US 6,513,381 · Granted 2003-02-04
The Shoe Sensor That Measures Every Step You Take
Imagine tiny motion sensors built into the sole of your shoe that track exactly how fast you're moving, which direction you're tilting, and how hard you're accelerating with each step. By combining data from multiple accelerometers, this system can calculate your walking speed and movement patterns without needing a camera or GPS.
The plain-English version
What it protects
The claim covers a motion analysis system that uses at least two perpendicular accelerometers mounted to the bottom of a shoe, plus a tilt sensor, to measure linear acceleration, angular orientation, and rotational motion of the foot. What's protected here is the specific arrangement of these sensors working together to resolve acceleration data into a chosen direction (like horizontal movement), then integrating that data to calculate velocity and ultimately gait speed.
Why it matters
This patent laid groundwork for wearable motion tracking in sports and fitness, where knowing your exact movement patterns—acceleration, velocity, and gait—became valuable for training, injury prevention, and performance analysis. By putting the sensors directly in the shoe rather than relying on external cameras or GPS, the system works indoors, in any weather, and captures biomechanical detail that cameras alone cannot provide.
Real-world use
Every fitness tracker or smart shoe that measures your running cadence, stride length, or ground impact force relies on the same principle: accelerometers mounted to your foot detecting motion in real time.
Original USPTO abstract
A device comprised of at least a pair of accelerometers and a tilt sensor mounted in fixed relation to a datum plane defining surface (sole of a shoe) may be used for extracting kinematic variables including linear and rotational acceleration, velocity and position. These variables may be resolved into a selected direction thereby permitting both relative and absolute kinematic quantities to be determined. The acceleration is determined using a small cluster of two mutually perpendicular accelerometers mounted on a shoe. Angular orientation of the foot may be determined by double integration of the foot's angular acceleration (which requires a third accelerometer substantially parallel to one of the two orthogonal accelerometers). The two orthogonal accelerations are then resolved into a net horizontal acceleration or other selected direction which may be integrated to find the foot velocity in the selected direction. The average of the foot velocity corresponds to the subject's gait speed.
Patent details
- Publication number
- US 6,513,381
- Filing date
- 2001-07-26
- Grant date
- 2003-02-04
- Assignee
- Dynastream Innovations, Inc.
- Inventor(s)
- FYFE KENNETH R., ROONEY JAMES K., FYFE KIPLING W.
- CPC class
- G01P1/127
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