Tuesday, December 6, 2011

What Can Machine Vision Do For Me? A Management Guide

I believe that machine vision, (taken to mean the industrial application of computer vision techniques,) has three roles within a manufacturing operation. It can be used to replace human visual inspection, it can be used for process control, and it can be a sensor that enables other automation. Let’s run through each of those points.

Replacing human visual inspection

Despite 30 years of lean manufacturing many factories still employ people to sort good product from bad. This is a task that machine vision can perform with far greater consistency. Software doesn’t get bored, it doesn’t get distracted, it doesn’t need regular breaks and it doesn’t alter the standard depending on what mood it’s in.

On the other hand, software struggles to deal with any deviation the programmer failed to think of. For example, imagine the blue in a printed label changes shade slightly. An inspector may spot this but will decide that the product is fit for purpose and will let it go. Machine vision however may send it all to the reject bin.

Inspection automation sounds great – lower costs and improved customer protection – but it’s really hard to make work

Process control

Machine vision is very good at presence/absence discrimination, so it makes a good error-proofing tool. Yes it may be more expensive than a dedicated poke-yoke, but because it’s reconfigurable it may be cheaper in the long run. It’s also good at monitoring processes and detecting problems, like a broken drill, and changes, like when ink is running out. Best of all, these types of vision applications tend to be reasonably quick and inexpensive to implement.

Enabling automation

One of the headaches in automation, especially of part handling, is that it can be really expensive to fixture product for a robot to pick it up. But by giving the robot eyes it can cope with variation in part location. In fact vision guidance can eliminate the need to have a person orient parts for the robot – which leads to some frankly rather bizarre automation installations – so it saves both capital (the dedicated fixturing,) and revenue (the part sorter.)

This type of vision is complex and expensive to implement, but the number of people with such expertise is growing and there are more implementations to take a look at. Machine vision is definitely changing the economics of factory automation.

There we have it: machine vision can cut costs and prevent defects. Just think bigger than automating the work the end-of-line inspectors do.

1 comment:

Ron Mueller said...

nice quick overview !

You mention the pitfalls of replacing human visual inspection...
A lot is gained when machine vision is applied for pre-evaluation, where the definitely good parts are accepted and for the bad parts, the potential defect is labelled by the software.