6.2 Simulation model
Figure 6.2: The e-puck model in Webots
The e-puck model in Webots is depicted in figure 6.2. This model includes support for the differential wheel motors (including a simulation of encoders), the infra-red sensors for proximity and light measurements, the accelerometer, the camera and the 8 surrounding LEDs (see figure 6.3). The other e-puck devices are not yet simulated in the current model. The standard model of the e-puck is provided in the EPuck.proto prototype file which is located in the projects / default / protos / robots directory of the Webots distribution. Several examples are located in the projects / robots / e-puck / worlds directory of the Webots distribution.
Figure 6.3: The e-puck control window for simulation
The resolution of the camera was limited to 52x39 pixels, as this is the maximum rectangular image with a 4:3 ratio which can be obtained from the remote control interface with the real robot.
Another model was implemented in the e-puck_line.wbt world (see figure 6.4), which adds support for floor sensors. Floor sensors can be added to a real e-puck robot by inserting a special extension card with three sensors just below the camera of the robot. These sensors are actually simple infra-red sensors which allow the e-puck robot to see the color level of the ground at three locations in a line across its front. This is especially useful for implementing line following behaviors. The e-puck_line controller program contains the source code for a simple line following system which, as an exercice, can be improved upon to obtain the behavior demonstrated in the e-puck_line_demo.wbt demo, in which the e-puck robot is able to follow the line drawn on the floor, but also to avoid obstacles and return to the line following behavior afterwards. This model was contributed by Jean-Christophe Zufferey from the EPFL, who set up a series of exercices with Webots and extended e-puck robots.
Figure 6.4: An e-puck extension for line following
These models are open source and you are welcome to modify them. If you develop a useful modification and would like to share it, please let us know so that we can improve these models using your contribution.
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