The lateral-directional and longitudinal axes use a differential PI algorithm with MIMO control structures. It uses integral control in the roll and yaw axes. The boundary conditions are used to avoid integrator windup. The surface allocation strategy used a control power matrix inversion to avoid coupling excited by surface deflections. It also used a coupling derivative compensation to decouple the lateral-directional axes with a full-state feedback system. The sensor signals were sideslip, roll rate, yaw rate, lateral load factor, direction cosines and others. The lateral-directional control laws are mechanized as a PID controller for angle and sideslip, and a PI controller for wind-axis roll rate. The integrator dynamics are compensated by direct-link using pole-zero cancellation.
The integrators guarantee roll and sideslip authority. They compensate for model uncertainties and provide symmetric responses for an asymmetric load. To avoid integral saturation/windup issues, full-state feedback with orthogonal coordinate systems. The position of the integrator at the actuator input provided a self-limiting capability. The flight control law gains are scheduled wrt Mach number, dynamic pressure, and AOA. All of the loops use a phase advance filter to compensate for lag effects of the control system. The pitch and roll commands are prioritized over the yaw commands.
[[Eurofighter Control Law Control Surface and Integration Location]]
[[Eurofighter Lateral Directional Control Loops]]
[[Airbus A320 Flight Control System]] – decoupled the roll rate/sideslip with a gain matrix.
Eurofighter Roll Axis Feedback Loops
Eurofighter Yaw Axis Feedback Loops
Eurofighter Roll Command Path
[[Eurofighter Yaw Command Path]]
[[Eurofighter Disturbance Moment Compensation]]
- RealizationEurofighter2000[^1]
Backlinks:
[[Advantages of DPIA Controllers]]
[[DPIA Controller]]
[[Eurofighter Flight Control System]]
[[Full Carefree Handling]]
[[Integral Windup]]
[[MIMO]]
Phase Lag
State Feedback
[[Structured Uncertainties]]
[[Unstructured Uncertainties]]