Robot-assisted automated sorting techniques for plastic recycling

This report discusses the current state of the art of robot-assisted sorting and separation systems in waste processing for the recovery of recyclable materials. The sorting methods addressed here are limited to the waste disposed of by households and include the sorting of pre-sorted municipal waste, e. g. plastic sorting. The focus is on the challenges of proven material recovery facilities and why manual sorting is still a necessity for efficient waste sorting. Solutions are sought to eliminate the employment of humans partially or completely for waste sorting. Suitable gripping components are to be found, since one of the biggest challenges in waste sorting is gripping objects with different shapes, sizes, weights, positions, and materials. Not only existing techniques in the waste industry are addressed, but a broad spectrum is searched for possible universal grippers. This paper aims to provide a comprehensive overview of the state of the art of robotic systems in the waste industry and presents different types of grippers that can lead to a possible solution to the described challenge. By means of an evaluation system, the presented grippers were compared, revealing that the combination of individual gripping mechanisms is promising for waste handling. Furthermore, it was found that sufficient degrees of freedom in the wrist area of a robotic arm can facilitate better gripping quality.