CN104765377A - Unmanned helicopter flying control platform system based on QNX - Google Patents

Abstract

The present invention proposes a QNX-based unmanned helicopter flight control platform system, which solves the problem of the slow calculation speed of the processor carried on the current unmanned helicopter flight control platform, the overall volume is too large, the operating power consumption is high, and the on-board software The real-time performance and safety performance of the control system are not guaranteed. Adopt QNX Neutrino real-time operating system with very good real-time performance, equipped with high-performance and low-power PC104 core control board, use EKF (Extended Kalman Filter) algorithm for attitude calculation, data fusion, and through INS/GPS integrated navigation algorithm, Realize the autonomous flight of the autonomous unmanned helicopter flight control platform. At the same time, it also improves the management structure of the system software, improves the robustness of the software through the system modular design, ensures the safety and stability of the software system of the unmanned helicopter, and also improves the real-time performance of the system.

Description

QNX-based unmanned helicopter flight control platform system

technical field

The invention relates to a flight control platform system, in particular to a flight control platform system for an unmanned helicopter.

Background technique

Unmanned helicopter is a multi-disciplinary cross-coupling challenging frontier research direction, involving mechanical structure, aerodynamics, flight dynamics, system modeling, sensor data fusion, strapdown navigation system, embedded systems and other fields. A complete set of unmanned helicopter control platform consists of avionics system, navigation system and ground station system:

1. The avionics system is the basic component of the unmanned helicopter, which is mainly divided into hardware system and software system. The hardware system consists of at least one MCU or computer system and related expansion boards to realize online analysis of flight data, operation of control algorithms, communication with ground stations, and recording of necessary flight data.

2. The navigation system is composed of an attitude reference system and a position reference system. The attitude reference system provides the necessary flight attitude data for the avionics system, and the position reference system provides relevant information about the actual position of the aircraft.

3. The ground station system is composed of ground station software and wireless communication equipment. Through the wireless communication equipment, it exchanges information with the unmanned helicopter and monitors the unmanned helicopter in real time.

At present, unmanned helicopters usually choose embedded computers as the core control board onboard, and cooperate with external expansion function boards to form the hardware system of the avionics system. The navigation system includes INS (inertial navigation system, inertial navigation system) and GPS navigation system. The inertial navigation system is composed of a typical three-axis accelerometer, three-axis gyroscope, and three-axis magnetometer, which can provide the actual flight attitude of the unmanned helicopter; the GPS navigation system can provide the latitude and longitude, speed, altitude and other information of the location of the unmanned helicopter .

Foreign research in the field of unmanned helicopters started early and achieved many research results. Among them, the hummingbird helicopter developed by Stanford University adopts the differential chopping phase global positioning system as the navigation system, and detects the flight attitude and heading information of the unmanned helicopter through four GPS receivers on the body, without the use of inertial navigators, altimeters, etc. A device capable of autonomous hovering. But it does not use the inertial navigation system, the dynamic performance of the dynamic attitude of the unmanned helicopter is poor, and the flight control law is difficult to design; the Xcell-60 unmanned helicopter developed by MIT University uses GPS, six degrees of freedom IMU (inertial measurement unit), three The axis magnetometer forms a navigation system to realize autonomous hovering; the HeLion and SheLion unmanned helicopters developed by the National University of Singapore successively can realize vision-based trajectory tracking. The avionics system consists of 2 PC104 boards and a complete MNAV module (IMU module integrating MEMS technology, magnetometer, GPS receiver).

Domestic research on unmanned helicopters started relatively late, and the technology is relatively backward, but many research results have also been obtained. At present, many universities and research institutes conduct in-depth research in the field of unmanned helicopters, such as Northwestern Polytechnical University, Harbin Institute of Technology, Nanjing University of Aeronautics and Astronautics, Zhejiang University, etc. Among them, the paper "Software Simulation and System Design of Miniature Unmanned Helicopter Flight Control System" directed by Professor Li Ping of Zhejiang University introduced the software simulation of unmanned helicopters. This paper mainly combined various mathematical models to simulate the design of the unmanned helicopter system, and The attitude subsystem and navigation subsystem of the unmanned helicopter system are not perfect, and no physical test can be carried out, but the simulation verification of the unmanned helicopter system has achieved great research results.

