Absolute and Smart Inline Inspection is a Game Changer

We have witnessed in-line and at-line robotic measurement solutions gathering momentum over the past year with numerous solutions coming to market and supply companies being the subject of acquisitions. Metrology News sat down with ZEISS (Robert Wasilesky Global Key Account Manager – Automated Inspection) to gauge its views on the market, applications and the technology that will drive the growth in this market sector.

Q: When and how did ZEISS enter the inline robotic inspection market?

ZEISS acquired HGV Vosseler GmbH in 2012 to strengthen further measurement capabilities and extending ZEISS solution offering for the automobile vehicle body arena from quality control into process control. The acquisition was strategic and based upon the identified future trend to ‘Serial Measurement’ whereby 100% of primary features are inspected on 100% of production parts. HGV was a top 3 company for 3D inline measuring solutions based on optical measuring technology mounted on industrial robots, having developed a very strong presence in the domestic German automotive industry. ZEISS global reach provided the opportunity for HGV to deliver solutions to a wider potential and globalize the automotive customer base. In addition to 3D inline measuring technology, HGV also offered innovative optical image processing systems for quality inspection to a much broader array of manufacturing industries.

Q: Are the ZEISS robotic measurement solutions aimed predominantly at the automotive industry or do they have wider applications?

Our goal is to supply every measurement that is required by Industry 4.0. ZEISS automated measurement solutions range from dimensional inspection to surface defect analysis. Our customer base for ZEISS in-line and at-line solutions, with seamlessly integrated analytics, encompass consumer electronics, automotive, white-goods, aerospace frame and fuselage, aerospace power, medical and heavy machinery. Smart factories are being empowered by data analytics to fully adapt and control the production process. ZEISS metrology solutions are centric to the ‘intellectual spine’ of these ‘factories of the future’ regardless of industry.

Q: ZEISS recently launched its ‘absolute accuracy’ inline robotic inspection solution. What are the end user benefits of absolute measuring systems?

ZEISS has taken its expertise in the quality lab and has moved this to the shop floor. For too long the in-line measurement solutions used by the automotive industry for body-in-white (BIW) inspection required correlation with a quality laboratory dual horizontal-arm CMM. With ZEISS AICell trace absolute accuracy systems, we are delivering 100% production measurement efficiency with less wasted time and money by no longer needing the time-consuming and very expensive CMM comparison methodology driven off a set of ‘golden parts’. These past correlated solutions suffered double measuring uncertainties since both the CMM and the in-line system have measurement uncertainty as well, which must also be taken into consideration with the temperature variability affecting all in-line production measurements. Estimates of the annual correlation costs for the previous comparative measuring system are estimated to be in excess of $1 million per annum when all factors are taken into consideration.

In addition, the robots themselves experience significant ‘warm-up’ times again impacting these comparative measuring systems.  Any attempt to compensate for thermal drift in these systems is never the required 6 Degrees of Freedom (6DoF) offset but merely an inaccurate single offset value. The systems capability to offset in 6DOF is a key performance differentiator and a significant advantage against other systems.  Also, the system positioning capability is accurate by intrinsic calibration methods which give ZEISS AICell trace the performance edge over other solutions in accuracy, modularity and cost.

ZEISS AI Cell trace, absolute measuring systems, are calibrated and certified to the international ISO 10360 – 8 standard for measuring devices with optical sensors resulting in a traceable, certified inline CMM.

Q: The ZEISS AIMax cloud structured light sensor captures much more than the traditional single laser line scanner that has been used for inline measurement for decades. Why is structured light important for inline measurement applications?

A static ‘robot pose’ based solution, where there is no robot motion during part measurements is inherently more accurate than a robot-in-motion as it moves a laser line scanning sensor across the part surface. The static pose eliminates what would be another degree of measuring uncertainly – and one that is very difficult to measure and compensate. Some manufactures have introduced MEMS driven laser-line scanners to reduce robot motion but offer a very limited measuring range and associated data capture resulting in longer measurement times and considerably lower signal to noise ratios. The ZEISS AIMax cloud produces some of the cleanest point clouds in the industry regardless of material all in about 0.5 seconds.

The ZEISS AIMax cloud optical sensor uses structured light capturing the entire surface of the part, within its field of view (up to 100mm2 ), which also significantly reduces robot programming since less robot movement is need.  With competitor single line or even multiline solutions, more complex motion paths are required to measure individual features, one a time, which make the robot programs much more complex to build and maintain.

 ZEISS AIMax cloud measures hemmed edges with precision and detail like no other high-speed sensor. The calculated point cloud from the structured light scans allows for the generation of a full ‘Digital Twin’ – effective visualization is a critical tool in the relaying of measurement information.

Measurement of automotive sheet metal assembly part features and characteristics that were previously difficult to analyse inline such as rivets, nuts, studs and characteristic design lines can now all be measured with the capture of dense point clouds of a large area in a single robot pose. The sensor uses the full performance of its optical projector, projecting blue, red or green images, accommodating all surface reflectivity and providing optimal part characteristics measurements.

A four-robot integrated inline solution equipped with ZEISS AIMax cloud optical sensors can measure 120 part features per minute. A full BIW with 1000 features can be measured in a little over 8 minutes; this compares to 4 hours or more on a typical CMM – and with similar accuracies.

Q: In addition to dimensional and surface geometries what other sensor types does ZEISS integrate into its inline measuring solutions?

We offer two versions of the ZEISS AICell trace correlation free measuring solution. One solution, as we have discussed, offers absolute accuracy in-line measurements while the other is used for robot guided assembly tasks. AICell guide computes the 6D position of the robot mounted sensor in space with sub 20 micron precision. The system is used for robotic intelligent assembly tasks such as windshield fitting, door hanging, vehicle cockpit insertion etc. and again eliminates robot warm-up times, thermal growth and plant temperature issues which all effect robot assembly precision. ZEISS is the leader in Metrology Optimized Manufacturing, which I have coined MOM, with precision solutions for both in-line measurement and guidance.

And the ZEISS ABIS in-line system allows a wide range of surface defects to be detected including dents, bumps, waviness, thinning and cracks in sheet metal automotive parts and BIW on 100% of production. The ABIS catches stamping and assembly issues before value is added and it is too late.

Q: With high volume part inspection the volume of generated measured data is enormous. How does ZEISS present this data to plant management allowing improved process control?

ZEISS is focussed on the delivery of Industry 4.0 solutions. With our ZEISS PiWeb scalable IT solution for Quality Data Management customers have an analytical and data repository delivering ‘Intelligent Archiving’ of data. Pi Web offers a user API allowing for the creation of customer specific algorithms alongside an open source interface providing easy integration with custom and 3rd party applications. The PiWeb network solution saves enterprise-wide quality data onto a central server, which via secure internet connections, can be accessed from any location for display in the form of customizable informative reports.

Process data from production can also be managed by PiWeb which makes it possible to analyze the relationship between process parameters and measured part characteristics closing the process control loop. We also have a ZEISS PiWeb mobile app providing metrology data and analysis ‘on-the-go’ for plant floor personal.

Q: Predictive analysis driven by AI (Artificial Intelligence) appears to be coming very fast to manufacturing process control. What role does ZEISS see AI having in the future integrated with its measurement data processing.

At ZEISS, AI is now. Deep learning is already imbedded into many of the new measuring solution we are bringing to market such as the ZEISS SurfMax robotic defect recognition system launched a few weeks back. In the future we will use deep learning for application specific analytics driving enhanced predicative analysis to manufacturing process control.

For more information: www.zeiss.com/metrology