An Interface Method between a Drone or RC Model Remote Controller and Simulink Flight Simulation System

Abstract

The present invention relates to aircraft control technology, and discloses an interface method between a drone or model aircraft remote controller and a Simulink flight simulation system, characterized in that it includes: an SBUS signal level format conversion circuit connected between the SBUS output interface of the receiver of the drone or model aircraft remote controller and the USB port of the computer, for converting the SBUS signal output by the remote controller receiver into a UART serial signal and transmitting it to the Simulink flight simulation system of the computer; and an SBUS signal processing module embedded in the Simulink flight simulation system for parsing the SBUS serial signal converted and transmitted by the SBUS signal level format conversion circuit. The present invention can accurately transmit all signals output by the remote controller, and solves the problems of loss of control performance and accuracy caused by simulating a wireless remote controller as a flight joystick in the prior art.

Description

Technical Field

[0001] The present invention relates to the field of flight simulation technology. Specifically, it involves the application of using Simulink digital simulation software for flight simulation, which requires the use of a wireless remote control as a control device for the simulation system. Background Art

[0002] During the research and development of unmanned aerial vehicles (and other remotely controlled aircraft), flight simulation is a very crucial link. By running a flight simulation system, without actual flight, the computer can use numerical calculation methods to simulate the movement and various states of the unmanned aerial vehicle during flight, thereby analyzing and testing the flight performance of the unmanned aerial vehicle.

[0003] Generally speaking, as Figure 1 shown, a flight simulation system consists of a control command input device (i.e., a control device), a simulation computer running flight simulation software, and an analysis result storage device.

[0004] Commonly used control devices include flight joysticks, wireless remote controls, etc. Their function is to control the flight state of the unmanned aerial vehicle during the operation of the simulation software. In order to make the flight simulation process truly simulate actual flight, this control device strives to be the same as the control device used in the actual flight of the unmanned aerial vehicle.

[0005] Currently, the most widely used flight simulation software is the Simulink digital simulation software system. It is a block diagram design environment based on MATLAB, an engineering software for realizing dynamic system modeling, simulation, and analysis, and is widely used in the modeling and simulation of linear systems, non-linear systems, digital control, and digital signal processing. Simulink has a rich predefined module library, and the most useful module library for flight simulation is the Aerospace blockset. Users can also add relevant program modules according to their own needs.

[0006] In the flight simulation system, the control device that is most convenient to connect to the simulation computer is the flight joystick, as Figure 2 shown. The flight joystick can be directly connected to a computer through a USB port. After the joystick is connected, the Windows system of the PC computer can directly recognize that the USB port is connected to a "Joystick" module. In this way, in the flight simulation software Simulink, various control input values of this flight joystick can be read through this module.

[0007] For a drone flight system, its most commonly used and most applicable control device is a wireless remote controller for drones or model aircraft. This wireless remote controller consists of a remote control handheld unit and a remote controller receiver. During the flight of the drone, the drone operator controls the flight of the drone through the handheld unit. In the flight simulation system, the problem with existing wireless remote controllers for drones or model aircraft is that the signal format output by its receiver is SBUS, and the signal level and format of this signal are not compatible with the USB port of the computer and cannot be directly connected to the flight control computer.

[0008] The full name of the SBUS signal is SerialBus. It was initially developed by the remote controller manufacturer Futaba and is now widely adopted by remote controller manufacturers. It is a communication serial communication protocol, which is formally similar to the RS232 serial port protocol but uses TTL level for signal transmission. The two biggest incompatibilities between the SBUS signal and the UART communication protocol commonly used in current computers are:

[0009] (1) The level logic is opposite. SBUS is negative logic, with low level being "1" and high level being "0", while UART is positive logic, with low level being "0" and high level being "1";

[0010] (2) The communication baud rates are different. The baud rate refers to the number of binary data bits transmitted per second, measured in bps (bits per second). The SBUS baud rate is fixed at 100000 bps, while the UART baud rate range is: 110, 300, 600, 1200, 2400, 4800, 9600, 19200 bps.

[0011] To use a wireless remote controller for drones or model aircraft in the flight simulation system, the usual solution is to connect a joystick simulator between the remote controller receiver and the computer USB interface, as Figure 3 shown.

