How to set up a "splitted" tag-of-war?

October 22, 2007 10:13 AM

I want to setup a virtual tag-of-war in which two different teams are participating from different locations.

To accomplish this idea the force made by one team while pulling the rope is measured by a spring sensor. This data is sent to a motor or actuator on the other side in order to respond accordingly: to pull if the data received is bigger than the force currently made by the team or to push otherwise. The same process is followed for the other team.
Do you know a spring scale whose output can be read by a computer and a motor / actuator that can be controlled by a computer (and according to the readings given by the spring scale)?

posted by karvajavi to technology (9 comments total)

I've always heard it as "Tug of War," by the way.

Out of curiosity, are you actually planning to make this? If so, please post back with pictures and the like.
posted by DMan at 10:17 AM on October 22, 2007

Thanks for pointing out the mistake DMan. And of course, there will be photographs!
posted by karvajavi at 10:21 AM on October 22, 2007

To what degree is money an object? An Instron (or similar Materials testing machine) would work perfectly, but cost more than a pretty penny.... Still, you might look at the design a bit and see what you can cobble together.
posted by JMOZ at 10:34 AM on October 22, 2007

You probably want some sort of industrial electric motor with a linear power curve - so, if you double the voltage you get double the power. You could probably design a simple motor controller that takes input from a digital force meter to drive a speed controller attached to the motor.
posted by backseatpilot at 10:35 AM on October 22, 2007

Thanks JMOZ for the information. It seems pretty interesting but, by now, more complicated (aka expensive) of what I have in mind.
posted by karvajavi at 10:45 AM on October 22, 2007

Thanks backseatpilot. Surely it is a really funny thing to do!
posted by karvajavi at 10:48 AM on October 22, 2007

For the sensor side, any old spring will turn force into distance for you, so it becomes a simpler problem of measuring distance. A slide potentiometer, or a string wrapped around a rotary pot or encoder.
posted by moonmilk at 10:51 AM on October 22, 2007

Yep moonmilk. And thanks for your suggestion. The problem is that the data should be sent to other place and that's why I guess that "non-mechanic" solutions suits better. All in all it is a very suitable idea for the mock-ups.
posted by karvajavi at 11:03 AM on October 22, 2007

Hmm, that's true, but it wouldn't be that hard to get data from the cheap potentiometer solution into your computer for transmission to the other end. For instance, use a microcontroller board like the Arduino to send readings from the potentiometer over the serial port. Or attach the moving end of your spring to the scroll wheel on an old mouse, and read the scroll as increase/decrease in force.
posted by moonmilk at 11:48 AM on October 22, 2007