Aircraft Control Surface Actuators With Force-Torque Control
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Solution Overview
Problem
Existing aircraft actuator control systems face inefficiencies in controlling aerodynamic control surfaces, particularly under gust loads and during fast maneuvers, due to rigid position control leading to high loads and instability, and are not optimized for non-linear actuators.
Innovation Solution
Implementing a force/torque control strategy for actuators, which includes interfaces for pilot and autonomous control inputs, utilizing force/torque controllers with high processor clock rates and sensor feedback to regulate actuator positions within defined intervals, allowing for compliant response to gusts and reduced loads, and incorporating feedback mechanisms for gravitational compensation and virtual stiffness/damping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If rigid position control is used for actuators, then control precision is improved, but loads on control surfaces and actuators increase during gusts
Solution Approach 1:
The control system dynamically switches between position control mode and force control mode based on flight conditions. During gusts or fast maneuvers, the system transitions to force control to reduce loads, while maintaining position control during normal operations to ensure control precision. This dynamic adaptation resolves the contradiction by allowing the system to optimize for precision when needed and for load reduction when environmental conditions demand it.
2Reliability
If position-controlled actuators are designed conservatively to avoid instabilities, then reliability is improved, but non-linear actuators cannot be optimized
Solution Approach 1:
The control system changes operational parameters by switching between position control and force control modes. This allows conservative design margins to be reduced while maintaining stability, as the force control mode provides inherent stability during gusts. The system can now optimize non-linear actuators for specific flight conditions rather than requiring conservative designs for all conditions, improving both efficiency and reliability.
3Speed
If force/torque control is implemented with high processor clock rates, then control speed is improved, but device complexity increases
Solution Approach 1:
The control system is segmented into multiple independent force/torque controllers, each with its own processor operating at high clock rates. This segmentation allows parallel processing of multiple actuators simultaneously, achieving fast control response without requiring a single overly complex centralized processor. Each controller handles specific actuators independently, reducing overall system complexity while maintaining high control speed.
4Reliability
If multiple actuators are used to drive control surfaces, then redundancy is improved, but force fight issues occur
Solution Approach 1:
The system implements feedback mechanisms where force/torque sensors monitor the actual forces applied by each actuator. This feedback is used by the control system to detect and resolve force fights between multiple actuators. When force conflicts are detected, the control system adjusts actuator commands to eliminate opposing forces, maintaining stability while preserving the redundancy benefits of multiple actuators driving each control surface.
Data Source
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AI summary
The invention relates to a device and to a method for performing open -and closed -control of n actuators An (101 ), n = 1, 2,..., N, where N ≥ 1, which drive aerodynamic control surfaces (102) of an aircraft. The proposed device comprises a first interface (104) at which, by manually inputting of a pilot into an input means (110), predefinitions SVPilot for controlling the actuators An (101) are generated and made available and/or a second interface (103) at which, by means of an automatic flight controller (109) of the aircraft, predefinitions SVAutoPilot for controlling the actuators An (101) are generated and made available, a unit (105), which on the basis of the predefinitions SVpilot and/or SVAutoPilote actuator An (101), determines a reference variable FAn,soll for controlling the actuator An (101), wherein the reference variable FAn,soll specifies a setpoint force or a setpoint torque, and per actuator An (101) a force/torque controller REGn (106) for performing closed control of the actuator An (101) on the basis of the assigned reference variable FAn,Soll and a force/torque FAn generated by the actuator An (101) as a closed-control variable which is determined by a sensor device S1n, which is respectively present at or in the actuator An (101) or in the drivetrain of the respective actuator An (101).