A Real-time Collision Prevention System for Machine Tools

Abstract

Manufacturing processes become more and more complex. Therefore collisions within the working area of the machine tools occur more often. Those collisions often lead to tool and work piece damage. Especially when machining very large and complex work pieces, e.g. in the Aerospace Industry, where such a work piece damage is very expensive. Additionally, these collisions could cause the breakage of the whole machine, which will lead to downtime and high costs; especially the commissioning of the machine tool and the work piece involves high risk of collisions caused by manual machining. In order to solve this problem manufacturers offer different specialized crash protection mechanisms which have certain constraints or a lack of generality. Within this paper we present a collision prevention system based on a hull concept which monitors all machine axes regarding risk of collision without using physical sensors. It is necessary to consider a sufficient stopping distance for all moving machine parts to avoid a crash. These distances can be seen as hulls around the components depending on the maximum speed and deceleration values. Consequently, we present an approach to create these hulls, based on the CAD data of the machine tool, work piece as well as the tools. This leads to a virtual collision model which can be used as input data for the collision prevention system. The advantages as well as the current limitations of the introduced collision prevention system are discussed based on a machine tool in operation.