1. An Autonomous Robot for NERC Contest
Muhammad Usman Asad, Muhammad Amar, Asif Raza,
Osama Tahir, Asim Iqbal
1
2. Abstract
This paper discusses the development of an autonomous robot
designed to pick up the balls and pot into the goal posts of different
heights placed diagonally in the floor plan .The robot needs to be
completely autonomous and capable of playing the game according to
given guidelines. The contest is comprised of double elimination
rounds so speed is crucial
3. THE CONTEST
Background:
Inspired by the international contest “ABU ROBOCON” and having the capability
and capacity National Engineering Robotics Contest is regularly organized by the
department of Mechatronics Engineering, College of Electrical & Mechanical
Engineering every year.
Rules Outlines:
The goal of this year’s theme is to build an autonomous robot that has maximum
weight of 14kg and height of 65cm with covered area of 1300cm2. The robot has to
pick the balls from ball stand of specified height and to pot these picked as well as pre
loaded balls into the goal posts of different height.
4. MECHANICAL SYSTEM DESIGN
1. Chassis:
The robot main chassis is constructed
out of aluminum angles for weight
reduction. The size of chassis was
picked to minimize the area as per
defined in published guideline. The
robot was cut to these specifications
with a square pattern, giving rise to
an edge in line tracking.
5. 2. Ball Launcher
The design of shooter was an
important strategic link for the robot’s
success. To understand its
development, we started with a basic
study of the forces involved with
delivering a ball to the target. The
shooter consists of worm DC motor
that rotates at no- load speed of
200rpm. We use spring to propel the
ball, a system similar to the gun
mechanism. To analyze and
manipulate the performance of our
shooter system, we are going to pick a
mathematical model.
6. Equations defining the shooter mechanism
Fmax = k (Lfree - Lsolid) (1)
F = m× a (2)
F = K× x (3)
m × g = K × displacement (4)
F = B× v (5)
B = m× a/v (6)
7. ELECTRICAL SYSTEM DESIGN
1. Drive System
Two geared motors of three hundred rpm are used for powering the wheels.
For perfect detection of the line and junction on the floor plan, speed of the
motors must not be high. The problem is solved by using pulse width
modulation (PWM), thereby reducing the speed of the motors. There are two
main wheels, each of which is attached to its own motor. Woody slip
resistant wheels are used because slightest wheel slippage causes swear
problem in line tracking, junction detection and turning.
8. +Vs
+5V
2
2
1nF
+5V 1 2
A
+
-
12
12
330
4N25 IN5822
1
1
10k 1k +Vss
1nF
+5V
EN IN 1 IN 2 MOTOR 330
Ven
+5V L298N
1 X X OFF IN1
EN
0 0 0 OFF IN2
1k
0 1 1 OFF 10k
0 0 1 FORWARD +5V
0 1 0 REVERSE
330
+5V
1k
10k
10. Equations defining the robot main drive system
Well known mathematical model of
differentially driven vehicle is as follows:
wr (t) = vr (t) / R+ (L/2) (1)
wl (t) = vl (t) / R- (L/2) (2)
w (t) = (vr (t) - vl (t)) / L. (3)
R = (L (vr (t) + vl (t))) / (2(vr (t) - vl (t))) (4)
v (t) = w (t) R = (vr (t) + vl (t)) / 2 (5)
11. 2. Navigation System
+5V
The robot utilizes the Fairchild
Semiconductor QRD1114 QRD1114
emitter/detector pairs to locate the 1k
<2v
8
5
white line on the floor plan. The 2 6
100k
V+
B
+ B/S
sensor can easily distinguish the
>4v OUT
7
reflective surface from the non- 330 47k
3 1 To uC
V-
- G
reflective one. When the sensor is
4v LM311
over the dark surface, the reflectivity
4
4.7k
is very low; when the QTI is over the
light surface, the reflectivity is very
high and will cause a different
reading from the sensor.
12. 3. Algorithm
LINE-SENSING ( ) JUNCTION-DETECT ( )
1 While True 1 Junction_head ← False
2 do 2 While TRUE
3 if Left sensor is on 3 do
4 then 4 if FL sensor is on or FR sensor is on
5 do repeat Take right turn 5 then Junction_head ←True
6 until left sensor is on 6 if Junction_head = True
7 else 7 then
8 do repeat Take left turn 8 if CL sensor is on or CR sensor is on
9 until right sensor is on 9 then count ← count+1
10 Junction_head ← False
11 break
12 return count
13. 3. Algorithm
TURN-90DGE-LEFT ( )
1 repeat Turn right motor ON and left motor off
2 until CL sensor is ON or CR sensor is ON
TURN-90DGE-RIGHT ( )
1 repeat Turn left motor is ON and right motor off
2 until CL sensor is ON or CR sensor is ON
TURN-180DGE-RIGHT ( )
1 TURN – 90DGE-LEFT ( )
2 TURN – 90DGE-LEFT ( )
15. POWER MANAGEMENT
Power management in autonomous
robots is difficult task. Robot has to
complete the given task in maximum
four minutes so power system should
be strong enough to drive the robot
and to shoot and pick the balls.
Maximum of 48V could be used as
per mentioned in rules outline. The
microcontroller, motor controller and
the sensor arrays are driven off from
one of the two 6V batteries
16. CONCLUSION
This project to build an autonomous robot is successfully completed.
Although we are not able to qualify for the finals but it was a worthwhile
experience to build such a autonomous robot. Our design is unique and
innovative because of our chassis and shooting mechanism. Its simplicity
made it stand out.
17. AKNOWLEDGEMENT
The financial support at Institute of Quality and Technology Management (IQTM)
University of The Punjab, Lahore is greatly acknowledged. Authors will also like to
thank Mr. Umar Farooq, Lecturer at Department of Electronics &
Telecommunication Engineering, University of The Punjab Lahore, for his untiring
efforts during the course of the project.
18. REFERENCES
[1] National Engineering Robotic Contest website-E.M.E. N.U.S.T. [on-line]
http://www.ceme.edu.pk/nerc
[2] National Engineering Robotic Contest website- E.M.E. N.U.S.T. [online]
http://www.ceme.edu.pk/robocon
[3] Joseph Register, Veena Ramasamy, Ryan Copley, Fazir Mohammed, “
Autonomous Robot for IEEE SoutheastCon Contest,” Senior design report,
University of South Florida.
[4] Gordon McComb, “Robot Builder's Bonanza”, McGraw-Hill Professional
Publishing, 2005
[5] Rajput, Jahanzeb; Memon, Farida; Unar, Mukhtiar A., "Simulation of a
Differentially-Driven Vehicle Robot in Simulink®," 9th International
Multitopic Conference, IEEE INMIC 2005, vol., no., pp.1-6, Dec. 2005
[6] A differential drive [online] http:// planning. cs. uiuc. edu/ node659.htm
[7] V. Peri and D. Simon, “Fuzzy Logic Control for an Autonomous Mobile
Robot,” North American Fuzzy Information Processing Society Confer. Ann
Arbor, MI, June 2005
