Research On Key Technology Of High-speed And Multi-dimensional Moving Target Pose Measurement

The core equipment and components in the field of aviation mostly require high locomotion capacity.In order to guarantee that major equipment in this area maintains good performance such as high accelerating ability,high maneuverability,and multidimensional controllability in complex environmental conditions such as high speed,weightlessness and strong flow field interference,measurement of the position and attitude,with high accuracy and high robustness,must be conducted.For example,in order to guarantee the ability of the new generation of high speed aircraft,China has launched the research on the stable suspension and the safe delivery of loads.However,due to the disturbances of high-speed flow,the successful separation of loads and aircraft cannot be guaranteed,and there even exists the possibility that loads might hit the aircraft after separation.Therefore,in order to optimize the structure and performance of high-speed aircraft delivery system and reduce the risk of this process,wind tunnel simulation experiment has become a particularly important means.In the wind tunnel simulation experiment,in order to obtain the separation characteristics of aircraft load,it is necessary to realize high-precision measurement of the six dimensional pose information of the high-speed moving target after its separation under complex wind tunnel environment.The vision measurement,with its advantages of high sample frequency,strong environmental adaptability and noncontact measurability,is widely utilized in the pose measurement of moving object under wind tunnel environment.The characteristics of wind tunnel measurement environment,however,often includes strong flow interference,low illuminance and cross media.What is more,the targets of the measurement tend to include the undesirable characteristics of fast moving,small volume and large moving space,which bring obstacles to realize the high-speed,high-precision,large scale and multi-dimensional measurement of high-speed moving target in complex environment.These difficulties seriously restrict the upgrading of high speed aircraft mounting and combat capability.Thus,in order to solve the aforementioned difficulties,the specific research contents are developed as follows:(1)After considering the complex environmental characteristics of wind tunnel,such as dark narrow space,intense vibration and strong airflow,a research is conducted to reveal the relationship between parameters,such as the angle of incident light,and image quality of micro glass bead composite,and to present a high speed serial image acquisition method containing complex pose information of targets with which the high speed data acquisition of high speed small targets under the condition of strong vibration and narrow space is realized.In addition,the detection and location technology of the ultra-thin micro glass bead hybrid material marks is proposed and applied to realize the accurate detection,positioning and attaching of patterns on the surface of the measured object.The pattern thickness is only 60um.Moreover,in order to evaluate the image acquisition quality of high-speed dynamic moving object,a quality evaluation method of high speed serial image utilizing SNR model,is applied to evaluate the image acquired by the acquisition method provided in this article.The result shows that the signal to noise ratio of the sequence image,acquired by the ultra-high speed data acquisition method in wind tunnel environment,is higher than 3,which meets the measurement requirement and forms the foundation of the dynamic measurement of high speed targets in complex environment.(2)In order to solve the problem of image distortion which is caused by the multiple optical media whose refractive index is not consistent and exerts a negative influence on the measurement accuracy,a multi-refraction camera imaging model considering the complexity of cross-media environment is proposed.Furthermore,a binocular stereo vision theory in cross-media environment is presented,and the spatial relation of the two camera is studied and established.On this basis,a calibration technology in cross-media environment based on planar target is proposed,which successfully achieves a high calibration precision.The experimental results show that by using the calibration proposed in this paper,the measurement accuracy of the visual system is improved by 35%.(3)Because of the large amount of data and the lack of conspicuity of image features in high-speed multi target sequence images,it is difficult to have the image processed accurately.In order to solve this problem,the method of restoring image for high-speed moving targets with six dimensional pose information is studied.First,aiming at the problems of small imaging area,inadequacy of obvious shape and gray features,an image feature matching method based on trajectory is proposed.The method has the advantages of high precision and efficiency.Second,in order to solve the hiding problem caused by the rolling of the targets,a reasonable spatial design of mark points on target surface is conducted,and an identification method based on cooperatively encoded spatial marks is presented.Third,in order to solve the problem of low precision caused by large deformation,large lens distortion and low resolution of ultra-high speed cameras,a pose parameter optimization method based on prior knowledge model is proposed.The laboratory verification result shows that compared with the original system,the accuracy of the optimized measurement system is improved by 33%,which ensures the accuracy and stability of the high speed moving target pose measurement system.Finally,utilizing the aforementioned key technology,a high-precision dynamic multidimensional pose measurement system is built,which possesses position measurement RMS error less than 0.103mm,pitch and yaw angle measurement RMS error less than 0.107 degree and the roll angle measurement RMS error less than 0.65 degree.The measuring frequency can reach 5000Hz,and the measurement range is 800mm × 800mm × 300mm.then the wind tunnel.Furthermore,high speed moving target pose measurement experiments in wind tunnels are conducted.The six dimensional pose information of the targets with the initial speed of 8m/s is measured by the measurement system under the condition of both the transonic flow and the supersonic flow.And then the six dimensional pose information of the targets measure with the initial velocity of 2m/s and large roll angle is measured under the condition of subsonic airflow.The measurement results show that the measurement system is fast,and the measurement results are stable which indicates the high robustness of the system.