AutomataKit BLDC Driver
What
The MMKBLDC Project is my attempt at building a decent controller for Brushless Motors. BLDCs are excellent sources of mechatronic actuation: they're power dense and serve the motion control justice present in most state of the art robotics. However, controlling them is non-trivial, and requires the combination of some EE expertise, some control expertise, and some hardware know-how.
Why
This project is largely a follow-on to my Teensy-Powered Brushless Motor Controller, and with this new work, may the TESC project RIP. A moment of silence.
TESC, April 2016 - August 2016
As the world turns,
so did those motors.
Once around is never enough
How
The driver uses an ATxmega microcontroller to drive phase voltages through a gate driver, through half-bridges, through motor windings. An encoder reads motor position back to the microcontrolelr, and shunt resistors measure current flowing through the motor coils. With this information, we can use some maths to determine where the motor's magnetic field is, and control that to drive position and torque outputs.
Development Notes
See circuit chatter, firmware chatter
At the moment, it's doing open loop 6-step commutation.
Learning About Brushless Motors and their Control
See the (ongoing) notes I put together to explain the wizardry of BLDC driving under / eductation.
Viable Commands
none yet - firmware in development
Test
Keycode: 127
- to test networking, this will reply with a payload packet containing
127, 12, 24, 48and will toggle an LED on the board
Reset
Keycode: 128
- issues a software microcontroller reset
- if the microcontroller is already hung up, this will not work
eRPM Target
Keycode: 141 Argments: Electrical RPM, int32_t, in electric phase periods / minute Returns: Ack, uint8_t, 141
- sets motor spinning at the set electrical rpm.
Read Current RPM
Keycode: 142 Arguments: none Returns: Electrical RPM at time of read, in electric phase periods / minute
Reproducing This Work
All automatakit works are open source, and while we cannot sell you boards, if you have an interesting application, get in touch to ask about collaborating.
To reproduce boards and load code, see the document 'Reproducing Automatakit Work'