Fast Restart of Manufacturing Cells Using Restart Points

When an error occurs in a manufacturing cell it sometimes means that the whole cell has to be emptied and then re-initialized before production can continue. Obviously, this is not an optimal approach. Instead, an automatic restart as close as possible in state and space to the one where the error first occurred should be strived for. One way of achieving this is by using the concept of restart points, that is, production states from which a cell can continue its work after the occurrence of an error, sometimes transparently. By restarting from such restart points a lot of actions do not need to be taken. Nonetheless, the restart points have to be identified. This paper presents a control system architecture (known as CHAMP) that, among other things, enables the fast restart of a machining cell after the occurrence of different error types through the use of restart points. The different error types that can be handled are described and the necessary actions to obtain fast restart are presented.