System and method for rotational position tracking of brake lathe adjustment assembly

A method of resurfacing a brake disc of a vehicle brake rotor assembly, the method comprising:

• providing an on-vehicle brake lathe system having a lathe body with a driving motor, at least one cutting head operably attached to the lathe body, an adapter, a rotatable drive shaft driven by the motor for rotation about a lathe axis of rotation, and an alignment mechanism coupling the adapter for rotation about an output axis to the drive shaft;
• attaching the adapter of the on-vehicle brake lathe system to the vehicle brake assembly coaxial with a brake rotor assembly axis of rotation;
• activating said driving motor to rotationally drive said brake rotor assembly via said adapter, said alignment mechanism, and said drive shaft;
• during rotational movement of said alignment mechanism
• generating a runout measurement signal indicative of a phase and inclination of said lathe axis of rotation with respect to said brake rotor assembly axis of rotation,
• generating rotational position measurement signals indicative of current rotational positions about said lathe axis of rotation for each of a first disc coaxial with lathe axis of rotation and a second disc coaxial with said lathe axis of rotation, wherein said first and second discs each include facing surfaces orientated at an oblique angle to said lathe axis of rotation, wherein a rotational position of said first disc relative to said rotational position of said second disc establishes said output axis inclination, and wherein a rotational position of said first and second discs as a unit about said lathe axis of rotation establishes a phase of said output axis;
• generating a control signal in response to said runout measurement signals and to said rotational position measurement signals associated with each of said first and second discs, said control signal representing required changes in said rotational position of said first disc, said rotational position of said second disc, and/or said rotational position of said unit about said lathe axis of rotation necessary to align said output axis with said lathe axis to within an acceptable runout tolerance;
• aligning said output axis and said lathe axis of rotation by altering the rotational positions of said first and/or said second disc within said alignment mechanism in response to said control signal to achieve said required changes;
• and
• rotationally driving said drive shaft, said alignment mechanism, and said adapter to rotate the vehicle brake assembly with respect to the at least one cutting head to resurface the brake disc of the vehicle brake rotor assembly.