title: How to simulate soft ground in webots？
body: <p>My robot is a  Skid-Steered mobile robot ,which built in the soft sand, so I need to verify the dynamics of my wheeled mobile robot in the soft sand, that is, I want to give a torque to the wheels motor to check the movement of the robot, but I don't know how to simulate the situation of the soft sand in webots, please help to give me a solution,thank you very much.</p>