This paper describes the components and programming of a robot tank project at Texas Tech University. The tank is programmed to follow an iron wire without human interference using sensors to detect the wire and an H-bridge circuit to control motor movement. An ultrasonic transmitter and receiver are used for remote control of the tank. The project is estimated to be completed by early December and within a $4,820 budget. Programming of the tank's movement and speed are discussed. The Basys Board is used to integrate all components and direct the tank's motion.

1. Written Report for Project Lab at Texas Tech University
Ever Prieto
IEEE R# 10423050
Texas Tech University
October 21, 2011

2. 1
Abstract
This paper describes parts and how they work for a programmed robot tank that follows
an iron wired without human interference. Progress made and what is necessary to make
this project work is also discussed as well as the components that make this project
possible.

3. 2
Table of Contents
List of Figures ..................................................................................................................... 3
List of Tables ...................................................................................................................... 4
1. Introduction.................................................................................................................... 5
2. H bridge.......................................................................................................................... 5
3. Transmitter..................................................................................................................... 7
4. Receiver ......................................................................................................................... 7
5. Sensors ........................................................................................................................... 7
6. Software ......................................................................................................................... 8
7. Basys Board ................................................................................................................. 11
8. Conclusion…………………………………………………………………………….12
References......................................................................................................................... 14
Appendix A Reference Forms.......................................................................................... 15
Appendix B Written Lab Report Evaluation Form.......................................................... 16

4. 3
List of Figures
Figure 1: H Bridge incorporated with the motor controller circuit.................................... 6
Figure 2: Transmitter Schematic........................................................................................ 6
Figure 3: Proximity Sensor Digital Output........................................................................ 8
Figure 4: Flowchart for the programming. ........................................................................ 9
Figure 5: Basys Board inputs and outputs. ...................................................................... 11
Figure 6: Gantt chart…………………………………………………………….……….13
Figure 7: Estimated Budget……………………………………………………………...13

5. 4
List of Tables
Table I: Speed Table. ....................................................................................................... 10

6. 5
1. Introduction
The 2011 fall project for Project lab 1 requires a tank robot to follow an iron wire
laid down on the ground without any human interference. It must have a remote
controlled on and off using an ultrasonic signal transmitter and receiver. Using a 40-50
kHz an ultra sound frequency will be transmitted. The receiver senses the ultrasonic
sound from the transmitter and switches on a relay making the tank work. It must also
turn left and right. Two sensors on each side of the tank are going to detect the iron wire
and determine where to turn. Once the sensor detects the wire it will send the output to
the Basys board to make the tank turn. The tank will be programmed using a Basys 2
board. The speed of the tank will be control by the 8 switches on the Basys board.
2. H Bridge
The H Bridge enables voltage to go through a load in either direction. It’s an
electronic circuit that can be used to let DC motors either run forward or backwards.
They are already integrated circuits but can also be built from discrete components. The
H bridge is the main component that makes the motor controller circuit work. The H
bridge it the one that makes the motors go forward, backward, turn left or right. Figure 1
shows the H Bridge incorporated with the motor controller circuit that makes the
movement of the tank. [1]

7. 6
Figure 1: H Bridge incorporated with the motor controller circuit
3. Transmitter
Figure 2: Transmitter Schematic.

8. 7
Figure 2 explains how the transmitter works. It transmits ultrasonic sound of frequency
between 40 and 50 KHz. The receiver senses the ultrasonic sound from the transmitter
and switches on a relay. This ultrasonic transmitter uses a 555 timer IC configured as an
astable multivibrator generating continuous signals of a set frequency of 40 to 50 KHz as
long as its reset pin is held high. The resistor and capacitors values are chosen such that
the 555 will output a signal frequency about 40KHz. If pair with a matching ultrasonic
receiver it can help a robot avoid running into walls or make it go the way desired. [2]
4. Receiver
The ultrasonic receiver is used to capture waves from the air transmitted by a matching
ultrasonic transmitter located somewhere else. When the frequency waves hit the
Receiver, the receiver vibrates and produces electric impulses which are amplified by the
two op amps in the circuits. These amplified outputs are fed into the 567 IC. [2]
5. Sensor
For this project, two sensors have been located on each side of the tank to detect
the iron wire. The sensors have a sensing range of 0-8mm and it has a normally open
output. It has a 12 mm diameter and its a 3-wire NPN. It can take 10-30 DC voltage with
a 1 KHz switching frequency. On Figure 3 you can see that that the sensor has a digital
output so it goes to low once it detects the iron wire.

