Gain-scheduled Autopilot Design Research Articles

Robust gain-scheduled autopilot design with anti-windup compensation for a guided projectile

Robust gain-scheduled autopilot design with anti-windup compensation for a guided projectile

Gain-Scheduled Autopilot Design and Validation for an Experimental Guided Projectile Prototype

This paper investigates the design and validation of a gain-scheduled skid-to-turn autopilot for an experimental canard-guided, fin-stabilized 80-mm-guided projectile prototype in a hardware-in-the-loop (HIL) wind tunnel-based setup. The projectile dynamics are a priori unknown and are determined from open-loop system identification experiments conducted on the test setup. To this end, a nonlinear airframe model is discussed and considered for linearization around equilibrium operating points. The linear model parameters are estimated from several data collection experiments, resulting in a family of linear models. This knowledge is leveraged in a second step to compute a family of robustly stable multiobjective disturbance-rejection and reference-tracking controllers, which are implemented on the HIL test setup using a zero-pole gain interpolation scheme. The time-domain performance of the autopilot is finally assessed by the means of numerical simulations and experimental results gathered from the test setup, demonstrating the excellent suitability of the proposed approach.

Robust gain-scheduled autopilot design for spin-stabilized projectiles with a course-correction fuze

This article explores the design of a pitch/yaw axis load factor autopilot for a class of 155-mm spin-stabilized ammunition which incorporates a novel nose-positioned course correction fuze system used for trajectory correction. The projectile full nonlinear model is discussed and a procedure for obtaining the system q-LPV model necessary for control synthesis is exposed. Important properties relevant to axis cross-coupling, internal modes and stability properties specific to this kind of system are also highlighted. A comparison of full- and reduced-order mixed-sensitivity H∞ linear compensators with an additional model following constraint for the design of the projectile autopilot is presented. Robust stability with respect to aerodynamic and actuator/sensor modeling uncertainties is verified via standard μ-analysis tools throughout the projectile flight envelope. Nonlinear 7-DoF trajectory simulation results are finally presented for a single or dual control surface actuator configuration.

Gain-scheduled bank-to-turn autopilot design using linear parameter varying transformations

A gain-scheduled autopilot design for a bank-to-turn missile is presented. The approach follows previous work for a longitudinal missile autopilot. The method is novel in that the gain-scheduled design does not involve linearizations about operating points. Instead, the missile dynamics are brought to a linear parameter varying form via a state transformation. A linear parameter varying system is defined as a linear system whose dynamics depend on an a priori unknown but measurable exogenous parameter. This framework is applied to the design of a coupled longitudinal/lateral bank-to-turn missile autopilot. The pitch and yaw/roll dynamics are separately transformed to linear parameter varying form, where the cross axis states are treated as exogenous parameters. These are actually endogenous variables, and so such a plant is called quasilinear parameter varying. Once in quasilinear parameter varying form, a family of robust controllers using p, synthesis is designed for both the pitch and yaw/roll channels, using angle of attack and roll rate as the scheduling variables. The closed-loop time response is simulated using the original nonlinear model and also using perturbed aerodynamic coefficients.