CN103630138A

CN103630138A - Unmanned aerial vehicle visual navigation method based on camera head calibration algorithm

Info

Publication number: CN103630138A
Application number: CN201310681795.2A
Authority: CN
Inventors: 成怡
Original assignee: Tianjin Polytechnic University
Current assignee: Tianjin Polytechnic University
Priority date: 2013-12-09
Filing date: 2013-12-09
Publication date: 2014-03-12

Abstract

The invention belongs to the field of visual navigation and particularly relates to an unmanned aerial vehicle visual navigation method based on a camera head calibration algorithm. By utilizing the camera head calibration algorithm as well as the result of template corner point detection, the position solution of a carrier is achieved, and data fusion with parameters of an inertial navigation system is realized by use of a UKF ((Unscented Kalman Filter), so that the errors of the inertial navigation system are corrected by visual navigation information to obtain accurate navigation coordinates. The visual navigation method is suitable for the characteristics of high positioning accuracy, miniaturization and low cost of small-sized and medium-sized unmanned aerial vehicles, and has theoretical and practical values.

Description

Unmanned plane vision air navigation aid based on camera head calibration algorithm

Technical field

The invention belongs to vision guided navigation field, relate to a kind of unmanned plane vision air navigation aid based on camera head calibration algorithm, special high position precision, microminiaturization and requirement cheaply for SUAV (small unmanned aerial vehicle).

Background technology

In recent years, " predator ", " global hawk ", the A160 of unmanned plane (UAV) the increasingly important ，Ru of effect U.S. development militarily, the HALE unmanned plane of the “Ying”， Western European countries (EADS company) of France.The Unmanned Aerial Vehicle Powerplants of the U.S. is 1 two-way turbojet engine, and control system adopts inertia+" nautical star " space radio guidance system data correcting mode.Onboard modules reconnaissance equipment comprises side-looking radar, electro optical reconnaissance system, radio technique reconnaissance and radio electronics countermeasurer, integration data reception and transmission system, ATACCS target designation system (TDS), forwarding unit etc.Maritime version also will be equipped with the scanning radar of water surface moving target selective system.U.s.a. military affairs expert is by analyzing the effect use experience of the Global Hawk unmanned air vehicle, find that this machine also has a series of shortcomings, the weight and volume that is mainly useful load is limited, and energy resource system underpower sets out to guarantee that all reconnaissance equipments move simultaneously at every turn.Therefore, with respect to large-scale warplane, unmanned plane requires to have low cost, small size, low-power consumption, high-precision feature, so that its transportation, transmitting and recovery.

Advanced navigational system is to determine that unmanned plane completes the key of combat duty, raising viability.Nearly ten years, no matter in location, tracking, still in the development aspect autonomous information processing and unmanned plane load, make substantial progress, as Modern Satellite airmanship, inertial navigation system, communication and monitoring technique etc., in addition, new visually-perceptible and treatment facility are also provided on unmanned plane.In order to execute the task in complex environment the unknown, dynamic change, in most of the cases, unmanned plane is used GPS (GPS) navigator fix and inertial navigation system (IMU).The estimated accuracy of GPS directly depends on that the quantity of the satellite that participates in location and receiving equipment receive the quality of signal and the impact in radio station.In addition, the radio frequency interference of neighbouring device or channel stop up all may cause the unreliable of location estimation, and these problems are ubiquities and are difficult to solve.When cannot using or obtain effective gps signal, the navigational system of unmanned plane can only rely on inertial navigation system, and high-precision inertial navigation system is fixed against high-precision sensor, and this has increased cost on the one hand, has increased on the one hand the load of unmanned plane.In addition, because the growth in time of the site error of inertial navigation system accumulates, so must be proofreaied and correct by external information, if carried as settings such as radio, laser scanners, for middle-size and small-size unmanned plane (MUAV), load weight is a maximum constraints.And vision sensor is lightweight, power consumption is little, detection range is far away, resolution is high, be the preferred load of middle-size and small-size unmanned plane vision navigation.

