An Autonomous Robot for NERC Contest Muhammad Usman Asad, Muhammad Amar, Asif Raza, Osama Tahir, Asim Iqbal 1
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
THE CONTESTBackground: 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.
MECHANICAL SYSTEM DESIGN1. 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.
2. Ball LauncherThe design of shooter was animportant strategic link for the robot’ssuccess. To understand itsdevelopment, we started with a basicstudy of the forces involved withdelivering a ball to the target. Theshooter consists of worm DC motorthat rotates at no- load speed of200rpm. We use spring to propel theball, a system similar to the gunmechanism. To analyze andmanipulate the performance of ourshooter system, we are going to pick amathematical model.
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)
ELECTRICAL SYSTEM DESIGN1. 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.
+Vs +5V 2 2 1nF +5V 1 2 A + - 12 12 330 4N25 IN5822 1 1 10k 1k +Vss 1nF +5VEN IN 1 IN 2 MOTOR 330 Ven +5V L298N1 X X OFF IN1 EN0 0 0 OFF IN2 1k0 1 1 OFF 10k0 0 1 FORWARD +5V0 1 0 REVERSE 330 +5V 1k 10k
Equations defining the robot main drive systemWell 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)
2. Navigation System +5VThe 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.
3. AlgorithmLINE-SENSING ( ) JUNCTION-DETECT ( )1 While True 1 Junction_head ← False2 do 2 While TRUE3 if Left sensor is on 3 do4 then 4 if FL sensor is on or FR sensor is on5 do repeat Take right turn 5 then Junction_head ←True6 until left sensor is on 6 if Junction_head = True7 else 7 then8 do repeat Take left turn 8 if CL sensor is on or CR sensor is on9 until right sensor is on 9 then count ← count+1 10 Junction_head ← False 11 break 12 return count
3. AlgorithmTURN-90DGE-LEFT ( )1 repeat Turn right motor ON and left motor off2 until CL sensor is ON or CR sensor is ONTURN-90DGE-RIGHT ( )1 repeat Turn left motor is ON and right motor off2 until CL sensor is ON or CR sensor is ONTURN-180DGE-RIGHT ( )1 TURN – 90DGE-LEFT ( )2 TURN – 90DGE-LEFT ( )
POWER MANAGEMENTPower management in autonomousrobots is difficult task. Robot has tocomplete the given task in maximumfour minutes so power system shouldbe strong enough to drive the robotand to shoot and pick the balls.Maximum of 48V could be used asper mentioned in rules outline. Themicrocontroller, motor controller andthe sensor arrays are driven off fromone of the two 6V batteries
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 worthwhileexperience to build such a autonomous robot. Our design is unique andinnovative because of our chassis and shooting mechanism. Its simplicitymade it stand out.
AKNOWLEDGEMENTThe financial support at Institute of Quality and Technology Management (IQTM)University of The Punjab, Lahore is greatly acknowledged. Authors will also like tothank Mr. Umar Farooq, Lecturer at Department of Electronics &Telecommunication Engineering, University of The Punjab Lahore, for his untiringefforts during the course of the project.
REFERENCES National Engineering Robotic Contest website-E.M.E. N.U.S.T. [on-line] http://www.ceme.edu.pk/nerc National Engineering Robotic Contest website- E.M.E. N.U.S.T. [online] http://www.ceme.edu.pk/robocon Joseph Register, Veena Ramasamy, Ryan Copley, Fazir Mohammed, “ Autonomous Robot for IEEE SoutheastCon Contest,” Senior design report, University of South Florida. Gordon McComb, “Robot Builders Bonanza”, McGraw-Hill Professional Publishing, 2005 Rajput, Jahanzeb; Memon, Farida; Unar, Mukhtiar A., "Simulation of a Differentially-Driven Vehicle Robot in SimulinkÂ®," 9th International Multitopic Conference, IEEE INMIC 2005, vol., no., pp.1-6, Dec. 2005 A differential drive [online] http:// planning. cs. uiuc. edu/ node659.htm 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