[0012] This joystick simulator is a circuit module that simulates the received SBUS signal into a flight joystick control signal and then connects to the simulation computer through a USB port. Thus, the purpose of controlling the simulation target in the aircraft simulation system through a drone or model aircraft remote controller is achieved.

[0013] The problem with such a connection method is that the joystick simulation module simulates the S control signal of the wireless remote controller for drones or model aircraft into a joystick control signal, and there are quite significant differences in the formats of these two signals. As a result, the functions of the wireless remote controller for drones or model aircraft cannot be fully utilized, and thus the control of the simulation target in the simulation system is quite restricted. The specific manifestations are:

[0014] (1) The SBUS signal contains 16 channel control signals with 11-bit (i.e., 2048 levels) precision and 2 button switch channel information. In the "Joystick" module recognized by the Windows system of the simulation computer, the maximum number of channels for the joystick control signal is 6. If more than 6 channels of control signals are required in the flight control program, the simulation cannot proceed;

[0015] (2) Key information is missing. In addition to the values of each channel, the SBUS signal also contains key information related to flight safety, that is, whether the receiver can receive a valid remote control signal and whether it enters the failsafe mode. These information are crucial for the flight management part in the flight control program. In the absence of this information, it is difficult for the flight simulation system to operate effectively;

[0016] (3) The channel order cannot be changed. In the joystick simulator, only the channels of the SBUS can be simulated as joystick channels for output according to the channel order, which limits the range of SBUS channels that can be collected. Taking the number of joystick channels in the "Joystick" module as 6 as an example, in this case, only the first 1-6 channel signals of the SBUS signal can be converted, and the 7-12 channel signals cannot be collected;

[0017] (4) The channel precisions are inconsistent. The channel precision of the SBUS is 2048-level integers, while the channel precision of the "Joystick" module is double-precision floating-point numbers. The advantage of floating-point numbers is that they can represent a large range of numbers, but they are an inaccurate approximation. After the two signals are converted, the channel precision is lost.

[0018] Therefore, an interface between a drone or model aircraft remote control that can convert SBUS serial signals into UART serial signals and can identify and parse SBUS serial signals and the Simulink flight simulation system has become the goal pursued by those skilled in the art. Summary of the Invention

[0019] The purpose of the present invention is to solve the problem that the existing Simulink flight simulation system cannot recognize the incompatibility between the serial port UART and the SBUS serial signal, resulting in the inability to accurately receive and parse the SBUS serial signal in the Simulink flight simulation system, leading to the loss or distortion of control signals.

[0020] To achieve the above invention purpose, the technical solution of the present invention is: an interface between a drone or model aircraft remote control and the Simulink flight simulation system, characterized in that it includes:

[0021] An SBUS signal level format conversion circuit is connected between the SBUS output interface of the remote control receiver of the UAV remote controller and the USB port of the computer, and is used to convert the SBUS signal output by the remote control receiver into a UART serial signal and transmit it to the Simulink flight simulation system of the computer; and

[0022] An SBUS signal processing module embedded in the Simulink flight simulation system is used to parse the SBUS serial signal converted and transmitted by the SBUS signal level format conversion circuit.

[0023] As a preferred solution, wherein, the SBUS signal level format conversion circuit includes:

[0024] A level inversion circuit is used to perform level logic inversion on the SBUS signal output by the remote control receiver of the UAV remote controller;

[0025] A decoding chip is used to receive the SBUS protocol with a baud rate of 100000bps and output a serial signal in the standard of the 3V-TTL level UART asynchronous communication protocol through parsing;

[0026] A USB-UART conversion module is used to convert the USB port of the computer into a standard UART serial port, so that the Windows system of the computer recognizes that the USB port is connected to a serial communication UART module, receives and transmits the serial signal of the UART asynchronous communication protocol standard sent by the decoding chip to the SBUS signal processing module of the Simulink flight simulation system.

[0027] As a preferred solution, wherein, the level inversion is a common emitter triode level inversion circuit;

[0028] The decoding chip is a ZR003U1 chip;

[0029] The base of the triode is connected to the SBUS output interface of the remote control receiver of the UAV remote controller, the emitter is grounded, and the collector is connected to the input terminal (SIN) of the ZR003 U1 chip; the output terminal (UART OUT) of the ZR003U1 chip is connected to the receiving terminal (RXD) of the USB-UART conversion module; the output terminal of the USB-UART conversion module is connected to the USB interface of the computer and transmits the UART serial signal output by the ZR003U1 chip to the SBUS signal processing module;

[0030] The voltage output terminal (5V OUT) of the USB-UART conversion module is connected to the power supply voltage interface (VCC) of the ZR003U1 chip and the collector of the triode, and is used to supply power to the ZR003U1 chip and the triode.

