Linorobot Project

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camp .

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Apr 27, 2022, 2:14:42 PM4/27/22
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    This evening we have a special presentation by the owner of the Linorobot Project, Juan Miguel Jimeno.
 
Wed April 27 at 7PM West Coast Time
Zoom: https://us06web.zoom.us/j/85431823055?pwd=Ulh3ZytyMTczM1FjNkJscWRKTXlsdz09
Zoom Meeting ID: 854 3182 3055, Passcode: 53370
 
linorobot2
https://github.com/linorobot/linorobot2
 
    If you're interested in ROS, Linorobot is an excellent starting place. It features a virtual and physical robot with standardized parts. Linorobot is modular and scalable to build the robot YOU want. Plus, it's an excellent ROS trainer. It has an active community https://groups.google.com/g/linorobot in which you're liable to see some familiar faces.
    Some time ago, Mark Womack suggested an Example Robot project for the HBRC. In my travels, if we were to develop a really good example reference platform, It would look like Linorobot.
    Hope to see you this evening for Robot News, Club News, What-I-need-help-with, and Show-and-Tell. So, get your robot running!
 
Looking forward...
Camp

camp .

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Apr 27, 2022, 7:49:05 PM4/27/22
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Tonight!

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Chris Mayer

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Apr 28, 2022, 12:41:27 AM4/28/22
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The video will be up shortly on our YouTube channel.

Mark Womack

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Apr 28, 2022, 5:40:33 PM4/28/22
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Sorry I missed this. I'm looking forward to the video! 

Mark

Chris Albertson

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Apr 28, 2022, 6:39:51 PM4/28/22
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Are there any design files for the chassis itself?   I've been looking, but I guess not in the right place.    I was expecting CAD files of some kind.

What I do find is very well done.  This is a perfect example of a "Standard" mobile platform robot.



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Chris Albertson
Redondo Beach, California

camp .

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Apr 28, 2022, 8:04:00 PM4/28/22
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> Are there any design files for the chassis itself?
 
 
Also, note the mech and robots folders in the urdf folder.
 
- Camp

Chris Albertson

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Apr 28, 2022, 8:21:37 PM4/28/22
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I should have said, that of course the critical dimensions are in the URDF files.    I was looking for at least 2D CAD drawings that called out a list of parts to be made or even better 3D files that could be printed.

I was going to suggest Linorobot to a beginner.  But he would have to know how to make all the parts from only the data in the URDF files.   Many people need more concrete instructions, photos of the assembly process, and so on.      Me?  I could adapt this to any wheeled platform but I was thinking of others.

I'm help make a "simplest possible" physical build.    I would say to start with a HDPE cutting board bought from the kitchen section on Amazon then print some mounting parts and attach with wood screws.

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camp .

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Apr 28, 2022, 8:28:10 PM4/28/22
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... and I believe this is where the Xacro gets kicked off from the Gazebo launch file.
 
----------------------------------------------- snip -----------------------------------------------
robot_base = os.getenv('LINOROBOT2_BASE')

urdf_path = PathJoinSubstitution(
[FindPackageShare("linorobot2_description"), "urdf/robots", f"{robot_base}.urdf.xacro"]
)
def generate_launch_description():
----------------------------------------------- snip -----------------------------------------------
 
linorobot2/linorobot2_gazebo/launch/gazebo.launch.py
 
- Camp

Scott Monaghan

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Apr 28, 2022, 8:30:38 PM4/28/22
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I missed the live meeting but just watched the video!!! Super cool!

Am I correctly remembering that the components for building a basic linorobot are under $300?

I have considered converting Ro-Bud to ROS and Iinorobot2 could be a great starting platform! 

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camp .

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Apr 28, 2022, 8:39:46 PM4/28/22
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> I have considered converting Ro-Bud to ROS and Iinorobot2 could be a great starting platform!
 
