Extremely wide view of the omni-vision performs highly advanced for the vehicle navigation and target detection. However moving targets detection through omni-vision fixed on AGV (Automatic Guided Vehicle) involves more complex environments, where both the targets and the vehicle are in the moving condition. The moving targets will be detected in a moving background. After analyzing the character on omniorientational vision and image, we propose to use the estimation in optical flow fields, Gabor filter over optical flow fields for detecting moving objects. Because polar angle θ and polar radius R of polar coordinates are being changed as the targets moving, we improved optical flow approach which can be calculated based on the polar coordinates at the omniorientational center. We constructed Gabor filter which has 24 orientations every 15°, and filter optical flow fields at 24 orientations. By the contrast of the Gabor filter images at the same orientation and the same AGV position between the situation which there aren't any moving targets in the environment and the situation which there are some moving targets in the same environment, the moving targets' optical flow fields could be recognized. Experiment results show that the proposed approach is feasible and effective.
To detect and recognize multi-targets in the sequence image tracking system a new method is proposed. Moving targets were separated from the background by difference of multi-frame. According to the dynamic threshold table the image was made binary, then invariant characteristics were extracted from every target. These characteristics were used for recognition of targets by BP neural network. The result of computer simulation shows that the method is practical and has high speed in detection and recognition for moving multi-targets.
In this system, the segmented-mirror consists of three submirrors. They are hexagonal with 250 mm diagonal. The shape of each submirror is spherical with 3000 mm radius and the departure of each radius from the mean radius is less than 0.025 mm. A special S-H test device is used for co- focus measurement. It includes nine sub-apertures in three groups and each group is for a submirror. There are six displacement actuators in this system. The based unites of it are flexure hinges. The actuator is driven by a stepping motor with ten subdivisions. Six capacity displacement sensors are used in this experiment system. It is made in Tianjin University. A computer is used for data collecting, calculating and controlling. A special method for co-focus is developed in our work. By using this method the error of co-focus, i.e. the tilt error of submirror, is less than rms 0.035 arcseconds. The methods of calibration and maintaining for co-phase are also introduced in this paper. After once calibration, the diffraction limit image can be observed in about 220 mm aperture at (lambda) 650 nm, and it can be maintained about 20 minutes.
In this system, the experiment mirror has 500 mm aperture and 6 mm thickness. There are 58 actuators and three fixed points in it. A Shack-Hartmann test apparatus is used for the measurement of wavefront aberration. In this apparatus an ingenious equivalent of lenslet array is used. All image points formed by it appear very clear theoretical diffraction pattern. And a CCD from a TV camera is used. Like European Southern Observatory, we use quasi-Zernike polynomial to fit the wavefront aberration for correcting. But in our work correction is to the whole wavefront aberration (except lateral focus and longitudinal focus). In our work, another important character is that the damp least square method is used for determining the forces. The correction results are the root mean square of wavefront aberration about 0.02 - 0.04 micrometers . A circle including measuring and correcting the wavefront aberration takes about 3.3 minutes. A more precise algorithm proposed by us is used for calculating the wavefront aberration for checking.
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