The e-puck robot is equipped with 8 IR proximity sensors placed as illustrated here:

Next figure is the raw data aquisition of IR0 (a front sensor) when the robot starts againts a wall and goes backwards. The X axis shows the number of steps of distance from the wall. 1000 steps correspond to 12.8cm.

Next figure is the computed sensor information (reflected light - ambient light) data aquisition of IR0 IR1 IR6 IR7 (the four front sensors) when robot is going backwards from a wall. The X axis represents the number of steps. 1000 steps correspond to 12.8cm.

The next three figures show some noise on the sensor measurement due to the activity of the stepper motor turning at 100steps/s 400steps/s and 800steps/s. Sampling is made at 64Hz. This noise comes from the power supply of the e-puck. It seem to increase when battery is going down.