I believe it's the right dimensions out of the box. ~10" square base and ~3.5" wheels.   :]
 
- Camp

Scott Monaghan

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Apr 28, 2022, 9:05:05 PM4/28/22
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Or so they would have been…

But Ro-Bud is in the middle of an aesthetic and practical locomotion upgrade.

See attached vid:)

IMG_4748.MOV

Chris Albertson

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Apr 28, 2022, 10:22:02 PM4/28/22
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Is that a timing belt that is repurposed as a tank track?   Or did you print it.

BTW I have a robot chassis with two of those plastic yellow motors.   I bought an encoder kit for it.   It is cheap and easy to install.  They make a slotted disk that press fits to the white output shaft and it comes with a "C" shape IR sensor.    It can gets decent results. You could also print the slotted disk.  

If you do move to ROS, then you'll want decent odometry and motor speed control encoders allow this
Here is how it fits to the motor
amazon.com/DC-Motor-Gearbox-Plastic-Encoder

And here is a link to the sensor on a PCB
amazon.com/Measuring-Optocoupler-

Or you can buy the bare sensor.  
amazon.com/dp/B00M1PMFGE

With not encoders, how are yu keeping the robot's path straight?     Are you motors running at the same speed just by luck or maybe you have a gryo?


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Scott Monaghan

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Apr 28, 2022, 10:31:34 PM4/28/22
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Hi Chris,

I modeled the belt track in Fusion360 (loosely based off a timing belt, then I printed it in flexible TPA.

I actually have a ton of encoders and ir photo interrupter sensors, but I’m not using them right now. 

To keep the robot straight:
- Right now I use the BNO055 absolute orientation sensor to detect deviation from target heading and adjust the motor throttle accordingly.
- Soon I plan on updating the robot to use a visual target’s centroid and do the same thing.





Thanks sir!

Marco Walther

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Apr 28, 2022, 11:21:07 PM4/28/22
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On 4/28/22 19:21, Chris Albertson wrote:
> Is that a timing belt that is repurposed as a tank track?   Or did you
> print it.
>
> BTW I have a robot chassis with two of those plastic yellow motors.   I
> bought an encoder kit for it.   It is cheap and easy to install.  They
> make a slotted disk that press fits to the white output shaft and it
> comes with a "C" shape IR sensor.    It can gets decent results. You
> could also print the slotted disk.

I built some magnetic/quadrature encoders our of plywood on the
backside-motor shaft of those motors in 2015;-) Much better resolution.
It should be much easier today with a 3D-printer;-) The magnets were dia
1mm * 1mm height

