Systems and methods for measuring drivetrain power transmission

Abstract

Power transmitted from a cyclist to a bicycle through crank arms is indirectly measured by performing calculations on direct physical measurements. The direct physical measurements are taken from sensors that can be non-rotationally coupled to the frame of the bicycle. The sensors can be integrated into the frame or installed as a module within a standard, unmodified bicycle bottom bracket. Measured power can be viewed by the cyclist using a wirelessly connected user interface device.

1 . A system, comprising:
 a measurement side inner bearing cup having an outside diameter, configured to fit within a measurement side outer bearing cup having an inside diameter, wherein an open volume is formed between the outside diameter of the measurement side inner bearing cup and the inside diameter of the measurement side outer bearing cup;   a first load sensor, coupled to the measurement side inner bearing cup at a first position along the outside diameter and within the open volume, wherein the first load sensor is configured to provide a first analog electrical signal responsive to an applied force;   an analog-to-digital converter configured to sample the first analog electrical signal into corresponding digital values; and   a processor coupled to the analog-to-digital converter and configured to:
 generate a set of force values using a first set of the digital values; 
 generate a rotational velocity value using a second set of the digital values; 
 calculate a torque value by using the set of force values; and 
 calculate a power value by multiplying the torque value with the rotational velocity value.