At RoboTeam Twente we make a team of small soccer robots which autonomously plays against other teams. On a field of 9 by 12 meters, 8 of our robots cooperate as a team against the opponent’s team. On the inside, the robots are packed with circuit boards. These are used for driving the four wheels of the robot, kicking the ball and various other functions. In this story, I would like to tell you more about the PCBs of our robots.
Our robot holds three main PCBs. One board contains the high voltage circuitry which drives the solenoid we use to kick the ball. The second board holds the microcontroller, which handles the communication with the central computer and control systems. A third board is implemented four times for each robot: once for each wheel. It contains a motor driver for the three-phase motors we use.
High Voltage Board
The high voltage board uses a flyback converter to transform 12V to 300V. The high voltage is used to charge a 680µF capacitor. Since the voltage needs to be achieved in a few seconds, the 12V side produces currents up to 6A at a switching frequency of 100kHz.
After charging, the capacitor is discharged over a solenoid using an IGBT. This produces a current up to 50A. The solenoid creates a magnetic field, which propels an iron bar. This bar then collides with the ball, to kick it away with a max speed of 6.5 m/s.
The board with the microcontroller is the brain of the robot. It receives all commands from the central computer, which it processes and executes. The command package contains several commands, like ‘kick’, ‘dribble’ and ‘drive in this direction at this speed’. The desired direction and speed are transformed to a speed for each wheel, which is sent through PWM to the motor boards.
The motor boards contain a dedicated motor driver IC with internal H-bridges. Using a PWM as input, they deliver the desired output to the three-phase motors, with a maximum current of 1.5A per wheel. The motor boards are plugged into the microcontroller board using board-to-board connectors. This means replacing boards for maintenance is easy.
Since we’re now in a prototyping phase, the fast production times by Eurocircuits really help us out. We’re able to develop our design a lot faster, and with the assurance that the quality is high enough so traces don’t tear when replacing small components. Additional functions like beveled edge connectors help us with producing user-friendly boards that can connect with PCI-e headers.
We would like to thank you for your support! It makes a big difference in time and quality of our work.
Electrical engineer at RoboTeam Twente
RoboTeam Twente, Bastile Room 204A, De Hems 10, 7522 NL, Enschede, The Netherlands – firstname.lastname@example.org