[FOSS-GPS] Mobile Robot Experimentation

Wed Sep 17 18:49:38 PDT 2014

before anything else, check what accuracy you get
with the rover parked for a couple of hours.

to isolate which one between rover and base
is noisier, download data from the nearby CORS,
then process your base versus CORS and your rover
versus CORS separately.

keep your base as close as possible to the rover.
that's the best way to mitigate iono delay
without dual-frequency tracking data.

turn on the GPS on the rover for some time
before it departs, as it should help with
ambiguity resolution.

try to elevate the antenna above the body
of the robot, so as to minimize multipath
and EM interference.

On Wed, Sep 17, 2014 at 6:06 PM, <foss-gps-request at lists.osgeo.org> wrote:

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> Today's Topics:
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>    1. Mobile Robot Experimentation (Sean Hyde)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Wed, 17 Sep 2014 17:05:35 -0400
> From: "Sean Hyde" <sean.a.hyde at gmail.com>
> To: <foss-gps at lists.osgeo.org>
> Subject: [FOSS-GPS] Mobile Robot Experimentation
> Message-ID: <0ddc01cfd2bb$20551d40$60ff57c0$@gmail.com>
> Content-Type: text/plain; charset="us-ascii"
>
> Hey Guys,
>
>
>
> I've been playing around with RTKLib for a couple months now and have run
> into some issues and I was wondering if anyone had any idea on how to
> improve performance.
>
>
>
> ---Setup---
>
> Base Station:
>
> NVS08C on custom PCB using the receiver to power the antenna
>
> Antenna is Taoglas Limited AA.161.301111
> (
> http://www.taoglas.com/images/product_images/original_images/AA.161.301111.
> pdf)
>
> Antenna is on a 12" x 24" steel plate
>
> Connected via FTDI->USB to Rasperry Pi
>
> Raspberry Pi runs str2str to send the data to Windows laptop running
> rtknavi
> using wifi backhaul
>
>
>
> Rover:
>
> NVS08C on custom PCB using the receiver to power the antenna
>
> Antenna is Taoglas Limited AA.161.301111
> (
> http://www.taoglas.com/images/product_images/original_images/AA.161.301111.
> pdf)
>
> Antenna is on a 18" x 18" steel plate
>
> Connected via FTDI->USB to Rasperry Pi
>
> Raspberry Pi runs str2str to send the data to Windows laptop running
> rtknavi
> using wifi backhaul
>
>
>
> The Rover setup is on a small mobile robot with a top speed of about 3mph.
> It is in a city (Pittsburgh), but the sky is relatively unobstructed.
>
>
>
> I'm running rtknavi in Kinematic mode using only GPS, L1+L2, 15deg
> elevation
> mask.  The position that I input for the base station is a 5 hour average
> (though it seems to have lost some precision when I pasted it?).  I have
> tried both Continuous and Fix and Hold Integer Ambiguity Res.  I'll try to
> attach screen shots of rtknavi.
>
>
>
> Right now, it kind of works.  I can get relatively jitter-free floats and
> occasionally fixes, but these fixes don't last long and I'm not sure they
> are actually globally accurate (ie: if you restart the software, you may
> get
> a fix, but it may be several meters from your last fix).  Sometimes a fix
> goes away and never seems to come back.
>
>
>
> I'm wondering if you guys have any suggestions to improve these results.
>
> Better antennas? (Which ones?)
>
> Trying to get better placement of the base station?
>
> Different settings in rtknavi?
>
> Continuous vs Fix and Hold?
>
>
>
> Thanks!
>
> -Sean
>
>
>
>
>
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