Tracking Mirror Research Articles

A physical survey of meteoroid streams: Comparing cometary reservoirs

In this work, we present an optical survey of mm-sized meteoroids using the Canadian Automated Meteor Observatory’s (CAMO) mirror tracking system. The system tracks meteors to magnitude +7.5 through an image-intensified telescopic system which has a spatial accuracy of ∼1m and a temporal resolution of 10ms. We analyse 41 meteors from 13 showers with known parent bodies, recorded between 2016 and 2022. We fit a numerical ablation and fragmentation model to our data which models meteoroid fragmentation as erosion into 10µm to 500µm constituent grains and used the observed wake as a hard constraint on the model parameters. We measure average bulk meteoroid densities which are consistent with in situ measurements: 602 ±155kgm−3 for Jupiter-family and 345 ±48kgm−3 for Halley-type showers. The Geminids had the highest measured bulk density of 1387 ±240kgm−3, consistent with carbonaceous material. We fail to reproduce the high bulk density (>3000kgm−3) for Jupiter-family meteoroids previously reported in the literature derived using fragmentation models on data sets with fewer observational constraints. We also provide estimates of the meteoroid grain sizes, grain mass distributions, and energy necessary to trigger the erosion for meteoroids in the analysed showers.

First holistic modelling of meteoroid ablation and fragmentation: A case study of the Orionids recorded by the Canadian Automated Meteor Observatory

18 mm-sized Orionid meteoroids were captured in 2019 and 2020 by the Canadian Automated Observatory’s mirror tracking system. Meteor position measurements were made to an accuracy of ∼1m and the meteors were tracked to a limiting magnitude of about +7.5 at the faintest point. The trajectory estimation shows the intrinsic physical dispersion of the Orionid radiant is 0.400°±0.062°. An erosion-based entry model was fit to the observations to reproduce ablation and fragmentation for each meteor, simultaneously reproducing the light curve, the dynamics, and the wake. Wake observations were found to directly inform the grain mass distribution released in the modelled erosion. A new luminous efficiency model was derived from simultaneous radar and optical observations and applied in the modelling to improve its accuracy. The results show that the apparent strength of Orionids varies with radiant location and time of appearance during the period of shower activity. The average differential grain mass distribution index was 2.15, higher than found from in-situ estimates, possibly due to the evolution of the physical properties of meteoroids since ejection. All Orionids showed leading fragment morphology which was best explained by stopping the erosion at the peak of the light curve, leaving a non-fragmenting meteoroid with ∼10% of the original mass. The inverted Orionid meteoroid average bulk density of ∼300kgm−3, corresponding to porosities of ∼90%, is consistent with in-situ measurements of larger dust particles by Vega-2 at 1P/Halley and Rosetta at 67P.

A 3D Passive Laser Tracker for Accuracy Calibration of Robots

Laser trackers are usually used to measure spatial positional error of the moving targets on large-scaled objects, such as the airplane profile. It is a spherical coordinate system with a dual-axis tracking mirror actively controlled by the built-in servo system to direct the laser interferometer beam always toward the reflecting target. It is very expansive when used in testing the spatial positional accuracy of industrial robots, which are rapidly growing for factory automation in recent years. Therefore, simplified from the laser tracker structure, a 3D passive laser tracker (3DPLT) for measuring spatial trajectory of a moving target is proposed. It is composed of a 2D rotary stage and a linear telescopic mechanism with an end-ball, which can be magnetically sucked by the moving target. The rotational angles of the 2D rotary stage are measured by two respective encoders, and the radial displacement of the telescopic mechanism is detected by an equipped laser interferometer. The world coordinate of the target can be obtained by the coordinate transformation from the spherical measuring system of 3DPLT. Multibody system error modeling is used to analyze the measurement error of the instrument, and testing methods of the main error sources are also proposed. After accuracy calibration and error compensation, the measurement error of the 3DPLT is 49.2 μm, which is good enough to calibrate the spatial trajectory error of the robot.

Algorithm Design of Mirror Tracking System

In the current national defense background, the requirements for the performance of weapons are increasing day by day, the speed of the flying target and the flight state provide important parameters for the improvement of the characteristics of weapons, ballistics and ammunition. In the shooting range test, the high-speed flying target is tracked and photographed to obtain important indicators such as the flight status of the flying target in high-speed flight. This paper studies a ballistic tracking camera system based on a rotating mirror. It is composed of a system, which can track the flight trajectory of the flying target in the air in real time, and obtain important information of the flying target in flight through high-speed camera shooting. Design the mirror tracking system to capture the flight status of the flying target, analyze the flight trajectory parameters of the target through MATLAB, and optimize the accuracy and response speed of the motor control algorithm. The motor turns the mirror to reflect the flying target to the high-speed camera. The feasibility of the system is ver ifi ed. Th e tot al sc ann ing range of the system for tracking flying targets is 90°, and the scanning accuracy is ±0.5°.

