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A Hall-effect-sensor-based position observer that is suitable for mitigation of torque ripple in permanent-magnet synchronous machines is derived. The observer includes an initial commissioning routine to compensate for the offset in the placement of Hall sensors, which is shown to be necessary for effective control of torque harmonics. Using the position observer in lieu of a high-precision encoder, the overall cost of control-based torque-ripple mitigation is reduced significantly. In addition to the observer, an enhancement is made to a recently developed torque-ripple mitigation algorithm. Specifically, the algorithm is modified to compensate for sensor delay. Proposed methods have been validated in simulation and hardware. Index Terms--Permanent-magnet machines, position measurement, torque control, torque measurement.