The second term preferably uses the following formula: v 2=max(0, |e|???K dz) sign(e) [0017] where: v2 is the desired second term; max( ) is the maximum function returning the maximum of its arguments; and Kdz is a predetermined constant indicative of the size of the dead zone. [0018] The desired function of print head position versus time may be formed by double integrating a desired function of