-- Marco
>
> If you do move to ROS, then you'll want decent odometry and motor speed
> control encoders allow this
> Here is how it fits to the motor
> amazon.com/DC-Motor-Gearbox-Plastic-Encoder
> <https://www.amazon.com/DC-Motor-Gearbox-Plastic-Encoder/dp/B08LQ2DPHQ/ref=sr_1_34?crid=257A554C8JH1Z&keywords=encoder+disk+for+plastic+gear+motor+smart+car&qid=1651197761&s=toys-and-games&sprefix=encoder+disk+for+plastic+gear+motor+smart+car%2Ctoys-and-games%2C123&sr=1-34>
>
> And here is a link to the sensor on a PCB
> amazon.com/Measuring-Optocoupler-
> <https://www.amazon.com/Measuring-Optocoupler-Interrupter-Detection-Arduino%EF%BC%885pcs%EF%BC%89/dp/B08977QFK5/ref=sr_1_5?crid=283C9V0J7U413&keywords=ir+slot+sensor&qid=1651197980&sprefix=ir+sslot+ensor%2Caps%2C105&sr=8-5>
>
> Or you can buy the bare sensor.
> amazon.com/dp/B00M1PMFGE
> <https://www.amazon.com/dp/B00M1PMFGE/ref=sspa_dk_detail_0?psc=1&pd_rd_i=B00M1PMFGE&pd_rd_w=sVWGK&pf_rd_p=0c758152-61cd-452f-97a6-17f070f654b8&pd_rd_wg=xB1TI&pf_rd_r=2E3HQ9JVDKWARB3BQWSW&pd_rd_r=431611de-a874-4192-be86-a63c7a8c0402&s=hi&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyR1ZFUlA2U0EyQ0lLJmVuY3J5cHRlZElkPUEwODY3NzkwMTdYSEFYSlNNSTlGMSZlbmNyeXB0ZWRBZElkPUEwMDI0NTU4M0NWT0IxNjRKTkZMNyZ3aWRnZXROYW1lPXNwX2RldGFpbCZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=>
>
> With not encoders, how are yu keeping the robot's path straight?     Are
> you motors running at the same speed just by luck or maybe you have a gryo?
>
>
> On Thu, Apr 28, 2022 at 6:05 PM Scott Monaghan <scott.m...@gmail.com
> <mailto:scott.m...@gmail.com>> wrote:
>
> Or so they would have been…
>
> But Ro-Bud is in the middle of an aesthetic and practical locomotion
> upgrade.
>
> See attached vid:)
>
> On Thu, Apr 28, 2022 at 7:39 PM camp . <ca...@camppeavy.com
> <mailto:ca...@camppeavy.com>> wrote:
>
> > I have considered converting Ro-Bud to ROS and Iinorobot2 could be a great starting platform!
>
> I believe it's the right dimensions out of the box. ~10" square
> base and ~3.5" wheels.   :]
> - Camp
>
> On Thursday, April 28, 2022, 08:30:38 PM EDT, Scott Monaghan
> <mailto:hbrobotics+...@googlegroups.com>.
> To view this discussion on the web visit
> https://groups.google.com/d/msgid/hbrobotics/48a754ba-0b6c-4cc8-ae3e-ded6857cda86n%40googlegroups.com
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>
> --
> Scott Monaghan
> 413.244.9344
> scott.m...@gmail.com <mailto:scott.m...@gmail.com>
> www.linkedin.com/in/scott-monaghan
> <http://www.linkedin.com/in/scott-monaghan>
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>
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> --
> Scott Monaghan
> 413.244.9344
> scott.m...@gmail.com <mailto:scott.m...@gmail.com>
> www.linkedin.com/in/scott-monaghan
> <http://www.linkedin.com/in/scott-monaghan>
> Resume: https://tinyurl.com/yxhq5eul <https://tinyurl.com/yxhq5eul>
>
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> Chris Albertson
> Redondo Beach, California
>
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IMG_20150424_171950_1024.jpg
IMG_20150423_220031_1024.jpg

Pito Salas

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Apr 29, 2022, 7:27:08 AM4/29/22
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Hi all

I have a lot of experience with Linorbot. We've built a differential drive using a ammo box (from Harbor Freight) as a container and build a tracked vehicle from  a chassis we bought online. I would be glad to share my experiences and code and everything. My hardware partner also designed a custom board to make the wiring cleaner and I am glad to share that design as well. 

Problem is that I don't really have the time right now to focus on writing all this up. Also it is constantly changing as we learn new things. If there is interest, maybe we can do a zoom meeting (I am in Boston) where I can do a show and tell and answer questions or something like that.

Full disclosure - I've only been doing robotics for around 5 years (but with 30 years of Software Engineering) so there are others in this group with more knowledge and experience than I have.

Overall I think the Linorobot.org instructions are great and the platform is a great one from my perspective. We are betting on it.

Pito Salas
Faculty, Computer Science
Brandeis University

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<IMG_20150424_171950_1024.jpg><IMG_20150423_220031_1024.jpg>

camp .

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Apr 29, 2022, 9:55:56 AM4/29/22
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Hey Pito,
Jump into one of our Tuesday ROS Discussion Group meetings. We'll make it a Special Presentation.   ☝️🤖

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