WEEK 7

Date:  28 October - 1 November 2013

Subject : 1) Research about the Integrated Circuit, relay, gear system used in Smart Grass Cutter technology.
            

Introduction:

The purpose of this task is to continue a research about above mention components that will be used in this project. the research include basic design, the application and etc. 

Objectives: 

1. To find the suitable component that will need used in this projects.

Project Description:

Information is gathered using resources such as the internet, the books and journals available in the library. the other source is from Jalan Pasar which is the place that distributed all electronic and electrical components. Below is the components description.  


1.  L293D

The L293D is a dual h-bridge driver IC. The IC is also referred to as a push-pull four channel driver. An h-bridge is ideal for driving motors. The L293D provides two h-bridges for driving both motors on the robot base. The motor direction is controlled by logic signals from the microcontroller. Two signals per motor are required to control the direction.
       In previous week, I have mention about the H Bridge circuit that used to control the motor and it must need a transistor to control the direction. So, this IC might be used in DC motor circuit. Figure 1 shows the connection for the motor. 

Figure 1: Connection to the Motor

Figure 2: Detail Connection Using H Bridge

Figure 2 show more detail in motor connection. I have used a simulator that control the motor direction by using Proteus software. Below is the expected result.


1.1 Expected Result

Figure 3: Motor Circuit in Proteus

Figure 4: Motor Forward Result

Figure 5: Motor Reverse Result

Motor driver operation left side as following :

MOTOR MOTION	EN1=PIN_C0	IN1=PIN_C1	*IN1=PIN_C2
FORWARD	1	0	1
REVERSE	1	1	0
STOP	0	0	0

Motor driver operation right side as following:

MOTOR MOTION	EN2=PIN_C3	IN2=PIN_C4	*IN2=PIN_C5
FORWARD	1	0	1
REVERSE	1	1	0
STOP	0	0	0

 
2.  Tamiya Geared Motor

Figure 3: Tamiya Geared Motor

The Tamiya double gearbox is a compact unit with two independent motors and gear trains. The kit includes two motors and all gears and parts to build any of the four possible gear ratio configurations (12.7:1, 38:1, 115:1, and 344:1). Although it is not typical, it is possible to assemble each side with different gear ratios. There are two possible output axle locations (for any given gear ratio, only one output location is possible).

3.  Relay

 

A relay is an electrically operated switch. Many relays use an electromagnet to operate a switching mechanism, but other operating principles are also used. Relays find applications where it is necessary to control a circuit by a low-power signal, or where several circuits must be controlled by one signal. Figure 4 shows the basic design of relay.

  

Figure 4: Basic Design of Relay

The output of each PIC pin is 5V with max output current of 20mA or 0V with 0mA output. The voltage is not enough to run high power device e.g. motor, solenoid. Thus we need a relay to control these high power items. A simple switching circuit (using NPN transistor, C9013) will be used to energize / de-energize the input coil of the relay. The relay output is single pole double throw (SPDT). And its coil can be energized using 5V and de-energized using 0V. Normally the relay output NC and COM will be connected. When the input coil of relay is energized, output NO and COM will connect. The switching can be used to control item which is less than 250Vac and 10A.

Problem Encountered:

From this research, I have to interface with proteus software to simulate the DC motor drive by using IC L293D. The result show the good working as i expected. All components/material that have been research was suitable to use in this project. However the project is still on schedule and will proceed as how the project was planned.


Project Outcome:

More outcome has achieved from this research. Next planning is want to research about  the design for Smart Grass Cutter. One of my idea is i will used some material such as prospect to become the body of grass cutter. My research project is on schedule and I should encounter no problems finishing it.