Development of a very faint meteor detection system based on an EMCCD sensor and matched filter processing

The mass ranges of meteors, imaged by electro-optical (EO) cameras and backscatter radar receivers, for the most part do not overlap. Typical EO systems detect meteoroid masses down to 10− 5 kg or roughly magnitude + 2 meteors when using moderate field of view optics, un-intensified optical components, and meteor entry velocities around 45 km/sec. This is near the high end of the mass range of typical meteor radar observations. Having the same mass meteor measured by different sensor wavelength bands would be a benefit in terms of calibrating mass estimations for both EO and radar. To that end, the University of Western Ontario (UWO) has acquired and deployed a very low light imaging system based on an electron-multiplying CCD camera technology. This embeds a very low noise, per pixel intensifier chip in a cooled camera setup with various options for frame rate, region of interest and binning. The EO system of optics and sensor was optimally configured to collect 32 frames per second in a square field of view 14.7 degrees on a side, achieving a single-frame stellar limiting magnitude of mG = + 10.5. The system typically observes meteors of + 6.5. Given this hardware configuration, we successfully met the challenges associated with the development of robust image processing algorithms, resulting in a new end-to-end processing pipeline now in operation since 2017. A key development in this pipeline has been the first true application of matched filter processing to process the faintest meteors possible in the EMCCD system while also yielding high quality automated metric measurements of meteor focal plane positions. With pairs of EMCCD systems deployed at two sites, triangulation and high accuracy orbits are one of the many products being generated by this system. These measurements will be coupled to observations from the Canadian Meteor Orbit Radar (CMOR) used for meteor plasma characterization and the Canadian Automated Meteor Observatory (CAMO) high resolution mirror tracking system.

Pedestrian Re-identity Based on ResNet Lightweight Network

With the development of deep learning technology, pedestrian re-identity technology has been widely used in multi-target tracking and cross mirror tracking tasks. In this paper, the classical deep learning ResNet18 network is used for pedestrian re-identity tasks. The advantage of the network is that it can easily realize lightweight deployment. In addition, the labeled smooth cross entropy loss function and migration learning technology are used in the process of training the network, which can realize the accuracy of map 67.8 on the Market1501 data set while lightening the network, and promote the engineering landing of pedestrian re-identity network.

High precision meteor observations with the Canadian automated meteor observatory: Data reduction pipeline and application to meteoroid mechanical strength measurements

ContextThe mirror tracking system of the Canadian Automated Meteor Observatory (CAMO) can track meteors in real time, providing an effective angular resolution of 1 arc sec and a temporal resolution of 100 frames per second. AimsWe describe the upgraded hardware and give details of the data calibration and reduction pipeline. We investigate the influence of meteor morphology on radiant and velocity measurement precision, and use direct observations of meteoroid fragmentation to constrain their compressive strengths. MethodsOn July 21, 2017, CAMO observed a ~4 second meteor on a JFC orbit. It had a shallow entry angle (~8°) and 12 fragments were visible in the narrow-field video. The event was manually reduced and the exact moment of fragmentation was determined. The aerodynamic ram pressure at the moment of fragmentation was used as a proxy for compressive strength, and strengths of an additional 19 fragmenting meteoroids were measured in the same way. The uncertainty in the atmosphere mass density was estimated to be ±25% using NAVGEM-HA data. ResultsWe find that meteor trajectory accuracy significantly depends on meteor morphology. The CAMO radiant and initial velocity precision for non-fragmenting meteors with short wakes is ~0. 5′ and 1 m s−1, while that for meteors with fragments or long wakes is similar to non-tracking, moderate field of view optical systems (~5′, 50 m s−1). Measured compressive strengths of 20 fragmenting meteoroids (with less precise radiants due to their morphology) was in the range of 1–4 kPa, which is in excellent accord with Rosetta in-situ measurements of 67P. Fragmentation type and strength do not appear to be dependent on orbit. The mass index of the 12 fragments in the July 21 meteoroid was very high (s = 2.8), indicating possible progressive fragmentation.

A Measurement Noise Rejection Method in the Feedback Control System Based on Noise Observer

In the conventional feedback control system, the control accuracy is affected by the measurement noise. In this article, a novel method is proposed for the purpose of the measurement noise rejection in the single-input single-output (SISO) feedback control system. By adding an inner noise observer loop in the conventional feedback loop, we apply the “observer-based” control method into the sensor output signal processing. The proposed method is capable of reducing the measurement noise in frequencies overlapping with the control bandwidth without affecting the tracking ability of the feedback control system. Moreover, this method is simple in that its noise suppression ability is merely decided by the ${Q}$ -filter, which can be set as a constant. In addition, a necessary and sufficient condition for the system stability is presented considering the uncertainties of the real plant. It is shown that when the ${Q}$ -filter is zero, the uncertainties of the plant cannot influence the stability of the system. To verify the effectiveness, both the tracking performance and noise rejection performance of the proposed method is simulated, comparing with the conventional feedback control system. Finally, laboratory experiment is conducted with a tracking mirror control system.

