Patent Application
20090216391
It is common in aircraft with Fly-By-Wire (FBW) Flight Control Systems that they are designed to protect against both random failures and design errors. Protection against random failures is generally achieved by using redundant channels of equipment. The flight control system generally provides a normal mode that uses redundant channels of inertial signals, such as provided by a micro electromechanical system (MEMS) attitude and heading reference systems (AHRS) or an Inertial Reference System (IRS). Each AHRS or IRS has three gyroscopes and three accelerometers and a microprocessor with software to calculate a full complement of inertial signals. The complexity of the microprocessor and software causes such signals to be susceptible to hardware or software errors, and they are generally considered to be not fully analyzable for design errors.
Protection against design errors is generally achieved by augmenting the flight control normal mode with a simpler backup mode that can be activated in the event of a design error in the normal mode. The backup mode requires a subset of inertial signals (generally only body rate signals) that are simpler in design and hence are fully analyzable against design errors. The inertial signals for the backup mode generally have relaxed accuracy requirements compared to the signals for the normal mode. The backup mode inertial sensors are also generally redundant to protect against random failures. This means the flight control system requires duplicate sets of redundant inertial sensors—one set for the normal mode and another set for the backup mode. This duplication of inertial sensors increases the cost of the flight control system.
For the reasons stated above and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for an effective and efficient control signal system.
The above-mentioned cost of requiring duplicate sets of inertial sensors are addressed by embodiments of the present invention and will be understood by reading and studying the following specification. The following summary is made by way of example and not by way of limitation. It is merely provided to aid the reader in understanding some of the aspects of the invention.
In one embodiment, a flight control system is provided. The system includes a reference system and flight control actuators. The reference system includes one or more sets of gyroscopes and accelerometers. At least one set of the gyroscopes and accelerometers are configured to provide a first output of a first set inertial signals for normal mode flight control and second output of a second different set of inertial signals for backup mode flight control. The flight control actuators are configured to be controlled by one of the first set of inertial signals and the second set of inertial signals.
The present invention can be more easily understood and further advantages and uses thereof more readily apparent, when considered in view of the detailed description and the following figures in which:
In accordance with common practice, the various described features are not drawn to scale but are drawn to emphasize specific features relevant to the present invention. Reference characters denote like elements throughout Figures and text.
In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the inventions may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that logical, mechanical and electrical changes may be made without departing from the spirit and scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the claims and equivalents thereof.
Embodiments of the present invention provide a system that uses the same set of gyroscopes to provide inertial signals for both the normal flight control mode and for the backup flight control mode. To provide further background, prior art flight control system 100 is illustrated in the block diagram of
Referring to
In
As the flight control diagram 300 illustrates in this embodiment, once the normal mode flight controls signals and the backup flight mode flight controls signals have been generated (306 and 313), it is then determined if the backup mode flight control is to be used (315). If the backup mode flight control is not to be used (315), the normal mode flight control signals are used (308). If the backup mode flight control is activated (315), the backup mode flight control signals are used (314). It is then determined if the flight is finished (316). If the flight has finished (316), the process ends. If the flight has not finished (316), the process continues with the generation of first and second inertial signals at (302) and (310) respectively.
Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement, which is calculated to achieve the same purpose, may be substituted for the specific embodiment shown. This application is intended to cover any adaptations or variations of the present invention. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof.
