MAVLINKHUD
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Overview

The GND parameter group (specifically GND_EFFECT_COMP) configures the Ground Effect Compensation feature for ArduCopter.

When a multicopter is very close to the ground, the downward air from the propellers (prop wash) creates a high-pressure bubble under the frame. This high pressure can "fool" the barometer into thinking the drone has suddenly dropped in altitude, causing it to jump or bounce during landing/takeoff.

Key Concepts

1. Pressure Compensation

This system uses a model of the vehicle's thrust to estimate the pressure increase caused by the ground and subtracts it from the barometer reading.

  • Trigger: The compensation is only active when the vehicle is within a certain distance of the ground (based on rangefinder or takeoff altitude).

Parameter Breakdown

  • GND_EFFECT_COMP:
    • 0: Disabled.
    • 1: Enabled.

Integration Guide

  • Symptom: If your drone hovers stably at 5 meters but "balloons" or jumps when you try to land it, enable GND_EFFECT_COMP.

Developer Notes

  • Library: libraries/AP_Baro.
  • Algorithm: Uses the estimated thrust and the current height above ground to calculate a dynamic pressure offset.

GND_EFFECT_COMP

Default 1
Range 0 1

GND_EFFECT_COMP: Ground Effect Compensation Enable/Disable

Description

Enables or disables the ground effect compensation feature.

Values

Value Meaning
0 Disabled
1 Enabled
  • Default: 1

Description

This parameter activates the Ground Effect Compensation logic for multicopters.

  • Phenomenon: When a drone flies close to the ground (usually within one rotor diameter), the air pressure builds up underneath it ("Ground Effect"), increasing lift. This can cause the drone to "float" or become jumpy during landing.
  • Function: The autopilot detects when it is entering ground effect (based on barometer and throttle/climb rate mismatch) and automatically reduces the target throttle to maintain a smooth descent.
  • Benefit: Smoother landings and reduced tendency to bounce or balloon upon touchdown.
View Source
Glide Slope Configuration (GLIDE) GPIO Configuration (GPIO)