Therefore, the present invention is intended to research and how utilizes visual information aided inertial navigation system, the unmanned plane vision air navigation aid research that proposition is demarcated based on camera head, for the high position precision of applicable middle-size and small-size unmanned plane, microminiaturization and feature cheaply, has theory and practical value just.

Summary of the invention

The location technology of primary study unmanned plane vision navigational system of the present invention.Solution utilizes Camera Calibration Algorithm camera coordinates, thereby calculates carrier positions, solves the problem of data fusion of visual information and inertial navigation system parameter, realizes the correction of visual information to INS errors, obtains accurate navigation coordinate.Concrete research approach as shown in Figure 1.Main contents are as follows:

1) based on camera head calibration algorithm, realizing carrier positions resolves;

2) design UKF wave filter is estimated the position of the motion state of unmanned plane and visual signature, thereby obtains the navigational parameter of unmanned plane.

Accompanying drawing explanation

Fig. 1 is research approach figure of the present invention.

Fig. 2 is the principle that visual information and inertial navigation parameter are merged in UKF filtering of the present invention.

Embodiment

The specific design thinking of key link is as follows:

(1) based on camera head calibration algorithm, realizing carrier positions resolves

By 3 steps, complete:

A) set up each coordinate system of system: set up world coordinate system (x _w, y _w, z _w), carrier coordinate system (x _o, y _o, z _o), (x of camera coordinates system _c, y _c, z _c), phase plane coordinate (x, y), image coordinate (u, v).

B) Corner Detection of camera calibration template: utilize harris Corner Detection Algorithm, detect the position coordinates of angle point in template.

C) camera inside and outside parameter matrix M ₁, M ₂resolve: by angle point two-dimensional coordinate and three-dimensional coordinate, according to formula 1, resolve the interior place parameter matrix of camera, thereby calculate the coordinate of carrier under world coordinate system.

z_{c} = [\begin{matrix} u \\ v \\ 1 \end{matrix}] = [\begin{matrix} a_{x} & 0 & u_{0} & 0 \\ 0 & a_{y} & v_{0} & 0 \\ 0 & 0 & 1 & 0 \end{matrix}] [\begin{matrix} R_{3 \times 3} & t_{3 \times 1} \\ 0 & 1 \end{matrix}] [\begin{matrix} x_{w} \\ y_{w} \\ z_{w} \\ 1 \end{matrix}] = M_{1} M_{2} X_{w} - - - (1)

(2) data fusion based on UKF filtering

Utilize UKF wave filter to merge visual information correction inertial navigation system measuring error.Definition unmanned plane deflection is (φ, θ, ψ), and gyro bias is (b _p, b _q, b _r), visual information is (φ _v, θ _v, ψ _v), system state variables is selected x=[φ θ ψ b _pb _pb _r] ^t, observational variable is selected [φ _vθ _vΨ _v], set up state equation and the observation equation of system, utilize UKF filtering recurrence equation to estimate the position and attitude information of carrier, the principle that merges visual information and inertial navigation parameter based on UKF filtering is as shown in Figure 2.

The invention has the advantages that, the navigational system that navigation video camera and MEMS inertial navigation device form is with low cost, and volume is little, easy to operate, precision is high, meets the needs of the aspect such as load, size, power, cost of SUAV (small unmanned aerial vehicle), has a good application prospect.

Claims

1. the unmanned plane vision air navigation aid based on camera head calibration algorithm is utilized resolving of camera head calibration algorithm camera position, thereby provide carrier positions information, and adopt the data fusion of UKF filtering realization and inertial navigation system parameter, thereby realize the correction of vision guided navigation information to INS errors, obtain accurate navigation coordinate.

2. the unmanned plane vision air navigation aid based on camera head calibration algorithm according to claim 1, is characterized in that, adopts camera head calibration algorithm to realize the location compute of carrier.

3. the unmanned plane vision air navigation aid based on camera head calibration algorithm according to claim 1, is characterized in that, design UKF wave filter is estimated the position of the motion state of unmanned plane and visual signature.