MAVLINKHUD
Download Android App Professional ArduPilot Ground Station
Full Parameter PDF

Overview

The MAX parameter group (often appearing as PSC_MAX_ in the full parameter list) defines the hard Kinematic Limits for the Position Controller.

These limits ensure that the autopilot never requests a velocity that exceeds the physical capabilities of the vehicle or the desires of the pilot for smoothness.

Key Concepts

1. Velocity Limits (MAX_VEL_...)

  • MAX_VEL_XY: The maximum horizontal speed allowed in autonomous modes (Auto, Guided).
  • MAX_VEL_Z: The maximum climb and descent rate.

2. Position Error Limits (MAX_POS_...)

Defines the maximum allowed distance between the vehicle's actual position and its "Target" position before the controller stops trying to close the gap instantly (preventing violent corrections).

Parameter Breakdown

  • MAX_VEL_XY: Horizontal velocity limit (m/s).
  • MAX_VEL_Z: Vertical velocity limit (m/s).

Developer Notes

  • Library: libraries/AC_PosControl.
  • Context: These are the "Inner" limits of the navigation system. The higher-level mission speed (WP_NAV_SPEED) is usually capped by these.

MAX_POS_XY

m/s
Default 0.2
Range 0.1 5.0

Max XY Position Delta (MAX_POS_XY)

Description

MAX_POS_XY is a safety and smoothing parameter for ArduBlimp.

It limits how far the blimp's target position can "Jump" in a single update cycle. Because blimps have very high inertia and move slowly, sudden large changes in requested position can cause the control loops to become unstable. This parameter ensures that the requested path remains smooth and achievable by the blimp's low-thrust propulsion.

Tuning & Behavior

  • Default: 0.2 m/s.
  • Usage: For larger, slower blimps, you may need to reduce this value to 0.1 to ensure smooth autonomous movement.
View Source

MAX_POS_YAW

rad/s
Default 0.3
Range 0.1 5.0

Max Yaw Position Delta (MAX_POS_YAW)

Description

MAX_POS_YAW limits how fast the blimp's heading target can rotate. This is crucial for avoiding large, oscillating yaw movements in airships with high rotational inertia.

View Source

MAX_POS_Z

m/s
Default 0.2
Range 0.1 5.0

Max Vertical Position Delta (MAX_POS_Z)

Description

MAX_POS_Z limits how fast the vertical target position can move in ArduBlimp. It ensures that altitude changes are smooth and don't overwhelm the blimp's limited vertical thrust.

View Source

MAX_VEL_XY

m/s^2
Default 0.5
Range 0.1 5.0

Max Horizontal Velocity Delta (MAX_VEL_XY)

Description

MAX_VEL_XY acts as an acceleration limit for the blimp's horizontal flight. It prevents the autopilot from demanding sudden bursts of speed that would cause the blimp to pitch or swing violently.

View Source

MAX_VEL_YAW

rad/s^2
Default 0.3
Range 0.1 5.0

Max Yaw Velocity Delta (MAX_VEL_YAW)

Description

MAX_VEL_YAW limits the rotational acceleration of the blimp. This prevents the propulsion system from trying to snap the blimp's heading too aggressively, which could damage the frame or motors.

View Source

MAX_VEL_Z

m/s^2
Default 0.5
Range 0.1 5.0

Max Vertical Velocity Delta (MAX_VEL_Z)

Description

MAX_VEL_Z limits vertical acceleration. It ensures that the blimp's transition between climbing and descending is handled smoothly by the buoyancy and motor control logic.

View Source
MAVLink Stream Configuration (MAV) Moving Baseline Configuration (MB)