In context
As manufacturing shifts toward intelligent automation, the need for precision assembly in confined spaces—such as inside aerospace and automotive engines—has grown. Traditional bolt assembly robots often struggle with limited axial and radial space, and existing end-effectors tend to be bulky or require complex control. This work addresses that gap with a compact, lightweight solution.
What was reported
Researchers at Dalian University of Technology designed a robot-mounted end-effector for automatic bolt assembly, targeting M4, M5, and M6 external hexagonal carbon steel bolts. The actuator measures 58 mm in length, 24 mm in diameter, and weighs about 150 g, making it suitable for confined spaces.
The mechanical design includes a magnetic socket that can be quickly swapped for different bolt sizes, and an automatic propulsion and reset mechanism using a tensile spring and spiral groove. This reduces the motion control burden on the robotic arm. Stress simulations in Inventor confirmed that all parts remain within allowable stress limits during both tightening and disassembly.
The control system uses an STM32 microcontroller with voltage and current dual closed-loop control. By regulating current, the system indirectly controls tightening torque, eliminating the need for a torque sensor and thus reducing size and weight. PID controllers were tuned via Simulink simulations. Practical tests showed the actuator can accurately perform installation, disassembly, and tightening of the specified bolts.
Why it mattered
This work demonstrates a practical approach to automating bolt assembly in tight spaces, potentially improving efficiency and reducing manual labor in maintenance and production of complex equipment. The lightweight, sensor-less design offers a path toward more versatile robotic end-effectors for industrial automation.
The automatic propulsion and resetting functions in bolt assembly process simplify the motion control of manipulator carrying the actuator.
Source: 《机器人》期刊 (robot.sia.cn) · Published 2025-09-16 · “机器人末端自动化螺栓装配执行器的设计与控制”