9. 8
Figure 3: Proximity Sensor Digital Output
6. Software
The programming of the project is straight and simple. Once the switch is turn on
the tank is going to go forward. The proximity sensors will be detecting the wire and
make the tank turn following the iron wire. Figure 4 shows the flowchart of the program.

10. 9
Figure 4: Flowchart for the programming
The speed of the tank will be control by the eight switches on the Basys board.
Each switch is a different bit in an 8 bit binary register that controls the pwm. Figure #
shows the concept of the speed as it increases by 90 percent pwm.

11. 10
Table I: Speed Table.
Speed Step Data Bits
Speed 1 0000
Speed 2 0001
Speed 3 0010
Speed 4 0011
Speed 5 0100
Speed 6 0101
Speed 7 0110
Speed 8 0111
When turning, one motor will slow down and the other will speed up so it can
turn at both acute and obtuse turns. The turning will be determined by the sensors
depending on which one of the sensors the iron wired is detected.

12. 11
7. Basys Board
The Basys board is where all the information comes and goes. The Remote, the Proximity
Sensor and the Power are the inputs of the Basys board. Then the Basys board sends the
output to the H Bridge circuit which directs the tank motors motion. Without the Basys
Board this project would not work. It’s like the brain of the project. Figure 5
demonstrates the inputs and the outputs of the Basys Board for a better understanding.
Figure 5: Basys Board inputs and outputs

13. 12
8. Conclusion
The H Bridge along with the motor controller circuit is what makes the tank
move. It’s the most important circuit so the tank can have motion. The ultrasonic
transmitter along with the ultrasonic receiver echoes signals transmitted by the proximity
sensor so it can follow the iron wired without losing its track. With each sensor located
on each side of the tank, it will detect the wire sending the output. The velocity of the
tank is programmed to change so it can continue to follow the path without any human
interference.
This project is estimated to be finish by the first week of December. Figure 6
explains the amount of time that’s going to take each group member to finish and who
does what.

14. 13
Figure 6: Gantt chart
The estimated cost for the whole project is about $4,820 and figure 7 goes more in detail
of the things necessary for the project and their cost.
Figure 7: Estimated Budget

15. 14
References
1. ^ The Using MOSFETS Website, A better H bridge. Cadvision
2. Department of Electrical and Computer Engineering, Texas Tech University.
“Electrical Engineering some useful sonar circuits,”
www.blackboard.ttu.edu/webct/urw/lc2044122011.tp0/cobaltMainFrame.dowebct
September 21, 2011.

16. 15
Appendix A
Reference Forms
1. Department of Electrical and Computer Engineering, Texas Tech University.
“Electrical Engineering some useful sonar circuits,”
www.blackboard.ttu.edu/webct/urw/lc2044122011.tp0/cobaltMainFrame.dowebct
September 21, 2011.
2. Cook, Chris. Class PowerPoint, 3 October 2011
3. Shoemaker, Harry. Class PowerPoint, 3 October 2011.

17. 16
Appendix B
WRITTEN LAB REPORT EVALUATION FORM
Student Name: Course Number:
Please score the student by circling one of the responses following each of the statements.
1) The student's writing style (clarity, directness, grammar, spelling, style, format, etc)
A B C D F Zero
2) The quality and level of technical content of the student's report
A B C D F Zero
3) The quality of results and conclusions
A B C D F Zero
4) Quality of measurements planned/ taken
A B C D F Zero
Grade: