Camera-based monitoring of machines with mobile machine elements for collision prevention

A method for failsafely controlling an automated machine having a machine element moveable through a plurality of predefined movement phases, the machine having a drive for driving the mobile machine element in accordance with said predefined movement phases and at least one object sensor for detecting an object in the vicinity of the mobile machine element, the method comprising the steps of:

• providing an image acquisition system for acquiring image data of the mobile machine element;
• moving the mobile machine element through the predefined movement phases,
• providing a database containing reference image data acquired by the image acquisition system corresponding to the plurality of predefined movement phases;
• determining a stopping time corresponding to the time period required from a stop command to bring the mobile machine element to rest;
• thereafter monitoring the operation of the automated machine via the image acquisition system by acquiring instantaneous image data of the mobile machine element;
• correlating the instantaneous image data and the reference image data in order to determine a current position of the mobile machine element, wherein the current position is determined as a position allocated to one of said plurality of predefined movement phases whose reference image data is most similar to the instantaneous image data;
• estimating a future position of the mobile machine element relative to the current position of the mobile machine element using the reference image data in the database, wherein the future position is a maximum reachable position from the current position within the stopping time;
• establishing a safety region around the current position of the mobile machine element, wherein a dimension of the safety region is determined as a function of the estimated future position;
• detecting an entry of the object into the safety region by means of the at least one object sensor;
• generating a stop command when an object entry into the safety region is detected;
• and
• controlling said drive in response to said stop command.