Robotized Moving Line Assembly Based on Sensor Fusion
Heping Chen*, Thomas Fuhlbrigge and George Zhang
ABB Corporate ResearchCenter
2000 Day Hill Road
Windsor, Connecticut06095
*
Tel: 860 285-6925
Assembly tasks using industrial robots have increased in both number and complexity over the years because of the increasing requirements of product quality and quantity.However, assembly robots are still a small portion of total robot sales each year. One of the main reasons is that it is difficult for conventional industrial robots to adjust to any sort of change. Therefore, more intelligent industrial robotic systemsare rapidly expanding the realms of possibility in assembly applications because they can perform assembly tasks with high autonomy and adaptability to the environments.
Moving line assembly (Assembly is performed while the part is moving) is an intelligent robotic system based on vision, force and position sensor fusion. The robot can track the moving object while performing the assembly process.Moving line assembly receives more and more attention in both academia and industry because the work cells are fully automated without stopping the assembly line. Therefore, it can save huge amounts of manufacturing resources by replacing "Stop-stations" where robots work in a stationary and fully calibrated environment.
There is some research work in the moving line assembly. Some researchers used stereo vision systems. The processing of stereo information enables a robot to determine the position and orientation of an object in the robot coordinate frame. However, an accurate calibration between the camera coordinate system and robot coordinate system has to be realized. Because the stereo vision system requires high quality camera and accurate calibrations, the existing systems are costly, error prone and not robust enough for daily use at the workshop. Also the complicated computation for determining the position and orientation of an object makes the system difficult to be implemented in real time applications.
This paper discusses an assembly technology while the object is moving using visual and force servoing. The wheel loading process, which assemblies the wheel into the wheel hub of a vehicle on a moving assembly line, is used as an example to demonstrate the developed technology. A working system has been set up and experiments of loading wheels onto the wheel hub have been implemented and performed successfully. The experimental results demonstrate that the developed technology can be used for assembly while the assembly line is moving randomly.
Presenting author biography
Heping Chen is a research scientist at Robotics and Automation Lab, ABB Corporate Research Center, ABB Inc. He received his Ph.D. in Electrical and Computer Engineering from Michigan State University, Michigan, in 2004. He published more than 40 journal/conference papers and several patents. He received several awards including the Best Paper Award from the distinguished IEEE Transactions on Automation Science and Engineering, Quality Salute Award from ABB Inc., the Most Outstanding Graduate Student Award from MichiganStateUniversity and the Highly Commended Awards from the Journal of Industrial Robots. His research interests include industrial robotics and automation, machine vision, sensor fusion, micro/nano robotics, and control system design andimplementation.