Contents of the invention

In order to solve the problems in the prior art, the present invention aims at the deficiencies of the software and hardware of the domestic unmanned helicopter flight control platform, and proposes the unmanned helicopter flight control platform system based on QNX, and also improves the management framework of the system software, through system modularization The design improves the robustness of the software, ensures the safety and stability of the software system of the unmanned helicopter, and also improves the real-time performance of the system.

The present invention is realized through the following technical solutions:

A QNX-based unmanned helicopter flight control platform system, the system includes an airborne avionics system, a ground station system, and a manual control system; the airborne avionics system includes a core control board, a sensor acquisition circuit board, and a steering gear Drive circuit board, XTend wireless module and remote control signal receiver; Wherein, core control module is PC104 embedded computer, and described PC104 is used for running QNX real-time operating system, and runs airborne software system, and described airborne software system includes posture Calculation algorithm, data fusion algorithm, and flight control algorithm; the airborne avionics system communicates with the manual control system and the ground station system through a remote control signal receiver and XTend wireless module to obtain control signals of the manual control system , the control command of the ground station system and data such as real-time flight position and attitude are sent to the ground station system for real-time monitoring of the flight status of the unmanned helicopter; the core control board communicates with the MCU of the sensor acquisition circuit board to obtain unmanned The real-time flight parameter data of the helicopter; the core control board communicates with the MCU of the steering gear drive circuit board to obtain the remote control signal of the manual control system, and at the same time outputs the steering gear control signal of the unmanned helicopter to each steering gear to control the drone. man helicopter.

As a further improvement of the present invention, the core control board receives the data of the GPS receiver through the serial communication expansion board; the airborne avionics system also includes an inertial navigation system INS, and the software system also includes The INS/GPS integrated navigation system of the EKF algorithm fuses the attitude data measured by the INS and the GPS satellite data through the EKF algorithm to obtain more accurate position data and attitude data of the unmanned helicopter flight control platform.

As a further improvement of the present invention, the sensor acquisition circuit board includes an MCU, an inertial measurement unit IMU, a magnetometer, and a barometer; wherein, the IMU uses the SPI communication protocol, the barometer uses the I2C communication protocol, and the magnetometer uses a TTL level serial communication protocol.

As a further improvement of the present invention, the steering gear drive circuit board includes an MCU and a steering gear driver, wherein the steering gear driver includes a recoverable fuse to protect the steering gear and power supply, and adopts optocoupler isolation technology to isolate external devices MCU interference.

As a further improvement of the present invention, the airborne software system is developed based on the QNX Neutrino real-time operating system, uses a multi-threaded system framework, and performs multiple tasks; in order to effectively realize automatic control, a hierarchical and modular structure based on the PIOS architecture is adopted , various operations on the UAV are organized through various modules.

As a further improvement of the present invention, the ground station includes a foreground, a background, and a kernel; wherein, the foreground directly interacts with terminal users, mainly providing users with an easy-to-use, user-friendly graphical interface, and the background is used for data transmission, through The wireless channel communicates with the on-board software modules. The beneficial effects of the present invention are: the QNX-based unmanned helicopter flight control platform system proposed by the present invention solves the problem of the slow computing speed, excessive overall volume and low operating power consumption of the processors carried on the current unmanned helicopter flight control platform. High, real-time performance and safety performance of the airborne software control system lack of guarantee. It adopts the QNX real-time operating system with very good real-time performance, equipped with a PC104 core control board with high performance and low power consumption, and uses attitude calculation algorithms, data fusion algorithms, and flight control algorithms to realize the autonomous flight of the autonomous unmanned helicopter flight control platform. At the same time, it also improves the management structure of the system software, improves the robustness of the software through the system modular design, ensures the safety and stability of the software system of the unmanned helicopter, and also improves the real-time performance of the system.

