Humans have it easy. We intuitively use our eyes and sense of touch to grab and move objects. The mobility of our arms and hands are unrivaled by any machine. The ultimate industrial automation challenge in principal is to apply these natural processes to robot handling. To be able to remove randomly placed items from a container as a human accomplishes requires the complex interaction of image recognition system software, robots and a sophisticated handling strategy.This intelligent removal of items, i.e. the automated picking of unsorted components, is referred to as random bin picking. After picking up the part from a container they must then be perfectly positioned onto production lines as well as on assembly lines. The industrial scale automation of this process offers three key advantages without having to invest in additional machinery to be integrated into existing facilities:
•Increases output through higher productivity •Allows shop personal time for other requirements •Greater reproducibility/consistent quality
“There are plenty of ideas and models on the market that address this yet most only function under laboratory and test conditions. Such concepts have failed in the past because of process reliability in actual work environments. We have since been able to create process reliable solutions for customers that achieve the cycle times and high availability rates they demand”, reports Thomas Mattern, head of R&D for Automation Systems at Liebherr Verzahntechnik GmbH.
The core of this challenge is the seamless interaction of various complex processes and technologies. In this case computers, software and strategy perform activities that are controlled by the human brain. Additionally, each individual process must be inherently reliable. Specifically advances in image recognition technology and computing power in standard PCs promote process reliability and its marketability.
Reference projects demonstrate what can presently be achieved using versatile robot systems. Liebherr has created complete systems, among other sectors, for the automotive industry. This includes the efficient channeling of non-rotationally symmetrical components which arrive randomly in a bin and can be placed into production lines and hardening ovens. The beginning of a production line is the key point where picking from the bin is necessary.
Liebherr developed and tested this technical solution under practical conditions in cooperation with the Fraunhofer Institute. These systems must comply with the constraints of actual production customer specifications and on-site safety regulations at all times. The Fraunhofer Institute contributed its knowledge derived from many years of research as well as its experience in camera systems and software. An important breakthrough occurred with the object recognition system. The 3-D laser scanner precisely recognizes the components for picking. Outside light of any type in the production building has zero effect on the ability to pick a part. It will even recognize black, brown and rusty parts. The accompanying software segments identify and select information about items and constraints in the bin provided.
Specially developed grippers with additional axes enable collision-free access and the removal of items from the container. Subsequently this allows for precise positioning of the item into a fixture or pallet. The mobility of the human “gripping apparatus” cannot be completely copied, but can be adequately mimicked. For maximum precision the component in the mechanical gripper is aligned through an in-process inspection method accurate to a tenth of a millimeter. In cases of gripping failure the system continues with minimal delay due to a special automatic correction strategy.
Custom bin-picking solutions for components weighing between 1 and 50 kilograms deliver the potential for productivity and efficiency increases in other industries besides the construction machinery industry including automotive, commercial vehicles, general engineering, aerospace technology and other commercial industries.
“When creating process reliable solutions like these engineering performance and skills must always be factored into handling strategies. This is especially applicable when interacting with complex systems and production lines. With 40 years of automation technology experience custom-ers can rely on us to provide a full service from the first consultation onward especially when it comes to complicated tasks”, stresses Mattern with regard to the significance of overall expertise in finding answers to hard questions.
Years of automation systems experience in a variety of sectors and industries with a diversity of requirements, constraints, regulations and other similar factors have enabled Liebherr to achieve bin-picking process reliability for a variety of industrial applications that otherwise have only been possible under laboratory conditions. Mattern summarizes: “This is only possible by combining theoretical knowledge from the research institute with practical experience from Liebherr as the systems provider and then analyzing and implementing the individual production conditions and specifications in close collaboration with customers.”