Does the Hover Thrust Estimate takes into account the current attitude of the quadrotor?

PX4 Autopilot
1

Hi,

Does the Hover Thrust Estimate takes into account the current attitude of the quadrotor?

Or should I multiply it by 1/cos(tilt) to get the thrust to hover ?

Other question: Why does the hover thrust change while flying ?

Thank you :smiley:

2

The reason the hover throttle keeps changing during flight is that the battery voltage gradually drops as the battery is drained. Most ESCs used in drones don’t actually do strict closed-loop speed control of the motor. Instead, they use a simple open-loop approach, adjusting the effective phase voltage by switching the MOSFETs on and off with PWM. As you know, motor speed is roughly proportional to voltage.

So when the battery voltage goes down, you get a lower motor speed at the same throttle value. To maintain the same hover thrust, the hover throttle has to increase. For example, if your drone hovers at around 40% throttle at the beginning of the flight, you’ll often see it hovering closer to 60% throttle when the battery is nearly depleted.

1 Like
3

Thank you, it’s very clear