Perfomance of Servo Motor Control System for a Mini Vending Machine

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Published on International Journal of Engineering & Industry
Publication Date: March 25, 2019

Wai Phyo Aung, Htut Ko Win & Than Toe Aung
Department of Electronic Engineering, TU (Loikaw)
B.E (EC)-2018,TU (Loikaw)
Loikaw, Kayah State, Myanmar

Journal Full Text PDF: Perfomance of Servo Motor Control System for a Mini Vending Machine.

One of the fast-paced technologies is the vending machine, which is a machine that dispenses automatically, products such as beverages, tickets, snacks, etc., by inserting currency or credit to the machine. Vending machines are generally used in public and private areas such as malls, markets, business and government offices, schools and along the streets. The main project that constructing Arduino based vending machine is sucessfully done as a graduation project. As a part of Vending Machine Project; this analytical research paper mainly carried out the mechatronic principle ,hardware design and digital software implemtation of the system. Performance analysis of a servo motors control system is recordably done as a research paper after finishing a graduation project“ Design and construction of a microcontroller based mini vending machine”.

Keywords: Mechatronic, Design, Microcontroller, Arduino & Servo Motor.

1.1 Introduction to Servo Motors
The high-torque standard servo can rotate approximately 120 degrees (60 in each direction). User can use any servo code, hardware or library to control these servos, so it’s great for beginners who want to make stuff move without building a motor controller with feedback & gear box, especially since it will fit in small places.
Motor specifications are as follow:
• Weight: 55 g
• Dimension: 40.7 × 19.7 × 42.9 mm approx.
• Stall torque: 9.4 (4.8 V), 11 (6 V)
• Operating speed: 0.17 s/60º (6 V)
• Operating voltage: 4.8 V a 7.2 V
• Running Current 500 mA-900 mA (6 V)
• Stall Current 2.5 A (6V)
• Dead band width:5 µs
• Stable and shock proof double ball bearing design
• Temperature range:0ºC -55ºC
The servo motor basically composed of three basic parts.
• Controlling Device
• Output Sensor
• Feedback system
Servo motor is DC motor which consist of following parts
• Stator winding
• Rotor winding
• Bearing
• Shaft
• Encoder
Most servo motors have the following three connections:
• Black/Brown ground wire.
• Red power wire (around 5V).
• Yellow or White PWM wire.
It will be connected the power and ground pins directly to the Arduino 5V and GND pins. The pulse width modulation(PWM) input will be connected to one of the Arduino’s digital output pins.

1.2 Introduction to Arduino Uno
Before we can understand the UNO’s hardware, we must have a general overview of the system. After code is compiled using Arduino IDE, it should be uploaded to the main microcontroller of the Arduino UNO using a USB connection.
The main microcontroller doesn’t have a USB transceiver, it need a bridge to convert signals between the serial interface (UART interface) of the microcontroller and the host USB signals.
The bridge in the latest revision is the ATmega 16U2, which has a USB transceiver and also a serial interface ( UART interface). To power Arduino board, use the USB as a power source. Another option is to use a DC jack. To reset board, should use a push button in the board. Another source of reset should be every time, open the serial monitor from Arduino IDE.
The ATmega328 microcontroller is the MCU used in Arduino UNO R3 as a main controller. ATmega328 is an MCU from the AVR family, it is an 8-bit device, which means that its data-bus architecture and internal registers are designed to handle 8 parallel data signals.
ATmega328 has three types of memory.
1. Flash memory: 32KB nonvolatile memory. This is used for storing application, which explains why don’t need to upload the application every time to unplug arduino from its power source.
2. SRAM memory: 2KB volatile memory. This is used for storing variables used by the application while it’s running.
3. EEPROM memory: 1KB nonvolatile memory. This can be used to store data that must be available even after the board is powered down and then powered up again.

The first modern coin-operated vending machines were introduced in London, England in the early 1880s, dispensing postcards. The machine was invented by Percival Everitt in 1883 and soon became a widespread feature at railway stations and post offices, dispensing envelopes, postcards, and notepaper. The internal communication in vending machines is typically based on the MDB standard, supported by National Automatic Merchandising Association (NAMA) and European Vending & Coffee Service Association (EVA). After payment has been tendered, a product may become available by the machine releasing it, so that it falls in an open compartment at the bottom, or into a cup, either released first, or put in by the customer, or the unlocking of a door, drawer, or turning of a knob.
Beverage Vending Machine Using PLC and SCADA can operate and control automatically the beverage preparation by using PLC. It can monitor the parameter of the process in the plant using SCADA technology because SCADA system is used as supervisor or monitor for the process through an animation. In this plant, several operations will run simultaneously by the help of PLC. In the first process, the pump feed the ingredients to the process ingredients tank from the reservoir. In the second process the liquid concentrate of different beverages (Orange and Mango) are mixed with the ingredients in their respective tanks. In the third process the bottles filled with the beverages moves to the packaging unit by a conveyor which will by a conveyor motor. These are all automated processes leads to more accuracy and flexibility of the system.
An RFID Based Arduino Controlled Coffee/Tea Vending Machine gives the access through only RFID which avoid the misuse of machine. A small RFID reader is fitted on the machine. The identity card which contains RFID tag is given to each employee. According to estimation the numbers of cups per day as per client’s requirement are programmed. Then an employee goes to vending machine show his card to the reader then the drink is dispensed. But when employee wants more coffees than fixed number, that person is allow for that but that employee has to pay for extra cups and amount is cut from the salary account.

As a servo motor control vending machine , Arduino UNO board, Nokia LCD 5110, four servo motor and four push-buttons are used. Rectifier circuit is used for LED string light. Uno is used to program for the vending machine while LCD is for showing the information such as inserting coil and making a selection. User can choose the product by touching the related button. For the servo motor, it is used for the dropping of the product.
Firstly, after supplying the power to Arduino board, it is started running with the program install in it. Then, LCD starts working by showing the information, project group number and name. In addition, it asks the user to insert the coin for buying the product. Then, the user must insert appropriate coin to the coin insert hole. As soon as the user inserts the coin, LCD monitor asks the question “Please make a selection”.