Touchscreen Interface Tester

Would this really be necessary? If it's the screen he's wanting to test that would need a mechanical apparatus, though I would assume these screens have already been well tested in target environments. But if it's an application interfaced to the touch screen, it seems to be that could be tested by imitating the data going across the interface (often just a serial stream). The application would have no way of telling the signals apart.

The screen should not permit invalid data sequences and never transmit them, but you could assume those might be a possibility, and write a trap in the application anyway. You could also manually sit there for a half hour and poke at it yourself, capturing the data. Mix this in with randomized data sequences.

Otherwise I think you're going to have to build something, and it won't be cheap and it won't be very fast.

-- Gordon

BRW wrote:

Thanks for the reply Gordon.

The application he's testing is written explicitly for the touchscreen using COTS software that interfaces with the COTS touchscreen system. There is no easily accessable "port" (neither software nor hardware) between the actual touchscreen and the application. He doesn't want a partial test of a hacked system. What is desired is a true "end-to- end" test from the user's perspective. It's the only way to be sure of the robustness of the application as a whole.

I'm glad you mentioned speed since I didn't cover that. It doesn't have to be fast. One touchscreen press every 3-5 seconds would be fine. The idea would be to run the automated test all night or even several days.

BRW

BTW, thanks for the article this month in N&V (or was it Servo?) about surplus suppliers. There were some great sources that I didn't know about.

BRW

A Lynxmotion 5 robot arm, at $279, should do the job. The accuracy is moderate but good enough for touch-screen testing.

That's the plastic version. You might have to get the aluminum and ball bearing version, at $452.39, or the robot may wear out before the touch screen does.

Make an x/y bridge/trolly operated by two servos (use drawer rails and rollers from lowes/homedepot) with a third servo mounted on the trolly to do the screen touching (use a servo setup similar to below). Probably all components needed for ~$100. From my tinkering, I got ~425 discrete positions from a standard servo with ~190 deg rotation range.

Since you'd have to buy the hardware, then invest time and energy to program it, why not find a college kid or two willing to do this for $8-10 an hour. If you're really wanting a user's perspective for testing it needs to be human, or else a very expensive and complicated test rig that will simulate human responses - mistakes in positioning, too light or too forceful of touches, and everything else a mechanical simulation probably won't do.

At $10 an hour you can hire a couple of kids and get 30-40 hours of testing. Splurge and buy them some Pepsi and pizza. Make that part of the test - how your buddy's software does with a messy screen!

Not to take away a job for our robot friends, but some things are still better (cheaper) done by humans. Robots are generally only cost-effective over the long term, say simulating months or years or testing.

-- Gordon

BRW wrote:

Damn, I threw this out a month ago because I couldn't get any tackers: Free: Roland A3 size DXY-980 Plotter. Mind you, it was in Australia.

Don...

How many different touch positions does he need to test? You could put a solenoid at each position. Solenoids are pretty cheap, easy to drive, etc.