Phase Lag is a frequency-dependent delay. Control systems that do not consider phase lag can exhibit stability issues with signals that are phase delayed. Phase lag can be a manifestation of unwanted control system feedback dynamics.
Pilot-Induced Oscillations – a type of undesirable phase-lag pilot interaction.
PWPF Modulators – introduce phase lag into a control system
HL-10 Hydraulic System – maintains rate if one hydraulic system fails
Transfer function of an Integrator – integrators add -90 deg of phase lag
Current Management in Motor Drivers – lower bandwidth causes more phase lag
Gyroplane Rotor – flapping hinge causes a 90 deg phase lag
Eurofighter Flight Control Laws – control loops are phase advanced to compensate for inherent phase lag of the control channel (hardware and software)
Eurofighter Roll Command Path – no phase lag except the actuator
Disadvantages of PWPF Modulators – introduces phase lag
Reduced Order Models – reduced-order aircraft models have a delay to approximate the higher-order phase lag
PSS Phase Compensation Network – compensates for the phase lag
[[Control Surface Rate Limits]] – hitting the rate limits increases the phase lag
Dual Active Bridge Converter – power flows from the side of the leading phase to the side of the lagging phase
RASCAL Forward Path Delays – show delay times of various components
Phasor Diagram of a Capacitor – voltage lags the current by 90 degrees
Phasor Diagram of an Inductor – current lags the voltage by 90 degreePade Approximation – can be used to model phase lag
MCLAWS Simulink Model – included aerodynamic phase lag
BP5.1 – phase lags caused by control path delays must be included in functional specifications
[[B-47 Fly-By-Wire]] – phase lag of the autopilot caused a 1.5 Hz limit cycle
[[Pipelined ADC]] – introduces a latency of \(p\) cycles
[[BP7.4]] – should minimize the low-frequency lag
[[Smith-Geddes Criterion]] – predicts PIOs with the phase lag
[[Mitchell Hoh PIO criterion]] – uses phase delay characteristics to identify PIO-prone aircraft
Type 2 PIO – you must investigate the aircraft behavior in the 180 phase lag region with full stick inputs
[[Advanced Actuation System]] – reduces the low-frequency phase lag
[[C-17 Pitch Control Laws]] – new pitch law modifications reduced phase lag in the filter
[[B-2 Residual Pitch Oscillations]] – The phase lag of the transonic shock model could be tuned to produce 0 damping
[[F-117 Autothrottles]] – introduce a 90 deg phase lag
[[Dragonfly Flight]] – the front pair of wings lags 90 degrees behind the rear pair of wings in forward flight
[[Destructive Interference]] – caused by 180 deg out of phase
[[Duda PIO Criterion]] – ensure that there is no rate-limiting before 160 deg phase lag
[[F-16 Auto-GCAS Analog Output Circuitry]] – specifies the phase of the output signal relative to the input signal
ADS-33E– specifies phase delay for rotorcraft
Sources
- TenLittleAlgorithms
- cookFlightDynamicsPrinciples2007
- [3] NATO, Ed., Flight Vehicle Integration Panel Workshop on Pilot Induced Oscillations: = (Atelier sur le Pompage Piloté). in AGARD advisory report, no. 335. Neuilly-sur-Seine: AGARD, 1995.
Backlinks:
[[Digital Filter Design]]
[[Disadvantages of DFBW]]
Pilot-Induced Oscillations
[[Spatial Filtering]]
[[System Robustness]]