I-RIM Conference 2019 October 18 - 20, Rome, Italy ISBN: 9788894580501 Robotic task optimization in food industry 1st Giulio Rosati Department of Industrial Engineering University of Padova Padova, Italy giulio.rosati@unipd.it 2nd Silvio Cocuzza Department of Industrial Engineering University of Padova Padova, Italy silvio.cocuzza@unipd.it 3rd Matteo Bottin Department of Management and Engineering University of Padova Padova, Italy matteo.bottin.1@phd.unipd.it 4th Nicola Comand Department of Management and Engineering University of Padova Padova, Italy nicola.comand@phd.unipd.it Abstract—The market demand for product customization is increasing. In particular, the customization of food products, such as 3D cakes, is performed by skilled operators with problems in ﬁnding them in peak production periods. Fortunately, text and drawing decorations can be translated into trajectories that can be followed by industrial robots, thus making it possible to fulﬁll the same task. However, the redundancy of the task and the synchronization with the external equipment, such as conveyors, make trajectory planning particularly demanding. In this paper, an optimization technique that considers all these parameters is presented, which allows to reduce cycle time and therefore energy consumption. Index Terms—Robot, redundancy, path planning, food industry I. INTRODUCTION The market demand of 3D cakes and of big chocolate struc- tures is rapidly increasing [2]. Unfortunately, the operation of writing customized text/drawing decorations over cakes using melted chocolate or icing is now performed by skilled staff, with problems in ﬁnding them in peak production periods. Nowadays several 3D food printers have been developed [1], [3], [6], [8], but also conventional printers with edible ink have been used [3]. However, the usual application of food customization relies on small adjustments of the ﬁnal product: small drawings, different text and similar. This is particularly true in cake industry, where the cake can be personalized by adding a person or a company name. This small adjustments do not justify a high investment cost of a dedicated machine, but need a fast equipment that is easy to reconﬁgure for each single product. Industrial robots seems to be perfect for this purpose [4], [5]. Text and drawing decorations can be easily transferred to the robot by deﬁning speciﬁc viapoints to be interpolated. These viapoints form a trajectory that reproduce the personalized element to be printed on the surface of the cake. Each viapoint is described by n parameters (required to deﬁne its position and orientation in space), but the task itself This work is partially supported by EPSON Robotics within the Win-a- robot Contest of 2018 is redundant: each position can be reached by rotating around the surface normal, thus there are inﬁnite robot conﬁgurations [7] that can fulﬁll the task. Even if this redundancy can be exploited by the last joint rotation, the equipment is usually too big to be installed aligned with the last joint axis, so its installation is required to be off-axis. As a result, the aforementioned redundancy affects all joints value. In this paper, an optimization technique that takes care of the redundancy is developed. To further improve the work, a linear conveyor is included in the workcell: this aspect will show how our solution could be ready for a real industrial scenario with a high throughput. II. OPTIMIZATION TECHNIQUE Let’s consider a trajectory f(x(t)) that expands in 3D space on a surface. This trajectory can be discretized in multiple via points to be used in the robot path planning. If the robot is redundant, so the number of parameters required to uniquely deﬁne it conﬁguration are more than the degrees of freedom of the structure, inverse kinematics results in inﬁnite possible solutions. That’s said, for each point the joint values are a function of the Cartesian position x and the redundant parameters values: q(t) = g(x(