It means nothing that it shows rotation in Mission Planner when moving only the compass. This has been explained several times by some of us in this thread. The HDOP indicated in your house also means nothing even if 1.4 was good. Which it isn’t. Do you understand what Horizontal Dilution of Precision means?
The Here 2 has an IMU build in, so rotating it does not only rotate the compass.
I know you guys have mentioned this several times I’m obviously confused with the dynamics of what each thing does or doesn’t do.
On a good note I tested the rover last night and it worked very well.
Its to do with PDOP or HDOP I think and also is there a way to improve HDOP/PDOP or is it purely based on conditions when the rover is used & now visible the satellites are?
Like I said before on the cheap GPS module I had HDOP was 0.6. On the Here 2 it’s never gone below 1.1. Is there a way to improve this other than improving where you are to increase visible satellites? Both gps modules have been tried in the same conditions so I’m not sure how the Here 2 is showing a higher HDOP value compared to my other gps module
The attached is the basic horizontal positional accuracy of the uBlox M8N chip. I have always assumed that with an HDOP of 1 this would be the expected positional accuracy of these GPS units. CEP is statistical meaning that 50% of the positional reading over a 24hr time period with >6 sats visible will be within a 2.5m circle. So some will be better and some will be worse. If you need significantly better accuracy than that then you will need to shell out more money for a better system.
It’s water under the bridge now but what you should have done is define what you wanted to accomplish 1st, research or ask for advice about how it can be achieved and then buy hardware.
Thanks for the info. Is there a better gps module I could grab? I don’t want to use RTK as I want to avoid having a base station. I did see a YouTube video of a gps gnss module claiming 1cm accuracy but is this even possible & if so how much is something like this?
I think you will need RTK but maybe you could use a Fixed Base Station service rather than your own. I actually looked in to this a few years ago and got as far as locating the closest Leica network antenna about 5km away at a local airport. The technical details of getting this to work was way beyond my mild interest.
There are pay services used for farming and other activities.Maybe there are free ones available to you. A quick Google search of “rtk base stations uk” turned up some interesting information.
Near any of these places?
Daresbury, Inverness, Shoeburyness.
Check out this post. It’s what he is using in NZ:
I have the gnss mode already on 67 and have now changed the SBAS to 1. Thank you
Also I need to take my rover out into an open field and run some decent tests. Right now it’s all been in my back garden surrounded by bushes, trees & houses hence why the HDOP is poor.
I’ve been told that even the house windows are an issue due to signals reflecting off of them and confusing positioning of the rover.
So I will do that when I have some time.
Also I will take the rover to the car park & run a waypoint along a straight line & see if the tuning is spot on as that may also be an issue.
Another thing I’ve noticed is that the left motors move slightly stronger than the right motors. In servo control they are both set to the centre which is above 1500 because when it’s on 1500 it still moves. So I’ve put that up to 1650 and both sides of the motors are not moving.
I will soon be hooking up a raspberry pi to the Pixhawk via telemetry. Wanted to know if there’s a way to view battery 2 via telemetry instead of Battery 1? Thank you
View in thew GCS? If so sure, just select the battery 2 values you want to monitor from the User Items menu and they will show up in the HUD.
what are the plans for the Pi?
potentially a visual tracking system rather than using gps. A friend of mine is very knowledgable with the Pi so he suggested something like this instead of using solely gps for navigation. He knows how to program it and he has loads of Pi’s spare so he will give it a try.
@dkemxr not sure what GCS is. I’ve seen people connecting the Pi via telemetry so instead of battery 1 I want to receive data about the battery 2. I will try the User Items as you’ve instructed. Thank you
GCS = Ground Control Station = Mission Planner many times
Google “ardurover visual odometry” for some interesting info.
just seen this:
At the beginning it says gps disabled & further into the video it shows the waypoints on mission planner that the rover is following via visual odometry. Seems like it sticks to the WP’s really well. If it’s in a field can it do this?
Can this be more accurate that using gps or rtk?
no, Even if it were very accurate it still needs to know where it is in the world. i.e. it may be able to tell its moved EXACTLY 5m. But unless it knows where it started this is not very useful.
rtk is basically as good as it gets, as with everything there is no free lunch
Why the resistance to RTK? Based on some of your posts that you subsequently deleted your use case seems very similar to the mower application Kenny has posted about here and in other threads. Essentially an accurate grid auto mission. He has a very large mower with a big cut swath, you have a small Rover with presumably a small “search” path so your requirements or more stringent that his and he’s using RTK with Lora Telemetry.
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But if you use both gps and visual odometry, which I’m guessing you can do would it improve accuracy by a huge amount or not much?
Odomotry might tell you how far you have moved, but you start location is still only as accurate as the GPS.
Use the stuff you have now and go out a test it, make some maps, then see where the improvements need to be.
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