27-06-2011, 04:28 PM
fly by wire.ppt (Size: 3.01 MB / Downloads: 378)
FLY BY WIRE
INTRODUCTION TO AN FBW
The term "fly-by-wire" implies a purely electrically-signaled control system.
It is used in the general sense of computer-configured controls.
where a computer system is interposed between the operator and the final control actuators or surfaces.
This modifies the manual inputs of the pilot in accordance with control parameters.
FLY-BY-WIRE
Fly-By-Wire was designed so that the pilot moves his controls that provided electrical inputs into a computer.
The computer then uses information from other inputs and then calculates the proper control changes.
This command is transmitted by WIRE to an actuator or a servo back to the wing/tail which moves the control surface.
AN OVER VIEW OF FBW
Automatic Stability Systems
Fly-by-wire control systems allow aircraft computers to perform tasks without pilot input. Automatic stability systems operate in this way. Gyroscopes fitted with sensors are mounted in an aircraft to sense movement changes in the pitch, roll and yaw axes. Any movement (from straight and level flight)
Block diagram shows the command of an automatic stability system in fbw
THERE ARE TWO TYPES OF SYSTEMS IN FBW THEY ARE
ANALOG SYSTEM
DIGITAL SYSTEM
ANALOG SYSTEM
Fly-by-wire replace hydromechanical or electromechanical flight control systems with electronic circuits.
The control mechanisms in the cockpit now operate signal transducers, which in turn generate the appropriate electronic commands.
These are next processed by an electronic controller with an analog signal.
DIGITAL SYSTEM
A digital fly-by-wire flight control system is similar to its analog counterpart.
The signal processing is done by digital computers and the pilot literally can "fly-via-computer". It increases the flexibility of the flight control system.
The digital computers can receive input from any aircraft sensor.
This also increases the electronic stability, because the system is less dependent on the values.
ADVANTAGES OF FBW
The F-8 digital fly-by-wire program served as the springboard for DFBW technology to be used in both military and civilian aircraft.
satellite manufacturers also routinely use the technology in their vehicles and spacecraft.
Space Shuttle
Several unmanned aerial vehicles (UAVs)
Comparison b/w analog and digital system
Analog system Digital system
Accuracy low 1) Accuracy high
Circuit Complication 2) circuit is simplified
Calibration is tough 3) calibration is easy
DISADVANTAGES OF FBW
Further developments
Fly-by-wireless
Power-by-wire
Fly-by-optics
CONCLUSION
Higher accuracy
Due to the elimination of the mechanical contacts wear and tear is reduced.
The control system used in this type is far more intelligent then the conventional system.