5 Strategy

Last updated:

$Date: 2002/11/11 19:23:37 $

This part deals with the general strategy for the conception of a robot for the Coupe de France de Robotique (in French, http://www.anstj.org/robot/index.html) / the Eurobot (in English, http://www.anstj.org/robot/concours/eurobot/garde_en.html).

1. How to move on the field

In this competition, we use a flat rectangular field (2m x 3m).

What wee need:

• Go fast (we have only 1min30s to win a match)
• Abitily to turn round and round (the field is small)
• Robustness: ability to go through the game field strewed with pucks and balls.
• Easy to control.

If the field is flat, the simplest way to achieve these requirements it to use 2 motrice wheels, and 2 free rollers. Of course, at any moment only 1 of the 2 rollers touch the ground. The robot switch form one roller to the other when it accelerate, brake, turn or bump into something. For the ability to turn round in the corners, we propose a circular robot with the 2 motrice wheels on a diameter, and the 2 rollers on the perpendicular diameter.

For a simple and efficient control, we propose to use only 2 types of deplacement: straight line and turn round. Curves are to complex and seem not necessary in this competition.

2. How to manage time

We have 1min30 to win, it's short and maybe it's important that the robot adapt his behavior with the remaining time. For example, in a first time it will try to ensure a minimal point, then it could try to make complex things (like stack up 3 pucks), and a the end, it has to score the last point (for example put a single puck rather than to keep it for a stack).

It's also very important for the robot, to detect dead lock situations.

Match are very short, so it's better to have multi-tasks robot that could quickly adapt it's behavior with output events.

How to do that, well you need some timers, an interrupt handler, and ... it will be easier with a real-time multi-tasking system (we use RTEMS, see part VIII).

3. Relative versus Absolute Positioning

Of course, an absolute positioning (this means that you precisely know were you are in the field) is great, but it has a cost and it's not always necessary. It mainly depend on the subject of the competition: for a soccer or basket ball game it's necessary, but this year the robot could works fine without on absolute positioning. Of course, it's a good thing to cover the field when you look for pucks, but you could ensure that without knowing your position.