Thread: Robot to Lead Labor Day Mackinac Bridge Walk
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Unread 05-09-2014, 16:58
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Re: Robot to Lead Labor Day Mackinac Bridge Walk
I wanted to add some more technical information here. About the Robot.

We used 8" AM pneumatic wheels, which worked extremely well on all surfaces. However, keep in mind that the wheels have some compression, so if you choose to use them, you may have to play with center drop amount or/and air pressure. Of course, most outdoor surfaces aren't as grippy as carpet either.

We used a single CIM per side on the robot. We considered using 2 CIM's per side, but in the end the performance of single CIM's was just fine.

We used 8+ batteries simultaneously on the robot. Safety was a big factor - that many batteries can create a decent amount of amperage. To protect against that, each individual battery had it's own 120 amp main breaker, and then those wires met at a single 120 amp main breaker that protected the electronics.

We actually put a laptop on-board, then used a wireless microsoft X-box controller to drive the robot. We had an inverter available to plug the laptop into power from the batteries: I'm not entirely sure if they used that or not.

The photovoltaic cells were 19V with a anti-backfeed charging regulator. Some day we'll get around to seeing how much this actually helps charge the robot. With multiple batteries, the amp or two we might get out of the cell divided down really is little more than a maintenance / trickle charge when the robot isn't in use.

I'm going from memory, but I think the top speed was around 8-10 mph, using the single cim per side through a cimple box with a sprocket reduction to the wheels. Talons were used as the speed control.

A "cruise control" was written which was little more than a hold-current joystick position. Pushing and holding a trigger while driving saved the joystick's current position, and then the right joystick was programmed to 'trim' speed and balance by making incremental adjustments to both motors when it was pushed. When the cruise control button was released, all outputs set back to zero as a safety precaution.

If you have any questions, PM me (since that emails me).
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