The invention relates to a method for collision avoidance, a method for adjusting the distance and a method for actoric lifting movement of inkjet heads (4). For this purpose, in a digital printing machine (100), a sensor / camera (14) is provided for monitoring the sheet (1000). the inkjet heads (4) are individually raised and lowered again and vibration optimized according to the invention for collision avoidance. In order for the machine (100) with defective sheets (1001) does not have to be stopped. Can advantageously reduces waste and so the machine's performance should be better exploited.