Well Field Oriented control is imo largely about controlling the magnetic field to be in the optimal orientation relative to the rotor, and also the usual mechanisms that are used to do that. It’s not quite clear what exactly it means. It’s a control scheme, I guess. However it can be implemented in different ways and honestly I never really settled on the difference between sine control and FOC for instance, it is certainly very minor.
All the rest of the servo driver and motor design and gearbox or drivetrain and gcode interpreter is another story.
Ultimately, it increases energy efficiency and increases resistance to lost steps basically, compared to the open loop you are probably using right now.
The trinamic drivers sometimes have a feature, discussed elsehwer on this forum an in the datasheet, that measures how close the motor is to skipping a step. If you leverage that you can get the superb precision and repeatbility of stepper motors and improve your energy efficiency and torque at the same time, with relatively little effort. It can’t be as good as a true well done FOC system, but it can be better than a crummy one.
It depends a lot on what kind of angular resolution you need, honestly the requirements of a good arm type robot are pretty strict I seem to remember. Very small angular errors lead to considerable errors in effector position due to the large leverages.
To be honest if you want to deliver a robot ina reasonable timeframe I would leverage that feature of the trinamic driver and stick with stepper motors unitil the other details are better worked out. There must be lower hanging fruit.
And again if you want to use SimpleFOC in your project, don’t use you custom boards, contribute to the next generation flagship SimpleFOC board and then use that. Otherwise most of your efforts will never do anybody else any good. A half finished system is not much good to anyone, and it’s a lot of work to really finish something, plus it makes not sense to do it all on your own when there is wisdom and a head start on the subject here in the community.
There is a company making small cobot arms in Montreal, I have seen I think called Mechademic. I had read about them and was stoked to see one at an art show doing paintings one time. They are extremely expensive and the company says it’s partly because the actuators are so expensive. A good robot arm has to have effector positioning repeatability in the range of 25 microns. That’s a lot. They have to use harmonic gears etc, but I think they are probably brushless motors with optical encoders behind that. If you want a more economical system surely you will need a different approach. I honestly think stepper motors with those trinamic drivers are a pretty good option in place of a harmonic gear system like that. The best bet is to write a good driver to harness the coolstep and other features of the driver really well, so you can monitor for lost steps, regulate the field in a way similar to a crude FOC system, etc., and it’s going to be way way cheaper. That would be a significant accomplishment, to make a rotary actuator with really good properties using stepper motors and a nice ass driver.
I don’t know if there are drivers with similar features but higher current capability, that would be good stuff. Perhaps an advanced cooling solution would be good stuff, like submersing it in deionized water or something could get you to 3 amps or so. Larger stepper motors also have much more torque per amp.