Patent ID: 7835887

Claim:
A method for determining performance of a sub-assembly device driven by a direct current (DC) motor, the method comprising; using a DC motor controller for: energizing a direct current (DC) electric motor with electrical power such that a sub-assembly device driven by a rotational movement of said motor achieves a desired target operating speed; capturing pulse width modulation data from said motor, said data representative of a torque response of said sub-assembly device; plotting said captured pulse width modulation data on a time axis and determining a transition wherein said sub-assembly device transitioned from a startup operation comprising startup data to a steady state operation comprising steady state data; comparing said plotted startup data to an ideal curve defined for said sub-assembly device to determine whether a torque reduction of said sub-assembly device in said startup operation has fallen below a predetermined operational startup parameter; averaging at least a portion of said steady state data over a desired timeframe window to obtain a performance value of said steady state operation; and comparing said steady state performance value to a threshold defined for said sub-assembly at said target operating speed; based on a result of either of said comparisons, determining whether said sub-assembly device is performing within an accepted operational parameter; and performing a maintenance operation in response to a signal that said sub-assembly device is not operating within said accepted operational parameter.