OHSC will be a hybrid stepper motor controller using foc techniques based on the modern powerstep01 driver and a powerful stm32f4 microcontroller.
The goal is to develop a stepper motor controller that can operate at stall conditions smoothly the same way expensive industrial servo motors can.
A high resolution rotary encoder with sub microstep resolution is used to provide feedback.
The development will also be documented on hackaday.io (https://hackaday.io/project/163904-ohsc-hybrid-stepper-motor-controller)
The initial idea came from researching direct drive steering wheels for racing simulators. Servo motors are often used by simracing enthusiasts as they provide accurate and strong force feedback but also come with a hefty price tag.
When sacrificing some smoothness a stepper motor can be bought for a fraction of the price but i had to realize that there are no cheap modern hybrid stepper drivers available at all that would be fit for the task.
Another use case of hybrid steppers can be in robotics and automation applications where projects like odrive already allow hobby 3-phase motors to be used. Sometimes a more powerful stepper might be the better or cheaper choice
The first goal is to design a driver able to create some smooth torque and a force feedback application based on usb hid/pid.
This will certainly please the simracing community and hobbyists looking to get into force feedback for cheap.
The basic principle of the current prototype is a foc loop that permanently adjusts the current electrical position by sending bursts of step impulses in stepclock mode. This allows to prevent the motor from skipping full steps and always provide the maximum amount of torque.