From controlling to measuring
Timo de Vries
We are using an ESP32-Wroom Module to control most of the robots functions. The via the connection module incoming velocity commands are converted to motor speeds and passed to the ESC Modul. In return the ESP-Module sends encoder data and data from the imu to our server. Besides, driving the kicking and dribbling devices have to be controlled by the ESP32.
In the soccer small size league, the robots are playing with a standard golf ball, which may be accelerated up to a speed of 6.5 m/s, representing a total kinetic energy of roughly 1 joule. From a variety of options to do so, we have chosen to use an electromagnetic kicking-device, because it meets several crucial requirements like a high reliability and a sufficient „firing-rate“.
Through a flybacktransformer energy is stored in a capacitor. While kicking, this energy is dumped into a coil within milliseconds and the coil is attracting a ferromagnetic plunger, which then hits and accelerates the ball.
In the Future
Our current focus of optimization is to choose a good ferromagnetic material allowing for a high flux-density and low eddy-currents and to develop a high speed, low noise capacitor charging circuit, which also meets high safety standards.
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 out 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.