Here’s a video of a Line Follower robot that I made for a competition organized by Government College of Engineering, Aurangabad during my early days of Robotics Exploration. I did not end up with pole position in the event but the Robot did attract lots of praises.
Tidbit: Autobot was the first robot to enter the track after preliminaries/ qualifying round. That made me really nervous as I had no benchmark nor was I sure which part of the track could be more challenging and neither did I get a chance to tune if needed. But the bot did the job (and since then our love become eternal :D)
About the Bot
This bot uses a very simple Microcontroller board that controls the motion where the goal is to follow a line in a given map. Autobot was made during 2007-08. Three of us built the robot during our 2nd year in Engineering. Unfortunately, this was pre-smartphone days so I was not able to make a good video (who knew I would someday post this on my website). Nevertheless a good friend came along with to participate in the event and also helped record this video. I wonder if the organizers made any video. Below are some of the key components.
The Brain (8051)
The robot uses a P89v51RD2 based microcontroller board with some basic interfaces for pushbuttons, LEDs, and motors. It also provides for some basic communication protocols such as SPI and an easy-to-program interface.
Sensors
We use two IR sensors mounted on either side of the robot that is able to detect variation in the darkness of the surface based on the amount of reflected light received. Each sensor board is a pair of IR transmitter and receiver.
Tidbit: The sensors were ideally suited for indoor environments but this event happened outdoors with sunlight hitting some parts of the track. Those who know about IR sensors know Sunlight is detected by receivers as IR signal making its output useless for detecting tracks. So as a last minute change I went to a nearby store, got some black insulation tape and covered the IR transmitter-receiver block with it. This trick greatly improved detection after some early failures during pre-qualification round! Thank God to insulation tapes!
Program
The algorithm is standard line-following logic. The robot is programmed using assembly C based instructions using a simple if.. then type code in an infinite loop. The logic is as listed below:
- Turn left if the left IR sensor detects white line - Turn right if the right IR sensor detects white line - Continue forward if both sensors or neither detect white line
There was some additional logic included to handle some cases to increase or decrease speed based on the change in the sensor signal.
Body
This robot was never designed for a line-following challenge. It was designed for another competition that involved speeding through a challenging track with obstacles, varying surfaces, hills, and valleys. 2 geared DC motors (12V, 100 RPM) were used for rear wheels. As a result, we designed the robot lightweight and ensure rugged tires for tough surfaces and avoid slips. However, being a budget robot most parts are salvaged using cardboard sheets, plywood and anything else we could find to suit the requirements while ensuring it satisfies size restrictions.
That was it! This was a fun experiment and am sure I could have made it so much better had I pursued it further but I could not at the time. However, once I get more time I will probably resume some of my works in robotics.
Parts Used
- The controller board originally provided by Thinklabs seems to be still available on sale here. If the item gets removed I have attached a pdf screenshot describing the board.
- The front wheels are taken from a toy we had. The rear wheels are easily available in any electronics store that sells robot parts.
- The overall body was designed using several blocks/ plywood/ cardboard pieces that we salvaged from various sources.
- 2 Standard IR sensors (~5cm range) to detect white lines on black surface or vice-versa (Equivalent Part)
- A standard 12V, 100RPM DC geared motor was used. I do not have the detail of the exact part number but it is similar to this one from Robotshop.
Acknowledgement
- This robot was originally developed by 3 of us (My colleagues during my engineering days, Madhuri and Riddhi) for the original Speedster competition
- I was able to develop the Line follower robot, thanks to the early training from Thinklabs Technosolutions based in Mumbai, India. The controller board was a part of their Robotics Kit
- Another friend from Engineering (Krushna) helped me during the competition day at GCOE, Aurangabad.
- Thanks to GCOE, Aurangabad for the event organization.
