Aircraft Flight Control Actuator Saturation Prevention
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Solution Overview
Problem
In the PAFCS system, when the control stick operation amount is too large, the SAS actuator becomes saturated, leading to ineffective control commands and a risk of airframe attitude divergence due to excessive attitude control commands exceeding the actuator's operating range.
Innovation Solution
The system incorporates a gain value generator that decreases the attitude control command as the required control amount increases, multiplying it by a value less than or equal to 1, and adds a stabilization control amount to prevent actuator saturation, along with a correction signal to adjust the control stick's neutral position, ensuring effective stabilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the control stick operation amount is large to achieve rapid attitude change, then the response speed is improved, but the SAS actuator enters saturation state and loses effectiveness
Solution Approach 1:
The neutral position of the control stick is dynamically adjusted based on the magnitude of the operation amount. When the operation amount exceeds a threshold, the neutral position shifts to reduce the attitude control command, preventing actuator saturation while maintaining pilot control authority.
Solution Approach 2:
The system changes the parameter of the control stick's neutral position angle according to the operation amount. By varying this parameter dynamically, the system ensures the SAS actuator operates within its effective range while responding to pilot inputs.
2Stability of the object's composition
If the attitude control command is increased to correct airframe attitude quickly, then the stabilization performance is improved, but the actuator operates beyond its operating range and becomes ineffective
Solution Approach 1:
The system applies a preliminary counteracting adjustment to the neutral position before the actuator enters saturation. By anticipating the saturation condition and adjusting the neutral position in advance, the system prevents the actuator from becoming ineffective while maintaining attitude stability.
Solution Approach 2:
The system uses feedback from the operation amount detection to dynamically adjust the neutral position. This closed-loop control ensures the attitude control command remains within the actuator's operating range while achieving the desired stabilization effect.
3Device complexity
If the control system uses mechanical connection between control stick and steering mechanism to simplify the system, then the device complexity is reduced, but the control precision is limited by the actuator's operating range
Solution Approach 1:
The neutral position adjustment mechanism acts as an intermediary between the pilot's control input and the SAS actuator. This intermediate adjustment layer refines the control command to ensure it remains within the actuator's precise operating range while maintaining the simplicity of the mechanical connection.
Data Source
AI summary
An aircraft is provided with: an attitude control command calculating section which calculates an attitude control command for target attitude on the basis of a control stick operation amount; a gain value generating section which generates a gain value equal to or less than 1 which decreases as the control stick operation amount is larger; a multiplication section which multiplies the attitude control command for target attitude by the gain value; and a addition section which adds a rate damping control command to the attitude control command for target attitude multiplied by the gain value and outputs a result to a subtraction section for calculating an SAS command.