Discussion - Designing a Chassis (Making a Mobile Robot Pt 11)

Articulated Robotics Content Discussions
#1

Currently no blog post for this video

This is the discussion topic for the video and blog post linked above. Please keep all replies relevant to the content, otherwise create a new topic.

#2

Hi, I like the way you make a pretty neat looking chassis out of a plastic container - turned out really well.

Can you let us know what you did to make the lids when 3D printed - you have the design done in Blender, so what other software did you use to get from that to the 3D printer (I am hoping you didn’t have to redo it in a CAD program)

Also, what are motors you used (I may have missed the names or they may be mentioned in another video)

Thanks.

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#3

Thanks Duncan!

Re the modelling, the Blender model was just a very rough mockup, dimensions were just a guess, it was mostly to get a vibe for the mounting locations, colours, etc. For the 3D printing I designed the plates in Fusion 360, but they were very simple and so didn’t take long even with my pretty limited CAD skills. Just a rectangle the right size with a lip around the edge, and a round corner on the ones that needed it.

I had originally planned to share the files, but in the end they were pretty specific to my container and my needs, and there are also some improvements I would want to add. If someone does actually have a need for those exact plates for that container, I’d be happy to redo them and share them, it would take less than an hour.

Re the motors, I think it is mentioned in a couple of spots but it is specifically these ones which have annoyingly been out of stock for quite a while. I’m sure you can find very similar ones around though.

So far I’ve found that although they are not as powerful as other cheap motors I’ve tried (e.g. on my prototype robot), they have worked a bit more smoothly and played nice with the PID controller in the Arduino code. I haven’t really put them through their paces yet though.

Edit: For what it’s worth, if anyone in Australia wants to buy the same container I think it was this one, not sure if the same design is available internationally.

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#4

Thanks for that - very helpful! I have been playing with the electronics for a bit and designing overly fancy chassis in Blender, but I think I will go the plastic container path just to get things moving :slight_smile:

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#5

Hi Josh,

could you please share the 3d print files for 3 hole covers and pi cam and Lidar?
if you did already, where can I find them?

Regards,

John

#6

Hi John, I thought I had but apparently not.

Lidar mount: LIDAR A1 Mount by Dingo_aus - Thingiverse (apparently made by @Dingo_aus ?? Thanks!)
Camera enclosure: Raspberry Pi Camera v2 Case with GoPro-style Mount by MmmPeanutButter - Thingiverse
Camera base: Modular Mounting System 2020 Bracket by kwfredeen - Thingiverse

Regarding the plate covers, as I mentioned to Duncan above I haven’t made them available as I’d want to redesign/make some tweaks to them before I released them publicly, but unless someone has exactly the same container I do for the chassis (again linked above) then they’re not of much use anyway.
If you do have exactly that container, let me know and I’ll spend the half hour or whatever it takes to redo the plates.

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#7

Hi Josh,

Thank you. I bought a box exactly same. I am lucky because I live in Australia Melbourne…
Thank you your time and effort for me.

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#8

Hey John, sorry for taking so long to get back to you. I finally redid those models last night and they are available here. That has the 3 STL files and also the Fusion file for the project.

I haven’t reprinted them since redesigning so hopefully they are alright and I haven’t made any mistakes!
Obviously print with the flat side down.

I have not made holes for cables to go through, I just drilled them on mine, but if you want a neater solution it would be fairly straightforward for you to modify the files above with appropriate slots and mounting holes for your gear.

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#9

Thank you very much Josh.
I will print them today ^^

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#11

I tried using meshes(stl) but I keep getting errors while trying to visualize in rviz

[ERROR] [1671440558.512675983] [rviz2]: FileNotFoundException: Cannot locate resource...

#12

Sorry for the delay in replying to this!
I have also had issues getting meshes to work properly in the past - it absolutely can be done but can be a pain.
I think the problem I had last I looked into it was getting the meshes to work in both Gazebo and RViz at the same time, I could only get one or the other.

If you supply a full path to the STL file it should work. Alternatively if it is in a ROS package there is a package:// syntax e.g. here.

Also IIRC Collada (.dae) files are a slightly better format, but if STL is what you’ve got that should be fine.

#13

I got it working with the full path and the retriever syntax file://. for some weird reason, package:// didn’t work for me

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#14

hello, can you provide me the connection diagram between the pins of the motor and the L298

#15

Yes, truly grateful, let me ask you: why is it that when I run the command “ros2 run serial_motor_demo gui,” my robot runs for about 1-2 seconds and then stops? Please help me, I sincerely appreciate your assistance.