Robot Model drops off the floor after running the simulation

I imported a model in webots simulation from URDFs in ROS. The robot is a tricycle drive with 3 castor wheels. I have followed the wheel style as in the webots style guide and changed accordingly. My problem is that when I run the simulation the robot's wheels drops off the floor and is not able to move. Just chassis is on the floor and the wheels hangs down.

Your robot is probably too heavy for the physics configuration.

You can fix this by changing the fields values of the WorldInfo node (https://www.cyberbotics.com/doc/reference/worldinfo). Here are the important fields:

• ERP: you probably want to increase the default value which works fine for small and light objects (try setting it to ~0.6)
• basicTimeStep: here you might decrease the default value to 16 (or even 8) this will make the simulation runs slightly slower because it computes more steps but much more stable.
• contactProperties: You probably need to add a contact property defining the properties of the contact between the floor and your robot's wheels (to increase the friction, and decrease the spongyness of the contact).

Here is an example of contact properties:

ContactProperties {
  material2 "MyRobotWheelContactMaterial"
  coulombFriction [
    8
  ]
  softCFM 1e-5
}