Detection of drum position in laundry appliance

A laundry machine includes a cabinet and a laundry holding drum rotatably supported within the cabinet for rotation. The drum includes a drum end (726) including an annular series of regularly spaced deformities (950). A motor drives rotation of the drum. A light source (910) is positioned in the cabinet to illuminate a location through which the annular series of deformities are passed by rotation of the drum. A light detector (910) receives reflected light from the light source off the drum end. A controller is operatively connected with the motor and the light detector, the controller being configured to operate the motor to drive the drum, and to receive signals from the light detector and process the signals to determine rotational characteristics of the drum.