Life & hacking

Some of you may have been wondered that I haven’t blogged for weeks. Well, it has been a quite busy time working on a robot for university:

The challenge was to follow a double-line on a DIN A4 sheet and to draw a line in between with a pen. The budget was limited to 200 Euro and time was from mid of April until end of June. We worked in group with 8 persons. Nothing else was given except the optional chance to get a ready to use AVR board for controlling.

So, the first choice was if we wanted to create a plotter/printer like device or rather a mobile one. We decided to take the mobile approach because it simply seemed more fun. Mechanics were rather simple as we used two stepper motors without any gearing. The wheels are put on each side to be able to do a 360° turn without moving the pen in the centre:

For detecting the lines we used three CNY70 infrared sensors after we failed with line sensor. The currents from the sensors are converted using a simple op-amp circuit and connected to the digital ports of the ATMega16 processor. Most of the electric stuff on the photo is just used to drive the step motors.

Programming all this was rather tricky because a simple microcontroller with 1 KB SRAM and 16 KB Flash is really different to the normal desktop programming I am used to. Luckily there is a gcc for this AVR processors.

In the end we took a too high risk at the presentation and lost the track at the last curve. We had to use a slower program to reach the end. So we did not get the price for the fastest solution but at least the subjective price for the most beautiful robot.

You can watch our presentation video on YouTube!