Search found 12 matches

by keithmgould
Sat Jul 14, 2018 10:29 pm
Forum: General Bullet Physics Support and Feedback
Topic: why are importers in the examples directory?
Replies: 4
Views: 1074

why are importers in the examples directory?

Trying to get a sense of the cpp code layout, and was surprised to find some things in the examples directory that did not feel like examples. 1. the Importers, such as URDF importers. 2. pyBullet. Can someone please help me understand the nature of the examples directory? Or should things be moved ...
by keithmgould
Mon Jul 09, 2018 2:50 pm
Forum: General Bullet Physics Support and Feedback
Topic: When building URDF models, which visualizer do you use?
Replies: 3
Views: 1252

Re: When building URDF models, which visualizer do you use?

it has utilities to show inertial boxes and in wireframe mode it can show joint axis etc That is fantastic. 1. I've looked through the quickstart a few times, and did not find instructions for how to do this. Did I miss it, or is that information somewhere else? Is there an example with instruction...
by keithmgould
Thu Jul 05, 2018 5:26 pm
Forum: General Bullet Physics Support and Feedback
Topic: modelling gearbox backlash
Replies: 7
Views: 1540

Re: modelling gearbox backlash

Running into some trouble, hoping someone has some insight. I'm using the method explained in my post above. Yet it seems the constraints via the "limit" tag are not holding when there is resistance. Posting code here so its super easy to show the problem. The very basic setup is a a "balancer" robo...
by keithmgould
Tue Jul 03, 2018 5:43 pm
Forum: General Bullet Physics Support and Feedback
Topic: When building URDF models, which visualizer do you use?
Replies: 3
Views: 1252

When building URDF models, which visualizer do you use?

Curious what the community uses when building out a model. Rviz? URDF-viewer? Would love to hear what you use, and why. I'm not really sure what the options are, so even a mention of what you don't use (and why not) would be helpful. Do any of the visualizers allow you to see the points in your link...
by keithmgould
Sat Jun 30, 2018 3:12 am
Forum: General Bullet Physics Support and Feedback
Topic: modelling gearbox backlash
Replies: 7
Views: 1540

Re: modelling gearbox backlash

Hey guys, After a bit of tinkering around I think I came up with a dead-simple solution for this: Body: the main link. Gear: a cylinder link. Attached to Body via a continuous joint. Wheel: a cylinder link. Attached to Gear via a revolute joint with upper and lower limits. Then set the force of the ...
by keithmgould
Fri Jun 29, 2018 10:01 pm
Forum: General Bullet Physics Support and Feedback
Topic: modelling gearbox backlash
Replies: 7
Views: 1540

Re: modelling gearbox backlash

Thank you for the ideas!

It feels like idea 2 might be the way to go, though I'm new to Bullet, so I'm not certain. I'll try to get it working, and report back here.
by keithmgould
Fri Jun 22, 2018 4:33 pm
Forum: General Bullet Physics Support and Feedback
Topic: modelling gearbox backlash
Replies: 7
Views: 1540

Re: modelling gearbox backlash

Hello, and thanks for responding. I've added a new section to the main description above which I believe answers your question. Thank you for any thoughts!
by keithmgould
Thu Jun 21, 2018 5:50 pm
Forum: General Bullet Physics Support and Feedback
Topic: modelling gearbox backlash
Replies: 7
Views: 1540

modelling gearbox backlash

Hello! I have a DC Motor with a gearbox and the gearbox gives backlash[1], in this case between dc motor and final shaft due to loose gears. It's about 0.1512 rads (or 8.663 degrees). I'd like to include this backlash in a motor model. Did not see much reference to "backlash" in this forum's history...
by keithmgould
Fri Jun 08, 2018 4:51 pm
Forum: PyBullet Support and Feedback
Topic: Position control for robot base?
Replies: 13
Views: 3178

Re: Position control for robot base?

Ah, I missed that it was happening *during* the simulation. Sorry for the bad advice! Hope you have it all sorted now :)
by keithmgould
Tue Jun 05, 2018 7:49 pm
Forum: PyBullet Support and Feedback
Topic: Position control for robot base?
Replies: 13
Views: 3178

Re: Position control for robot base?

I'm also new.

I _think_ what you want is just resetBasePositionAndOrientation(). Find more detail in the quick-start guide:

https://docs.google.com/document/d/10sX ... og8ua34um1
by keithmgould
Thu May 31, 2018 10:07 pm
Forum: PyBullet Support and Feedback
Topic: how to determine rotational velocity relative to direction robot is "facing"
Replies: 1
Views: 658

Re: how to determine rotational velocity relative to direction robot is "facing"

Believe I've figured it out. My guess above is correct, or at least, it works, though it might not be the best or most "pybullet/bullet" way to do things. Below is the code I used to verify. I take R2D2, rotate him about the Z axis a bit, and set him spinning "forward." At this point, what I'd want ...
by keithmgould
Thu May 31, 2018 6:25 pm
Forum: PyBullet Support and Feedback
Topic: how to determine rotational velocity relative to direction robot is "facing"
Replies: 1
Views: 658

how to determine rotational velocity relative to direction robot is "facing"

This feels like a common question but I could not find it... Generally: I'm looking to know rotational velocity relative to world orientation. Specifically: I have a "balancing robot", (a stick on two wheels), where the stick is the base link. I want to know how fast it's falling "forward", and "for...