An aircraft fly-by-wire flight control system
By introducing an ultimate backup controller into the aircraft fly-by-wire flight control system, the problems of common-mode failure and erroneous signals in the fly-by-wire flight control system are solved, ensuring flight safety and avoiding uncontrollable states and vibrations of the aircraft.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- AVIC XAC COMMERCIAL AIRCRAFT CO LTD
- Filing Date
- 2022-12-14
- Publication Date
- 2026-06-09
AI Technical Summary
Existing fly-by-wire flight control systems have the risk of common-mode failure in their software and complex electronic hardware design, and cannot effectively avoid the uncontrollable state of the aircraft caused by redundant components simultaneously emitting erroneous signals.
Design an aircraft fly-by-wire flight control system, including a flight controller, a control stick, elevator actuators, and a final backup controller. The final backup controller switches to the backup controller in case of system failure or issuance of erroneous commands, ensuring flight safety.
In the event of failure of all redundant components or issuance of erroneous commands, the ultimate backup controller mitigates catastrophic flight risks, avoids aircraft vibration issues caused by "two brains" control, and ensures flight safety.
Smart Images
Figure CN118182819B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of aircraft design, specifically flight control system technology, and more specifically to an aircraft fly-by-wire flight control system. Background Technology
[0002] As is well known, modern fly-by-wire aircraft are mostly highly complex integrated systems, usually implemented using software and complex electronic hardware. This greatly reduces the number of components required, thereby saving installation space and reducing weight, and significantly improving the aircraft's economy.
[0003] However, due to the inherent properties of software and complex electronic hardware, it is impossible to ensure the completeness of the design by fully testing and verifying the product. In other words, there may always be a trigger that causes all the components that were originally considered redundant to fail or issue erroneous commands, leading to an uncontrollable state of the aircraft. In the safety assessment process, this is called common mode failure. In recent years, the common mode mitigation problem of software and complex electronic hardware design has been listed as a key point in the airworthiness review process.
[0004] To mitigate common-mode problems in aircraft design, two internationally recognized solutions have been proposed. One is to design redundant components in dissimilar forms to reduce the likelihood of them simultaneously encountering common design errors. However, this design suffers from the inability to guarantee synchronization between redundant components. The other is to design an independent backup control unit. When all redundant components fail, this function is activated to regain control of the aircraft for safe flight and landing. This design is superior to the first in some respects, but it only addresses the problem of simultaneous failure of redundant components and cannot solve the problem of them simultaneously sending erroneous signals. (Invention Content)
[0005] Based on the needs of aircraft development and the shortcomings of existing technologies, this invention proposes a fly-by-wire flight control system for aircraft. This method can control the elevator flight through a final backup controller when the traditional fly-by-wire flight control system fails or issues erroneous commands, thus ensuring flight safety.
[0006] A fly-by-wire flight control system for an aircraft includes a flight controller, a control stick, a first elevator actuator, and a second elevator actuator. The flight controller adjusts the gain of control stick commands via an air data computer signal and sends control commands to the first and second elevator actuators respectively. The first and second elevator actuators jointly control the elevator movement. The system is characterized by a final backup controller, which is interconnected with the control stick, flight controller, flap control computer, final backup activation switch, and second elevator actuator. The flight controller includes a first command processing module, and the final backup controller includes a second command processing module and a final backup switching module. The first elevator actuator is controlled by the first command processing module of the flight controller, and the second elevator actuator is controlled by the final backup switching module of the final backup controller. The final backup switching module is controlled by the final backup activation switch, enabling switching between the first and second command processing modules.
[0007] The aforementioned fly-by-wire flight control system is characterized in that the command sensor on the control stick converts the mechanical position of the control stick into an electrical signal, which is then transmitted to the flight controller and the ultimate backup controller.
[0008] The aforementioned fly-by-wire flight control system is characterized in that the first command calculation module of the flight controller multiplies the position signal of the control stick command sensor by a corresponding ratio based on the airspeed value sent by the air data computer, and generates normal control commands for the first elevator actuator and the second elevator actuator. The normal control commands are simultaneously sent to the first elevator actuator and the ultimate backup switching module of the ultimate backup controller.
[0009] The aforementioned fly-by-wire flight control system is characterized in that the second instruction calculation module of the ultimate backup controller receives the position signal from the control stick instruction sensor, and then, based on the flap retraction / extension status sent by the flap control computer, multiplies the position signal from the control stick instruction sensor by a corresponding ratio to generate the ultimate backup control instruction for the second elevator actuator. The ultimate backup control instruction is sent to the ultimate backup switching module of the ultimate backup controller, so that the ultimate backup control instruction is always in a hot backup state.