Description of drawings

Fig. 1 is the unmanned helicopter control platform system schematic diagram based on QNX of the present invention;

Fig. 2 is a block diagram of unmanned helicopter hardware structure of the present invention;

Fig. 3 is the circuit principle diagram of sensor acquisition circuit;

Fig. 4 is a circuit schematic diagram of the remote control signal and the steering gear drive circuit;

Fig. 5 is a schematic diagram of data sharing among airborne software modules;

Fig. 6 is a schematic structural diagram of the airborne software;

Figure 7 is a hierarchical structure diagram of the ground station.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

The invention provides a complete QNX-based unmanned helicopter control platform, and develops a set of INS/GPS integrated navigation system based on EKF (extended Kalman filter) algorithm for the unmanned helicopter control system. The INS/GPS integrated navigation system uses the EKF algorithm to convert the attitude data (including three-axis gyroscope data, three-axis accelerometer data, three-axis electronic compass data, and barometer data) measured by the INS (inertial navigation system) to the GPS navigation system. The obtained satellite data are fused to obtain more accurate position data and attitude data of the unmanned helicopter flight control platform, and provide a cheap position and attitude reference system for unmanned helicopters. According to the motion characteristics of the unmanned helicopter, the flight control law is designed, including pitch control, roll control, heading control, fixed height control, and fixed point control.

The unmanned helicopter flight control platform system of the present invention, as shown in accompanying drawing 1, is made up of airborne avionics system, ground station system and manual control system, and this control platform system controls radio-controlled helicopter and receives radio-controlled helicopter to send The data. Among them, the airborne avionics system communicates with the manual control system and the ground station system through wireless devices (remote control receiver, XTend wireless module), and obtains the control signals of the manual control system and the control commands of the ground station system. At the same time, the flight parameters of the unmanned helicopter are transmitted back to the ground station system for real-time monitoring of the flight status of the unmanned helicopter. The avionics system changes the flight behavior of the radio-controlled helicopter by controlling the steering gear of the radio-controlled helicopter, and then measures the actual attitude data of the radio-controlled helicopter through the onboard INS (inertial navigation system), so as to realize the control of the radio-controlled helicopter by the avionics system.

The avionics system includes a hardware system and a software system. The hardware system is divided into a core control module and an external expansion module. The core control module is a PX104 embedded computer, and the external expansion module includes a pose unit, a communication unit, and a control signal input and output unit; software The system includes attitude calculation algorithm, flight control algorithm, and ground station software.

For the small man-made helicopter flight controller, the embedded computer system based on PC104 is mainly used at present. An embedded computer standard developed by the PC104 Association for embedded applications in the industrial field. The PC104 standard uses a pin socket connector, which can ensure the reliability of data transmission in environments with strong interference and vibration. It is designed for some special embedded computing environments. These features are especially suitable for unmanned helicopters. This connection method of PC104 also integrates other modules, such as image data acquisition module, analog/digital conversion board, serial communication expansion board, power supply board, etc. The system does not need to be reconfigured during the integration process, so there is a better compatibility.

The block diagram of the hardware structure of the unmanned helicopter is shown in Figure 2. The core control board PC104 runs the QNX Neutrino real-time operating system, and runs the airborne software system. The core control board communicates with the MCU (STM32F405) of the sensor acquisition circuit board to obtain real-time flight data of the radio-controlled helicopter (ADI16355 is the IMU (inertial measurement unit), HMR3000 is the electronic compass, and MS5611 is the barometer); the core control board communicates with the remote control signal and The MCU (STM32F103) of the steering gear drive circuit board communicates to obtain the remote control signal of the manual control system, and at the same time outputs the steering gear control signal of the radio-controlled helicopter to each steering gear; the core control board communicates with the ground station system through the Xtend wireless device, Obtain the control command of the ground station system and send the real-time flight position and attitude data to the ground station system for real-time monitoring of the flight status of the unmanned helicopter; the core control board receives the data of the GPS receiver through the serial communication expansion board, and Reserve two serial communication expansion interfaces.

The circuit principle diagram of the sensor acquisition circuit is shown in Figure 3. ADI16355 (IMU inertial measurement unit) adopts SPI communication protocol, barometer MS5611 adopts I2C communication protocol, HMR3000 (magnetometer) adopts TTL level serial port communication protocol, and in order to ensure the real-time performance of sensor data acquisition, STM32F405 is used as the data acquisition MCU, which has abundant IO port resources, the main frequency can reach up to 168MHz, and the working voltage is 3.3V. In order to better install the IMU and improve the vibration reduction effect, an installation box is specially designed for the sensor data acquisition unit.

