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Overview

The HEEL parameter group (specifically HEEL_MAX) configures the safety limits for ArduRover Sailboats.

"Heeling" refers to the lean angle of a sailboat caused by wind pressure on the sails. While some heel is normal, excessive heel can lead to a capsize or lose rudder effectiveness.

Key Concepts

1. Heel Limit (HEEL_MAX)

This is a safety threshold. If the sailboat leans (heels) past this angle (degrees), the autopilot will automatically ease the sails (release the sheets) to dump wind pressure and right the boat.

  • Purpose: Capsize prevention.

Parameter Breakdown

  • HEEL_MAX: Maximum allowable heel angle in degrees.
    • 0: Disabled (Danger!).
    • 20-30: Common for many small monohulls.

Integration Guide

  • Tuning: Set this slightly below the angle where your hull's deck begins to submerge or where you lose steering authority.

Developer Notes

  • Library: Rover/sailboat.cpp.
  • Context: Requires an accurate Roll measurement from the IMU.

Sailing maximum heel angle

HEEL_MAX: Sailing maximum heel angle

Description

When in auto sail trim modes, the heel (roll angle) will be limited to this value using PID control.

Values

  • Range: 0 to 90
  • Units: deg
  • Increment: 1
  • Default: 15

Description

This parameter sets the safety limit for the sailboat's heel (tipping) angle. If the boat tilts more than this angle due to strong wind, the autopilot will automatically release the mainsheet (or depower the wingsail) to bring the boat back upright.

  • Primary Use: Preventing capsize and reducing excessive weather helm (tendency to turn into the wind) which causes drag.
  • Mechanism: The value acts as a setpoint for a PID controller in the Attitude Control library. When the actual heel exceeds HEEL_MAX, the controller calculates a "sheet out" value to reduce sail power.

Source Code

ardupilot/Rover/sailboat.cpp

Heading Correction Configuration (HDG) Height Override Configuration (HGT)