Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication
Reexamination Certificate
1997-10-15
2001-01-09
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
C701S059000, C706S015000, C706S020000, C706S044000
Reexamination Certificate
active
06173218
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to methods and system for performing propulsion control in a vehicle and, more particularly, to methods and system for accurately determining propulsion commands in real-time.
BACKGROUND OF THE INVENTION
While, as will be understood from the following description, the present invention was developed for generating accurate and time-critical propulsion commands for a vehicle's propulsion system.
Propulsion systems in vehicles, such as vertical takeoff and landing aircraft, satellites and ejection seats, provide forces for controlling the operation of the vehicle. These propulsion systems are controlled by controllers that provide control distribution commands to the propulsion systems. The control distribution commands must provide timely and accurate commands in order for the propulsion system to keep the vehicle operating within predefined limits. For example, the controller in a vertical takeoff and landing aircraft must accurately supply control distribution commands to the propulsion system according to analysis of pilot entered commands, aircraft position and motion, and predetermined limits of the propulsion system, aircraft, and pilot. If the control distribution commands are untimely or inaccurate, jet engine response can lag or misinterpret pilot inputs to the point of causing dangerous pilot induced oscillations. If the control distribution commands are inaccurate, jet engine total flow requirements will not be satisfied leading to engine flameout, degraded performance, or catastrophic failure.
Currently, controllers provide control distribution commands using iterative or multiple step algorithms implemented on digital microprocessors. This approach includes linear optimization or pseudo-inverse procedures that are inherently iterative in nature and have varying times of convergence. Iterative algorithms, when used for complex vehicle control, require extensive calculations and thus, have difficulty performing the required computations in real-time. When the iterative and multiple step algorithms cannot be executed in real-time, non-optimal approximate solutions are generated, thereby reducing the accuracy of the control distribution commands.
Another method of generating control distribution commands is a non-iterative linear technique, which uses mode switching when control limits are reached. This results in complex mode switching logic that is impractical to implement and verify. Another method implements multi-dimensional linearly interpolated data tables. This method requires excessive memory to store the data and is unable to execute the linear interpolation algorithms in real-time.
In summary, the present methods for providing control distribution commands require excessive microprocessor memory and complex mode switching, and are generally insufficient for providing real-time implementation.
The present invention is directed to overcoming the foregoing and other disadvantages. More specifically, the present invention is directed to providing a method and system for generating accurate control distribution commands in real-time.
SUMMARY OF THE INVENTION
In accordance with this invention, a method and system for generating propulsion commands for controlling a propulsion system of a vehicle is provided. The propulsion system includes at least one propulsion effector. The system includes at least one sensor for sensing vehicle position and motion, a control device for generating control signals, and a generator for generating desired vehicle forces/moments from the sensed vehicle position and motion and the generated control signals based on predefined vehicle control laws. Also included is a neural network controller for generating propulsion commands for the at least one propulsion effector based on the generated desired forces/moments, wherein said neural network controller was trained based on pregenerated vehicle control distribution data.
In accordance with other aspects of this invention, the vehicle control distribution data is generated off-line using a linear iterative search algorithm that determines propulsion effector commands from the desired vehicle forces/moments. The linear iterative search algorithm proportionally deviates desired forces/moments or deviates in a prioritized order from desired forces/moments to determine propulsion effector commands.
In accordance with still other aspects of this invention, the neural network controller is a unified or a decoupled structure with activation functions. The activation functions are sigmoidal, radial basis or linear functions.
In accordance with further aspects of this invention, the neural network controller is trained off-line using dynamic derivatives and a node decoupled extended Kalman filter technique or a gradient descent technique.
In accordance with yet other aspects of this invention, the neural network controller is implemented as an analog electronic circuit, a computer program, or an application specific integrated circuit.
As will be readily appreciated from the foregoing summary, the invention provides a new and improved method and system for providing control distribution commands to a vehicle's propulsion system. Because command processing time is greatly reduced, time delays in processing control commands and dangerous propulsion system responses are avoided.
REFERENCES:
patent: 5705956 (1998-01-01), Neely
patent: 5781701 (1998-07-01), Wang
patent: 5943295 (1999-08-01), Varga et al.
patent: 5943660 (1999-07-01), Yesildirek et al.
Arthur Gertrude
Christensen O'Connor Johnson & Kindness PLLC
Cuchlinski Jr. William A.
The Boeing Company
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