Helicopter Autopilot Redundancy With Electromechanical Fail-Safe Control
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Solution Overview
Problem
Helicopter pilots face instability and fatigue due to the need for constant cyclic control, which is exacerbated by the high cost of traditional autopilots, making them uncommon in light helicopters.
Innovation Solution
An autopilot system with redundant inner and outer loops, utilizing electromechanical actuators and sensors like MEMS rate sensors, GPS, and magnetometers to provide automatic flight control without a hydraulic system, ensuring stability and redundancy in both normal and failed modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a traditional autopilot system is installed to provide hands-free operation and reduce pilot fatigue, then the ease of operation is improved, but the cost of the system becomes prohibitively expensive
Solution Approach 1:
The autopilot system is divided into two independent control loops: an inner loop for attitude control (pitch and roll) and an outer loop for navigation functions. This segmentation allows each loop to be optimized independently and reduces overall system complexity and cost while maintaining hands-free operation capability.
Solution Approach 2:
The system replaces complex hydraulic actuation systems with electromechanical actuators that use electric motors and linkages to control flight surfaces. This substitution significantly reduces system cost, weight, and complexity while providing sufficient control authority for light helicopters.
2Reliability
If redundant systems are implemented to ensure stability and reliability during power failures, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The system incorporates fail-safe features that are pre-configured to activate automatically upon power failure. The inner loop attitude control is designed to maintain stability without external power, and the electromechanical actuators include mechanisms to hold position or return to neutral, cushioning against the harmful effects of power loss before they can compromise flight safety.
Solution Approach 2:
Different levels of redundancy are applied to different parts of the system based on their criticality. The inner loop attitude control, which is critical for immediate flight stability, receives higher redundancy and protection compared to the outer loop navigation functions. This localized approach to redundancy optimizes reliability while minimizing overall system complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system allows for hands-free operation and reduced pilot fatigue by maintaining stable flight orientations and modes, such as hover or forward flight, while being cost-effective and compatible with various helicopter types.
Implementation Method 1
a motor coil arrangement for receiving a drive current that produces rotation of the output shaft
Implementation Method 2
shorting the motor coil arrangement responsive to a failure of the power source such that the motor provides a braking force
Data Source
AI summary
A helicopter autopilot system includes an inner loop for attitude hold for the flight of the helicopter including a given level of redundancy applied to the inner loop. An outer loop is configured for providing a navigation function with respect to the flight of the helicopter including a different level of redundancy than the inner loop. An actuator provides a braking force on a linkage that serves to stabilize the flight of the helicopter during a power failure. The actuator is electromechanical and receives electrical drive signals to provide automatic flight control of the helicopter without requiring a hydraulic assistance system in the helicopter. The autopilot can operate the helicopter in a failed mode of the hydraulic assistance system. A number of flight modes are described with associated sensor inputs including rate based and true attitude modes.