From controlling to measuring.
We use an “ESP32-Wroom” module to control most of the robot’s functions. The incoming speed commands via the network module are converted into motor speeds and forwarded to the ESC module. In return, the ESC module sends encoder data and data from the “imu” to our server. In addition, the control of the kick and dribble devices is handled by the ESP32.
In the “soccer small size” league, the robots play with a standard golf ball that may be accelerated to a maximum speed of 6.5 m/s . This corresponds to a total kinetic energy of about 1 joule . From a variety of options, we chose an electromagnetic kicking device because it meets several crucial requirements, such as high reliability and a sufficiently high “firing rate”.
A flyback transformer charges two capacitors in less than a second. When the ball is kicked, the energy stored in them is then fed within milliseconds into a coil that attracts a ferromagnetic round bar. This then hits the golf ball and accelerates it. During development, special attention was paid to the implementation of safety features such as a discharge circuit and a flashing LED that warns of high voltages.
Currently, research is still underway to improve the kicker dimensions (length, diameter, number of turns, etc.) and to select a well-suited ferromagnetic material.
Since the Robocup Competitions are held in different countries around the globe, the available radio frequencies may vary. To be more flexible we are using a seperate Network Module which can be switched with other modules to use different frequency areas.
To interact with our robots we need a user-friendly interface which can be accessed even if the robot is assembled and shell is mounted. We decided to use a removeable UI which can be plugged in at the interface module on the right side of our dribbling device. When the external UI is plugged in, the ESP32 gets notified and shows internal data on the display. Furthermore, robots can be controlled thru a rotatory encoder mounted on the external UI.
Task of the ESC Module is to control the BLDC-Motors of our robots. Since BLDC motors are relatively new in this speed region, there aren’t any prebuild speed controllers in our form factor, so we decided to design our own module. In order to safe space, we split the module in half and arrange them on top of each other, forming a pcb sandwich. That way every board has circuits and connectors for two motors. The communication between all boards is realised with our Main Hub.