Controlling a "fork lift" type mechanism.

[Brad Voracek]

Obviously it is fairly simple to just move it up and down, however, we have been thinking of ways to control the forklift height mechanism with a slider, or maybe even preset position switches.

I could do the switches, with like limit switches on the robot and move the lift until we hit these, however, I'm wondering how hard it would be to maybe use a dimmer slider type switch, then directly go from the 0-255 given from that, and go to a height based off that value. For example if it's at 127 it goes to the middle spider, 140 is right above that, etc. We're thinking of ways to do it with the gear tooth sensor right now, and it looks somewhat promising, I'm just wondering if you guys know of other (better) ways to do this?

Thanks.

[Alex698]

Maybe use reed (magnetic switches) for 3 positions? Just hook them right up to the digital in(s). Just an idea.

[AdamHeard]

How is the lift actuated?

If it is rotary, just put a potentiometer on then.

A potentiometer will give you a precise value per anglular rotation and they don't shift around. Once you have it hooked up you can use software to tell the arm to go up or down until it hits the necessary value.

[Daru]

With '05 robot, we tried attaching a pot to our driveshaft for our forklift. We then had a few preset positions, which we could go to with buttons on the joysticks.

The pot kept turning itself, even though it was mounted, and became uncalibrated. I'd recommend you really hunker that thing down.

Also, make it so when you go to a pot value, give it a range of values to stop in, or else you'll get it bobbing up and down.

We ended up taking it off because it was unreliable. If we were given more than a day to get that working, it would have been great ;)

[Brad Voracek]

Hmm, I've been doing some reading and a pot may work well, the only thing that worries me is I don't know how many rotations of our motor it will take to reach peak, as the design/build's team design is not finalized =p;

I think a pot would work though, but I may need a 10 revolution one. I also found something about absolute shaft encoders, which seem perfect. If anyone could recommend me a decent absolute shaft encoder or a decent 10 turn pot it would be appreciated.