Abstract

We present a description of a simulator of legged robots. The simulator allows the definition of different models of robots as well as different shapes for the ground. The robots are provides with many physical sensors (touch sensors in feet, inclinometers, an active camera,...), virtual sensors (stability sensor,...) and different motors that can be commanded either individually or coordinately. The controller of the robot is a separate module that the user can re-program at his convenience interfacing with the simulated robot as he would done with a real robot and without worrying about the internal structure of the simulator. Additionally, the simulator provides tools to monitor the workings of the robot controller: for instance it allows the drawing of traces for those mobile element (body, feet, ...) that the user want to monitor along the time. As a last feature, the simulator includes the definition of landmarks identifiable with the robot camera (if they are at sight) and that can be useful to test navigation algorithms for legged robots [13].

Up to now, only the kinematic of the robots is simulated and no dynamic effect is taken into account. Additionally, we assume detectable but traversable ground with infinite friction and we also assume that individual leg movement can not produce robot's displacements (leg movements have to be explicitly coordinated to produce a robot's body movement [4]). This allows to accelerate the simulation and, in general, it is sufficient to test the robot controllers.

In this document the simulator is described either from the point of view of the end user and from the point of view of the programmer. In the first place we present the general structure of the simulator and how it can be installed. Then, we include the description of the user interface, explaining how the controllers can be executed to observe its effects and how the different parameters of the robot and the ground can be displayed and modified on line. Next we describe how to program a new robot controller detailing how to interface with robot's sensors and actuators from a user program. Finally we outline future extensions of our work.