Aircraft Control System Relative Positioning
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Solution Overview
Problem
Existing control systems for vehicles, particularly aircraft, face difficulties in accurately controlling position and velocity relative to a moving reference vehicle, requiring operators to consider both the controlled vehicle's and reference vehicle's positions and velocities, making the task more complex.
Innovation Solution
A control system that uses sensors on the controlled vehicle to determine its position and inertial movement, combined with data from a receiver that communicates the reference vehicle's position and movement, allowing for calculation and comparison of relative values, and commanding flight control devices to achieve and maintain selected positions and velocities independently of wind or attitude.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional control systems command airspeed or inertial speed with heading control, then the vehicle can be controlled along a desired path, but the operator must know the vehicle's orientation and calculate control inputs based on both the vehicle's and reference vehicle's positions and velocities, increasing operational complexity
Solution Approach 1:
The control system introduces an intermediary coordinate system transformation mechanism that converts reference vehicle-centered commands into vehicle-body-axis control inputs. The system automatically calculates the rotation matrix based on the vehicle's heading angle, serving as a mediator between the simple reference-frame commands and the complex body-axis actuation requirements.
Solution Approach 2:
The system continuously monitors the vehicle's heading angle and position relative to the reference vehicle, using this feedback to dynamically adjust the coordinate transformation. This feedback loop ensures that the control commands remain accurate even as the vehicle's orientation changes during operation.
2Measurement precision
If sensors are used to determine proximity or position of the reference vehicle, then relative position can be measured, but the operator must still consider both vehicles' positions and velocities independently, making control more difficult
Solution Approach 1:
The system merges the position and velocity data of both the controlled vehicle and reference vehicle into a single relative state representation. By combining these measurements and expressing them in the reference vehicle's coordinate system, the operator only needs to consider the relative state rather than independently tracking both vehicles' states.
Solution Approach 2:
The system changes the parameter representation from absolute positions and velocities of both vehicles to relative position and velocity in the reference vehicle's coordinate system. This parameter transformation simplifies the control task by reducing the number of independent variables the operator must manage.
3Adaptability or versatility
If control commands are given in terms of longitudinal, lateral, or directional axes of the aircraft, then control inputs can be applied, but the operator must know which direction the aircraft is pointing to determine the correct control axis and direction
Solution Approach 1:
The system inverts the traditional control approach by allowing commands to be given in the reference vehicle's coordinate system rather than the controlled vehicle's body axes. This inversion eliminates the need for the operator to mentally transform commands based on the vehicle's heading, as the system handles the coordinate transformation automatically.
Data Source
AI summary
A system for controlling flight of an aircraft has sensors (37, 43), a receiver (45), and a digital control system (57), all of which are carried aboard the aircraft. The sensors (37, 43) determine the position of the aircraft relative to the earth and the inertial movement of the aircraft. The receiver (45) receives transmitted data (51, 55) communicating the position and movement of a reference vehicle relative to the earth. The control system (57) calculates the position and velocity of the aircraft relative to the reference vehicle using the data from the sensors (37, 43) and the receiver (45) and then commands flight control devices (33) on the aircraft for maneuvering the aircraft in a manner that maintains a selected position and/or velocity relative to the reference vehicle. The system allows use of a graphical or tactile user interfaces.