This paper mainly uses the technology of FPGA to control the aircraft. This system is developed with DE2-115 board. The hardware is implemented by Verilog language, including the accelerator addition and subtraction module, unlocking module, left and right rotation control module, front and back left and right direction control module.
PC and keyboard can be used to control the aircraft. The test meets the design requirements. With the continuous development of electronic technology, aeromodelling has been used in more and more fields, such as fire protection, construction, survey and other fields. Modern aviation model movement can be divided into five categories: free flight, line control, radio remote control, simulation and electric control. According to the power mode, it can be divided into piston engine, jet engine, rubber power model aircraft and powerless model glider, etc. [1].
The maximum lift area of the aeronautical model is 500 square centimeters; the maximum weight is 25 kilograms; and the maximum working volume of the piston engine is 250 milliliters. Moreover, the activities of aeromodelling science and technology can stimulate the participants’ambition.
The process of making and testing flight can cultivate the children’s practical ability and creativity, and promote their learning and understanding of foreign languages, computers, electronics, physics, even management and other disciplines. Goal-oriented preparation can cultivate their sense of responsibility, perseverance and spirit of cooperation. As a result, aviation models are becoming more and more popular with the general public.
At present, most of the aeromodelling technology mostly uses single chip technology, and the innovation of this paper lies in the use of FPGA technology. FPGA is the product of further development on the basis of programmable devices such as PAL, GAL, CPLD and so on. As a semi-customized circuit in the field of application specific integrated circuits (ASIC), it not only solves the shortcomings of customized circuits, but also overcomes the shortcomings of the limited number of gate circuits of the original programmable devices.
This paper chooses Cycle IV EFPGA chip as the core of system processing. This chip only needs two power supply, simplifies the power distribution network, reduces the cost of circuit board, reduces the area of circuit board, thermostatic element and shortens the design time. Furthermore, with a flexible transceiver clock architecture, you can make full use of all available resources of transceivers to implement a variety of protocols. The chip also reduces the core voltage, which is the smallest low power FPGA transceiver in the industry, which makes the cost lower and is also far ahead in terms of reaction speed. Moreover, the use of FPGA to design model aircraft will make the aircraft flight more stable, more rapid response, so that the aircraft can be flexible in the air to carry out various flight operations. Let the controllers be more at will, more fond of aeromodelling. Let more and more people fall in love with model sports.
The system block diagram is shown in Figure 1. This design collects the key information of the operator on the keyboard and transmits it to the FPGA chip through RS-232 serial port. The signal received by the FPGA is sent to the corresponding module by a decoder according to the different keys. For example, Y is the key of the accelerator. When the signal that Y is pressed by the FPGA is valid, it is transmitted to the accelerator module. The other modules do not work. The output of the accelerator module is sent to the X9313 potentiometer to make the slider displace and generate different voltages.
This will enable the aircraft to enter the refueling status. The hardware part is composed of throttle add and subtract control module, left and right direction control module, left and right rotation control module, unlock module and so on. A module designed to identify which button is pressed for the received signal. It can quickly identify the key signal and then generate enabling signals according to the received key information and transmit them to the next module for its work. In the figure, SenData signal is the received key signal; CLK is the clock signal; rest_n is the reset signal; a, b, c, d, e, f, g, h, m are the enabling signals. The throttle design is divided into the throttle module and the throttle reducing module, which are used to control the aircraft’s throttle and the throttle reducing respectively. The aircraft accelerates when it enters the throttle state, and then slows down. In the figure, iin is the delay signal transmitted by the adder; bin is the control signal transmitted by the adder to control the inversion of the output signal x9313Y_INC; x9313Y_UPDN and x9313Y_CS are both output pins. The front and rear control modules are divided into front control module and back control module, which are used to control the forward and backward directions of the aircraft respectively. In the figure, iin is the delay signal transmitted by the adder; bin is the control signal transmitted by the adder to control the inversion of the output signal x9313Y_INC; x9313Y_UPDN and x9313Y_CS are both output pins. The left and right rotation control module [1] is divided into left rotation control and right rotation control, which are used to control the left and right rotation of the aircraft respectively. In the figure, iin is the delay signal transmitted by the adder; bin is the control signal transmitted by the adder to control the inversion of the output signal x9313Y_INC; x9313Y_UPDN and x9313Y_CS are both output pins.
Because there are many modules in this system, we take the accelerator as an example to illustrate how the accelerator is realized. SenData signal is transmitted to the chip from RS232 serial port, then the decoder reads the signal through the decoder and then analyses it to get that the W key is pressed by the tester, and then generates a enabling signal and passes it to the adder, which makes the adder work and generates delay signal i[3] and control signal b, and then transmits it to the accelerator module. The accelerator module receives various control signals and enters the working state, and then adds them.
The output of the throttle module is sent to the X9313 potentiometer to make the slider displace and produce different voltages, which will make the aircraft enter the refueling state. In order to check whether the circuit is correct, the device pin is set and compiled again. Then the downloadable file is downloaded to the development board DE2-115 in the form of USB, and the output pin is connected to the input pin of X9313 chip. The test results are correct. Through the above data, it can be shown that using FPGA is more convenient, more efficient and easier to simulate and test. With the design of FPGA, the power consumption of the device is smaller, the signal is more stable, the anti-interference is stronger, the system is more stable and the upgrade is more convenient. It can also add new functions according to the actual needs, just need to change or add some programs in the FPGA chip. The theoretical research and practical application of FPGA technology are receiving more and more attention. Moreover, the use of FPGA to design model aircraft will make the aircraft flight more stable, more rapid response, so that the aircraft can be flexible in the air to carry out various flight operations. Let the controllers be more at will, more fond of aeromodelling. Let more and more people fall in love with model sports.