Strain-gauge auto-zero without using rotational angle
Assignee4Iiii Innovations Inc.
InventorArthur William HARE
Life of this patent
Estimating the term…
Abstract
A power meter has a strain-gauge attached to a crank of a pedaled vehicle to measure a bend force applied to the crank. The power meter also includes an accelerometer positioned on the crank to sense a Y-axis acceleration. The power meter also includes a controller having a processor and memory storing machine-readable instructions that when executed by the processor cause the controller to: read a bend force value from the strain-gauge, read an accelerometer value from the Y-axis accelerometer, calculate a correction factor based on the accelerometer value and a maximum error force value, and subtract the correction factor from the bend force value to determine an auto-zero bend force value that is corrected for an effect of gravity on the crank.
Claims15
A power meter for a pedaled vehicle, comprising:
- a strain-gauge for sensing a bend force applied to a crank of the pedaled vehicle;
- a Y-axis accelerometer for sensing a Y-axis acceleration relative to the crank;
- and
- a controller having a processor and memory storing machine-readable instructions that when executed by the processor cause the controller to:
- read a bend force value from the strain-gauge;
- read an accelerometer value from the Y-axis accelerometer;
- calculate a correction factor based on the accelerometer value and a maximum error force value;
- and
- determine an auto-zero bend force value that is corrected for an effect of gravity on the crank by subtracting the correction factor from the bend force value.
A strain-gauge auto-zero method for determining a correction factor for a bend axis of crank of a pedal powered vehicle that corrects for an error force caused by mass of the crank and a pedal, comprising:
- capturing, from a strain-gauge, a bend force value indicative of a force applied to the crank;
- capturing an accelerometer value from a Y-axis accelerometer;
- calculating the correction factor based on the accelerometer value and a maximum error force value;
- and
- determining an auto-zero bend force value by subtracting the correction factor from the bend force value.
Dependencies are inferred from the claim text.