Among them we looked at several two degrees of freedom robots. One is called as an RR robot. R here stands for the rotary joint. There are two rotary joints in the robot. P corresponds to the prismatic joints. There is a rotary and a prismatic joint. And, we assume several things to simplify our simulation. We assume that there is no gravity, there is no friction, or any other non-linear term. The equation of motion only contains the inertial term and the Coriolis and centripetal term. And the desired repetitive motion of this robot is some repetitive trajectory. So, the robot keeps on doing the same thing over and over again. And we are going to perturb the model in the model with controller by multiplying each model parameter by 1 + Î where Î is a small number.

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