The schematic diagram of the remote control signal and the steering gear drive circuit is shown in Figure 4. The output signal of the remote control receiver is a PWM signal with a frequency of 50Hz and a positive pulse width of 1ms-2ms, but the controller processes digital, so the PWM analog signal must be described with an accurate value. The driving signals of the steering gear and the ESC must be PWM signals, so the MCU is required to have PWM capture and output functions. Since the update period of the signal is 20ms, the MCU can meet the requirements without too high a main frequency, so the STM32F103 with a lower cost is used to process the receiving of the remote control signal and the output of the driving signal. In order to improve the safety of the driving circuit, the steering gear drive has added a resettable fuse to protect the steering gear and power supply, and at the same time adopts optocoupler isolation technology to isolate the interference of external devices to the MCU.

The airborne software system is developed based on the QNX Neutrino real-time operating system, using a multi-threaded system framework to perform multiple tasks. In order to effectively realize automatic control, a hierarchical and modular structure based on PIOS architecture is adopted, and various operations of UAVs are organized through various modules. This structure provides good flexibility and extensibility for new modules and functions. There is no direct communication interface between modules, and modules do not expose any public functions, that is, each module runs in its own thread. Each module can call library functions to access each UAVObject, read and update data, and perform data interaction through this structure, as shown in Figure 5.

The airborne software system needs to ensure that all hardware can work normally and effectively, and can monitor the working conditions of each module, and at the same time communicate and cooperate well with the ground station system. Its basic tasks include: collect navigation data; Run the flight control algorithm; Receive remote control signals and send steering gear and motor control signals; communicate with ground stations; Record online flight data. In each execution cycle, these tasks must be executed in a strict and orderly manner, and some special tasks need to be executed in time to ensure flight safety.

UAVObjects in Figure 5 is a data container shared between modules. In order to realize data sharing, usually a Module updates object data, and then another Module uses these data. There are three types of UAVObjects in this system: Regular Data Objects, Timer Objects (used to control the update rate of other Objects) and Settings Objects (used to control the operation of the module).

The flight controller onboard software structure is shown in Figure 6. On-board software consists of different modules, one for each type of equipment or task.

(1) The Sensor module is used to collect all sensor data and provide the following measurement data for the AHRS module and Navigation module acceleration; Angular rate; Magnetic field front; Geographic location with longitude, latitude and altitude as coordinates; The speed of the NED axis.

(2) The AHRS module is a navigation attitude reference system, which calculates the UAV attitude angle based on the current sensor data.

(3) Navigation module, which reads the online flight data required for automatic control and estimates the measurement status. It also includes a complete set of INS/GPS navigation algorithms to provide the position and attitude information of the aircraft for UAV flight control.

(4) The Stabilization module is a stabilization module, which is the inner loop controller of the UAV. The input is the current remote control amount or the control amount of roll, pitch, yaw output by the position loop and the current attitude of the UAV, through the PID controller The output is the control amount in the three directions of roll, pitch and yaw.

(5) The AutoControl module realizes the automatic flight control law. In the flight control software, this is the only module that does not interact with the hardware. Its main functions include obtaining the flight attitude and position information of the UAV sent from the Navigation module, operating the control algorithm based on the current flight state, and generating control signals. Drive the servo steering gear.

(6) Actuator is the execution module, which collects the roll, pitch, yaw control quantities and throttle control quantities output by the Stabilization module, and converts them into the control outputs of each steering gear and throttle through the swashplate of the drone.

(7) Telemetry is a wireless communication module, which is used for communication between the airborne system and the ground station system through the 2.4G module, to realize the download of required online data and the upload of user commands/track instructions.

(8) Logger is a data recording module that records flight data in real time and uses SSD memory as a storage medium.

(9) ManualControl is to analyze the input of the remote control commands of the ground remote control, collect the joystick commands of each channel of the remote control, and realize the switching of flight modes and ground-assisted flight. It is a very necessary manual backup module during the experiment.

(10) Manager manages all the above-mentioned modules, completes the interaction of internal data of the software system through the global shared data scheme, namely the PIOS mentioned above, and monitors the running status of each module.

The ground station acts as a user terminal, monitoring the flight status of the UAV and uploading commands through radio. In the flight test, the online flight data of the unmanned helicopter is downloaded from the airborne system to the ground station for display. The task of the ground station is to provide users with a friendly and real interface, monitor the flight process, and realize data visualization. The ground station is divided into three layers: foreground, background and core, as shown in Figure 7.