[0031] As a preferred solution, the SBUS signal processing module parses the SBUS serial signal by the following method:

[0032] First, establish a data buffer of about 70 bytes, and send the received SBUS serial signal byte by byte to the buffer for storage. When the read byte is equal to 0x0F, it is judged as the start of a data frame. Starting from this byte, intercept a string with a length of 35 bytes, perform an exclusive OR check on the intercepted string, and then compare it with the value of the 35th byte. If the results are the same, the intercepted string is a valid SBUS signal, and then the SBUS serial signal is parsed byte by byte.

[0033] As a preferred solution, the specific steps for the SBUS signal processing module to parse the SBUS serial signal are as follows:

[0034] S1, Start;

[0035] S2, Read the string in the buffer;

[0036] S3, Set the counting variable i = 1;

[0037] S4, Determine whether the i-th character is equal to 0x0F? If so, go to the next step S7; if not, go to S5;

[0038] S5, Set i to i + 1;

[0039] S6, Determine whether i exceeds the maximum value? If not, return to step S4; if so, go to step S11;

[0040] S7, Calculate the exclusive OR check value of the string composed of the i-th to i + 33rd characters;

[0041] S8, Determine whether the i + 34th character is equal to the exclusive OR check value? If equal, go to the next step; if not equal, go to step S5;

[0042] S9, Resolve the SBUS information. The i + 1st to i + 32nd characters represent the SBUS instructions of channels 1 - 16, and the i + 33rd string contains the instructions of channels 17 - 18, as well as the information on the disconnection state of the remote control and the out-of-control protection state;

[0043] S10, Obtain the valid SBUS information and output the result;

[0044] S11, output the SBUS information obtained from the last run of this program.

[0045] An interface between a drone or model aircraft remote controller and a Simulink flight simulation system according to the present invention. By adopting this interface method, in the drone flight simulation system, the same wireless remote controller as in actual flight can be used to control the simulation object. All the original control information in the SBUS signal output by the wireless remote controller, including channel data, flight safety-related information, etc., can be directly obtained by the flight simulation system. It can accurately transmit all the signals output by the remote controller, avoiding the loss of control performance and accuracy caused by simulating the wireless remote controller as a flight joystick. Brief Description of the Drawings

[0046] Figure 1 is a structural diagram of a drone flight simulation system in the prior art;

[0047] Figure 2 is a connection schematic diagram of a drone flight simulation system and a flight joystick controller in the prior art;

[0048] Figure 3 is a schematic diagram of a drone flight simulation system and a drone or model aircraft joystick controller connected by simulating the joystick in the prior art;

[0049] Figure 4 is a schematic diagram of the principle of an interface between a drone or model aircraft remote controller and a Simulink flight simulation system according to the present invention;

[0050] Figure 5 is a schematic diagram of an interface between a drone or model aircraft remote controller and a Simulink flight simulation system according to the present invention connected between a computer and a drone or model aircraft joystick controller;

[0051] Figure 6 is a circuit diagram of the SBUS signal level format conversion circuit according to the present invention;

[0052] Figure 7 is a flowchart of the method for analyzing the SBUS serial signal of the SBUS signal processing module according to the present invention. Detailed Description of the Preferred Embodiments

[0053] The following is a detailed example of the preferred embodiments of the present invention in conjunction with the accompanying drawings, but the protection scope of the present invention cannot be limited by the preferred embodiments.

[0054] See Figure 4 、 5 , the present invention aims to provide an interface between a drone or model aircraft remote controller and a Simulink flight simulation system, which includes:

[0055] An SBUS signal level format conversion circuit 1 is connected between the SBUS output interface of a remote control receiver 100 of a drone remote control and the USB port of a computer 200, and is used to convert the SBUS signal output by the remote control receiver of the drone or model aircraft remote control into a UART serial signal and transmit it to the Simulink flight simulation system 200 of the computer; and, an SBUS signal processing module 2 provided in the Simulink flight simulation system 200 is used to parse the SBUS serial signal converted and transmitted by the SBUS signal level format conversion circuit 1.

