A CAD-based probing and localisation method for arbitrarily fixed workpiece

In this paper an efficient method for automatic probing and localisation of 3D workpiece arbitrarily fixed to the machine table of a five-axis milling machine is presented. First, by formulating localisation problem as minimizing a least-square question an explicit solution is obtained. Based upon this solution and sensitivity analysis, we present some guidelines and develop a CAD-based automatic probing strategy. By means of the knowledge about the approximate location of workpiece computed by 3D localisation algorithm as estimator, together with the CAD model of workpiece, we then generate online a new collision free probing trajectory to probe additional point on a neighbourhood of the previous sampling point. Utilizing the newly measurement point, we improve the Euclidean transformation which in turn is used together With the CAD model, to generate another collision free probing path to probe more points on the surfaces of workpiece. This process continuous until the workpiece is accurately located. Experimental results show that this algorithm overcomes the need of home surface identification process and is thus suitable for real-time implementation in manufacturing or inspection process.