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Autononmous docking mechanism and others.

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amitjo
(@amitjo)
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Hi,

   - It would be interesting to see some practical information to implement a low-cost autonomous docking solution specifically for indoor robots. This could for example be used to implement autonomous charging for the robot.

   - Practical information or suggestions to implement cliff detection, bump detection and obstacle avoidance will also be very useful.

Thanks and regards,

Amit.


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robotBuilder
(@robotbuilder)
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@amitjo

Most robot vacuum cleaners implement a working and thus practical docking solution. The robot design is a component in the solution. Different robots, different possible solutions. So first design a practical robot. Once you have settled on its sensory system and physical abilities you can then think about how to use that sensory system for docking purposes.

Robot vacuum cleaners also offer practical solutions like infrared proximity sensors for obstacle avoidance and cliff detection and they also implement some kind of bumper for direct physical contact with obstacles.

So first you need to specify your robot design and preferably actually build it before you can think about a practical docking system for that particular robot.

 


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THRandell
(@thrandell)
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@amitjo  @robotbuilder

That’s a lot of material to cover 😉     You can find some stuff on instrumented bumpers on this site.

For an approach to a robot charging station check out Chris and Dawn Schur’s site 

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

 

Good Luck   Tom


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robotBuilder
(@robotbuilder)
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@amitjo

@thrandell
Hadn't seen that site before. Google flags it as Not secure. Not sure what that potentially means in terms of web safety. I see there are a lot of other robot related topics there as well.
http://schursastrophotography.com/robotics/

 

This post was modified 3 weeks ago by robotBuilder

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DroneBot Workshop
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Posted by: @robotbuilder

Google flags it as Not secure. Not sure what that potentially means in terms of web safety.

It means that the site owners are too cheap to purchase a proper security certificate, or too clueless to implement a free LetsEncrypt certificate LOL!  Chrome flags it as unsecure, as it is HTTP instead of HTTPS.  They have been doing that since October 2017.

And I've been guilty of this as well. You would have seen that warning on my own website on September 8th for a few hours as I had purchased a new certificate but had neglected to install it. My own fault entirely, as I had made a note on my calendar but didn't look at it.  It’s something I have to do every two years, so I tend to forget about it.

Bottom line - I'm pretty sure that the site is perfectly safe to use, as long as you aren't submitting any sensitive information to them.

😀

As for autonomous robot docking, as @amitjo pointed out a docking mechanism would be specific to the robot  design, so it would be a pretty difficult topic to cover and would apply to only one design.

I remember seeing a robot design in Byte magazine (anyone else remember Byte?) back in the 1970s that was able to charge itself with its arm - the "fingers" were designed to plug into a standard US/Canadian style wall outlet!  I believe with that early technology the wall outlet had to be at an exact location.

It might make a good topic as part of a robot series - I've been building an outdoor robot all summer (which is why you haven't heard a lot from me over the summer) but I have no intention of having it charge itself as it uses a couple of LiPo batteries.

However, I had thought of doing that with the other robot I've been "secretly" working on, the one formerly known as "DB1".  So eventually you might actually see a video about the subject here, but it will be specific to that robot (whatever I rename it to, as it's changed a LOT since the original design).

So consider this "kind-of accepted", with the understanding that you may not be seeing it for a while!

😎

Bill

"Never trust a computer you can’t throw out a window." — Steve Wozniak


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amitjo
(@amitjo)
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Topic starter  

@thrandell

Thanks thrandell. The link provided is very informative. Hadn't seen it before!

Thanks Bill, Take your time! No hurry. Just though of of suggesting few topics that if covered on DroneBot Workshop will add to its list of very relevant and useful topics (all at one place). A docking mechanism for DB1 type of robot is what I had in mind so that would be perfect!

You mentioned not autonomously charging LiPo batteries. Is that due to its fire hazard probability?


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DroneBot Workshop
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Posted by: @amitjo

You mentioned not autonomously charging LiPo batteries. Is that due to its fire hazard probability?

Yes, exactly. I won't even leave the batteries in the robot when I'm not using it, they get stored in a fireproof (and explosion proof) container, with a big bag of sand on top of them.  And when I do charge or discharge them, I'm always in the room with them, with a fire extinguisher handy just in case.