[0056] The SBUS signal level format conversion circuit 1 described in the present invention, as Figure 6 shown, its core part is a decoding chip 12 for converting the SBUS format to a UART signal, a USB-UART conversion module 23, and a signal level inversion circuit 11.

[0057] See Figure 5 、 6 , specifically, the SBUS signal level format conversion circuit 1 includes:

[0058] A level inversion circuit 11, which is connected to the SBUS output port of the remote control receiver, and is used to perform a level logic inversion on the SBUS signal output by the remote control receiver of the drone or model aircraft remote control;

[0059] A decoding chip 12, whose signal input end is connected to the output end of the level inversion circuit 11, and is used to receive the SBUS protocol with a baud rate of 100000bps, and through parsing, output a serial signal in the standard of the 3V-TTL level UART asynchronous communication protocol;

[0060] A USB-UART conversion module 13, which is connected to the computer USB port, and is used to convert the computer USB port into a standard UART serial port, so that the Windows system of the computer recognizes that the USB port is connected to a serial communication UART module; its input end is connected to the output end of the decoding chip 12, and receives and transmits the UART asynchronous communication protocol standard serial signal sent by the decoding chip to the SBUS signal processing module of the Simulink flight simulation system.

[0061] In this embodiment, the level inversion 11 is an NPN transistor common emitter inversion circuit, which can also be replaced by various other level inversion circuits; the decoding chip 12 is the ZR003U1 chip. The function of the ZR003U1 chip is to receive the SBUS protocol with a standard baud rate of 100000bps, parse it through its built-in decoding function, and output a 3V-TTL level serial signal that conforms to the UART asynchronous communication protocol standard; the base of the transistor is connected to the SBUS output interface of the remote control receiver 100 of the drone remote control, the emitter is grounded, and the collector is connected to the input terminal SIN of the ZR003U1 chip; the output terminal UART OUT of the ZR003U1 chip is connected to the receiving end RXD of the serial data of the USB-UART conversion module 13; the output terminal of the USB-UART conversion module 13 is connected to the USB interface of the computer, and the UART serial signal output by the ZR003U1 chip is transmitted to the SBUS signal processing module; the voltage output terminal 5V OUT of the USB-UART conversion module 13 is connected to the power supply voltage interface VCC of the ZR003U1 chip and the collector of the transistor, and is used to provide power to the ZR003U1 chip and the transistor. There are two optional baud rates for the UART serial signal output by the ZR003U1 chip, which are 38400 and 115200 respectively, and are determined by the pin levels of BAUD 0 and BAUD 1 of the ZR003U1 chip. In the present invention, BAUD 0 = 0, BAUD 1 = 1, and the output serial signal baud rate is 34800. Each byte of the output serial UART signal contains: 1 start bit and 1 stop bit. The function of the USB-UART conversion module 13 is to convert the USB port of the simulation computer into a standard UART serial port. Thus, after the SBUS signal level format conversion circuit 1 of the present invention is connected to the USB port of the computer, the Windows system of the computer can recognize that the USB port connected is a serial communication UART module.

[0062] The power supply required for the ZR003U1 chip in the SBUS signal level format conversion circuit 1 and the transistor of the signal level inversion circuit 11 is provided by the 5V power supply in the USB-UART conversion module 13.

[0063] Through the above SBUS signal level format conversion circuit 1, a physical connection is achieved between the drone or the model airplane wireless remote control and the simulation computer. The computer then recognizes the connected USB port as a standard UART serial interface. And the SBUS signal is converted into a UART signal and transmitted to the SBUS signal processing module 2 in the Simulink flight simulation system 200.

