My 1st Rover Project

In the current ArduCopter 3.6.5 release they have an SD card reliability improvement fix in the Changelog. I see no such fix for Rover. Maybe it’s there but not documented, not sure.

I think I’ve found the problem why there’s a solid red light. When I configure both the external compass & the pix hawk calibration when you turn them around the external compass comes up with green numbers in the minus for the X Y axis. It says like -217 etc.
The pix shows up in the positive over 1000 for each axis, hope I’m making sense as I’m not in front of everything.

It didn’t do this before but for some reason it’s always showing up like this regardless of how many times I recalibrate it

On side not I would like to calibrate via telemetry but when I start the wizard and select the telemetry port it asks if I’m using Linux, I
Click no then it comes up with an error message

I suggested you disable compass 2 many posts ago. Don’t use the Wizard, go to the Mandatory Hardware screen and select the calibration you want to perform. To connect via the telemetry radios select the Com port the ground radio is on in the upper right pull down and then choose 57600 baud and connect.

Sounds like you have a lot of interference where the Pixhawk is mounted. Offsets should never really total above 600 on any compass I think. I think all my externals are usually around 200 or less. Like the other Dave says disable the internal until you can get the interference under control. My internals are all below 600 but I have made sure the controller is in somewhat of a decent spot

I already disabled the internal compass completely. When I move the external gps/compass around it doesn’t turn.
Seems it’s only being used as the gps & not a compass. I also pressed “Force External Enabled” and still it wants to detect the pix for the direction it’s pointing and using the external solely for gps tracking.

I would like both compass/gps to all be done via the external module but still unsuccessful in doing so.

The Accelerometer calibration only detects the pix’a movement & when I try using the external compass module it doesn’t detect anything and says calibration failed.

@David_Boulanger @dkemxr

I guess I don’t understand your previous post. I thought you were saying the green bars seen during compass calibration were active for 2 compass’s. If that’s true then 2 are enabled. Go back to the Compass calibration screen and press the big green button at the top “Pixhawk/Px4”, then uncheck compass 2, make no other changes and re-do the compass calibration.

Will try this evening once home from work. Will let you know the results. Many thanks Dave

OK. By repeating the Wizard you can be wiping out progess. No reason to use it after initially, I never use it.

Ardurover is using an EKF to fuse different sensors together. If you only turn the compass module, all other sensors (gyros i.e.) stay stationary and the EKF rejects the movement of the compass.

I tried that already but it was still picking up the internal compass because when I tried to calibrate the accelerometer it kept saying failed when I tired doing it with the external compass.
Then after a few failed attempts I switched the using the pix itself and it said calibration successful. So it was still thinking the pix was being used to calibrate it

I did not get what you were trying to say. Calibrating the accelerometer and calibrating the compass has nothing to do with one another.

This is making no sense. To calibrate the accelerometer all you really need to do is with the vehicle level select the “calibrate level” button on the Mandatory Hardware>Accelerometer Calibration screen. Then perform the compass calibration from the Mandatory Hardware>Compass screen. Because I have no idea what you have done correctly this is why I suggested pressing the “Pixhawk/PX4” button and doing the calibration again. Then uncheck compass 2.

And/or post the parameter file and we can determine what compass’s you have from the Device ID’s and can turn them off another way.

When the pixhawk moves around and you can see it on MP what’s making the direction of the rover move in MP? Is it the external gps compass alone or is it the pix or is it both?

I thought that the external gps/compass would also show movement in the hud screen as well as gps tracking which is why I tried doing the accelerometer calibration only using the external compass/gps module.

Also haven’t had time to do what you’ve instructed but once I do it like you’ve explained it should be ok

The HUD will move around with NO compass active from the Z-axis Gyro. This doesn’t tell you anything.

As Sebastian said there is no correlation between accel calibration and the compass or GPS.

What you should do, and it’s the initial config for any craft, is work your way thru the Mandatory Hardware in the order it shows in Mission Planner. Accell Calibration, Compass and Radio Calibration are the screens you should sequence thru. Other things we covered:
Disable the Safety Switch
Turn off all fail safes and Geofence
Enable Arming and set a switch for Arm/disarm.
After confirming basic drivng in manual switch to Steering Mode and make sure it’s turninbg in the right direction. If not reverse the Steering servo channel in Mission Planner.

Don’t take a short cut and try an Auto Mission until all of this is correct. In fact don’t bother with an Auto Mission until Throttle and Steering are tuned.

1 Like

The external GPS/compass is just that. It does not contain an accelerometer or any other sensors.

What I’ve found is that the rovers wheels want to shimmy left and right rapidly whilst moving forward in steering or auto mode. I need to get it going straight before going into Randys Tuning mode.

When I reverse the steering it steers left constantly so something’s not right there. When I’ve changed the trim parameters it changes the shimmy but still can’t get it to go straight without the wheels going crazy.

@David_Boulanger mentioned something about reversing the steering for the servo and receiver input but still it does the same thing. Not sure where I’ve gone wrong here

You set the proper steering direction from the Transmitter with the vehicle in manual mode. You set the proper direction in Assisted modes (Steering) with the Steering servo channel from Mission Planner. First one then the other.

At what condition are your PID parameters at? Default (hopefully) or after you have jacked them all around before basic functionality has been achieved? It’s very difficult to know where you are with the configuration of this vehicle with your approach to basic configuration.

The way I test if the autopilot corrects the steering in the right direction is to switch to acro mode pick the rover up and yaw it left an right. The wheels should move in the same direction as the rear of the rover, so if you turn it nose right, the back goes to the left and the wheels should also move left. Just like a driver would countersteer in a drift. If it does not do that, reverse the servo out channel for the steering servo. Check if your steering input still goes in the right direction and if not, reverse the steering channel in your TX or the RC input channel in ardurover.

Hey Pete, regarding the info you posted about the Here RTK GNSS:

•The base station needs a certain amount of time to meet the accuracy requirements of your input. Testing shows that, in an open area without shelter, to achieve the absolute accuracy of 2m takes a few minutes; to reach the absolute accuracy of less than 30cm takes around an hour; to reach the accuracy of 10cm takes a few hours.

It then goes on to say:
•It should be noted that the absolute geographic accuracy of the base station here will affect the absolute geographic accuracy of the rover module without affecting the relative accuracy between the base station and rover. If your application does not require UAV with high absolute geographic accuracy, you do not need to set the base station’s precision too high, resulting in long survey time. Even if the accuracy of the base station is 1.5 to 2 m, the position accuracy of the rover module relative to the base station can still reach centimeter level.

So with my rover does the above highlighted paragraph apply or would I need to wait 2+ hours?

Is this how all RTK’s are regarding time required to obtain cm accuracy? This isn’t what I was expecting. Is there anything out there on the market that can do this process quicker or are we talking about £1,000’s for what I’m after?

Like you’ve said this is something that I can look into further down the line when I’ve achieved the best possible results from the hardware that I currently have. But I’m interested in what’s to come once I reach the advanced stage & will want to evolve further in accuracy

@dkemxr @count74 thank you for both your knowledge on this I will perform these mods today & see if there’s any improvement.