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GRUNT
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Re:General Status??? - 2008/12/05 22:58 Interesting design, does it attach to the floor?

Hello Croc4,

Good question. The docking station is designed to be placed against a wall.

Thanks for the other comments.
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Marcus8675
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Re:General Status??? - 2008/12/24 10:30 Hey guys, been a while since I have been here. I just saw this post and prototype document. Great progress!! Can I make a few comments...

I love the spring loaded base contacts, it allows for missalignment and provides positive presure to the contact points.

The concept of designing for a standard 5 1/4" bay is a great idea, you should have adjustable positions on the base height to accomodate any possiable bay instalation.

Also, just an idea, what about extending the ground contact a bit farter then the positive contact to alow a first make/last break connection with the ground. Also, I worry about any spikes durning the connection process that may reset the PC.

The PC-BOT exposed terminals worry me. I asume this is a fairly direct connect to the bot's main batts. With that large area exposed and on the surface of the bot, I can totally see it running up aginst a metal coffee table or something and causing a direct short. Might want to consider some sort of cover that retracts upon positive contact with the base.

All and all, I love it!! How soon till you offer it up?

Oh, also GRUNT. Do you think you can contact me sometime, I am interested in purchasing a 2nd M3 and was courious on the prices and avaiability.

Nice to see ya all again.

Post edited by: Marcus8675, at: 2008/12/24 10:32
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c6jones720
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Re:General Status??? - 2008/12/24 16:29 From, experience with my own version of a 914 charger, spikes and sparks when a robot docks/undocks can be a bit of a problem.

Spikes and sparks are basically the equivalent of switch bounce. The root problem is transients caused by moving electrical contacts which are passing current at that time.

I know the situation can definately be eliminated:

On my robot what worked very well was a mechanism that allows the robot to detect that it has docked with the charger but does not immediately connect the battery to the charger contacts.

An ADC tells the computer that the charging voltage is present. At this time the robot should have stopped moving.

Using a relay under software control, the robot can connect the charger supply to its own battery with no chance of spikes or sparking. All you do is put a short delay between the docking and the charging operations.

The software control loop is a finite state machine that does this:

1 - home in on charger
2 - check adc to see if voltage is present
3 - repeat 1 until we have docked
4 - if docked wait 100ms or so
5 - close relay contacts and apply charge voltage to battery

This works.
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