UAV flight control system is the core of the control device, as much as brain of the UAV. Whether equipped with flight control system is also an important symbol to distinguish general aviation model and UAV.
After an early period of flight with remote control, the current control has been developed to autonomous flight and intelligent flight. The change of navigation mode required higher demands on the precision of flight control computer .UAV missions are putting forward higher requirements with the increasing complexity of flight control computing speed; and miniaturization requirements for flight control computer power and volume also made high demands. Not only requires high precision computer control accuracy, but also requires the ability to run complex control algorithms, miniaturized UAVs requires small volume, good mobility, and thus requires smaller size computer.
Among the processor chip, the most suitable for small flight control computer CPU chip comes as TI's TMS320LF2407, TI's TMS320LF2407 from kynix semiconductor its operation speed and numerous peripheral interface circuit is very suitable for small UAVs complete real-time control functions.
It uses a Harvard architecture, multi-stage pipeline operation, the data and instructions can be read while on-chip resources include built 16-channel 10-bit A / D converter and with automatic sorting function to ensure that up to 16 have the same conversion during the conversion carried out without increasing CPU overhead; 40 channels can be individually programmed or reuse of general-purpose input / output channels; 5 external interrupts; integrated serial communications interface (SCI), it may have with other controllers in the system asynchronous (RS 485) the ability to communicate; 16-bit synchronous serial peripheral interface (SPI) can easily be used to communicate with other peripherals; module also provides a watchdog timer (WDT) and cAN communication module.
Flight control system building blocks
Flight control system real-time flight data collected for each sensor, the control terminal receiving a radio transmission of data and control commands from the ground control station upstream channel sent by the calculation processing, output control instructions to the executing agency, to achieve the UAV control device and task management and control various flight modes; while the UAV state data and engines, airborne power systems, mission equipment working state parameters of real-time transmission to the airborne radio data terminals, via a radio downlink channel transmission back to the ground control stations.
Divided by function, the hardware of the flight control system comprising: a main control module, signal conditioning and interface modules, data acquisition modules, and servo drive module.
Function Module
Various functional modules together, constitute the core of the flight control system, and the main control module is the core of the flight control system, which signal conditioning modules, interface modules, and servo drive module is combined in only need to modify the software and simple peripheral circuit changes We meet on the basis of a series of small UAV flight control and flight management functional requirements, enabling the development of a multi-use model, the purpose of reducing system development costs. System performs the following functions:
(1) complete high-precision multi-channel analog signal acquisition, including the gyro signal, heading signal, rudder angle signal, engine speed, cylinder temperature signals, static and dynamic pressure sensor signal, the power supply voltage signals.
Due to limited CPU comes with A / D accuracy and the number of channels, so the use of additional data acquisition circuit, chip select and control signals are decoded by EPLD circuit.
(2) the output switch signal, analog and PWM pulse signals can adapt to different implementing agencies (such as the rudder machine, servo aileron, elevator machine, airway and throttle servos, etc.) control requirements.
(3) the use of multiple communication channels, respectively, to achieve and airborne data terminal, communication GPS signals, sensors and digital equipment related tasks. Since the CPU itself SCI serial channel configuration can not meet the system requirements, the design using multiple serial port expansion chip 28C94 to expand eight serial ports.
System software design
The system's software design is divided into two parts, namely the program logic decoding circuit chip EPLD flight control system design and application design.
Logic programming
EPLD used to construct digital logic control circuit, the decoding and isolation as well as the A / D, D / A, 28C94 chip-select signal and a read / write control signal.
The software is designed using schematic entry and VERILOG HDL language programming hybrid design approach, design and implementation to follow the design input →→→ design verification device programming process. IspLSI1048 system uses two chips, were used to achieve the A / D, D / A control and serial port expansion chip 28C94 control parameters derived from the interest-wing UAV network.
System Application Design
Not only because the C language to write application programs, system programs, but also as assembly language directly on the computer's hardware control program written in portability. Due to the DSP as the core design of the system involves a large number of peripheral port operations, and to consider the subsequent porting work, so the flight control system of selection of BC 3.1 application is designed, respectively, to achieve flight control and flight management capabilities.
