Sometimes agopenGPS is not that accurate

Software
1

Hello, I have also built a GPS, I have tested now a few times and most of the times it is spot on, between 2-4 centimeters. But sometimes it goes to 20 cm and it then it does not correct the offset from the line. If i then turn of the GPS and turn on the steering wheel an then engage the GPS back then it goes back to the line. Does anyone have suggestions what could be the problem and how I can fix that because it now it is off the line?

I use a pcb V5, the antenna is on the roof of a non-suspended cab.

thank you in advance Louis!

2

V5? Picture board plz?

3

Are you using rtk?

4

Even without RTK, AOG should steer to the guidance line and not stay 20 cm off for a longish time. It could be 20 cm off from the correct line but that was not the question here.

5

I wondered if the offset was not shown onto the app, basically if the antenna tought it was in the right place but actually it was 20 cm apart. If it does show then is the 20cm offset random or downhill?

6

Sorry, could you say that in other words. I don’t think I can follow you.

Do you mean “the antenna thought it was in the right place”? The GNSS receiver always thinks it is in the right place even if it never exactly is (could be off a cm or a micrometer). The GNSS receiver does not know the right place, AOG neither, AOG only knows what the GNSS receiver tells (gyro helps for short term errors).

If AOG shows the machine 20 cm off, it assumes the correct path is 20 cm from the current path unless there is a SW bug or HW is not properly tuned (like WAS calibration) etc.

7

I meant if there is gps drift. With no rtk the antenna drifts to one side without that showing on aog, if the aog shows the drift then my question is not valid anymore.

8

Aog wont show you the drift. You can have perfectly tunned autosteer and drive ab line in aog within 0cm error, but in real life when you look behind you, you will see it drifted. If aog shows you 20cm error than its not about gps drift, its about settings.

Pls try:

  • Use pure pursuit mode
  • Drive ab line with constant speed around 8km/h
  • Set Look Ahead Speed Gain to 1
  • You should see a yellow dot in front of the tractor thats running away from you and tractor is trying to catch it. Move that dot further away with Hold Look Ahead slider, if this doesnt stabilize the steering error than your was is not working propertly, wrong 0 point set or wrong CPD and Ackerman
3 Likes