Rotorcraft Flight Control Integrator Freezing for Landing Transitions
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Solution Overview
Problem
Rotorcrafts face challenges in transitioning between flight and landing states due to complex flight dynamics and the need for precise control of landing gear, which existing systems struggle to manage efficiently, especially in unstable conditions like pitching ships or gusty winds.
Innovation Solution
A system and method using a flight control computer with wheel sensors to determine the weight-on-wheels state, employing a state machine with in-flight, single gear, in-transit, and on-ground states to generate control augmentation signals through hold loops, freezing integrators to maintain stability and prevent erroneous inputs during state transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rotorcraft uses a simple flight control system without state machine management, then the device complexity is reduced, but the reliability of flight state transition control deteriorates
Solution Approach 1:
The flight control system dynamically adjusts the operational state of integrators based on the current flight state (in-flight, single gear, in-transit, on-ground). The state machine continuously monitors wheel contact status and transitions between states, enabling the system to adapt its control behavior to match the current phase of landing or takeoff operations
Solution Approach 2:
The landing and takeoff process is segmented into distinct flight states: in-flight, single gear, in-transit, and on-ground. Each state has specific control requirements, and the state machine manages transitions between these segments. This segmentation allows the control system to apply appropriate integrator management strategies for each phase, improving overall reliability
2Measurement precision
If the rotorcraft uses wheel sensors and state machine to determine weight-on-wheels state, then the measurement precision of flight state is improved, but the device complexity increases
Solution Approach 1:
The wheel sensors automatically detect wheel contact status and generate WOG signals without requiring manual input or complex external monitoring systems. The state machine uses these signals to self-determine the current flight state and automatically transitions between states based on predefined criteria, reducing the need for additional complex measurement equipment
3Stability of the object's composition
If the rotorcraft freezes integrators during single gear and in-transit states, then the stability during state transition is improved, but the loss of time in control response increases
Solution Approach 1:
The state machine prepares for state transitions by monitoring wheel contact status in advance. When transitioning from in-flight to single gear state, the system anticipates the need to freeze integrators and begins the transition process early. This preliminary action allows the system to maintain stability while minimizing the actual time integrators remain frozen, as the decision to freeze is made before the transition is complete
Data Source
AI summary
A rotorcraft having a plurality of wheels, each wheel configured to receive weight of the rotorcraft when in contact with a landing surface, a plurality of wheel sensors, each wheel sensor associated with a respective wheel and having circuitry configured to generate a wheel on ground (WOG) signal indicating that the respective wheel is in contact with the landing surface, and a flight control computer (FCC) in signal communication with the plurality of wheel sensors, the FCC operable to execute a first hold loop having a first integrator and providing first control augmentation of a rotorcraft flight system, the FCC further operable to freeze the first integrator according to a number of WOG signals received from the plurality of wheel sensors, the FCC further operable to generate a first control signal according to a first value provided by the first integrator while the first integrator is frozen.