ardupilot/libraries/AP_Scripting/applets/copter-slung-payload.md

Slung Payload

This script moves a Copter so as to reduce a slung payload's oscillation. Requires the payload be capable of sending its position and velocity to the main vehicle

Parameters

• SLUP_ENABLE : Set to 1 to enable this script
• SLUP_VEL_P : Oscillation controller velocity P gain. Higher values will result in the vehicle moving more quickly in sync with the payload
• SLUP_DIST_MAX : maximum acceptable distance between vehicle and payload. Within this distance oscillation suppression will operate
• SLUP_SYSID : System id of payload's autopilot. If zero any system id is accepted
• SLUP_WP_POS_P : Return to waypoint position P gain. Higher values result in the vehicle returning more quickly to the latest waypoint
• SLUP_RESTOFS_TC : Slung Payload resting offset estimate filter time constant. Higher values result in smoother estimate but slower response
• SLUP_DEBUG : Slung payload debug output, set to 1 to enable debug

How To Use

1. mount an autopilot on the payload connected to the main vehicle using telemetry
2. ensure the vehicle and payload autopilots have unique system ids
3. copy this script to the vehicle autopilot's "scripts" directory
4. within the "scripts" directory create a "modules" directory
5. copy the MAVLink/mavlink_msgs_xxx files to the "scripts" directory

How It Works

The script's algorithm is implemented as follows

1. Consume GLOBAL_POSITION_INT messages from the payload
2. Calculate the payload's position vs the vehicle position
3. Use a P controller to move the vehicle towards the payload to reduce oscillation
4. Simultaneously the vehicle moves back towards the original location. The speed depends upon the SLUP_WP_POS_P parameter