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Re: GPSD For Real Time Application

From: Kai Harrekilde-Petersen
Subject: Re: GPSD For Real Time Application
Date: Sun, 29 Dec 2019 17:37:45 +0100
User-agent: Android


Search for "Kalman filter". The internet is full of great resources that explains how to apply Kalman filtering to vehicle dynamics(2D and 3D)

As Bernd points out, since your locomotive is literally on rails, your problem should be relatively simple, since there are only so few solutions to the Kalman filter response (I'm assuming you have a model of the tracks in 2D/3D).

I would more look into adding a 2D (or 3D) accelerometer than a gyro, since the train is (very) unlikely to do significant yaw/pitch/roll movements (unlike small planes, helicopters and motorcycles).

Speed and acceleration along the tracks should be easy to find. Same with elevation. The only complication I can think of is when the train goes through a fork, and you need to determine which path it took.

Seasons Greetings,


From: Bernd Zeimetz
Sent: Sun Dec 29 17:22:32 GMT+01:00 2019
To: Kashyap Gada
Cc: address@hidden
Subject: Re: GPSD For Real Time Application

On 12/29/19 4:48 PM, Kashyap Gada wrote:
Dear Bernd,

How can we mix gyro data with GPS to get better location?

Well, a programming language of your choice and math?

Vehicle Locomotive, Can get wheel tick.

Then you should be able to get the current speed in a very exact way
without gps. If it is a locomotive, I'd also assume that it is running
on rails. As the position of railways is known in advance, you can use
that information in the calculation of your position.

What can additional sensors be?

As I've mentioned, a gyrosensor.
Or speed sensors on wheels/motor whatever gives an exact speed.


On Sun, Dec 29, 2019 at 9:11 PM Bernd Zeimetz <address@hidden
<mailto:address@hidden>> wrote:


On 12/27/19 7:31 PM, Kashyap Gada wrote:
My application -
Record some events/sensor readings in a moving vehicle 100MPH using a
Ublox Neo-M8U GPS. Accuracy required is better that 5 meters.

additionally to the comments you've got so far:
I think you should at least have an additional gyro sensor which gives
you some movement data to combine with what you've got from the GPS.
Also if you have other sensors in your vehicle - use them.
You did not mention which kind of vehicle and what you are doing with it
- but if you are not 100% sure that you'll always have good gps
reception (or that you are not close to chinese pig farms with fake gps
transmitters), you *will* have to use additional sensors.

 Bernd Zeimetz                            Debian GNU/Linux Developer                      
 GPG Fingerprint: ECA1 E3F2 8E11 2432 D485  DD95 EB36 171A 6FF9 435F

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