Sensorless localization of a minimally-actuated robotic system for automated pallet de-strapping

Abstract

Purp ose – In this paper, we detail the design and prototyping of a smart automa- tion solution for de-strapping plastic bonding straps on shipping pallets, which are loaded with multiple containers secured by a top-cover as they move on a conveyor belt. Design/metho dology/approach – The adopted design methodology to have the system perform its function entails using the least number of sensors and ac- tuators to arrive at an economic solution from a system design viewpoint. Two prototypes of the robotic structure are designed and built, one in a research labora- tory and another in an industrial plant, to perform localized cutting and grabbing of the plastic straps, with the help of a custom-designed passive localizing struc- ture. The proposed structure is engineered to locate the plastic straps using one degree-of-freedom only. An additional strap removal mechanism is designed to collect the straps and prevent them from interfering with the conveyor. Findings – The functionality of the system is validated by performing full-process tests on the developed prototypes in a laboratory setting and under real-life operat- ing conditions at an automotive original equipment manufacturer (OEM) assembly facility. Testing showed that the proposed localization system meets the specified requirements and can be generalized and adapted to other industrial processes with similar requirements. Practical implications – The proposed automated system for de-strapping pal- lets can be deployed in assembly or manufacturing facilities that receive parts in standard shipping pallets that are used worldwide. Originality/value – To the authors’ best knowledge, this is the first mechanically- smart system that is used for the automated removal of straps from shipping pallets used in assembly facilities. The two main novelties of the proposed design are the robustness of the strap localization without the need for computer vision and a large number of degrees-of-freedom, and the critical placement and choice of the cutting and gripping tools to minimize the number of needed actuators.