We have been working with the e-puck robot in Webots. However, one thing myself and others have noticed is that over time, the wheels of the e-puck become disconnected as a result of impacting several objects. This is becoming quite a problem, as this can cause the e-puck to move in unexpected ways (or not at all).
This can happen with no errors in the console, but the problem is exacerbated if there are a few "ODE Message 3: LCP internal error, s <= 0 (s=0.0000e+00)" errors. The main observable impact is the robot movement and the wheels spinning strangely. I've observed the wheels even rotating along the wrong axis, like a coin being flipped.
Open the genetic algorithm sample world (in samples-> curriculum -> advanced_genetic_algorithm). Allow it to run through. You will see the fitness increase and rapidly drop off - this is not caused by the GA itself, but rather when the wheels start to become an issue. In extreme cases you may observe the wheels wobbling or appearing farther apart. In later generations the e-puck will not move, although the wheels will be spinning.
Have others encountered this? And does anyone know a viable solution?