CN103196453A - Design of four-axis aircraft visual navigation system - Google Patents

Abstract

The invention belongs to the field of visual navigation, and in particular relates to design of a four-axis aircraft visual navigation system, which comprises a visual system module, an inertial navigation measuring module, a visual image wireless transmission module, a visual image processing module and an aircraft motion control module; a machine-mounted camera and an inertial measurement element are adopted for achieving on-line measurement; the collected information is treated off line through a wireless transmission mode and is wirelessly transmitted back to a machine-mounted high-speed processor for achieving control, therefore, the requirement on weight of the aircraft and control accuracy is solved, and the problem of transmission delay is solved through adding delay information in a navigation algorithm. The four-axis aircraft visual navigation systematic disclosed by the design has important application value.

Description

Design of Vision Navigation System for Quadcopter

technical field

The invention belongs to the field of visual navigation and relates to a design of a visual navigation system for a four-axis aircraft, in particular to a design capable of realizing the collection of visual information of the four-axis aircraft, wireless transmission, position and attitude measurement by an inertial navigation unit, and flight control functions of the four-axis aircraft.

Background technique

A quadcopter is a form of unmanned aerial vehicle (UAV) that uses a Global Positioning System (GPS) for navigation and an Inertial Navigation System (IMU). The estimation accuracy of GPS directly depends on the number of satellites participating in the positioning and the quality of the signal received by the receiving device and the influence of the station. In addition, radio frequency interference from neighboring devices or channel congestion can lead to unreliable position estimates, which are ubiquitous and difficult to resolve. When the effective GPS signal cannot be used or obtained, the navigation system of the UAV can only rely on the inertial navigation system, and the high-precision inertial navigation system relies on high-precision sensors, which increases the cost on the one hand, and increases the cost of wireless on the other hand. Man-machine load. In addition, since the position error of the inertial navigation system accumulates with time, it must be corrected by external information. If you carry settings such as radios, laser scanners, etc., for small and medium-sized unmanned aerial vehicles (MUAVs), the load weight is a maximum limit .

The on-board camera and inertial navigation system are used to realize online measurement, and the collected information is processed offline through wireless transmission, and then wirelessly transmitted back to the on-board high-speed processor to realize control, which solves the requirements of aircraft weight and control refinement, In this way, there is a problem of transmission delay, so delay information compensation should be added to the navigation algorithm. The quadcopter visual navigation system proposed in this design has important application value.

Contents of the invention

The technical problem to be solved by the present invention is to design a visual navigation system for a four-axis aircraft to realize the function of determining the position of a carrier by using visual image information and inertial measurement elements. The technical scheme adopted in the present invention is: a visual navigation system for a four-axis aircraft, comprising a visual system module (1), an inertial navigation measurement module (2), a visual image wireless transmission module (3), a visual image processing module (4) ), the aircraft motion control module (5), the function description of each module is as follows:

The vision system module (1) is an airborne camera and a timing circuit, which realizes the acquisition and transmission timing of visual images and prepares for the next image processing; the inertial navigation measurement module (2) uses gyroscopes, accelerometers and pressure sensors to measure the aircraft Direction, acceleration, pressure (altitude) information to obtain the inertial navigation data for subsequent carrier position estimation; the visual image wireless transmission module (3) realizes the wireless transmission between the airborne camera and the image processing computer, and between the image processing computer and the microprocessor; The visual image processing module (4) is composed of off-line computers to realize image feature extraction, tracking, and recognition, and provides the position estimation of the quadcopter based on image information; the aircraft motion control module (5) realizes quadcopter based on microprocessor and control algorithm Shaft motor speed control.

Measures taken also include:

The timer in the above-mentioned visual system module module (1) can select a timer with different bits according to the timing accuracy.

Both the gyroscope and the accelerometer in the above-mentioned inertial navigation measurement module (2) are MEMS.

The image processing in the above-mentioned visual image processing module (4) adopts the optical flow analysis method and the fast corner method, and introduces image transmission delay compensation at the same time.

In the above-mentioned aircraft motion control module (5), the Kalman filter algorithm is used to fuse the image and the position estimation of the inertial navigation, and the PID controller is used to realize the speed control of the four-axis motor.

The purpose of the present invention is to design a visual navigation system for a quadcopter with light weight, low cost and full functions. The visual aided navigation is realized through the above five functional modules, which has strong practicability.

Description of drawings

Fig. 1 is the overall structure diagram of the present invention.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings.

The onboard camera in the vision system module captures the target image in real time. The timing circuit will start timing when the current image is transmitted wirelessly. When the image processing is completed and output to the microprocessor, the timing will end. This time interval is the transmission delay, which is transmitted in the subsequent filtering. Delay compensation is used. The inertial navigation measurement module uses MEMS gyroscopes and accelerometers to measure the direction and acceleration information of the aircraft, and then can calculate the position information, while the pressure sensor measures the pressure at the altitude of the aircraft and converts it into an altitude value. The visual image wireless transmission module is responsible for the wireless transmission between the airborne camera and the image processing computer, and between the image processing computer and the microprocessor; Estimation of the position of the quadrocopter; the motion control module of the vehicle is based on the microprocessor, kalman filter algorithm and PID control algorithm to realize the speed control of the four-axis motor.

The invention has the advantages of simple structure, low cost, convenient operation and complete functions of the designed four-axis aircraft visual navigation system.

Claims (5)

1. the present invention designs a kind of four-axle aircraft vision navigation system, realizes utilizing visual pattern information and inertial measurement component to determine the function of carrier positions.The technical solution adopted in the present invention is: a kind of four-axle aircraft vision navigation system, include vision system module (1), inertial navigation measurement module (2), visual pattern wireless transport module (3), visual pattern processing module (4), aircraft movements control module (5).It is characterized in that: vision system module (1) is airborne camera and timing circuit, realizes collection and the transmission timing of visual pattern, handles for next step image and prepares; Inertial navigation measurement module (2) utilizes gyroscope and acceleration to take into account direction, acceleration, pressure (highly) information that pressure transducer is measured aircraft, obtains the inertial navigation data that follow-up carrier positions is estimated; Visual pattern wireless transport module (3) is realized between airborne camera and pattern process computer, the wireless transmission between pattern process computer and microprocessor; Visual pattern processing module (4) is made up of off-line, realizes image characteristics extraction, tracking, identification, provides the location estimation based on the four-axle aircraft of image information; Aircraft movements control module (5) realizes the control of four spindle motor rotating speeds based on microprocessor, control algolithm.

2. a kind of four-axle aircraft vision navigation system according to claim 1 is characterized in that, the timer in the described vision system module module (1) can be selected the timer of different positions according to timing accuracy.

3. a kind of four-axle aircraft vision navigation system according to claim 1 is characterized in that, gyroscope and accelerometer in the described inertial navigation measurement module (2) are MEMS.

4. a kind of four-axle aircraft vision navigation system according to claim 1 is characterized in that, treatment of picture adopts optical flow analysis method and Fast Corner method in the described visual pattern processing module (4), introduces the compensation of image transmission delay simultaneously.

5. a kind of four-axle aircraft vision navigation system according to claim 1, it is characterized in that, in the described aircraft movements control module (5), adopt the location estimation of Kalman filtering algorithm fused images and inertial navigation, adopt the PID controller to realize the rotating speed control of four spindle motors.