making your own auto-docking/battery-recharging thing for your robot

Jim the Hermit

I've always wanted a robot that would recharge itself when the batteries are low. Where can I find how other people did it?

lardom

I just thought of something. Why dock at all? Program it to replace its own battery pack or at least have a robotic docking station that replaces it. I'm joking but OTOH an industrial robot that could replace battery packs would allow mobile warehouse robots to work nonstop which is an idea I'm sure we'll see at some point.

WBA Consulting

Larry, why are you joking about the battery replacement idea? I think that's brilliant and would be both mechanically and electrically simple to implement. Really, all you need is a setup that gives you an electrical connection that can easily be mechanically separated. In other words, standard JST LiPo or 7.2v RC Battery Pack style connectors are out of the question.
I can envision something similar to a cell phone battery that is simply held into a pocket and the connections are spring terminals (or a laptop battery as well). Design a cartridge style battery pack that is held into your robot with some sort of cam-lock mechanism. When docked into the "fuel transfer station", a servo driven "key" would engage into the cam-lock to "unlock and disconnect" the battery pack. A second set of servos in the dock could pick up the battery pack and place it into a similar setup in the dock for charging. Then drop in a second battery that is charged, engage the cam-lock, and send the robot on it's way. I could see the entire battery transfer process taking less than 2 minutes.

You may need to add 1 or 2 servos to your bot for the battery pack if a cam-lock setup won't be sufficient to give you a good enough connection for your current draw (the servos could engage stiffer spring terminals that could handle a greater current draw.) Of course that would mean your bot needs power while transferring so some sort of power through the "key" would need to be available.

Jim,
I recall seeing a few posts on the forum with similar thoughts and after doing a forum search for "docking", I found the ones (and then some) I was thinking of:

http://forums.parallax.com/showthread.php?102086-Scribbler-Auto-Docking-Videos&highlight=docking
http://forums.parallax.com/showthread.php?141640-Need-dock-charger-for-Eddie-amp-laptop&highlight=docking
http://forums.parallax.com/showthread.php?140100-Docking-Station&highlight=docking
http://forums.parallax.com/showthread.php?129512-Robot-to-determine-location&highlight=docking
http://forums.parallax.com/showthread.php?116096-Recharging-batteries-while-the-robot-is-powered-on.&highlight=docking
http://forums.parallax.com/showthread.php?105120-auto-docking.&highlight=docking

Peter KG6LSE

anderson Power poles ...:thumb:

W9GFO

My last charging dock uses neodymium magnets to make the electrical connection. The first attempt used the magnets to hold the connection together but the small contact point caused heating and loss of magnetism. The current one uses a face to face connection of the magnets and has been able to handle the 10 amp charge without issue. It also helps a lot in self alignment.

erco

I made an ultra-simple dock for a Scribbler robot, details at http://www.botmag.com/articles/scribbler.shtml

video http://www.youtube.com/watch?v=ujjgV6sTvo4

RobotWorkshop

Here are some links to more details on robot docking:

http://cres.usc.edu/pubdb_html/files_upload/237.pdf

http://homepages.inf.ed.ac.uk/rbf/CVonline/LOCAL_COPIES/BARNES/dock.html

http://www.schursastrophotography.com/robotics/dockinglogic.html

http://www.pelebot.org/pelebot/Buildyourpelebot/Powerandbatteries/Dockingstation/tabid/62/Default.aspx

http://www-ist.massey.ac.nz/conferences/icst05/proceedings/ICST2005-Papers/ICST_151.pdf

erco

Here are assembly instructions & schematics for the Octobot Survivor robot, which auto docks: http://www.mondotronics.com/PDFs/3-918_OctoBot_v125.pdf

NWCCTV

Jim the Hermit wrote: »

I've always wanted a robot that would recharge itself when the batteries are low. Where can I find how other people did it?

I was going to point you to erco's idea but realized he already did that after the post!!!!

Jim the Hermit

lardom wrote: »

Program it to replace its own battery pack or at least have a robotic docking station that replaces it.

When I was a kid, I imagined a robot plugging itself into a station for power. It'll then put it's dying battery pack onto a turntable. The table would have a another fully charged pack on the other side, and turn 180 degrees. The robot would pick up and install the new battery and the station would begin recharging the old one.

Jim the Hermit

Thanks everybody- I got a lot to think about

Code Chief

Seems like wireless charging is the state of the art, now it's being used by so many of the new mobile phones. There are YouTube videos showing how to make your own charging circuits for phones which don't normally support it. I wonder if wireless charging "pads" could simplify the robot charging requirement? It seems like it should be easier regarding logistics, because it could either just drive over a big pad with a charge receiver underneath, or just touch one side/back-up to the wall. The most promising part of this technology is (at least from the advertising) it appears the device doesn't have to be perfectly docked, reducing the additional engineering/sensors/programming/complexity just to get the thing docked properly.

erco

Wireless is cool, but it probably has low current limitations. With such cheap chargers available:

http://forums.parallax.com/showthread.php/147399-Gel-Cell-Charger-Deals

I'd be tempted to build the charger into the robot and make the bot plug itself into a 110 VAC outlet.

My next project!