Abstract:
Previous research developed a coin-operated public tap system to provide a convenient and
cost-effective solution for dispensing water in public spaces, thereby promoting efficient
water resource management. However, a key limitation of the existing system was its inability
to return change to users, necessitating the constant presence of an operator to manually
dispense change. This project aimed to address this limitation by developing an automated
system capable of sorting coins and dispensing change without human intervention.
The system was designed to sort coins based on their thickness, as Ugandan shilling coins
100, 200, and 500 Ugx vary in thickness. Using a vernier caliper, the thickness of each coin
was measured, and a 3D coin-sorting mechanism was designed using SolidWorks. The design
was then transferred to CURA to generate G-code files for 3D printing with PLA material.
The resulting coin-sorting system measured 164.1 mm in length, 7 mm in width, and 30 mm
in height, with an incline of 26.6° to ensure the smooth sliding of coins after overcoming
surface friction.
To facilitate the sorting process, chambers measuring 120 mm in height, and 30 mm in both
length and width, were designed to receive the sorted coins. These chambers were inclined at
an angle of 10°, allowing the coins to rest horizontally. The system was capable of holding up
to 70 coins per chamber. The sorting efficiency was tested using a confusion matrix, and
results showed that all coins were correctly sorted into their respective chambers, yielding a
100% efficiency rate.
In addition, pushing rods connected to servo motors were implemented to automatically
dispense coins as change, based on the specific denomination required. The accurate
dimensions used in designing both the sorting mechanism and the coin chambers were crucial
in achieving the system’s 100% efficiency in sorting and dispensing coins. As a result, it is
recommended that precise measurements be maintained in future designs to ensure optimal
performance and reliability in automated coin-sorting systems.