There was a horrible fire across the street this spring, in a unit identical to my own, and it started in their basement. It took 30 firefighters 7 hours to extinguish it, and they are still rebuilding the house.  Sadly one person died in it and one was severely injured. So fire safety is a top priority for me.

Bill

"Never trust a computer you can’t throw out a window." — Steve Wozniak


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robotBuilder
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@dronebot-workshop 

As for autonomous robot docking, as @amitjo pointed out a docking mechanism would be specific to the robot design, so it would be a pretty difficult topic to cover and would apply to only one design.

Actually I made that point to amitjo.

I remember seeing a robot design in Byte magazine (anyone else remember Byte?) back in the 1970s that was able to charge itself with its arm - the "fingers" were designed to plug into a standard US/Canadian style wall outlet!  I believe with that early technology the wall outlet had to be at an exact location.

Yes I remember the BYTE magazine.

The Newt robot.

https://archive.org/details/byte-magazine-1977-06/page/n35/mode/2up

And when I do charge or discharge them, I'm always in the room with them, with a fire extinguisher handy just in case.

Maybe build a fire extinguisher into the robot and heat sensors to set it off 🙂 Maybe use infrared sensors to keep the robot away from an open fire or electric bar heater.

 

This post was modified 3 weeks ago by robotBuilder

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Will
 Will
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Posted by: @robotbuilder

@dronebot-workshop 

And when I do charge or discharge them, I'm always in the room with them, with a fire extinguisher handy just in case.

Maybe build a fire extinguisher into the robot and heat sensors to set it off 🙂 Maybe use infrared sensors to keep the robot away from an open fire or electric bar heater.

Maybe just store the batteries in one of the flame-proof charging bags and leave them inside the bag when you put them onto the robot ?


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byron
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Posted by: @dronebot-workshop

It might make a good topic as part of a robot series - I've been building an outdoor robot all summer (which is why you haven't heard a lot from me over the summer) but I have no intention of having it charge itself as it uses a couple of LiPo batteries.

Aha, I though you must be up to something. But for an outdoor bot a self charging arrangement, provided it was put in an appropriate spot, and you don't live in a fire hazard area, should only mean a fried bot and maybe a flaming enclosure in extremis.   It would certainly be a very convenient way to get on outdoor bot charged.  

It should be possible to come up with a generic arrangement for outdoor bots that bots of quite a different range of sizes could adopt.  I would chip in to any design thoughts if only to get a share of the fortune to be made once the design is patented. 😎 


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DroneBot Workshop
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Posted by: @robotbuilder

Actually I made that point to amitjo.

My apologies, you did indeed make the post.  My error.

Posted by: @robotbuilder

Maybe build a fire extinguisher into the robot and heat sensors to set it off 🙂 Maybe use infrared sensors to keep the robot away from an open fire or electric bar heater.

LOL. I've already spent over 2500 dollars on this robot (half of that on the GPS RTK system alone) and I'm also at the limit of the maximum weight the chassis will hold. So I'm not really eager to add more stuff to it, not to mention designing a fire suppression system!

Plus, I'm racing the clock, as here in Montreal I probably only have about 4 or 5 weeks until we get our first snow storm. And it's a robot, not a "snow bot" LOL.  So I need to concentrate on getting the GPS RTK stuff finished before I have to bring it inside for the winter. The object recognition and other features can be developed indoors.

Posted by: @will

Maybe just store the batteries in one of the flame-proof charging bags and leave them inside the bag when you put them onto the robot ?

I transport them in those so-called "flameproof" bags, which I then insert into a steel ammunition case (with the seal removed, so the batteries can vent gas). There is no room in the robot itself to put one of these bags, but I'm not particularly concerned about the batteries catching fire while they are in the robot.

And there really is no point to charging the batteries inside the robot anyway, nor is there any reason to have a docking station for it.  It's not like I'm going to leave my priceless collection of electronics outside unattended!

@will One thing about your comment concerned me, but I may be misinterpreting it - I certainly hope you don't consider those "flameproof bags" to be a safe way of storing LiPo's, because they most definitely are not!  At best, they will reduce the flames long enough for you to extinguish them. But on their own they won't prevent a fire from spreading. 

