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Four-Point Regulation Algorithm for an End-Effector of a Flexible Drilling Robot

A new four-point algorithm for orientation and position regulation of an end-effector for a flexible drilling robot is presented in this paper．Four non-coplanar points in three-dimensional space can determine a unique sphere tangent to them, we can find out this sphere’s center point and radii and regard the shape of a workpiece surface in machining area approximately as such a sphere. A vector from the machining point to the center point is regarded as the one normal to the workpiece surface. By this principle, the algorithm firstly measured and calculated a vector normal to drilling machining area on curved surface by four points，and then calculated the difference between this normal vector and the axis of the spindle. If there is difference, the algorithm further figures out the angles of two revolving axes on end-effector and the displacements of three linear axes on robot main body, which should be adjusted．Simulation results of two kinds of curved surface show that the accuracy and efficiency satisfy the practical requirements using this algorithm．