(1) The front desk directly interacts with end users, mainly providing users with an easy-to-use and friendly graphical interface.

(2) The background is used for data transmission, and communicates with the onboard software module (ie, the Telemetry thread) through a wireless channel. The data receiving thread in the background continuously reads the serial port connected between the ground station and the wireless communication module Xtend, and updates the global shared database storage area created by the kernel layer; on the other hand, the data sending thread in the background continuously checks the global shared data storage area, In order to capture the user commands processed by the foreground in time, and then write them into the serial port.

(3) The kernel is a document class. As the host of global shared data, it integrates various processing and access algorithms, connects the communication thread and each view of the front/background, and designs two dynamic data links: When the background data receiving thread receives a new online data packet, the kernel updates its data in the global storage area and activates the foreground to call the display function; When the foreground processes a new user command, the kernel similarly updates its data storage area and activates the background to upload data to the onboard system.

The above content is a further detailed description of the present invention in conjunction with specific preferred embodiments, and it cannot be assumed that the specific implementation of the present invention is limited to these descriptions. For those of ordinary skill in the technical field of the present invention, without departing from the concept of the present invention, some simple deduction or replacement can be made, which should be regarded as belonging to the protection scope of the present invention.

Claims (6)

1., based on a unmanned helicopter flight parametric controller system of QNX, described system comprises airborne avionics system, earth station system and manual control system; It is characterized in that: described airborne avionics system comprises core control panel, sensor collecting circuit board, servo driving circuit board, XTend wireless module and remote signal receiver; Wherein, kernel control module is PC104 embedded computer, and described PC104 for running QNX real time operating system, and runs Airborne Software system, and described Airborne Software system comprises attitude algorithm algorithm, data anastomosing algorithm, Flight Control Algorithm; Described airborne avionics system by remote signal receiver, XTend wireless module respectively with described manual control system, described earth station system communication, obtain the control signal of manual control system, the control command of earth station system and the data such as real-time flight position attitude are sent to earth station system, for the state of flight of Real-Time Monitoring depopulated helicopter; The MCU communication of described core control panel and sensor collecting circuit board, obtains the real-time flight supplemental characteristic of depopulated helicopter; The MCU communication of core control panel and servo driving circuit board, obtains the remote controller signal of manual control system, the servos control signal of depopulated helicopter is outputted to each steering wheel, to control described depopulated helicopter simultaneously.

2. unmanned helicopter flight parametric controller system according to claim 1, is characterized in that: described core control panel expands by serial communication the data that plate receives GPS; Described airborne avionics system also comprises inertial navigation system INS, described software systems also comprise the INS/GPS integrated navigation system based on expanding Kalman filtering EKF algorithm, the attitude data recorded by INS by EKF algorithm and gps satellite data are merged, and obtain position data and the attitude data of unmanned helicopter flight parametric controller more accurately.

3. unmanned helicopter flight parametric controller system according to claim 1, is characterized in that: described sensor collecting circuit board comprises MCU, Inertial Measurement Unit IMU, magnetometer and barometer; Wherein, described IMU adopts SPI communication protocol, and barometer adopts I2C communication protocol, and magnetometer adopts the serial communication protocol of Transistor-Transistor Logic level.

4. unmanned helicopter flight parametric controller system according to claim 1; it is characterized in that: described servo driving circuit board comprises MCU and steering engine driver; wherein; described steering engine driver comprises can protect steering wheel and power supply by recovery-type fuse; adopt light-coupled isolation technology, isolation external equipment is to the interference of described MCU simultaneously.

5. unmanned helicopter flight parametric controller system according to claim 1, is characterized in that: described Airborne Software system, based on the exploitation of QNX Neutrino real time operating system, uses multi-threaded system framework, performs multitask; In order to effectively realize automatic control, have employed based on the stratification of PIOS framework, modular construction, the various operations of unmanned plane are organized by modules.

6. unmanned helicopter flight parametric controller system according to claim 1, is characterized in that: described land station comprises foreground, backstage and kernel; Wherein, foreground is directly mutual with terminal user, and be mainly user and provide a graphical boundary be simple and easy to, friendly interface, backstage is used for data and transmits, by wireless channel and Airborne Software module communication.