I. INTRODUCTION
Robot manipulators are largely used in packaging plants, especially for pick and place operations and box filling. In particular, packaging of small food products, like cookies or candies, requires high performance robots with short cycle times and precise motion control, even if their workspace is relatively small. Such performances can be obtained by means of lightweight parallel-drive or delta-like kinematics, whose advantages in terms of reduced moving masses and inertias are well-known. A typical example of this kind of manipulators is the FlexPicker IRB 340 manufactured by ABB [1], which is in fact a delta robot with 4 Degrees Of Freedom (DOF). A typical workcell based on IRB 340 or similar robots includes a vision system, in order to identify and localize products transported in unordered manner and in a large number on the conveyors.