After an early period of flight with remote control, the current control has been developed to autonomous flight and intelligent flight. The change of navigation mode required higher demands on the precision of flight control computer .UAV missions are putting forward higher requirements with the increasing complexity of flight control computing speed; and miniaturization requirements for flight control computer power and volume also made high demands. Not only requires high precision computer control accuracy, but also requires the ability to run complex control algorithms, miniaturized UAVs requires small volume, good mobility, and thus requires smaller size computer.
Among the processor chip, the most suitable for small flight control computer CPU chip comes as TI's TMS320LF2407, TI's TMS320LF2407 from kynix semiconductor its operation speed and numerous peripheral interface circuit is very suitable for small UAVs complete real-time control functions.
It uses a Harvard architecture, multi-stage pipeline operation, the data and instructions can be read while on-chip resources include built 16-channel 10-bit A / D converter and with automatic sorting function to ensure that up to 16 have the same conversion during the conversion carried out without increasing CPU overhead; 40 channels can be individually programmed or reuse of general-purpose input / output channels; 5 external interrupts; integrated serial communications interface (SCI), it may have with other controllers in the system asynchronous (RS 485) the ability to communicate; 16-bit synchronous serial peripheral interface (SPI) can easily be used to communicate with other peripherals; module also provides a watchdog timer (WDT) and cAN communication module.
Flight control system building blocks
Flight control system real-time flight data collected for each sensor, the control terminal receiving a radio transmission of data and control commands from the ground control station upstream channel sent by the calculation processing, output control instructions to the executing agency, to achieve the UAV control device and task management and control various flight modes; while the UAV state data and engines, airborne power systems, mission equipment working state parameters of real-time transmission to the airborne radio data terminals, via a radio downlink channel transmission back to the ground control stations.
Divided by function, the hardware of the flight control system comprising: a main control module, signal conditioning and interface modules, data acquisition modules, and servo drive module.
Function Module
Various functional modules together, constitute the core of the flight control system, and the main control module is the core of the flight control system, which signal conditioning modules, interface modules, and servo drive module is combined in only need to modify the software and simple peripheral circuit changes We meet on the basis of a series of small UAV flight control and flight management functional requirements, enabling the development of a multi-use model, the purpose of reducing system development costs. System performs the following functions:
(1) complete high-precision multi-channel analog signal acquisition, including the gyro signal, heading signal, rudder angle signal, engine speed, cylinder temperature signals, static and dynamic pressure sensor signal, the power supply voltage signals.
Due to limited CPU comes with A / D accuracy and the number of channels, so the use of additional data acquisition circuit, chip select and control signals are decoded by EPLD circuit.
(2) the output switch signal, analog and PWM pulse signals can adapt to different implementing agencies (such as the rudder machine, servo aileron, elevator machine, airway and throttle servos, etc.) control requirements.
(3) the use of multiple communication channels, respectively, to achieve and airborne data terminal, communication GPS signals, sensors and digital equipment related tasks. Since the CPU itself SCI serial channel configuration can not meet the system requirements, the design using multiple serial port expansion chip 28C94 to expand eight serial ports.
System software design
The system's software design is divided into two parts, namely the program logic decoding circuit chip EPLD flight control system design and application design.
Logic programming
EPLD used to construct digital logic control circuit, the decoding and isolation as well as the A / D, D / A, 28C94 chip-select signal and a read / write control signal.
The software is designed using schematic entry and VERILOG HDL language programming hybrid design approach, design and implementation to follow the design input →→→ design verification device programming process. IspLSI1048 system uses two chips, were used to achieve the A / D, D / A control and serial port expansion chip 28C94 control parameters derived from the interest-wing UAV network.
System Application Design
Not only because the C language to write application programs, system programs, but also as assembly language directly on the computer's hardware control program written in portability. Due to the DSP as the core design of the system involves a large number of peripheral port operations, and to consider the subsequent porting work, so the flight control system of selection of BC 3.1 application is designed, respectively, to achieve flight control and flight management capabilities.
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