Day: January 17, 2008

Slayer is a special robot for me. It was my first line following robot and he has won several National Robotics Contests in Spain (Robolid and X-Treme Robotrackers at Campus Bot).

It’s got just two motors: a servo motor to stick its nose to the line and a DC motor with a small gearbox to achieve the movement.

The control board is based on ATMega32 which is a very nice 8bit microcontroller equiped with 32KB of Flash and 2KB of SRAM memory.

The sensor board’s got 8 infrared sensors and its acquisition is multiplexed to minimize the required IO pins. Also, an ambient light cancelation is performed so that the robot could be able to run in different light conditions and (almost) over any surfaces.

The picture on the right shows the simulator developed to test the algorithm in the PC. It helped me to tune the PID controller and to check all the computation done by the microcontroller. Basically I developed a tiny “RTOS” for the ATMega32 with a cyclic scheduler to achieve the acquisition, computation and PID task in Real-Time at the desired frequency.

At these competitions, the robots have to follow a black line over a white surface as fast as possible by taking the correct way in all the branches. The right way is indicated by a small black line located in the side to which the robot should take in the incoming branch. For this reason, the algorithm’s got to be accurate enough in identifying the marks and branches as well as smooth enough to complete the track as fast as possible. Also, the track has got 90 degrees corners which usually become the headache of the competitors.

In this video you can watch Slayer in the Final round of Robolid 2006 competition. It got the fastest time and no penalties because it took all the branches correctly.

Hope you liked it.

Daniel

This robot was developed by my colleague and friend Alberto Calvo and me during our studies at University. We got the best possible mark because of the originality and complexity of it.

It’s got 8 Hitec servos (2 per leg) and it could perform some nice sequences of movement which looked really natural. All the control was achieved inside a Xilinx Spartan II FPGA and the code was entirely written in VHDL. The servo controller was a hardware core which accepted a 8bit word for the position and another 8bit word to set the desired speed.

The sequencer and the interface to the PC was implemented inside a PicoBlaze microcontroller synthetized directly into the FPGA. There was no kind of feedback and it just played the stored sequences in its memory but it was quite flexible since we managed to simulate them on the PC.

This is an old project (2003) and due to a data loss I cannot recover any videos or screenshots but I will try to rebuild it someday.

Regards,

Daniel