In order to do more realistic mobile robots simulation,
several elements of the real world should be present
in the simulated model, doing the simulated bodies to
behave in a similar way related to the reality. Especially,
it is necessary that the robot suffers from instability and
falls down if badly positioned and controlled, and also it
should interact and collide against the environment objects
in a realistic manner. To accomplish that, it is necessary
to model the physics laws in the simulation environment
(e.g. gravity, inertia, friction, collision). Nowadays,
several physics simulation tools exist used for the
implementation of physics laws in simulations. After
study different possibilities, we chose a widely adopted
free open source physics simulation library, called Open
Dynamics Engine - ODE1
.
ODE is a software library for the simulation of articulated
rigid bodies dynamics. With this software
library, it’s possible to make autonomous mobile and
legged robots simulations with great physical realism.
In ODE, several rigid bodies can be created and connected
through different types of joints. To move bodies
using ODE, it’s possible to apply forces or torques
directly to the body, or it is possible to activate and control
angular motors. An angular motor is a simulation
element that can be connected to two articulated bodies,
which have several control parameters like axis, angular
velocity and maximum force. With these elements, it’s
possible to reproduce articulations present in real robots,
humans or animals, with a high precision level.