[0010] The aforementioned fly-by-wire flight control system is characterized in that, when the flight controller is working normally, the first command processing module of the flight controller directly sends normal control commands to the first elevator actuator, and simultaneously sends normal control commands to the second elevator actuator through the ultimate backup switching module of the ultimate backup controller. The first elevator actuator and the second elevator actuator jointly control the elevator movement according to the normal control commands. When the flight controller malfunctions, the ultimate backup start switch is manually pressed, causing the ultimate backup switching module in the ultimate backup controller to send the ultimate backup control commands from the second command processing module to the second elevator actuator. The second elevator actuator controls the elevator movement according to the ultimate backup control commands. At the same time, the hydraulic power supply to the first elevator actuator is manually cut off, causing the first elevator actuator to enter a follow-up state.
[0011] The beneficial effects of this application are as follows: 1) The invention designs an ultimate backup controller. When all redundant components fail or any redundant component issues an erroneous command, the ultimate backup function avoids two types of catastrophic flight risks; 2) The ultimate backup control switching logic ensures that only one control command controls the elevator at any given time, avoiding the aircraft shaking problem caused by "two brains" controlling the same actuator. Attached Figure Description
[0012] Figure 1 This is a schematic diagram of the ultimate backup control design configuration.
[0013] Figure 2 This is a schematic diagram of the switching logic for the ultimate backup module.
[0014] Figure 3 This is a schematic diagram illustrating the logic of turning on the ultimate backup startup switch. Detailed Implementation
[0015] Referring to the attached figures, the design configuration of the aircraft fly-by-wire flight control system of this application is shown below. Figure 1 The system includes a flight controller, a control stick, a first elevator actuator, and a second elevator actuator. A control stick command sensor converts the mechanical position of the control stick into an electrical signal, which is then transmitted to both the flight controller and the ultimate backup controller. The first elevator actuator is connected to a first hydraulic source, and the second elevator actuator is connected to a second hydraulic source. The flight controller adjusts the gain of the control stick commands via an air data computer signal and sends control commands to both the first and second elevator actuators. The first and second elevator actuators then jointly control the elevator movement. An ultimate backup controller is integrated with the control stick, flight controller, flap control computer, ultimate backup activation switch, and second elevator actuator.
[0016] The flight controller includes a first command calculation module. Based on the airspeed value sent by the air data computer, the first command calculation module multiplies the position signal of the control stick command sensor by a corresponding ratio to generate normal control commands for the first elevator actuator and the second elevator actuator. The normal control commands are simultaneously sent to the first elevator actuator and the ultimate backup switching module of the ultimate backup controller.
[0017] The ultimate backup controller includes a second instruction calculation module and an ultimate backup switching module. The first elevator actuator is controlled by the first instruction calculation module of the flight controller, and the second elevator actuator is controlled by the ultimate backup switching module of the ultimate backup controller. The ultimate backup switching module is controlled by the ultimate backup start switch to realize the switching between the first instruction calculation module and the second instruction calculation module.
[0018] The second instruction processing module of the ultimate backup controller receives the position signal from the control stick instruction sensor, and then multiplies the position signal from the control stick instruction sensor by a corresponding ratio according to the flap retraction and extension status sent by the flap control computer to generate the ultimate backup control command for the second elevator actuator. The ultimate backup control command is sent to the ultimate backup switching module of the ultimate backup controller to keep the ultimate backup control command in a hot backup state.
[0019] When the flight controller is working normally, the first command processing module of the flight controller sends normal control commands directly to the first elevator actuator. At the same time, the normal control commands are sent to the second elevator actuator through the ultimate backup switching module of the ultimate backup controller. The first elevator actuator and the second elevator actuator jointly control the elevator movement according to the normal control commands. When the flight controller malfunctions, the ultimate backup start switch is pressed manually, which causes the ultimate backup switching module in the ultimate backup controller to send the ultimate backup control commands from the second command processing module to the second elevator actuator. The second elevator actuator controls the elevator movement according to the ultimate backup control commands. At the same time, the hydraulic power supply to the first elevator actuator is manually cut off, causing the first elevator actuator to enter the follow-up state.
[0020] See the ultimate backup module switching logic. Figure 2 The ultimate backup module receives the open / close command from the ultimate backup start switch, the normal control command from the first command calculation module, and the ultimate backup control command from the second command calculation module. If the ultimate backup start switch issues a "close" command, the ultimate backup switching module will select the normal control command from the first command calculation module and send it to the second elevator actuator. Under normal operating conditions, the ultimate backup start switch remains in the "closed" state. If the ultimate backup start switch issues an "open" command, the ultimate backup switching module will select the ultimate backup control command from the second command calculation module and send it to the second elevator actuator.