[0064] See Figure 7, the function of the SBUS signal processing module 2 embedded in the flight simulation program Simulink is to read the information transmitted by the SBUS serial port of the remote control receiver through the SBUS signal level conversion circuit 1 and parse it to restore the SBUS serial port information containing the remote control operation data sent by the remote control receiver. Table 1 shows the SBUS frame signal format input from the UART serial port of the flight control computer:

[0065] Table 1

[0066] Starting Byte - 1 Byte Data Byte - 32 Bytes Flag Byte - 1 Byte Check Byte - 1 Byte byte[0] byte[1] - byte

[32] byte

[33] byte

[34] 0xf0 Channel 1 - Channel 16 Control Values Flags XOR Check

[0067] Each frame of the SBUS signal sent by the remote control receiver contains 35 bytes. Among them, the first byte 0x0F is the frame header, followed by 32 bytes of control values for 16 channels. The value of each channel is an integer occupying two bytes, with the high byte first and the low byte second. The effective number of bits is 11 bits, and the integer value range is 0 - 2047. After the channel values is a flag byte Flags and a byte of exclusive OR checksum as the frame tail.

[0068] The definition of the flag byte Flags is as follows:

[0069] bit7 = channel 17 (a single-bit button switch channel)

[0070] bit6 = channel 18 (a single-bit button switch channel)

[0071] bit5 = remote control loss of connection status (a single-bit switch quantity)

[0072] bit4 = out-of-control protection status (a single-bit switch quantity)

[0073] bit3 = n / a

[0074] bit2 = n / a

[0075] bit1 = n / a

[0076] bit0 = n / a

[0077] The last checksum byte is the exclusive OR checksum value of the remaining 33 bytes excluding the first frame header byte.

[0078] The SBUS signal processing module 2 parses the SBUS serial signal through the following method: First, establish a data buffer of about 70 bytes. These about 70 bytes are arranged in a row. The SBUS signal level format conversion circuit 1 transports the received SBUS serial signal byte by byte to the buffer for storage according to the principle of right-in and left-out. In the interpretation process, the program reads the data in the buffer byte by byte. If the read byte is equal to 0x0F, it is initially judged to be the start of a data frame. At this time, starting from this byte, intercept a string with a length of 35 bytes. Perform an exclusive OR check on the intercepted string, and then compare it with the value of the 35th (i.e., the last) byte. If the results are the same, it indicates that the intercepted string is a valid SBUS signal. The signal decoding of SBUS can then begin, parsing the SBUS serial signal byte by byte: In the intercepted string, read the (i + 1)-th to the (i + 32)-th bytes (a total of 32 bytes) one by one. Every 2 bytes form an integer value for a control channel. The (i + 33)-th byte contains the information of button switch channels 17 - 18, as well as the information of the remote control loss of connection and out-of-control protection status, which can be obtained by reading bit by bit.

[0079] See Figure 6 , the method for the SBUS signal processing module to parse the SBUS serial signal specifically includes the following steps:

[0080] S1, Start;

[0081] S2, Read the string in the buffer;

[0082] S3, Set the counting variable i = 1;

[0083] S4, Determine whether the i-th character is equal to 0x0F? If so, go to the next step S7; if not, go to S5;

[0084] S5, Set i to i + 1;

[0085] S6, Determine whether i exceeds the maximum value? If not, return to step S4; if so, go to step S11;

[0086] S7, Calculate the exclusive OR check value of the string composed of the i-th to the (i + 33)-th characters;

[0087] S8, Determine whether the (i + 34)-th character is equal to the exclusive OR check value? If equal, go to the next step; if not equal, go to step S5;

[0088] S9, Solve the SBUS information. The (i + 1)-th to the (i + 32)-th characters represent the SBUS instructions for channels 1 - 16, and the (i + 33)-th string conforms to containing the instructions for channels 17 - 18, as well as the information of the remote control loss of connection status and out-of-control protection status;

[0089] S10, obtain valid SBUS information and output the result;

[0090] S11, output the SBUS information obtained from the last run of this program.

[0091] Through the above steps, all the SBUS input control instructions sent by the remote control receiver are obtained.

[0092] Finally, the control instructions of SBUS are output by the SBUS signal processing module 2 for controlling the simulation targets in the aircraft simulation system. The parsed SBUS control data can be divided into four groups:

[0093] (1) The manipulated shaping values of channels 1 - 16;

[0094] (2) The switch states of channels 17 - 18 for button switches;

[0095] (3) The state of the remote control losing connection;

[0096] (4) The state of failsafe protection.

[0097] The four groups of data are finally input into the simulation model to achieve the control of the simulation object.

