Current spikes during terrain following


Could someone help me to identify the cause of the current spike during this flight?

Log here: 2023-11-18 15-53-47.bin - Google Drive

It seems to coincide with a small elevation of the terrain, but it’s strange to me that this is the cause since there are other similar variations throughout the flight and it doesn’t happen again.
If that would be indeed the case, what’s the correct approach to smooth terrain following? I’m looking into PSC_VELZ_P right now but not sure if that’s the correct parameter to mess with.

We’re using ArduCopter 4.0.7 right now, but will update to 4.3 soon.


The current spikes, both up and down, seem real because it is reflected in the battery voltage too - not just a logging issue. However there is no corresponding change to throttle or attitude that might cause such very large current spikes. Nor do they seem directly aligned with altitude.
But there are corresponding changes in motor outputs (commanded by the flight controller) that seem to be causing the voltage and current changes.

The issue is, not all attitude changes or motor output changes cause the spikes
I’ve just shown a zoomed in example here, but if you look at the overall graphs of motor outputs and current, you’ll see there is plenty of motor output activity but only some current spikes.

This may indicate there is actually a physical problem somewhere, such as an intermittent bad connection or short.


Thank you @xfacta, we’ll try to find if there’s something odd.
I think the issue may be related with this one which you also looked into. It looks like there may be some problem with our power supply.

No, I dont believe its a similar issue at all. Your whole flight has power flag 5
which is: Power brick good + USB

1   MAV_POWER_STATUS_BRICK_VALID      // main brick power supply valid
2   MAV_POWER_STATUS_SERVO_VALID      // main servo power supply valid for FMU
4   MAV_POWER_STATUS_USB_CONNECTED    // USB power is connected
8   MAV_POWER_STATUS_PERIPH_OVERCURRENT   // peripheral supply is in over-current state
16   MAV_POWER_STATUS_PERIPH_HIPOWER_OVERCURRENT   // hi-power peripheral supply is in over-current state
32   MAV_POWER_STATUS_CHANGED         // Power status has changed since boot

I’d be concerned about what that USB device is - and USB connectors and cables are a notoriously good way to transfer vibrations to you flight controller.

A change in power flags for the appropriate reasons wont cause the current and voltage spikes you are seeing on the battery supply. You are more likely to experience power loss to some accessory or total loss to the flight controller associated with power flag changes.
You do have a couple (not a lot) of spikes in your 5vdc (Vcc) but they are not causing an issue and I believe they are just a symptom of the voltage and current spikes on the main battery supply - likely caused by a short or faulty part somewhere.

It’s not a device, but a second power supply delivering power to the flight controller in an attempt to avoid the problems from the last time, when we lost the GPS because of insufficient power. It’s plugged into the port labeled as USB on the carrier board and the wires are very thin and flexible, so it shouldn’t cause any additional vibrations.

OK I understand :slight_smile:
The second power input port might be a better option.

It’s still likely you’ve got a physical issue somewhere - a shorting out electrical connection, a motor mounting screw poking too far into a motor touching a winding… Or maybe ESCs are losing their PWM signal briefly, but I suspect that isnt the case, since the spikes are both up and down.
Could even be mechanical - folding prop adapters have given their fair share of trouble before.

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