Without knowing what [the motor size is] is, how can we help?
Right, sorry for forgetting. I was kind of desperate after searching for hours without finding much. The maximum dimensions I can tolerate is 2 inches long, and 1.5" for the diameter. This motor will be used for the shoulder joint, so weight really isn't an issue as long as it's < 400g.
Actually, when I said 37 oz-in @ 5760 rpm, I was assuming I was going to use a 1:64 reduction gearbox at most, with 90% efficiency to achieve 15 N*M @ 90 rpm. If there's a higher torque motor that allows a smaller gearbox, but still achieve 1.5 rotations/second, I can use that too.
I'm not aware of the distinction between current and position sensors. From my basic understanding, Hall sensors just measure a voltage difference along a cross-section of a wire due to non-uniform charge density caused by a Lorentz force. I need the rotor position to achieve the smoothest/strongest torque. Also, I will also count the sensor transitions to determine the rotation count. I'm comfortable with microcontrollers, so the interface shouldn't be a problem.
Thanks for helping jwatte