DESIGN OF LITTER COLLECTION ROBOT FOR URBAN ENVIRONMENT

Keeping sidewalks clean and tidy is a continuously tough task in modern urban environment, traditional solution of cleaning sidewalk is sanitation workers' manual sweeping. However, manual work is inefficient, laboring intensive and dirty. Main pollutants on the urban sidewalks are simple litter, they consist of recyclable waste such as paper, cardboard and metal cans, and non-recyclable waste like foam and food residue. Thus, the litter on sidewalks can be cleaned, collected and sorted by robots. This paper will discuss the entire design process of a novel litter collection mobile robot for urban sidewalks, including robot structure, drive system, litter collection mechanisms, and stress analysis and motion simulation. This robot can patrol on the sidewalks in urban environment while collecting and sorting litter along the way. Currently, for cleaning the road on urban street, motor sweeper vehicles are used. There are no motorized vehicles used to clean the sidewalks. Therefore, this robotic approach will fill the gap, avoiding inefficient and overwhelmed manual work. The robot is designed to adapt various terrains of sidewalks such as brick pavements, cement sidewalks, and asphalt sidewalks. The size of the robot is designed to fit most of sidewalks according to research of sidewalk standards. The litter collection robot consists of a robust chassis, a driving system, a litter collection system, a sensor system for obstacles avoiding, a navigation system for autonomous control and a vision system for litter sorting. For chassis, based on research on sidewalk size standard, its width is designed less than 80 cm to fit inside the sidewalk and at the same time leave enough space for pedestrians passing robot and conducting normal activities. Its height is designed more than 80cm (including robot arm) to make sure it can be noticed by pedestrians, which will avoid potential safety hazard to pedestrians. The weight of the robot is designed to be light weighted to make the robot easy to carry. Moreover, handles are designed in its structure for the convenience of worker's carrying. For driving system, a two-wheel driving system is designed to adapt various sidewalks. For litter collection system, a robotic arm with four-finger grippers is designed to pick up litter on the sidewalk, and two standard bins are used to contain recyclable and non-recyclable litter separately. Vision system is designed to detect presence and type of litter, so litter will be placed to different bins accordingly. Navigation system is included to enable the robot patrol along the pre-designed path. By applying abovementioned design, this litter collection robot provides a new autonomous approach for urban sanitation work in collecting and sorting litter on sidewalk.