INAV Mixing Configuration Files and VTOL Support

一、Mixer Configuration File

MixerProfile is a set of configuration settings including motor mixer, servo mixer, and platform type, primarily for experienced INAV users.
For detailed setup tutorials on VTOL (Vertical Take-Off and Landing) aircraft, please refer to the official documentation: https://docs.corewing.com/plane/other/inav/vtol-support.html
However, this feature is not limited to VTOL and is also applicable to air/ground/surface hybrid vehicles. The model's behavior depends on the platform type ( platform_type) set in the currently used mixer_profile, as well as the configured custom motor and servo mixer logic.
Current Support Status

• Except for the F411 flight controller (due to resource limitations), all other target boards currently support two mixer_profiles.
• F411 does not support VTOL mode switching because its resources are insufficient to support mixer profile switching and transition logic.
  VTOL Typical Configuration Logic
  In VTOL settings:
• One mixer_profile is used for multirotor mode (MR)
• Another mixer_profile is used for fixed-wing mode (FW)
  By default, switching from one profile to another requires a flight controller reboot to take effect.
  However, by using RC 模式：MIXER PROFILE 2, you can dynamically switch configurations during flight, for example, for mid-transition of VTOL aircraft.
  When switching, the flight controller automatically reinitializes the PID and navigation controllers required for the current mode (MR or FW).

1.1 Mixer Transition Input Usage Guide

In multirotor mode (MR mode), the transition input is typically used to increase airspeed, preparing for subsequent entry into fixed-wing flight status.
When transition mode is enabled, the related motors or servos will start moving according to the configuration:

• Motors may start pushing forward;
• Servos may change angle to adjust thrust direction (such as tilting rotors);

Important

Note: After entering Navigation Mode, the transition input will be automatically disabled to avoid interfering with autonomous flight control.

Recommended Reasons for Using Transition Mode
Enabling transition mode not only improves flight performance but also supports the following features:

• Failsafe logic support;
• Future feature expansion (such as automatic transitions in smart flight plans);
• Clearer flight status divisions.
  ❌ Not Recommended:
• Directly mapping motors to servo outputs;
• Or using complex logical conditions to control servos. These methods can easily bypass the flight controller's core logic, causing unpredictable behavior.

1.2 Servo Configuration Example (for Tilt Motors)

Description: Using smix configuration, when entering transition mode, the servo tilts the motor angle (e.g., +45°) to help gain airspeed.

Important

# Rule number; Servo number; Input source; Output magnitude; Servo response speed; Logic function number
smix 6 1 38 45 150 -1

• 1: Indicates controlling the first servo (Servo 1)
• 38: Transition input source number
• +45: Output +45 position (angle)
• 150: Speed for the servo to move from current angle to target angle
• -1: Indicates no logical conditions bound, executes by default when entering transition mode

1.3 Motor Configuration Example (for Transition Thrusters)

Motor Behavior Rules Explanation:

• throttle = 0.0: Default value, indicates this motor is not enabled, will not appear in diff output.
• 0.0 < throttle <= 1.0: Normal motor throttle mapping.
• -1.0 <= throttle <= 0.0: Flight controller sends a "stop" signal, this is a placeholder or used to control the motor not to spin.
• -2.0 < throttle < -1.0: Indicates that regardless of the current throttle, as long as transition mode is entered, the motor will run at a fixed speed. Actual speed = abs(throttle) - 1, for example, -1.200 represents 20% thrust.
  Flight Mode Configuration Recommendations:
• AirMode type: Should be set to STICK_CENTER
• Do not set to THROTTLE_THRESHOLD, otherwise the motor may continue to spin even with zero throttle until exceeding the threshold.
  Motor Configuration Example:
  The following is an example configuration for a Y3 VTOL aircraft, activating a thruster motor in transition mode with 20% thrust:

Important

# Multirotor tri-motor (VTOL)
mmix 0 1.0 -0.5 0.866 1.0 # Motor 1: Front left, with roll/pitch/yaw
mmix 1 1.0 0.5 0.866 -1.0 # Motor 2: Front right
mmix 2 1.0 0.0 -1.0 0.0 # Motor 3: Rear center
# Transition motor/Horizontal thruster (stopped by default, activates in Transition)
mmix 3 -1.200 0.0 0.0 0.0 # Motor 4 (numbered from 0, this is the 5th motor)

• -1.200 indicates continuous operation at 20% thrust in Transition mode.
• Setting yaw/pitch/roll to 0 means the thruster does not participate in attitude control.

二、RC Mode Configuration

✅Recommended Operation Method
It is recommended that pilots use a three-position/four-position switch on the RC transmitter (RC AUX channel) to control the following two functions of the flight controller:

1. Switch mixer profiles
2. Enable/disable transition mode
   Important Notes

• Switching profiles is prohibited when navigation mode is active (such as return-to-home/autonomous flight)
• Mixer profile switching must only be used after the flight controller has completed sensor calibration during runtime
• mixer_profile 1 is the default mode (generally used for fixed-wing FW)
• mixer_profile 2 is the auxiliary mode (used for multirotor MR)
  Control Logic Diagram (Three-position Switch)
  | RC Channel Value Range | Model Behavior |
  | --- | --- |
  | 1000 ~ 1300 | Fixed-wing mode (Profile 1), transition disabled |
  | 1300 ~ 1700 | Multirotor mode (Profile 2), transition enabled |
  | 1700 ~ 2000 | Multirotor mode (Profile 2), transition disabled |
  Diagram for Setting RC Mode:
  
  INAV Automated Transition:
  📌 Feature Description
  Automated Transition is mainly used in failsafe or navigation controller-triggered automatic return-to-home (RTH) processes, allowing VTOL models to:
• Use fixed-wing mode (FW) for return, which is more power-efficient and higher in efficiency;
• Use multirotor mode (MC) for landing, which is safer and more precise.
  TailSitter Support
  INAV 7.1 will begin to natively support tail-sitter VTOL, with the following setup method:

1. In the fixed-wing (FW) configuration profile, normally set the flight controller direction: set platform_type = AIRPLANE
2. When setting the flight controller direction, note that the motor thrust axis must align with the nose direction (in level flight attitude).
   In the VTOL configuration profile (i.e., MC mode), add a flight controller attitude offset: set tailsitter_orientation_offset = ON

三、Parameter Classification Explanation

Shared Parameters (Common for MC/FW)

• Servo settings: Servo min/center/max values
• Motor settings: motor_pwm_protocol, motor_poles
• Servo protocol and frequency: servo_protocol, servo_pwm_rate
• Flight controller direction calibration (Board Alignment)
• Timer overrides
  VTOL Parameters Specific to Each Profile
• platform_type (platform type)
• motor_stop_on_low (whether to stop motor on low throttle)
• tailsitter_orientation_offset
• motor_direction_inverted
• mmix (motor mixer)
• smix (servo mixer)
• PID, navigation PID, TPA, rates settings, etc.
  ————This article is referenced from the INAV official website: https://github.com/iNavFlight/inav/blob/master/docs/MixerProfile.md