 So, if applied force is not enough to bring the error to zero, this force will be increased as time passes.A pure "I" controller could bring the error to zero, but it would be both slow reacting at the start (because action would be small at the beginning, needing time to get significant) and brutal (the action increases as long as the error is positive, even if the error has started to approach zero).A derivative term does not consider the error (meaning it cannot bring it to zero