, a vision system, and a PLC system controlling the orderly operation of each device, the upgraded production line achieves a daily output of 3,000 units, eliminating the need for human intervention and significantly reducing labor costs. Currently, my country is placing increasing emphasis on its aviation industry, which is developing rapidly. Intelligent assembly systems based on industrial robots will greatly shorten product production cycles and powerfully promote the rapid development of national defense and military industries.
