Home » Articles » OEM Insight

Voices: OEM Insight

See the Nail. Hit the Nail—Part I

Algorithms Designed to Spot a Nail or a Bottle Cap or an Asparagus Spear Must Make Assumptions About What Those Objects Look Like

ControlDesign.com

By Ned Lecky

In addition to consulting on vision and embedded-system design, we own several rental properties, and while much of the renovation work is carried out by skilled, local craftsmen, the need to blow the cobwebs out of my brain once a day keeps my hand in the “delivery” end of property management—carpentry, sheetrock work, plumbing, wiring and painting.

As I contemplated writing this column, I drove another nail into a piece of pine trim and felt the nail speed slow and twist through various layers of 100-year-old wallpaper, plaster and lath. I also did what I often do in my work: I imagined how I’d design a vision system to perform the same task using the same tools.

I couldn’t do it. That task is as unachievable today as it was when I started programming robots as a college student in 1982. Fifteen years later, I wrote a Ph.D. dissertation on cognitive computing architecture, a topic that always interested me because I believe until we have thinking and reasoning computers that truly understand and analyze situations, complex real-time control systems based on vision or any other sensor technology are out of reach.

But there are practical, simple, real-time control applications for vision. The trick is to know what makes one simple and another not-so-simple.

This month and next I’d like to share some of the practical ways I’ve found to tell the difference between the doable and the lunatic fringe.

In vision applications, image quality and consistency determine success. While a high-quality camera with proper optics is very important, there are three aspects of image consistency before the image ever hits our camera that are much more critical to practical vision system success.

Consistency is everything. Every nail needs to be a nail. Specifically, it needs to be a #8 finishing nail, not a 16-penny common nail, not a carpet tack, not a rusted #8 finishing nail, either. Algorithms designed to spot an object make assumptions about what those objects look like. Violate the assumptions and your algorithm fails.

If we design for backlighting and use silhouette edges, then we always need backlighting. If we use combination lighting to highlight certain features, then we always must have that same lighting from the same orientation of the object. Lighting spectral content—LED, IR, incandescent, fluorescent, black light—is particularly important because objects are wavelength-dependent photon reflectors and can have markedly different appearances under different lighting conditions.

If we expect a clean background and extraneous objects appear suddenly behind our object, our algorithms are likely to be confused. Extraneous light or shadows can be equally damaging.

These requirements seem counter-intuitive—human cognitive vision processing is designed to tolerate huge variation in these areas. This difference is the key to any successful vision solution.

If you can get a consistent image, the next question is how to process and analyze the image. We are limited to programmable computers that only do what we tell them to do.

As a Ph.D. EE, I have an unhealthy love for DSP algorithms, two-dimensional signal processing, convolution, morphology, Fourier transforms, LaPlace and Z transforms, FIR and IIR filters and other traditional image-processing algorithmic paraphernalia. But an algorithm that uses carefully crafted, multi-step sequences of these image manipulations almost always relies on unwritten assumptions about those image consistency factors. Change one or any of them very much and the carefully crafted recipes fail. Ninety percent of the machine-vision solutions I’ve seen demonstrated successfully in the lab do not succeed for more than five minutes on an actual manufacturing line or in a real machine. Edge finding, blob counting and straightforward metrology algorithms are amazingly robust. Scratch or blemish grading, surface finish inspection and more qualitative measures generally are not.

Next month I want to spend some time discussing the reliability of real-time systems and review some real-world applications.

Ned Lecky is an ME and EE with 25 years of experience in control systems and machine vision. As owner of Lecky Integration, he consults for OEMs, system integrators and machine vision providers.

---

More Voices

See the Nail. Hit the Nail—Part I
11/10/2008
Algorithms Designed to Spot a Nail or a Bottle Cap or an Asparagus Spear Must Make Assumptions About What Those Objects Look Like

Knowledge Recommended
10/02/2008
Engineering Is Based on Knowledge and Experience, but in Developing Countries, Lack of Education and Economic Strength Create Problems

One Step Ahead
08/13/2008
Hard Economic Times Make SI Smarter

Keep Your Skill Set in Tune
07/08/2008
Just Because a Skill Has Been Automated or Replaced by Software, You Should Still Keep It Sharpened

What That Connector Really Costs
06/30/2008
All Connectors Look Good in the Sample Case or on the Shelf. It’s the Application That Will Get You Right In Your Maintenance Budget Pocket

Systems Vs. Machines
05/09/2008
Strong Project Management, Good Quality Control and Stringent Cost Monitoring Are Keys to Successful Systems

Customized Solutions Bring Future Benefits
04/18/2008
When a Manufacturer or a Machine Builder Has a Problem That Needs to Be Solved, Who Can They Count On?

FPGA Can Speed Development
04/06/2008
Standard FPGA-Based Platforms and Software Tools Have Enabled Applications That Were Previously Not Possible or Feasible

Do Your Duty Cycle Diligence
03/04/2008
In the Past, Gathering Duty Cycle Data From a Customer’s Installation Was a Logistical Nightmare

Remote Access Improves Service
02/12/2008
Why, as Industry Leaders in the Market, Can’t My Machines E-Mail Their Customers with Diagnostics?

Why Is Safety Information So Pricey?
01/02/2008
A Significant Portion of these Standards Don’t Contain Information Relevant to a Particular Application

Innovative Recruiting Practices
10/31/2007
Most co-ops students gain enough proficiency that a portion of their time can be charged to the projects that they’re working on.

