Overview
The CHUTE parameter group configures the emergency Parachute Release system. This system acts as a last-resort recovery method to save the vehicle and minimize ground impact energy in the event of a catastrophic failure (e.g., motor loss, mid-air collision, or loss of attitude control).
Key Concepts
1. Automatic Triggering
The parachute can be deployed automatically if the autopilot detects:
- Crash: Vehicle is tumbling or hitting limits.
- Critical Sink Rate: Falling faster than
CHUTE_CRT_SINK. - Motor Loss: Requires thrust loss detection to be active.
2. Motor Interlock
Crucial Safety Feature: When the parachute deploys, the autopilot IMMEDIATELY kills all motors. This prevents the props from cutting the parachute lines or entangling the chute.
3. Release Mechanism
- Servo: Moves a servo to a specific PWM position to release a latch/pin.
- Relay: Toggles a voltage pin (e.g., for a pyrotechnic charge or solenoid).
Parameter Breakdown
CHUTE_ENABLED: Master switch.CHUTE_TYPE: 10=Servo, 11=Relay.CHUTE_SERVO_ON/OFF: PWM positions for deployed/stowed states.CHUTE_ALT_MIN: Minimum altitude to allow auto-deployment (prevents accidental firing on the ground).CHUTE_DELAY_MS: Delay between killing motors and firing the chute (allows props to spin down).
Integration Guide
Testing (Ground)
- Remove Props.
- Set
CHUTE_ALT_MIN = 0(temporarily). - Arm the vehicle.
- Switch to a mode or flip a switch assigned to
Parachute Release(RC Option 22). - Verify the motors stop and the servo moves.
- Reset
CHUTE_ALT_MINbefore flight.
Developer Notes
- Library:
libraries/AP_Parachute - Integration: Tightly coupled with
AP_Motorsto ensure immediate shutdown.