Essentially every cobot I've worked with uses BLDCs instead of stepper motors in the joints. When searching for answers as to why I see a lot of posts that suggest one or the other, but nothing explains the consistent trend in the industry. The closest I've come to an answer is that stepper motors are worse with dynamic loads, but I don't understand why. Steppers have much higher precision due to their detant torque, so it seems like they should win out.
If anyone could help point me in the right direction I would greatly appreciate it.
Well, there are a few reasons to that.
Servos have a closed-loop mechanism, with an encoder or another device giving accurate feedback on the actual motor path. Steppers provide no feedback; control is through movement in incremental steps.
Servos normally boast consistent torque output over a wide speed range; copes well with short-term power bursts (e.g., due to rapid acceleration).
At low RPM, steppers performs better, while, closer to the maximum limit, torque is degrading; can provide holding torque in the power-off state.
There are also some other reasons for that trend. You can better idea of the difference in that article Steppers for a cobot