[0098] The above description is illustrative rather than restrictive for the present invention. The present invention aims to provide an interface between the remote control of an unmanned aerial vehicle or a model aircraft and the Simulink flight simulation system. Through this interface, the SBUS signal can be accurately converted into a UART signal, avoiding the loss of channel accuracy. Without departing from the spirit and scope defined by the claims, many modifications, variations or equivalents can be made, such as changing the model of the decoding chip and replacing the signal level inversion circuit, but all will fall within the protection scope of the present invention.

Claims

1. An interface between a drone or model aircraft remote controller and a Simulink flight simulation system, characterized in that: It includes: An SBUS signal level format conversion circuit (1), connected between the SBUS output interface of a remote control receiver (100) of an unmanned aerial vehicle or a model airplane remote control and the USB port of a computer, for converting the SBUS signal output by the remote control receiver (100) into a UART serial signal and transmitting it to the Simulink flight simulation system (200) of the computer; and An SBUS signal processing module (2) provided in the Simulink flight simulation system, for parsing the SBUS serial signal converted and transmitted by the SBUS signal level format conversion circuit (1); The SBUS signal processing module (2) parses the SBUS serial signal by the following method: First, establish a data buffer of about 70 bytes, and transmit each byte of the received SBUS serial signal to the buffer for storage. When the read byte is equal to 0x0F, it is determined that it is the start of a data frame. Starting from this byte, intercept a string with a length of 35 bytes, perform an exclusive OR check on the intercepted string, and then compare it with the value of the 35th byte. If the results are the same, the intercepted string is a valid SBUS signal, and then parse the SBUS serial signal byte by byte; The specific steps for the SBUS signal processing module to parse the SBUS serial signal are as follows: S1, Start; S2, Read the string in the buffer; S3, Set the counting variable i = 1; S4, Determine whether the i-th character is equal to 0x0F? If so, go to the next step S7; if not, go to S5; S5, Set i to i + 1; S6, Determine whether i exceeds the maximum value? If not, return to step S4; If so, go to step S11; S7, Calculate the exclusive OR check value of the string composed of the i-th to i + 33rd characters; S8, Determine whether the i + 34th character is equal to the exclusive OR check value? If they are equal, go to the next step; if not, go to step S5; S9, Resolve the SBUS information. The i + 1st to i + 32nd characters represent the SBUS instructions for channels 1 - 16, and the i + 33rd string contains the instructions for channels 17 - 18, as well as the information on the disconnection status of the remote control and the out-of-control protection status; S10, Obtain the valid SBUS information and output the result; S11, Output the SBUS information obtained from the previous run of this program.

2. The interface between a remote controller of an unmanned aerial vehicle or a model aircraft and a Simulink flight simulation system according to claim 1, characterized in that: The SBUS signal level format conversion circuit (1) includes: A level inversion circuit (11), for performing a level logic inversion on the SBUS signal output by the remote control receiver (100) of the unmanned aerial vehicle remote control; A decoding chip (12), for receiving the SBUS protocol with a baud rate of 100000 bps, and through parsing, outputting a serial signal in the standard of the 3V - TTL level UART asynchronous communication protocol; A USB-UART conversion module (13) is used to convert the USB port of a computer into a standard UART serial port, enabling the Windows system of the computer to recognize that the USB port is connected to a serial communication UART module, receiving and transmitting the serial signal in the UART asynchronous communication protocol standard sent by the decoding chip (12) to the SBUS signal processing module (2) of the Simulink flight simulation system (200).

3. The interface between a remote controller of an unmanned aerial vehicle or a model aircraft and a Simulink flight simulation system according to claim 2, characterized in that: The level inversion circuit (11) is a common emitter triode level inversion circuit; The decoding chip (12) is a ZR003U1 chip; The base of the triode is connected to the SBUS output interface of the remote control receiver (100) of the UAV remote control, the emitter is grounded, and the collector is connected to the input terminal (SIN) of the ZR003 U1 chip; the output terminal (UART OUT) of the ZR003U1 chip is connected to the receiving terminal (RXD) of the USB-UART conversion module; the output terminal of the USB-UART conversion module (13) is connected to the USB interface of the computer, and the UART serial signal output by the ZR003U1 chip is transmitted to the SBUS signal processing module (2); The voltage output terminal (5V OUT) of the USB-UART conversion module (13) is connected to the power supply voltage interface (VCC) of the ZR003U1 chip and the collector of the triode, and is used to supply power to the ZR003U1 chip and the triode.

Images