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Sunday, March 30, 2008

LED Earrings and external power supply problem

This weekend I worked like a dog on these bus stop robots. Finished just about everything down to LED earrings on Mrs. Robot. Drilled out eyes and made channels in the Styrofoam heads to run wiring harness's. I was going to share a digital channel to light LED's per head but decided to run each LED on it's own digital channel so I don't under power the lights.

A lot of soldering was accomplished and wiring harness's were run through the torso of the robot bodies and into an access area in the back. The wiring harness's and servo wires will hook to the controller which will sit between the two robots on the bench. My wife suggested creating a robotic purse with no bottom for the female robot. The purse will sit on top of the electronics which will make it easy for me to access and work on.

A couple of functions were added to the software to automatically turn eyes on and off as well as a wink function. I still need to choreograph some eye functions in the existing routines though.

One problem that's been dogging me for the last 2 weeks is using an external power supply for the controller. I use external power supplies on Robby and have done so on B9 with no problems. But on this project when I turn on the controller, it goes bezerk and then shuts down. I finally figured out the reason I can do it on Robby and B9 and not on the bus stop robots is because I'm using Servos and not regular motors which are in B9 and Robby. I don't understand why the difference between regular motors and servos but that's definitely the problem. And .... if I hook up only one servo it works. And .... if I turn it on with one servo and then plug in the second servo it also works. But if you turn the controller on with two servos it goes bezerk.

After hours and hours of trying different servos, different controllers, different wires, different voltage regulators and power supplies, etc. I finally decided to experiment dropping the voltage 1.3 volts. I'm using an adjustable voltage regulator with an LED readout of the voltage. When I dialed it down from 7.2 volts to 5.9 volts all of a sudden the problem was solved. Oh and something I neglected to say is it always worked with the vex batteries. So maybe the batteries aren't 7.2 volts after all. I also tried 6.1 and 6.2 and that seemed to work but what I know for sure is 7.2 is not liked by the vex controllers using servos.

This was figured out after dinner on Sunday and I still had to do a lot of frantic yardwork hanging over my head. So there just wasn't time to get any pictures or video of the robots yet. But our lawn looks nice.

Oh and one more feature I'm probably going to add is a wireless camera that may broadcast over the internet and record images. Kind of a like a robotic security system for the home. Too bad their legs don't walk because it would be even better if they could walk the perimeter. Phase II .....

1 comment:

Charlie said...

Jim That is so cool. I can't wait to see them.