Let's Make Robots!

Sensor activated LED moniter stopclock for robot events


Okay so im sure i will sort out some proper introductions later, but for now i shall make it breif. My name is Jack and I have built combat robots (ALA Battlebots, Robot Wars, Robotica) for about 5 years now, along with hosting many robotic events/meetings and pioneering UK battlebots on the internet. Recently i have decided to not only use the regular RC interface to control my robot but other fancy programmed methods too. This brought me into a lovely thing called "Make magazine" (which im sure your famillar with...lol) and upon opening up the latest "robots"episode (Yellow drum machine ftw) i saw a small artical on LED message boards with ps/2 keyboard interfaces to add in custom text/messages via a arduino. This got me thinking.

At my robotic event (RFRC) there are 3 types of competition, Deathball (a sort of robot version of soccer, with obsticals) Combat (the main event, where the robots fight to the death) and the final round: The assault course. In the assault course the robots have to navigate around, over, under and through many obsticals to reach their destination, effectively they just need to get from A to B in the quickest possible time, the fastest times are then put on the board and then from that we pick the winner. However, because the robots are so advanced nowdays we have found that they are completing the course a lot quicker with much closer times which makes it very hard sometimes to pick a winner. This called for two things:

A) redesign the course so its tricker to beat: Done

B) figure out a more accurate way to log the times rather than the traditional method of a stopwatch which isnt really accurate enough anymore.

When i saw the artical about the LED desplay it got me thinking, what if i used the screen/arduino but coupled it with the accuracy of robotic (sharp IR?) sensors? So when the robot starts the course it breaks a beam/gets seen by 1 sensor which starts a clock running on the LED screen, it runs the course and then when it crosses the finish line it activates a 2nd sensor which stops the clock; giving a accurate and very cool reading.I think it should be feasible, im not the best at code/arduinos though so any advice/thoughts/comments would be appreciated. The robots im designing it for are about 4 inches square and weight about 150grams.

Thanks, oh and if you want to see some other stuff i have done theres a link to one of my combat robots here:http://www.youtube.com/watch?v=mRdMt_xINvM


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Hi Jack, welcome to LMR.

Everything so far sounds good. Just got a few questions to get things moving:

• What's the minimum robot height likely to be?
• What is the course like at the start and end points?
• Is there only 1 robot competing at a time?

There are a few different ways to configure an IR sensor to trigger when the robot passes. You can have a diffuse sensor that bounces IR light off the robot to detect it, a sensor that emits an IR beam which bounces off a mirror/reflector and is broken by the robot, or an IR emitter/detector pair where the robot breaks the IR beam between the pair.
The emitter/detector pair option requires electronics on both sides of the start & finish lines, but on the other hand it'll be more reliable than the diffuse sensor, and doesn't require alignment like the reflector option.

Whatever you go for, I'd also recommend putting a little shield/hood/guard around the detector to minimise ambient light getting into the sensor. You can also 'modulate' the IR emitter to pulse at a certain frequency, which allows the detector to more easily distinguish the emitted IR against background interference.

Don't worry too much about the code at this stage, should be short and sweet for this project.

Well, that's a good enough place to start. Take a look at some of the IR sensor tutorials around LMR and the rest of the web, you might pick up some good inspiration.


Thanks for all that, Yes its only for one robot at a time. The minimum height would be around 1/2 a inch or around there abouts

Im going to speak to my tech guy about the sensors, ordering LED screens now :D oh and would you happen to be the nice guy who just subscribed to me on youtube? if so Jmemantzel ftw!