Raiders of The Lost Ark
It is the year 1936, and you are hired by the US government, to retrieve the “Ark of the Covenant” which is believed to still hold the ten commandments. Unfortunately, agents of Hitler are also after the Ark, and the onus is on you, to retrieve the Ark and return it safely. If the Nazis acquire it, their armies will be invincible and that would mean disaster. With the Nazis on your trail, time is running out and the perils of the journey are ever increasing. Now only you stand between the Nazis and their quest for invincibility.
Prizes worth 18,000 Rs + goodies to be won
Details
Objective:
Legend has it that the Ark is located at the “center” of an ancient Peruvian temple and it is all up to you to retrieve this prized treasure.
Problem Statement:
 Teams must build an autonomous bot capable of exploring an unknown maze/graph.
 After traversing the entire maze/graph, the bot must come to the “center” of the maze/graph.
Sample Arena
Arena Specifications:
• The arena is contained in a 210 cm x 210 cm area.
• The lines are black on a white background.
• The line width is 3 cm.
• All the intersections are at right angles.
• There will be at most 3 intersections at a point.
• There are no loops in the arena.
• *The starting point is at one end of the longest path in the graph.
• The maze/graph will have have only one unique center
• The distance between any two adjacent nodes in the graph should be considered as unity.
PreGame Setup
· Separate arena for practice will be provided for calibration/testing.
· Each team will be provided 5 minutes setup time before the main run on the final arena.
Definition of “center” of the graph:
The center of a graph is the set of all vertices of minimum eccentricity, that is, the set of all vertices A where the greatest distance d(A,B) to other vertices B is minimal.
* The center lies on the longest path in a graph . (Which can be modeled as a tree.)
Qualifying Round
 One run will be given to each team.
 The bot will be placed at the starting of the arena initially, and the timer will start on the announcement of the organizers after which the bot is permitted to move.
 The bot should explore the whole graph/maze and it should indicate that it has completed the traversal of the graph/maze by coming to a halt and blinking an LED.
 The maximum time given to complete the task is 5 minutes.
 The time taken to complete the task will be noted.
Final Round
 The bot will be placed at the starting point of the new arena.
 The bot should explore the whole graph/maze and it should indicate that it has completed the traversal of the graph/maze by coming to a halt and blinking an LED.
 The bot should then come to the “center” of the graph/maze and again halt and blink a LED.
 The run ends here and the corresponding time will be recorded.
 Team with Maximum score will be declared the winner.
Certification Policy:
 Certificate of Excellence: Awarded to the top 3 teams of the final round.
 Certificate of Merit: Awarded to teams who complete round 2
 Certificate of Participation: Awarded to teams who complete round1.
Rules
Bot Specifications:
 Each team is allowed to have only one bot.
 The bot must fit into a cube of dimensions 250 mm x 250 mm x 250 mm(lxbxh).
 The bot must use only onboard power supply. No external offboard power supply is allowed.
 The max voltage difference between any two points must not exceed 24V.
 The bot must be fully autonomous with all powering and motoring mechanisms self contained.
 Human operators are not permitted to enter any information into the bot during the event. The bot must not communicate with any wireless device also.
Disqualification
 Any bot not conforming to the specifications provided will be instantly disqualified.
 Any bot which damages the arena will be disqualified.
Team Specifications:
Minimum : 1 membersMaximum : 4 members
Judging Criteria
Scoring Criteria:
Key:
e  no. of edges traversed
ue  no. of untraversed edges
r  no. of restarts(maximum 3)
t  time in seconds
Round 1:
Score = 50e 50ue + (200 bonus)* 50r  t
Final Round:
Score = 50e 50ue + (200 bonus)* 50r  t + (500 or 100)**
* the bonus is for successful travesal of graph(valid for both rounds)
** (1)500 pts for correctly reaching the center
(2)100 pts if the bot stops 1 node away from the center
Resources
Center Of a graph
 A center of a tree is a node which minimizes the maximal distance to all other nodes in the tree. In other words, it's the collection of vertices whose longest distance to all other vertices is the smallest. ( http://en.wikipedia.org/wiki/Graph_center).
 Center of binary tree will be the mid point of the path corresponding to the diameter(longest path) of tree.Essentially, what you are supposed to do is find the longest path in the graph and then find the middle node on that path.As there is only one centre in the given graph, the length of the longest path will always be odd. (http://stackoverflow.com/questions/7094832/centerofbinarytree)

In the given arena, the starting point will be at one end of the longest path in the graph.
Introduction to graph theory regarding trees.
Exploring trees
Line following
In the problem statement, we are required to follow a 3cm black line on white background.
Now, if we hold an LEDLDR sensor or an IR sensor above the white line (light reflecting), the intensity of reflected light falling on the LDR will be much more than the intensity when it is held above the black floor (light absorbing). This phenomenon is used for line following.
There is a minimum of two sensors required for this task, one for detecting each edge of the line. If the sensor gives a high when above the floor and a low when above the ridge, then the simple algorithm for line following will be :
LEFT SENSOR 
RIGHT SENSOR 
LEFT MOTOR 
RIGHT MOTOR 
1  1  1  1 
0  1  0  1 
1  0  1  0 
Basic line follower tutorial
Basic line follower code:
Contacts
If you have any queries, please send an email to [email protected], or get in touch with the undersigned:
Shabbar Vejlani
+91 8983624950
Srihari Shankar
+91 8806922774