3 ms·

I'd also be curious to see a reference for Orientation/heading from a phone's gyroscope/compass can be pretty reasonable, but most mems accelerometers are pret

by binoct 10y ago

I'd also be curious to see a reference for Orientation/heading from a phone's gyroscope/compass can be pretty reasonable, but most mems accelerometers are pretty much crap for dead reckoning use when loosely attached to a person. I could definitely see some interesting ideas with cell tower position data + heading + pedometer estimation getting merged, but I have a hard time believing that works in practice.

dogma1138 10y ago
This isn't using a "pedometer" this is fusing the input from multiple sensors like gyro, accelerometer, magnetometer, barometer etc. as well as other location data (wifi/gps/cellular/beacons etc.) and extrapolating the location using a path prediction algorithm. Given a known starting point, or a known point in general this increases both the speed and accuracy of identifying your location considerably even outdoors.
- binoct 10y ago
  I think we're starting from the same assumptions - my reference to pedometer meant the software-fused data from whatever on-board inertial/nav sensing was available, 6DOF IMU, compass, etc... In practice in consumer products I most often see this provided as "estimated distance" based on a learned or hard-coded model of what a single step looks like from the IMU (the pedometer part) + the output of GPS/cell/wifi localization. I'm specifically curious about evidence for a commercial smartphone that can track you to room-level accuracy using only IMU + GPS. (Add in wifi or other RF triangulation and it's clearly a solved problem.) In practice with a cell-phone GPS receiver and IMU only, attached to a person it is a hard problem to track a path to within a few meters. Trying to use accelerometer data to get position information over more than fractions of a second in that situation is... tricky.
  - dogma1138 10y ago
    This is what Google does, the GPS updates are actually pretty infrequent, especially if you specify low power mode, or they detect a slow activity and or you are indoors. Google's location API fuses all the sensors, they rely heavily on sensor data for indoor tracking and it's been getting pretty darn good since they've introduced it 2-3 years ago. I've linked a few google talks in this thread already, and you can read about the Fused Location API.

by binoct 10y ago

dogma1138 10y ago

This isn't using a "pedometer" this is fusing the input from multiple sensors like gyro, accelerometer, magnetometer, barometer etc. as well as other location data (wifi/gps/cellular/beacons etc.) and extrapolating the location using a path prediction algorithm. Given a known starting point, or a known point in general this increases both the speed and accuracy of identifying your location considerably even outdoors.

binoct 10y ago
I think we're starting from the same assumptions - my reference to pedometer meant the software-fused data from whatever on-board inertial/nav sensing was available, 6DOF IMU, compass, etc... In practice in consumer products I most often see this provided as "estimated distance" based on a learned or hard-coded model of what a single step looks like from the IMU (the pedometer part) + the output of GPS/cell/wifi localization. I'm specifically curious about evidence for a commercial smartphone that can track you to room-level accuracy using only IMU + GPS. (Add in wifi or other RF triangulation and it's clearly a solved problem.) In practice with a cell-phone GPS receiver and IMU only, attached to a person it is a hard problem to track a path to within a few meters. Trying to use accelerometer data to get position information over more than fractions of a second in that situation is... tricky.
- dogma1138 10y ago
  This is what Google does, the GPS updates are actually pretty infrequent, especially if you specify low power mode, or they detect a slow activity and or you are indoors. Google's location API fuses all the sensors, they rely heavily on sensor data for indoor tracking and it's been getting pretty darn good since they've introduced it 2-3 years ago. I've linked a few google talks in this thread already, and you can read about the Fused Location API.