E-CAD/CAE II: State of the Art
10/04/2007
A key feature of third-generation CAE systems is the support of variant design and an efficient reusability of design projects to create product families.

E-CAD/CAE: a New Edge
09/11/2007
The complexity of the design projects done with these systems increased at the same pace as the performance of the systems being improved.

Reliability Demands a Plan
08/01/2007
This is a condensed version of reliability consultant Ricky Smith’s article posted at ControlDesign.com’s sister site PlantServices.com. Written from the end user viewpoint, you’ll find the full text at PlantServices.com/smith

Insight from issues past
06/07/2007
In celebration of our 10-year anniversary, here’s some of the most useful observations from contributing authors to Control Design’s OEM Insight column over the past 10 years.

Let’s open up RFID
05/08/2007
As a researcher, you want to look at what’s going on under the hood, but the things you may find to improve performance can’t always be tested because everything is proprietary.

How to ease into using RSS feeds
04/09/2007
We came across a helpful explanation of RSS in one of our sibling publications, Plant Services, and thought we should pass it on as a little different piece of OEM Insight you can use to better gather information.

Boost SQL server IQ
02/01/2007
When Microsoft released .NET technology, writing software for embedded operating systems such as Windows CE became as easy as writing a desktop application.

Successful SI relationship tips
11/12/2006
A little OEM insight says to expect integrators to bring their knowledge into your project, but your specific domain expertise is invaluable to avoid reinvention or, even worse, repeats of past mistakes.

System integrators bring value
10/11/2006
The most-often overlooked factor in selecting a system integrator to implement technologies or platforms new to the machine builder is their willingness to transfer knowledge and deliver source code.

We don't use system integrators
09/13/2006
This is the first of a two-part discussion about the relationship between the controls professionals at machine builder companies and independent system integrators. Next month: an SI’s take on the relationship.

Bridge the IT and automation disconnect
08/08/2006
As an OEM making automated packaging equipment, this company is caught in the middle of the battle between IT and automation at its customers’ plants.

It's all about insight
06/11/2006
Whether it's with a customer or a key technology supplier, the old fashioned art of talking with each other is really the only new way to survive today.

Always call for backup of PLC software programs
05/10/2006
This installment of OEM Insight warns astute customers about the dangers of losing PLC software programs, and how important it is to backup your PC programs while they are still alive in the processor.

Machine safety switches aren’t no-brainers
04/05/2006
A little OEM Insight shows that by following proven safety guidelines and performing risk assessments, engineers can identify the machine hazards, analyze the consequences, and design accordingly.

Don’t let the brain become a gray matter
03/15/2006
Because code visibility is low, it can be tempting for a controls programmer to cut corners, especially when there’s a deadline. Yet this is one of the biggest mistakes a programmer can make. Read why.

Yesterday's tools, today's challenges
02/08/2006
A little OEM Insight shows us that when new control systems are installed with the help of the machine builder, the latest proven control methods and strategies can revitalize performance.

Need dictates control platform choice
12/27/2005
History and a little OEM Insight shows that when hardware solutions based on proprietary firmware become obsolete, the cost of replacing them creates serious sticker shock.

Beware corporate safety standards
11/12/2005
Machine builders are often put in a tough situation by a dictated standard because they also must assume partial liability for something they didn’t engineer.

Need dictates control platform choice
11/05/2005
History and a little OEM Insight shows that when hardware solutions based on proprietary firmware become obsolete, the cost of replacing them creates serious sticker shock.

Exploring machine control options
11/05/2005
History and a little OEM Insight shows that when hardware solutions based on proprietary firmware become obsolete, the cost of replacing them creates serious sticker shock.

The perils of shipping too soon
09/15/2005
You better think twice before shipping a machine to a customer site before working out all the bugs it might encounter when it gets into a real production environment.

Building partnerships promotes profitability
07/17/2005
OEM Insight guest columnist Alan Metelsky, leader of the controls engineering group at Gleason Works, says there are better and more profitable ways to form relationships with your suppliers.

Automate, innovate and have success
06/09/2005
In this month’s edition of OEM Insight, a vision-guided robotics integrator believes innovation is motivated by the current business climate and is fostered positively by technical factors, and negatively by competitive pressures.

OEM Insight: Customer-Driven Machine Design
04/02/2004
For This System Builder, Studying Its Customers' True Business Issues Helped Create Better Machine Design

Purchasing as a competitive advantage
10/04/2002
A little OEM Insight shows that when sourcing their control systems, machine builders should factor in soft costs.

Machinery safeguarding design
06/08/2002
As this installment of OEM Insight reveals, when an operator sees the e-stop as an obstacle to doing his job, he will actively try to defeat the safety.

Interoperability and safety issues engage ODVA
11/05/2001
Open DeviceNet Vendors Assn. finalizes EtherNet/IP spec, moves on to safety network.

Open architecture: Hype and fiction
08/04/2000
In this installment of OEM Insight, the poor customer -- the manufacturing manager responsible for real production -- is caught in the crossfire of buzzwords and acronyms regarding open architecture.

A plea for simplicity
12/07/1998
In this installment of OEM Insight, guest columnist Andrew Sloley discusses the relationship of complexity and profit in control solutions.

Open systems? Who you gonna call?
08/09/1998
When you buy an open control system in pieces from different vendors, who takes responsibility for the system?

Asset management is a control strategy
06/08/1998
Guest columnist Dr. Carlos Talbott discusses managing process variation in this installment of OEM Insight.