Inquiry for follow-path code

Typically: "How do I... ", "How can I... " questions
coppelia
Site Admin
Posts: 10339
Joined: 14 Dec 2012, 00:25

Re: Inquiry for follow-path code

Post by coppelia »

If your robot/model is shaking, then something must be wrong: e.g. internal collision responses, wrong/bad link masses/inertias, etc.
Please post a minimalistic and self-contained scene that illustrates your problem, then I can have a look at it.

Cheers

Luis Nieto
Posts: 49
Joined: 26 Oct 2021, 01:35

Re: Inquiry for follow-path code

Post by Luis Nieto »

Hello! I have made a video of me demonstrating and explaining my issue with my project. I hope this helps clarify things. Thank you.

Video Link:
https://drive.google.com/file/d/1B7DfvI ... sp=sharing

fferri
Posts: 1193
Joined: 09 Sep 2013, 19:28

Re: Inquiry for follow-path code

Post by fferri »

Did you read Designing dynamic simulations and all design considerations?

coppelia
Site Admin
Posts: 10339
Joined: 14 Dec 2012, 00:25

Re: Inquiry for follow-path code

Post by coppelia »

Also, a video only allows to see a very little part of the problem. Best is to post a minimalistic, self-contained scene.

My guess is that the shapes are all generating collisions with each other. In the dynamics dialog, enabled Display contact points to get an idea if that is the case.

Additionally, you can't make your robot move like that: if you want each leg follow a specific trajectory, then each path needs to be attached to the robot's hip itself. Similar to what the demo model Models/robots/mobile/Asti.ttm is doing. In that model however, the path is just a local trajectory for each foot (i.e. no path object is used in that case).

Cheers

Luis Nieto
Posts: 49
Joined: 26 Oct 2021, 01:35

Re: Inquiry for follow-path code

Post by Luis Nieto »

How can I control how the shapes collide with each other? How can I prevent the areas that are causing collisions if I find them?

coppelia
Site Admin
Posts: 10339
Joined: 14 Dec 2012, 00:25

Re: Inquiry for follow-path code

Post by coppelia »

you need to adjust the shape's local respondable masks.

Cheers

Luis Nieto
Posts: 49
Joined: 26 Oct 2021, 01:35

Re: Inquiry for follow-path code

Post by Luis Nieto »

OK, I'd like to clarify my problem because I recently realized I've mentioned the wrong problem.

The problem with the robot model I have in my scene is that when in dynamic mode, the robot falls over on it's side. I hoped before that it would just stand still, but instead, it just falls over.

Maybe a way I can solve this is if I could somehow give my robot a center of mass and then control is somehow. Does Coppeliasim have a stability controller for legged mobile robots, or a way to establish a CoM and then control it while the robot walks?

Thanks for further advice on this.

coppelia
Site Admin
Posts: 10339
Joined: 14 Dec 2012, 00:25

Re: Inquiry for follow-path code

Post by coppelia »

You can't modify the center of mass during simulation... well, you can, but that doesn't make any sense.
Have a look at the demo robot models/robots/mobile/Asti.ttm: drop it into the scene. Then drop models/tools/center of mass visualization tool.ttm into the scene, and attach it onto Asti. This will display the center of mass for the whole model with an arrow, and indicate the total mass of the whole model.

Cheers

Luis Nieto
Posts: 49
Joined: 26 Oct 2021, 01:35

Re: Inquiry for follow-path code

Post by Luis Nieto »

How is stability or balance typically controlled in Coppeliasim especially for bipedal robots?

coppelia
Site Admin
Posts: 10339
Joined: 14 Dec 2012, 00:25

Re: Inquiry for follow-path code

Post by coppelia »

it is not. That's your task. Balance need to be kept by appropriately acting on joints, etc. You'll need to write a controller for that.

The Asti humanoid robot model in CoppeliaSim is executing a predefined movement sequence, that keeps the center of mass always centered above the feet. So the robot will walk in a quasi-static manner (i.e. no dynamic walking, as that would be a much more complex task).

Cheers

Post Reply