Altitude Regulation

Author: CislunarSpace

Site: https://cislunarspace.cn

Definition

Altitude regulation is one of the core tasks of the stratospheric airship control system, achieving active maintenance and adjustment of flight altitude through adjusting net buoyancy, attitude, or propulsive force. Since stratospheric airships are underactuated systems (limited thrust), altitude control requires comprehensive use of buoyancy regulation, aerodynamic control, and propulsion.

Control Objectives

ObjectiveDescriptionTypical Precision
Altitude maintenanceMaintain nominal altitude±100 m
Altitude trackingTrack desired altitude profile±50 m
Altitude schedulingCross-altitude layer transferFast and smooth

Control Methods

Passive Altitude Control

MethodPrincipleApplication Scenario
Static buoyancy trimBuoyancy = gravity, no net vertical forceSteady-state station-keeping
Altitude囊 designBallonet absorbs volume changesReduce altitude fluctuations

Active Altitude Control

MethodPrincipleEnergy Consumption
Ballonet regulationInflate/deflate helium to change buoyancyMedium
Ballast adjustmentJettison ballast or add weightLow
Powered climb/descentPropeller generates vertical componentHigh
Thermal regulationChange helium temperatureHigh

Control Law Design

Cascade PID

Outer loop (altitude):

uouter=KPh(href−h)+KIh∫(href−h)dtu_{outer} = K_P^h (h_{ref} - h) + K_I^h \int(h_{ref} - h) dt

Inner loop (vertical speed):

uinner=KPh˙(h˙ref−h˙)u_{inner} = K_P^{\dot{h}} (\dot{h}_{ref} - \dot{h})

References

  • Wang H, et al. Altitude Control for Stratospheric Airship Based on Thermal-Flight Coupling[J]. AIAA Journal of Guidance, Control, and Dynamics, 2025.
  • Li J, Chen W. Adaptive Altitude Control of High Altitude Airships[J]. IEEE Transactions on Aerospace Systems, 2024.