[0021] Because the first command calculation module generates control commands for the second elevator actuator by multiplying the position signal from the control stick command sensor by a corresponding ratio based on the airspeed value sent by the air data computer; and the second command calculation module generates control commands for the second elevator actuator by multiplying the position signal from the control stick command sensor by a corresponding ratio based on the flap retraction / extension status sent by the flap control computer; since the two control commands will inevitably differ, an important task that the final backup switching module needs to perform before switching commands is to smoothly transition the actuator control commands from the "first command calculation module" to the "second command calculation module" within 1 second, to prevent the second elevator actuator from receiving abrupt control commands.
[0022] See the logic for turning on the ultimate backup startup switch. Figure 3 The ultimate backup start switch is manually controlled to open / close and should be kept off under normal circumstances. If only one of the first or second elevator actuators fails, the ultimate backup start switch remains off. If both the first and second elevator actuators fail simultaneously, the ultimate backup start switch is opened. If the first elevator actuator's normal control command is incorrect, the first hydraulic power source is shut off, and the ultimate backup start switch remains off. If the second elevator actuator's normal control command is incorrect, the ultimate backup start switch is opened. If both the first and second elevator actuators fail, the first hydraulic power source is shut off, and the ultimate backup start switch is opened.
[0023] Assuming the control stick command sensor signal is 50 mm, the airspeed is 200 km / h (corresponding to a control stick command sensor generating elevator actuator control command ratio of 0.2), and the flaps are in the retracted state (corresponding to a control stick command sensor generating elevator actuator control command ratio of 0.095), the first command calculation module calculates the elevator actuator control command corresponding to the control stick command sensor as 50 multiplied by 0.2 equals 10 degrees, and the second command calculation module calculates the elevator actuator control command corresponding to the control stick command sensor as 50 multiplied by 0.095 equals 4.75 degrees.
[0024] Assuming that: the normal control command of the first elevator actuator fails, the normal control command of the second elevator actuator is incorrect, and the ultimate backup start switch is turned on, the ultimate backup switching module smoothly switches the control command of elevator actuator 2 from 10 degrees to 4.75 degrees within 1 second to control the second elevator actuator. At the same time, the first hydraulic source of the first elevator actuator is turned off, so that the first elevator actuator follows the second elevator actuator.
Claims
1. A fly-by-wire flight control system for an aircraft, comprising a flight controller, a control stick, a first elevator actuator, and a second elevator actuator, wherein the flight controller adjusts the gain of control stick commands via an air data computer signal and sends control commands to the first elevator actuator and the second elevator actuator respectively, and the first elevator actuator and the second elevator actuator jointly control the elevator movement, characterized in that... There is an ultimate backup controller, which is interconnected with the control stick, flight controller, flap control computer, ultimate backup activation switch, and second elevator actuator. The flight controller contains a first command processing module, and the ultimate backup controller contains a second command processing module and an ultimate backup switching module. The first elevator actuator is controlled by the first command processing module of the flight controller, and the second elevator actuator is controlled by the ultimate backup switching module of the ultimate backup controller. The ultimate backup switching module is controlled by the ultimate backup activation switch to realize the switching between the first command processing module and the second command processing module.
2. The aircraft fly-by-wire flight control system as described in claim 1, characterized in that, The control stick's command sensor converts the control stick's mechanical position into an electrical signal, which is then transmitted to the flight controller and the ultimate backup controller.
3. The aircraft fly-by-wire flight control system as described in claim 1, characterized in that, The first command processing module of the flight controller multiplies the position signal of the control stick command sensor by a corresponding ratio based on the airspeed value sent by the air data computer, and generates normal control commands for the first elevator actuator and the second elevator actuator. The normal control commands are simultaneously sent to the first elevator actuator and the ultimate backup switching module of the ultimate backup controller.
4. The aircraft fly-by-wire flight control system as described in claim 1, characterized in that, The second instruction processing module of the ultimate backup controller receives the position signal from the control stick instruction sensor, and then multiplies the position signal from the control stick instruction sensor by a corresponding ratio according to the flap retraction and extension status sent by the flap control computer to generate the ultimate backup control command for the second elevator actuator. The ultimate backup control command is sent to the ultimate backup switching module of the ultimate backup controller to keep the ultimate backup control command in a hot backup state.
5. The aircraft fly-by-wire flight control system as described in claim 1, 2, 3, or 4, characterized in that, When the flight controller is working normally, the first command processing module of the flight controller sends normal control commands directly to the first elevator actuator. At the same time, the normal control commands are sent to the second elevator actuator through the ultimate backup switching module of the ultimate backup controller. The first elevator actuator and the second elevator actuator jointly control the elevator movement according to the normal control commands. When the flight controller malfunctions, the ultimate backup start switch is pressed manually, which causes the ultimate backup switching module in the ultimate backup controller to send the ultimate backup control commands from the second command processing module to the second elevator actuator. The second elevator actuator controls the elevator movement according to the ultimate backup control commands. At the same time, the hydraulic power supply to the first elevator actuator is manually cut off, causing the first elevator actuator to enter the follow-up state.