AGV-Synchronized Assembly for Accurate Moving-Line Positioning
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Solution Overview
Problem
Automotive assembly lines face challenges in achieving high accuracy and speed due to irregular motion and vibrations of vehicle bodies, which current robot automation systems struggle to compensate for, especially when conveyor systems are in motion, leading to positioning errors and potential collisions.
Innovation Solution
A method utilizing real-time visual servoing and compliant behavior control, where two vision systems monitor the movement of Automated Guided Vehicles and the target area, allowing the assembly robot to synchronize its movements with the vehicle's motion, compensating for errors without stopping the conveyor, and using a force/torque sensor to adjust for external forces during assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If robot automation is used in assembly lines, then productivity and consistency are improved, but positioning accuracy deteriorates due to conveyor vibrations and irregular motion
Solution Approach 1:
The system continuously measures the actual position of the vehicle body and conveyor using sensors (laser scanners, encoders, vision systems) and feeds this information back to the robot controller. The controller dynamically adjusts the robot's positioning based on real-time feedback, compensating for vibrations and motion irregularities, thereby maintaining high positioning accuracy while operating at high speeds on a moving conveyor
Solution Approach 2:
The system transitions from static, predetermined robot programs to dynamic, adaptive control. The robot controller continuously updates its motion commands based on real-time measurements of conveyor position and vehicle body location, allowing the robot to adapt its positioning dynamically during the assembly process, thus maintaining accuracy despite the moving target
2Manufacturing precision
If the conveyor is stopped to determine target coordinates, then positioning accuracy is improved, but productivity deteriorates due to assembly line interruptions
Solution Approach 1:
The system performs preliminary measurements of the vehicle body's position and dimensions using laser scanners and vision systems while the vehicle is still moving on the conveyor. These preliminary measurements are processed in advance to calculate the precise target coordinates, so that when the robot needs to assemble, the positioning information is already available, eliminating the need to stop the conveyor
Solution Approach 2:
The system replaces mechanical stopping and physical measurement methods with optical and sensor-based measurement systems (laser scanners, cameras, encoders) that can accurately determine target coordinates while the vehicle is in motion. This substitution of measurement technology allows continuous conveyor operation while maintaining high positioning accuracy
3Manufacturing precision
If synchronous motion control is used to track vehicle movement, then positioning accuracy is improved, but device complexity increases due to additional sensors and control systems
Solution Approach 1:
The system uses multi-functional sensors and control components that perform multiple tasks. For example, the laser scanner and vision systems not only measure vehicle body dimensions but also track its position and orientation. The encoder system serves both to monitor conveyor speed and to provide feedback for robot positioning. This multi-functionality reduces the need for separate dedicated components, thereby limiting the increase in overall system complexity while achieving high positioning accuracy through synchronous motion control
Data Source
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AI summary
A method for assembling parts in an assembly line, such as an automotive final assembly line,is disclosed.The method comprises advancing a part along the assembly line with an Automated Guided Vehicle (AGV), arranging a first real time vision system to monitor the position of the AGV in at least two directions, and providing the readings of the first real time vision system to a controller arranged to control an assembly unit of the assembly line to perform an automated operation on the part that is advanced or supported by the AGV.An assembly line is also disclosed.