The flight control of the UAV and the control instructions of the onboard electronic equipment are mainly generated by the software in the ground control computer or the drone controller. These two independent control methods are mutually backups. The drone controller is mainly designed by the hardware circuit and embedded software, does not depend on the computer, so it has the advantages of high reliability, good stability, etc. It is one of the main ways to realize the remote control of the drone. The traditional unmanned aerial vehicle controller is mainly designed by the chip, such as the one-chip computer, ARM and 8279,etc., have the advantage such as simple system structure, but for the drone control The system's requirements for the command delay and timing synchronization of the measurement and control system increase the design complexity of the measurement and control equipment software, especially for the practical application requirements of the low-latency data transmission of the remote control channel of a roll-up and landing drone. The command delay generated by the drone controller is difficult to meet the drone landing control requirements. Using UAV controller based on FPGA design, full use of FPGA parallel data processing capabilities and synchronization design advantages, the keyboard scan, instruction encoding and display, instruction asynchronous serial transmission and other functional modules are integrated within the FPGA, the peripheral circuit only Including simple circuits such as AD sampling, level conversion, and driver chips to avoid the timing defects of MCU and other single-instruction-cycle chips. The hardware structure of the system is simpler, and the expandability is stronger. The command data of the remote control command is triggered to output. Less than 80 ms, it can meet the real-time remote control requirements of various types of drones. The drone controller is mainly composed of a control keyboard, a digital display board, and a controller data processing board. The control keyboard is composed of an 8x8 switch matrix keyboard and a heading controller, which mainly realizes the generation of drone controller keyboard scan codes and heading analog quantities. The digital display board consists of sixteen hexadecimal digital tubes. It mainly realizes synchronous display of control command codes and heading data. As the core component of UAV remote control controller, the controller data processing board adopts Altera's low-cost Cyclone4 series FPGA chip EP4CE10 as the core chip for instruction and data processing; in order to reduce FPGA hardware resource consumption, AD chip selects MAXIM's string. Line 12 Bits AD sampling chip MAX11105, the theoretical heading sensor control accuracy of up to 0.09 °; UART level conversion chip MAXIM 3379 chip MAXIM company to achieve, with good scalability. The controller signal processing board mainly realizes functions such as keyboard scanning and AD sampling of the unmanned aerial vehicle control commands, instruction encoding and display, and asynchronous serial transmission of remote control commands. System hardware block diagram shown in Figure 1. As shown in FIG. 1 , the FPGA on the controller data processing board performs row scanning and AD sampling on the 8×8 matrix keyboard and the heading controller analog signal on the control keyboard to obtain the keyboard scan code and the heading analog data, and the acquisition is performed. After the instructions and data are encoded, the instruction control code and the heading control data are obtained. The FPGA converts the encoded and converted data into two channels at the same time. All the way to drive the digital display panel to display in real time. The other channel is sent to the MAX3387 for RS232 level conversion according to the standard asynchronous serial communication protocol (UART) after the remote control framing, and finally contains the control. The asynchronous serial remote control data of the instruction is sent to the drone through the measurement and control device to realize the remote control function of the drone. The UAV controller software is integrated in the FPGA and programmed in VHDL language. It is compiled and simulated in the Quartus II software environment of Altera Corporation. The controller mainly includes function modules such as keyboard scanning, instruction encoding and display, and instruction asynchronous serial transmission. The signal flow of the system is shown in FIG. 2 . After the system is powered on, the FPGA performs a row scan and AD data acquisition for the control keyboard and the heading controller every 40 ms. After detecting that a control button is triggered, the FPGA starts the button debouncing recognition program, which will effectively control the keys of the keyboard. The scan code and AD acquisition data are converted into control command code and heading control data, and the command and data are divided into the same two ways, all the way into the LED driver module to generate the hexadecimal