6 ms·

Seems like you could do a better job of tracking progress between stations by detecting the specific acceleration signature of each segment of track. At least f

Seems like you could do a better job of tracking progress between stations by detecting the specific acceleration signature of each segment of track. At least for tracks that are not completely straight and level. Somewhat similar to the first primitive in-car navigation systems before GPS, that worked on dead reckoning with drift correction by matching the shape of the measured path to map data.

fire_lake 2y ago
Shazam for train tracks
- modeless 2y ago
  Now accepting funding offers at $10m post-money valuation cap
  - blitzar 2y ago
    Ai Powered Shazam for train tracks. Now accepting funding offers at $500m post-money valuation cap.
    - rvnx 2y ago
      Then in 5 years: "Turns out this was marketing for investors and that our classifier was using 99% of the time last location and itinerary as primary factor to determine location" The magic formula: "if is_train_moving, countdown to next station"
nuccy 2y ago
Acceleration signature depends on: - human driver - train capacity and current load - train model (or any powertrain variations) More reliable might be to check rail track features from accelerometer: tilt, turns, bumps, or a combinations of everything. Even sounds on turns, changes of backround during merging tunnels, etc. Integrated acceleration gives train speed, which is also useful along with other inputs.
- modeless 2y ago
  Yes, tilt, turns, and bumps are what I meant by accelerations, not just the train's forward acceleration.
  - sakjur 2y ago
    If you’re not putting the phone on the floor, wouldn’t the person holding it introduce a randomness factor that would make it much harder to reliably measure those? And then there’s sun curves, packed leaves, ice and the cars’ suspension. I think I’d struggle with finding a signal through all that noise.
    - Normal_gaussian 2y ago
      Ive seen two seperate demos of doing this for the london underground based purely on the accelerometer. Accuracy is poor when blind, but if you have any info about where the user last had a location fix it became very good. Neither company found sufficient interest to deploy the sensor.
    - TeMPOraL 2y ago
      Contribution from the phone being held should be easy to cancel out for the most part, as high frequency noise. It of course gets much easier if you have acceleration data from two or more devices held by different people.
- sofixa 2y ago
  > human driver Not in any even remotely modern system that will have a high degree of automation and if there's a driver, they're only closing and opening doors, and telling the train to get going.
  - AndrewSwift 2y ago
    I just took a one day initiation with the SNCF for driving trains in France. I assumed that everything would be automated but in fact nothing is. They explained that they regularly face situations that require human intervention (several times a day), and that even a little automation would reduce the level of attention on the part of the conductor. The conductor is required to interact with the controls at least every 30 seconds to avoid setting off alarms.
KeplerBoy 2y ago
On my local tram network you could even do that just by listening to the noises made by the inverters, which drive the motors. They have a very distinct hum that matches the rpm of the wheels. I once built a crude speedometer using SFTs, peak detection and kalman filtering.
dariosalvi78 2y ago
I believe that their intention is to have something that works on any track, without signatures. Collecting signatures would be cool, but a massive work if you want to have good coverage of cities AND phones. Maybe companies like Google or Apple have the data and the capacity to do so, smaller companies less likely.
- bornfreddy 2y ago
  I was surprised to read they don't collect any data. That would be a great way to gather samples to train the new generations of detection NNs on. If it is properly anonymized it shouldn't be a problem, imho (and I'm pretty paranoid wrt. privacy).

fire_lake 2y ago

Shazam for train tracks

modeless 2y ago
Now accepting funding offers at $10m post-money valuation cap
- blitzar 2y ago
  Ai Powered Shazam for train tracks. Now accepting funding offers at $500m post-money valuation cap.
  - rvnx 2y ago
    Then in 5 years: "Turns out this was marketing for investors and that our classifier was using 99% of the time last location and itinerary as primary factor to determine location" The magic formula: "if is_train_moving, countdown to next station"

nuccy 2y ago

Acceleration signature depends on: - human driver - train capacity and current load - train model (or any powertrain variations) More reliable might be to check rail track features from accelerometer: tilt, turns, bumps, or a combinations of everything. Even sounds on turns, changes of backround during merging tunnels, etc. Integrated acceleration gives train speed, which is also useful along with other inputs.

modeless 2y ago
Yes, tilt, turns, and bumps are what I meant by accelerations, not just the train's forward acceleration.
- sakjur 2y ago
  If you’re not putting the phone on the floor, wouldn’t the person holding it introduce a randomness factor that would make it much harder to reliably measure those? And then there’s sun curves, packed leaves, ice and the cars’ suspension. I think I’d struggle with finding a signal through all that noise.
  - Normal_gaussian 2y ago
    Ive seen two seperate demos of doing this for the london underground based purely on the accelerometer. Accuracy is poor when blind, but if you have any info about where the user last had a location fix it became very good. Neither company found sufficient interest to deploy the sensor.
  - TeMPOraL 2y ago
    Contribution from the phone being held should be easy to cancel out for the most part, as high frequency noise. It of course gets much easier if you have acceleration data from two or more devices held by different people.
sofixa 2y ago
> human driver Not in any even remotely modern system that will have a high degree of automation and if there's a driver, they're only closing and opening doors, and telling the train to get going.
- AndrewSwift 2y ago
  I just took a one day initiation with the SNCF for driving trains in France. I assumed that everything would be automated but in fact nothing is. They explained that they regularly face situations that require human intervention (several times a day), and that even a little automation would reduce the level of attention on the part of the conductor. The conductor is required to interact with the controls at least every 30 seconds to avoid setting off alarms.

KeplerBoy 2y ago

On my local tram network you could even do that just by listening to the noises made by the inverters, which drive the motors. They have a very distinct hum that matches the rpm of the wheels. I once built a crude speedometer using SFTs, peak detection and kalman filtering.

dariosalvi78 2y ago

I believe that their intention is to have something that works on any track, without signatures. Collecting signatures would be cool, but a massive work if you want to have good coverage of cities AND phones. Maybe companies like Google or Apple have the data and the capacity to do so, smaller companies less likely.

bornfreddy 2y ago
I was surprised to read they don't collect any data. That would be a great way to gather samples to train the new generations of detection NNs on. If it is properly anonymized it shouldn't be a problem, imho (and I'm pretty paranoid wrt. privacy).