Abstract—A robotic stacker serves to lift, deliver, retrieve, and place items from one position to another. Different designs for robotic stackers have already been developed. Mobility is one characteristic of robotic stacker; this gives it the freedom to travel from one location to another. Different gripping mechanisms for the interaction with the items have also been tested by previous researchers. This research study aims to design and evaluate an autonomous two-wheeled robotic stacker prototype that will stack cylinders based on weight. The controller used for the robotic stacker is the Arduino Mega 2560. The robotic stacker uses a two-finger gripping mechanism and arm to accomplish the stacking process. For movement, a line following system was developed. Three FC-123 infrared sensors are used for the line following system. For positioning, radio-frequency identification (RFID) tags are placed on the path and serve as stopping points. A RFID reader is then attached on the robotic stacker. Three load balances weigh the three cylinders for stacking order. Stacking of the cylinders is by weight, with the heaviest cylinder at the bottom. For the results, the pose accuracy of the arm-gripper assembly was ±0.1333 mm and ±0.2583 mm, during no load and maximum load operation respectively. The pose repeatability of the arm-gripper assembly was ±1.2521 mm and ±0.8112 mm, during no load and maximum load operation respectively. After final testing, the total stack offset was 16.13 mm. Distance accuracy was found to be ±1.933 mm, while the distance repeatability was ±10.6128 mm. Data from the trials were not sufficient to show a correlation between the attained distances and the stack offset. 
 

Index Terms—robotic stacker, line following, RFID point location system, two-finger gripper, stack alignment

Cite: RJ Lawrence C. Tiu and Edward B.O. Ang, "Development of an Autonomous Two-Wheeled Robotic Stacker Prototype" International Journal of Mechanical Engineering and Robotics Research, Vol. 9, No. 2, pp. 270-279, February 2020. DOI: 10.18178/ijmerr.9.2.270-279

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