digital display drive signal, the other way into the instruction asynchronous serial The sending module performs remote framing and control data loading, and finally sends remote frame data containing command data in accordance with the asynchronous serial data communication protocol (UART). According to the real-time requirements of the control instructions, the system design performs matrix scanning and AD sampling on the matrix keyboard and the heading controller once every 40 ms. When the key on the keyboard is triggered, the key destabilizes the recognition program and the output satisfies the response time. Required key 16-bit keyboard scan code. At the same time, the analog controller serial data collected by AD is serial-parallel converted and outputs 12 bits of parallel heading control data. The module's SignalTapII online simulation results are shown in Figure 3. KB_RL and KB_Y are row scan lines and column scan lines, KB_SEN is the keyboard scan enable signal, KEY_SCode is the keyboard scan code output after the key is triggered, SAD_CS is the chip's acquisition enable signal, SAD_SDT is the chip serial data input, SAD_PDT It is the result of the course controller after serial-to-parallel conversion. As can be seen from FIG. 3, a total of 2 control buttons are triggered in sequence, and a total of 2 keyboard scan codes are output: 7DFE and 7EFE. The heading controller output data bit 2EB, corresponding to the heading control angle value of about 66 °. The instruction encoding and display module encodes the received 16-bit keyboard scan code and 12-bit heading controller data according to the data transmission protocol and encodes the encoded control instructions and data to the instruction sending module. Meanwhile, To ensure the correct transmission of the command code and heading controller data, the module drives six hexadecimal digital display tubes to display the encoded command data and heading controller data in real time. The SignalTapII online simulation results of the instruction encoding and display module and the digital tube display results are shown in FIG. 4 . KB_INS is the instruction valid flag, KB_EDAT is the coded instruction code, and SAD_EDT is the coded angle value. LED_LE is the digital tube data latch signal, LED_BL is the digital tube enable signal, LED_DL is the digital tube data input terminal. As can be seen from FIG. 4, the encoded control command code and the heading controller angle are 033H and 66°, respectively. The result is 033 and 066. After the instruction sending module receives the coded control command and direction controller data, it converts the encoded instruction data into remote frame data, and outputs the remote frame data to the MAX3387 according to the asynchronous serial communication protocol (UART) for level conversion. The serial baud rate of the remote control frame data is 19 200, 8 data bits, 1 start bit, 1 stop bit, no parity bit. The result of the online simulation of the instruction sending module SignalTapII and the remote control frame data received by the computer is shown in FIG. 5 . YK_SEND_EN is the data transmission enable signal, Test_Vara is the transmitted 8 bits of parallel remote control data, and YK_UART_Out is the waveform signal of the asynchronous serial data FPGA output port. The drone controller is installed in a type of drone ground control station. After the ground station is powered on, the controller data processing board starts to work. Keyboard scans and AD sampling are performed on the 8x8 matrix keyboard and unmanned heading controller every 40 ms, and the collected data is converted into corresponding remote command codes in real time. , All the way to drive the digital display tube real-time display of the instruction code, all the way to convert the instruction code into RS232 asynchronous serial data sent to the UAV through the measurement and control equipment, controller data processing board in kind shown in Figure 6. The practical application results show that the technical indicators of the unmanned aerial vehicle controller based on FPGA meet the requirements of the application, and the delay of the control command group is less than 80 ms, and the equipment operation is stable and reliable. According to the control characteristics of UAV, a UAV controller design scheme based on FPGA is proposed in this paper. This method makes full use of FPGA parallel processing capability, simplifies the hardware structure of UAV controller, and reduces the remote control instruction group delay. At the time, it solved the timing matching problem of the measurement and control equipment, and it has good function scalability. The controller has been successfully applied in a certain type of drone system. We've been around for over 16+ years. We make sure our sound is The Best Sound. Customized Headphones, personalized gifts, promotional products custom , Bluetooth Earphones,Best Headphones TOPNOTCH INTERNATIONAL GROUP LIMITED , https://www.mic11.com
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April 20, 2023