How can I define a soft material or liquid environment?

[horsefacelee]

Hello
I want to simulate a biped human model walking in V-REP. I want to simulate the ground reaction force, but don't want to dealing with the balancing problem. Thus, I wonder is there any way I can define a soft material, that I can hang my model in the air, while the feet can touch that material but not stopped by it. Like walking in a water pool.

[coppelia]

Hello,

not sure I understand what you mean. If you don't want to deal with balancing then you have the possibility to use a construction that holds the orientation of your robot's trunk. Have a look at this post for instance.

Cheers

[horsefacelee]

I just want to simulate walking in a pond filled with thick liquid, is it possible to do so?

[coppelia]

Ok, I now understand. You can imitate that effect by adding a drag force to the masses that are in the imaginary water.

Basically for all dynamically enabled shapes that are in the imaginary water (i.e. below a certain z-coordinate), measure the velocity, then add a drag force that is inversely proportional to the velocity. This is basically exactly the same procedure of what was done with the Models/robots/ACM-R5.ttm robot, when it is swimming in the water (i.e. below coordinate z=0). Make sure you inspect its child scripts.

Cheers

[horsefacelee]

I wonder can I define a soft object? Since the current material I use for the feet of my robot doesn't look good. How could I define a material that could be simualte as flesh? Can I define "after enter the boundary slow it down" ? Not CoM enter certain height, but object enter the surface of other objects.

[coppelia]

V-REP does not offer simulation of soft bodies. But again, in your case you basically just want one or several links to slow down when entering a certain area: simply apply a force proportional but opposite to the velocity of the link. You can do this in a half-space that could represent a liquid, but you can also do this for links entering a specific cubic area: simply check if your link is in that area, if yes, apply that correction force.

Cheers