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Asked — Edited

Returning A Robot To A Home Point For Charging

hello all,

once again, my brain is giving me ideas that is outside it's current capability (LOL)

I am starting research for my next project (code-name T.A.D = Totally, Awesome, Droid).

one of (the many) functions i want him to have, is the ability to return autonomously to a designated point in the house for charging when his batteries get below a certain point.

The monitoring of the battery charge is not the issue ,as i can work out the script for that (famous last words), but its the returning to the point for charging.

i was thinking along the lines of purchasing a GPS board from Adafruit, but was not sure if the reception would be strong/accurate enough to drive it to the charger.

or a flashing light in a sequance/glyph for T.A.D to "look" for?


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Ill link to the topic when Im not on my phone but this was discussed previously, its one which needs bringing back to life too.

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Hi Rich,

i read through your "Jarvis" and "Melvin" projects for insight, inspiration and guidance, but was unable to see if you had achieved it?

did/have you?

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Simple answer - nope.

It's been on the list for some time but I've not got around to doing it (mainly because Jarvis doesn't move and Melvin is incomplete still).

I believe this may be the topic I mentioned earlier. It should be quite a long one with a lot of ideas batted around. I don't think anyone actually achieved anything but that was probably because they didn't try or were waiting for something else.


Even if you managed to get a GPS lock indoors, GPS is only accurate within 10 ft or so... Not nearly accurate enough to accomplish what you want to do... The easiest way to do it is give him a ride on a Roomba or iRobot Create as they have recharge/base station navigation built right in...

Another way to do it is to build some sort of infrared beacon system to guide your bot back to home base (this is the system the roomba uses)...


When talking about auto charging what we are really talking about is being able to navigate to a certain spot. There are more tasks involved, but that is the main one.

Here are some tasks that likely need to be performed for auto charging:

  1. monitor power levels
  2. detect a low power level (have a set or learned threshold)
  3. navigate to recharging spot
  4. successfully arrive at charging spot
  5. safely connect to charging spot
  6. do some power switching so the robot can charge without frying itself (if you have a 12 volt battery, pushing 12 volts output and connect the recharging volts of 14-20 volts (estimated) without turning off power to your robot then you have just pushed up to around 32 volts through your robot (sad times)).
  7. charge the battery
  8. sense when battery is charged
  9. do some power switching to turn off the battery charging and turn on the robot
  10. navigate away from the charging station and carry on with robot duties

Most charging stations use some sort of beacon to call out to the robot to say "here I am". If you couple that with a sense of direction like a compass that would aid the robot. If the robot had a sense of where it has traveled and can understand what room it is in (assuming it lives in more than one room) and I believe a neat way to do this might be with a glyph and use the camera so every room would be marked for the robot to understand where it us.

You'd want to use a compass, glyphs and a beacon as well as a lot of scripting. :)

For example for my robot if it lived upstairs at my home, the office on the east side of my house would be where it would recharge. It could go down the hall and into the master bedroom. So I would need 3 glyphs for each room and a 4 perhaps over the charging station in my office. If the robot wondered down to the bedroom, ran low on power it would need to acknowledge it needs to go east and find the glyphs in reversing order. First find the hallway glyph, then the office glyph, then the beacon and finally perhaps the charging glyph and center the picture in the camera view to dock with the charging station.


see the link that Rich mentioned or search for Automatic Battery Charger Docking

There were a lot of ideas discussed that may help with coming up with a way to do this.

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Great list Justin, something for us all to get our teeth into. I see its been about a year since this was last visited, I believe that if we break it in to chunks together we can achieve something. @DJsures do you have any thoughts on this topic, as it seems like a function that a lot of us would love to tackle?

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DJ mentioned that they have been working on a navigation system. We don't know much more than that, when it'll come, what it is etc. yet though.

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I am fishing a little, with any luck it will aid with our goal :-)


maybe, paint the ceiling of every room and the hall way with an infrared reflective qr code,and program a map into the robot so, he knows where he is all the time by looking at the ceiling and flashing an infrared super bright led to see the qr code,then when you install the charging station teach him where it is


Nothing to do with your question(sorry), but have you thought of TAD meaning technologically advanced droid? Sounds cooler but your open to the choice. Your bot, your rules.

(Now back to regular programming)

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I like it @Techpro, but being a fan of the TMNT and a child of the 80's I think I will stick with my choice.

Having looked into @Rich suggestion referance the roomba way of charging, I think I am going to go down that route and have T.A.D (when his battery reaches a predetermined level), go looking for an ir signal, of which there will be two ir leds positioned either side of a charging port (these will correspond with two ir receivers on T.A.D), once both ir receivers gain a signal T.A.D will reverse on to the charging port.

The rest is still to be worked out.



ARC has a map control. And have been thinking of extending it!

Fixed mini scripts. Choose what you need to make an auto map!

Just a sample of commands.

Movement commands.

Move forward for three seconds. Turn left or right. Stop Reverse for three seconds. Set speed.

Video commands.

Take picture or start video recording. Stop video recording.

Just some easy way to navigate. Got Idea from my parrot mini-drone software. The above does not require hardware, simple is better.

As to battery charging another thought! Use what nexus 7 (2013) has a nexus wireless charger with Qi! It's Qi part... We could try.

Just my two cents. J

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Hay all,

@DJsures has advised of a product that may work for this project, its an Pololu IR beacon, (Google it, as I am not sure how to add links from my tablet yet).

But this looks ideal, just wondering if this has been used previously on an ezb project and if so how did it go? Any script?

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Thanks @jdebay, to the rescue once again :-)


Take that thread with a sizable grain of salt. Unless Bravia can confirm he got it working. Robotmaker made a lot of claims and assertions about what would work with very little empirical evidence to back it up. He is no longer a member of this forum for reasons that are no longer evident (the posts in question have been deleted).

(wow, twice in one day. Haven't dealt with him in a year)