Design Of Control System For Five-axis Spray Painting Robot Based On PLC

Industrial robot, a crucial type of tool and equipment in manufacturing industry,has been widely employed on production under the transition of Chinese economyand industry. The spray paint robot (SP robot) has been widely used in the procedureof coating and finishing. However, due to its high price, high-tech requirements, lowadaptability to existing production and hysteretic response to market, these robots canhardly be accepted by the customers from small and medium-sized enterprises (theSMEs).This paper is dedicated to design a low-cost generic type of spray painting robotintegrated with operating performance and environmental protection, which can easilyaccess to the SEMs, quickly form productivity and thus promote sales. The design canlead the localization trend of spraying robot. Meanwhile, a new developing trend forfurniture coating has also been proposed through this development. For achieving thementioned above, related work organized as follows,(1) The objective and significance of this research have been analyzed, as well as thedomestic and overseas status of the SP robot development. The concept, along withthe feasibility, of the generic new SP robot applied to furniture manufacturing hasbeen displayed by realizing the function of fast spray on large plane.(2) The coating of security door and its frame are exemplified for the robot design.Based on the process and existing facilities of the SMEs, the five DOF structure isspecially selected to satisfy the fast linear motion and multi-spray face switch. Themechanism structure improves to the robot’s dynamic so as to ensure as secure andstable running.(3) Considering the multiple species and small batch manufacturing in the SMEs, aspecialized Data Acquisition Unit (the DAU) is designed for recognizing the variousshape of work piece and acquiring essential controlling parameters. The electricaldesign is proceeded on the basis of the structure type and the motion driverequirement. The controller and servo motor are selected by reference to the demandfor spray trajectory, point control and position accuracy. A set of the PLC ladderdiagram is compiled to control the robot for spraying.(4) The tool model and the paint deposition rate are depicted mathematically and the workpiece’s planar models are formed by dot matrixes detected by the DAU. Theparticular case of a decomposition algorithm together with a trajectory connectionmethod are involved to reduce the altitude of a single patch and join several patches inshortest distance so as to improve the efficiency of a unit spraying and the dynamicperformance of the robot. The appropriate overlapping is presented to control materuniformity near the border of two patches.(5) The progress of realizing the tool synchronous tracking function is summarized indetail. A noise test is implemented to find out the suitable rate of acceleration anddeceleration during fast linear spray. Besides, optimal coverage of overlappingbetween two patches is simulated on the software platform of MATLAB.