Tech Front: Reliable 3D Bin-Picking Solution
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 is to apply these natural processes to robot handling. To be able to remove randomly placed items from a container as a human requires the complex interaction of image recognition system software, robots, and a sophisticated handling strategy.
This intelligent removal of items, such as the automated picking of unsorted components, is referred to as random bin-picking. After picking up the part from a container the item must then be perfectly positioned onto production lines as well as on assembly lines. Custom bin-picking solutions for components weighing between 1–50 kg deliver the potential for productivity and efficiency increases in many industries including automotive, commercial vehicles, general engineering and aerospace.
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/higher output
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 require," said Thomas Mattern, head of R&D for Automation Systems at Liebherr Verzahntechnik GmbH (Kempten, Germany).
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 usability.
Liebherr has created complete bin-picking systems for the automotive industry and for other industries. These systems include efficient channeling of nonrotationally symmetrical components that 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 (Munich). These systems 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 3D 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, and subsequently 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.
With 40 years of automation technology experience, Liebherr has achieved bin-picking process reliability for a variety of industrial applications that otherwise have only been possible under laboratory conditions. "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 users," Mattern said. ME
For more information on Liebherr, go to www.liebherr.us, e-mail firstname.lastname@example.org, or call 734-429-7225.
Tech Paper Resources
Brought to Light
From SME’s beginnings to today’s new horizons, practitioners and researchers take pride in sharing their experience and insights to inspire, prepare and support the advancement of manufacturing. Over time there’s been a shift toward fewer written papers and more presentations and webinars, but the desire to communicate fundamental concepts, innovative breakthroughs, industry trends and best practices remains strong.
Complementing ME Media’s timely editorial coverage is SME’s continually updated collection of more than 17,000 technical papers and 1100 peer-reviewed journal articles. Both types of papers are available for individual purchase, as subscriptions and as a free benefit of SME membership. Go to www.sme.org/publications. Beginning in this issue, Tech Front will regularly explore highlights and topical slices of the SME Technical Papers. We’ll keep on eye on the research efforts, collaborations and conferences that support shop-floor improvements, showcase new developments and help attract future generations to a passion for manufacturing. The papers mentioned in Tech Front are located by entering the paper number in the search box at www.sme.org/techpapers.
An obvious starting point in checking out the SME Technical Papers is a list of top papers. It’s probably no surprise that topics related to lean dominate the top 25 downloads since 2009. The word lean appears in the titles of 18 of the 35 papers among these downloads, with six sigma, cell design, continuous improvement, setup/cycle time reduction, kanban, kaizen and just in time also appearing.
First on the list, with apologies to David Letterman, is "The Top Ten Secrets of Lean Success: How to Make Your Implementation Work" (paper TP09PUB115) by David R. Dixon of Technical Change Associates (Ogden, UT). The paper was presented at FABTECH in 2009 and has been downloaded 177 times in its English version. Due to its popularity, the paper was translated into French in 2012 (TP12PUB3). The author summarizes experiences over many years of launching lean initiatives with clients.
In another top-accessed paper, David Csokasy (DJC Group; Franklin, OH) and Paul Parent (ProSol LLC; Winsted, CT) answer their own question of the differences between managing in a traditional manufacturing environment as opposed to "Managing Lean Manufacturing" (TP07PUB2). Although the paper focuses on identifying and developing lean management techniques, Csokasy and Parent emphasize that the content is just as applicable to manufacturing organizations that operate more traditionally.
More on how to lead an organization through change is the topic of Kathy Miller and Shari Lewchanin’s 2006 paper. They list several common faulty assumptions of leaders and consultants, including assuming that a leader is ready to change and lead with logic, believing change will be simple, presuming that people who are ambivalent to change will resist it and thinking that leading change can be delegated. In "Leading Change: What a Surprise" (TP06PUB149), minimizing the surprise factor amounts to this: Successful leaders of change do more than merely announce the new direction and then leave the dirty work to others.
A model for companies determining "Critical Training Requirements for Lean Manufacturing" (TP07PUB15) was developed by S. Arunachalam, M. Ichimura, and T. Page based on surveys, interviews and company visits at several companies in the UK. Some of the important factors identified for workers in lean manufacturing—high motivation, teamwork and flexibility, and multiple skill sets—can be negatively influenced by an uptight working environment and lack of strategy in human resources.
Six sigma is the theme of several more popular papers. Another paper by S. Arunachalam, "Operational Excellence Through Six Sigma" (TP05PUB21), emphasizes how investing in quality improvement methodologies should be considered equally important to investment in equipment and machinery.
"Combining Lean and Six-Sigma for Optimal Results" (TP06PUB123) discusses these two powerful philosophies and their supporting tools for improving quality, productivity, profitability and market competitiveness in a holistic manner. Authors Elizabeth Cudney, Merwan Mehta, and Richard Monroe propose using the DMAIC process, a basic six-sigma tool, to merge the implementation of both philosophies, resulting in impressive results and substantially reduced waste and variation.
Maintenance can be a large overhead expense in most lean facilities. "Six Sigma Keys to Lean Maintenance Reliability in 30–60 Days" (TP04PUB308) by Howard C. Cooper uses DMAIC to help eliminate root causes of unscheduled downtime and scrap and rework (low yield) in several plants. With proper expertise, these methods can be implemented in 30-60 days for 70–92% reduction of unscheduled downtime. "Preventive Maintenance of Dies" (TP07PUB190), as author C. Padmanabhan from India describes, involves rectifying quality issues—like scratches, burrs and breakage—as well as quantity-related issues such as ejection, handling and packaging. The cost of preventing failure is less when compared with the cost of repairing. Just as important is a tool that is properly designed so its operation can be predicted. The data from die performance and production feedback will ensure positive results of preventive maintenance and become predictive maintenance. ME
TechFront is edited by Senior Editors Patrick Waurzyniak, email@example.com and Ellen Kehoe, firstname.lastname@example.org.
This article was first published in the July 2013 edition of Manufacturing Engineering magazine. Click here for PDF.