Robot Dog Kits

[engineeri...@gmail.com]

To follow up from last night's discussion on amazon under search "robot raspberry pi dog" are 2 models with sample videos of walking and features.

AmazonSmile: Freenove Robot Dog Kit for Raspberry Pi 4 B 3 B+ B A+, Walking, Self Balancing, Ball Tracing, Face Recognition, Live Video, Ultrasonic Ranging, Camera Servo Wireless RC: Computers & Accessories 

AmazonSmile: Petoi Bittle Bionic Open Source Robot Dog which has Customized Arduino board, Compatible with Raspberry Pi, Arduino IDE and graphical programming, Easy to operate and Rich curriculum resources: Computers & Accessories

I have the Freenove version, but the videos for the Petoi are impressive (and more expensive...)   For the Freenove version, have to add your own raspberry pi and batteries (which are also available on amazon). 

[Ross Lunan]

Impressive design , so who will be first to hack a ROS implementation on the Raspberry Pi version?

[David Murphy]

Looking at the pictures/video, seems the freemove version has more degrees of freedom? e.g. two servos in the shoulder vs one in the Petoi bittle dog?

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[Peter Finn]

Petoi was made by Rongzhong who developed  opencat https://www.hackster.io/petoi/opencat-845129  

[Chris Albertson]

Freemove looks to be the best one.   The price is fair as the kit contains 12 high-quality servos that are worth $10 each.  Toss in the other parts and it's actually a good deal.

As for adding ROS.  You'd need to add more sensors before that would make sense.  What is the payload carrying ability of this robot?  

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Chris Albertson
Redondo Beach, California

[engineeri...@gmail.com]

I had been using these allforbest  (18650 flat top recharable 3.7 40A 3000mA) batteries.

The amazon link is no longer valid though:

Page Not Found (amazon.com) 

I had ordered the flashlight batteries, and would have used them, but I realized they were only 1200mAh, and I was able to find 3000mh instead (above)

Super Bright 2000 Lumen 18650 Tactical Flashlight and 6PCS 3.7V High Capacity Rechargeable Battery+Batteries Charger, Zoomable, Water Resistant, 5 Modes Handheld Light - - AmazonSmile  

One thing is clear, the batteries fit, but it is a really snug fit....you can put them in out, but very difficult to take out.

with the 3000mh I have run them for ~20 minutes with the rasbperry pi on and motors testing the function on with out obvious issue.   Normally I have it powered by USB though, so I could not tell you when the batteries run out.

On Friday, February 26, 2021 at 2:27:26 AM UTC-8 cmay...@gmail.com wrote:

I found a good site with 18650 battery specs.

http://lygte-info.dk/info/Batteries18650-2011%20UK.html

It seems there are a LOT of Chinese fakes claiming 5000 or even 9000 mAh that usually come with a flashlight, so I have no idea what to buy for the Freenove Cat-Dog.

The sizes (from 65 to 70 mm) and form factors (flat top and button top) vary, so please let us know which batteries you used, and if they worked well as far as fit and how long they lasted.

Thanks!

[engineeri...@gmail.com]

Regarding the payload question, I am not sure. The documentation doesn't mention it.  But given the sounds of the motors, I had assumed that it wouldn't carry much more than what is is already carrying, (raspberry pi, pcb, batteries, acrylic frame, etc.)  Also, the robot software setup has a short run time, before it goes into a cool down mode....

[Robert Rodgers]

I may have to breakndown and get one of these

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[Robert Rodgers]

Ya know, if we can get dome sheets of acrylic and a file we can have the bodies cut out. I'm sure the other parts can be sourced fairly easily from Ebay. Cheaper if we buy them I  bulk. 

Just a thought. 

[Chris Albertson]

You can 3D print these bodies.  In fact the design could be improved by 3D printing, the design options of cut acrylic really limits what you can do.  3D prints cost 2 cents per gram and there is nearly zero scrap waste, likey about $2.50 total per robot.

If a few people want to work on developing this into a printable design, I'd offer to make 3D CAD files from a scan of the flat parts and  add enough improvements to android copyright issues.   (Literally price the flat parts in a scanner, then post the file.)

The biggest cost for a 3-DOF quadruped is the servo motors.  The better the quality of motors the better robot performance.   I tried making one leg from some way-cheap servos and the servos lasted only a couple hours of use.   You need to spend about $10 per motor for a toy-size dog like this.   This means about $120.

This kit is actually a good deal because the $130 price is less than you could otherwise buy the parts.

That said, a more useful outdoor robot would need to be much larger and the cost of the servos much higher at $70 to $110 each and you still need 12 of them.

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[Steve " 'dillo" Okay]

What do people think about building one of the Stanford Pupper or Doggo quadrupeds vs. one of these ? 

'dillo

On Thursday, February 25, 2021 at 8:38:48 AM UTC-8 engineeri...@gmail.com wrote:

[Chris Albertson]

On Sun, Feb 28, 2021 at 10:56 AM Steve " 'dillo" Okay <espre...@gmail.com> wrote:

What do people think about building one of the Stanford Pupper or Doggo quadrupeds vs. one of these ? 

Here is how to decide.  FIRST figure out what the robot is going to do and in what environment it will operate.

If the purpose is to experiment with walking gaits on a clear and clean indoor floor then "Pupper" would be good.  But maybe the robot is going to pick up trash on the side of a road, then it needs to be bigger.  The Doggo might be large enough to carry a small arm and some sensors.