I do use them when I charge and discharge the batteries, as some of the ones I own have a place to run the battery cables out to the charger. And I have some smaller, single battery sized ones that I place each battery in before I put them in my homemade battery vault. My "battery vault" is just a steel toolbox lined with two layers of drywall, the drywall creates what is called a "2-hour burn wall".  And I them place an 18-pound bag of sand on top of the toolbox, so if a fire does make it through, the plastic bag will melt and dump sand onto the toolbox, hopefully extinguishing the flames. And, of course, I have a smoke detector beside the whole assembly, and a fire extinguisher nearby.

And, most importantly, I always discharge them to storage voltage (3.8 volts per cell) before I put them away.

Check out this video where they do an extensive fire test of six different ways to store LiPo batteries. Number two is the so-called "fireproof bag", which fails miserably.

I've been working on a LiPo video since August, I'll release it soon. Stay tuned!

😎

 

Bill

 

 

 

"Never trust a computer you can’t throw out a window." — Steve Wozniak


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Will
 Will
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Posted by: @byron
Posted by: @dronebot-workshop

It might make a good topic as part of a robot series - I've been building an outdoor robot all summer (which is why you haven't heard a lot from me over the summer) but I have no intention of having it charge itself as it uses a couple of LiPo batteries.

It should be possible to come up with a generic arrangement for outdoor bots that bots of quite a different range of sizes could adopt.

How about a simple channel formed by 2 parallel walls ? The robot has two rods on it's top spaced by a few inches which rub on two bent-metal leaves protruding from the "roof" over the channel. When both rods touch the leaves, the circuit is closed and charging can proceed through them. When charging is complete, the robot simply moves on through the channel (and the next robot moves into place).


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DroneBot Workshop
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Posted by: @will

How about a simple channel formed by 2 parallel walls ? The robot has two rods on it's top spaced by a few inches which rub on two bent-metal leaves protruding from the "roof" over the channel. When both rods touch the leaves, the circuit is closed and charging can proceed through them. When charging is complete, the robot simply moves on through the channel (and the next robot moves into place).

Interesting idea. 

And if it has enough voltage and current, it could also be used to fry squirrels! Note that I'm sort-of kidding here, I'm actually an animal lover and wouldn't really want to hurt one. But as squirrels ate all the wires in my car this spring, resulting in a 1700 dollar repair bill, I might make an exception for them!  In my neighborhood, the squirrel population outnumbers the human population by about a factor of 10.

I do see the use for autonomously charging an outdoor robot if you are using it for security or to tend to your garden.  My robot's main purpose is to scare my neighbors and maintain my reputation as the weird old man who lives in the corner house!

😎

Bill

"Never trust a computer you can’t throw out a window." — Steve Wozniak


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byron
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Posted by: @will

The robot has two rods on it's top spaced by a few inches which rub on two bent-metal leaves protruding from the "roof" over the channel. When both rods touch the leaves, the circuit is closed and charging can proceed through them

Indeed a meritorious suggestion.  But wont the rods be connected to the battery which could then be short circuited.  However I expect some cleaver circuitry could be employed to prevent such disasters (maybe 🤔 )


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Will
 Will
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Posted by: @dronebot-workshop
Posted by: @will

How about a simple channel formed by 2 parallel walls ? The robot has two rods on it's top spaced by a few inches which rub on two bent-metal leaves protruding from the "roof" over the channel. When both rods touch the leaves, the circuit is closed and charging can proceed through them. When charging is complete, the robot simply moves on through the channel (and the next robot moves into place).

Interesting idea. 

And if it has enough voltage and current, it could also be used to fry squirrels!

[snipped]

My robot's main purpose is to scare my neighbors and maintain my reputation as the weird old man who lives in the corner house!

😎

Bill

You might have to give the squirrels aluminum track suits to lower their resistance enough for the terminals to notice their presence.

On the other hand, the screams, flash-bangs and smells from the self-immolating squirrels would undoubtedly accelerate your obvious desire for a label of eccentricity with the neighbours 🙂


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