Abstract
In this work one presents a control strategy for n unicycles in formation called "formation control". This in order to achieve a target-capturing task in 2D space including collision-avoidance. The strategy developed here is based on the Invariance Principle (IP) where we construct a set which contains the target and rather big to contain all unicycles. This set will be attractive for the formation by developing a cooperative control law. The stability of the formation is realized when all unicycles are in the attractive set.