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croc999
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Re:General Status??? - 2008/12/03 00:45 Has anyone put together a semi formal spec for charging?, I know I have seen several ideas floating around the web, but they are very robot design dependent.

having a spec would be a good place to start, for example

1. Will the robot still be operational during charging?, is there any issues with this?
2. Target charge time, will vary depending on battery capacity, but we should be able to swag an average charge time based X ahr batteries
3. charge completion, what mechanism will be used?
3a. will EOC (end of charge) be indicated from the charger if the robot is off?
4. indication of positive charging, is the robot actually connected to the doc.
5. Safety issues, will the charger always be on?, or will it be activated only when robot is present.
5a. what mechanism will be used to indicate robot present.

I know I must be starting to sound like a PIA, but without a common set of requirements things won't progress, As C6jones noted, its been 2+ years and still charging is not complete, it is not that difficult really, but there are some issues that need to be addressed by those who are battery/battery charger savvy.

Croc4
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GRUNT
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Re:General Status??? - 2008/12/03 23:11 Croc4,

Let me answer some of your questions regarding the specs. We have a prototype that we've built.

1. Will the robot still be operational during charging?, is there any issues with this? Yes
2. Target charge time, will vary depending on battery capacity, but we should be able to swag an average charge time based X ahr batteries. Charge Time 2 hours
3. charge completion, what mechanism will be used? Voltage monitoring circuit
3a. will EOC (end of charge) be indicated from the charger if the robot is off? It's built in/automatic to the Soneil chargers that we use. The LED goes from amber to green when fully charged.
4. indication of positive charging, is the robot actually connected to the doc. Yes via copper contacts
5. Safety issues, will the charger always be on?, or will it be activated only when robot is present. There is a relay and when the robot docks, the relay closes the loop on the circuit.
5a. what mechanism will be used to indicate robot present. Not sure what you mean by this one.

BTW: You're not a PIA, you're asking very valid questions.

Post edited by: GRUNT, at: 2008/12/03 23:12
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croc999
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Re:General Status??? - 2008/12/03 23:53 Good info Grunt,

Let me attempt to clarify some of my quickly scrawled points.

4. indication of positive charging, is the robot actually connected to the doc. Yes via copper contacts
- If there is a bad contact with the robot what happens?, or is it guaranteed to always make good contact if docked?

5. Safety issues, will the charger always be on?, or will it be activated only when robot is present. There is a relay and when the robot docks, the relay closes the loop on the circuit.

5a. what mechanism will be used to indicate robot present. Not sure what you mean by this one.
- if the robot drives onto the doc how does it trigger the charger to turn on? (sounds like some sort of relay trigger), and could this be triggered by some other object/person by mistake? (a nosey cat/doc/child for example), so the charger will only activate when the robot docks and no other time, this is what I meant by "robot present"

While I'm at it

Can you give any details about the charging station detection? what is the plan for having the robot find the charger?, is it done via web cam, IR beacon, RF Beacon?
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GRUNT
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Re:General Status??? - 2008/12/04 05:36

Post edited by: GRUNT, at: 2008/12/04 05:54
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GRUNT
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Re:General Status??? - 2008/12/04 05:54 Croc4 , here are a few more answers...

- If there is a bad contact with the robot what happens?, or is it guaranteed to always make good contact if docked? Nothing is ever guaranteed , but it should make a good contact 99.9% of the time. If it doesn't the PC-BOT should move away and re-dock

5a. what mechanism will be used to indicate robot present. - if the robot drives onto the doc how does it trigger the charger to turn on? (sounds like some sort of relay trigger), yes and could this be triggered by some other object/person by mistake? In it's current state yes. Keep in mind that it's 12v DC not 110/220v AC (a nosey cat/doc/child for example), so the charger will only activate when the robot docks and no other time, this is what I meant by "robot present". Understood. We still need to do some research to find out if we need to have more safeties in place. comments/suggestions?

Can you give any details about the charging station detection? what is the plan for having the robot find the charger?, is it done via web cam, IR beacon, RF Beacon? We've looked at both IR and RF beacons. I would welcome your comments on this if you have any further insight. I think trying to use the webcam, although very doable has too many variations.

I've also attached a file with some docking station bits. I thought it would give you some more context. Also in production, I think having the charging contact in the back of the robot would be better. That way you'd see more than a wall when the PC-BOT is charging and you connect to it from home. I see the PC-BOT going to the station rotating 180 degrees and then backing up into it.

Cheers!
File Attachment:
File name: Docking_Station_bits.zip
File size:42616 bytes
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croc999
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Re:General Status??? - 2008/12/04 10:01 Hey Grunt,

Interesting design, does it attach to the floor? (suction or some other mechanical mechanism), from the pic it looks like it could be knocked over? or slide across the floor when the robot tries to dock (not trying knock the design just curious)

given the voltage level it posses very little risk of getting shocked as you allude to, but kids and dogs tend to lick things they should not, I'd hate to see that happen, the other thing that comes to mind is what happens if the contacts are shorted by a curious child and their spoon? again this may be a small chance of ever happening, but you never know, my experience has been, if it can happen, it will happen.

My current plan for docking is to use the web cam to get to the docking station, then from there either use a light beam and sonar to complete the final last few inches, but this is still floating between my ears since and I have not finalized anything just yet. One idea that I am toying with is to use a network power switch, so once the robot is physically touching the contacts, it would then turn on the AC to the charger, then once complete it would power down the charger.

Or another option I tossed around was to use a micro controller to add some "brains" to the charger, it could then use a handshaking method via IR to control charging.

But at the moment these are just wish list items and I realize that because these are just vapor I'm spouting hot air since you have an actual docking device

Croc4
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