Investigation of thermal concentration effect in a modified solar chimney

In solar chimney the flow of air in the system plays a dominant role. Solar chimney systems are usually large and have a low efficiency. In this research a redesigned experimental solar chimney power plant with a modified collector layout was evaluated. A tracking mirror reflector was used to enhance the thermal concentration effect underneath the chimney. The emphasis was on increasing the temperature at the transition zone between the collector and the chimney base and creating an improved overall temperature difference. Mathematical analysis of the thermal and flow behavior of the currents, under the influence of the concentration effect from the reflector, led to the development of a simulation algorithm to assist in the evaluation process. A comparative analysis was applied to investigate the effect of thermal concentration on the air flow velocity under the chimney. The indicators were the variation of the overall thermal radiation in the transition zone and the instigated temperature rise with hourly ambient temperature change. The obtained results suggested up to 10.25% increase in the maximum temperature obtained at the chimney base. This induced a maximum air flow velocity improvement of 22.22%. The impeding effect of density reduction at the considered temperature range was checked against the total theoretical output power. At peak output when the power scored 56.867% rise from the average for the day, air flow velocity showed 25.316% increase while the air density was reduced by only 2.069% from the mean values for the day.

单反式光端机反射镜柔性支撑参数化设计与试验

In order to ensure the surface accuracy of the Pointing, Acquisition and Tracking (PAT) mirror in the harsh space environment, a flexible support structure with grooves on the bottom was designed. Due to the large number of parameters of flexible support structure, in order to avoid serious coupling between parameters, the orthogonal optimization method was used to optimize the parameters of flexible support structure, and then the finite element method was used to analyze the mechanical and thermal characteristics of mirror components. The simulation results show that the first-order frequency of the mirror module is 352.61 Hz, and the maximum surface error RMS under the combined action of 1 g gravity and 10 ℃ temperature rise (temperature drop) is λ/54.79(λ=632.8 nm), which can satisfy the dynamic and static stiffness and thermal dimensional stability. The ZYGO interferometer is used to detect the mirror surface shape in the temperature range of (20±10) ℃. The results show that the PV value of the mirror surface is better than λ/6, and the RMS is better than λ/43, which meets the requirement of RMS≤λ/40. The experimental results show that the design of flexible support parameters is reliable and meets the application requirements.

Experimental studies on efficiency enhancement of the parabolic solar collector combined with mirrors using the artificial neural network

ABSTRACT Solar energy has become the most promising renewable energy nowadays. To achieve best possible performance from a solar system, the photovoltaic panel is required to absorb maximum radiation in the possible effective way. More the radiation on panel results in more amount of electricity. The primary goal of the paper is to increase the amount of radiation using mirror and auto tracking arrangement to allow more rays to be concentrated on a small area, i.e. on a photovoltaic panel by introducing a new platform made in a shape of parabolic which is adjusted to follow the sun. Mirrors are going to be attached on a flat shaped frame with the PV panel at an angle of 120°, during the day for the purpose of reflection of maximum amount of radiation on the PV cells. Artificial neural network control is proposed to decide the exact maximum power point while tracking the sun. Due to the mirror effect all the rays will be concentrated on a small area of the photovoltaic panel which is fixed at the focus of the parabola. The nearest position while receiving direct sunlight is considered as the input taken from the database. This process minimises the number of motors for starting and results in reduced quantity of loss of energy in different weather conditions. The comparison has been studied for a fixed PV panel and this new PV panel with mirror and results are tabulated. The results show an increase of 32% in average efficiency by using the mirror and tracking system using the artificial neural networks technique.

MEMS tracking mirror system for a bidirectional free-space optical link.

We report on a bidirectional free-space optical system that is capable of automatic connection and tracking of an optical link between two nodes. A piezoelectric micro-electro-mechanical systems (MEMS) optical scanner is used to steer a laser beam of two wavelengths superposed to visually present a communication zone, to search for the position of the remote node by means of the retro-reflector optics, and to transmit the data between the nodes. A feedback system is developed to control the MEMS scanner to dynamically establish the optical link within a 10-ms transition time and to keep track of the moving node.

Improved Smith predictor control for fast steering mirror system

In this paper, a novel Smith predictor control strategy improved by a high bandwidth inner loop for fast steering mirror (FSM) tracking control system based on a charge-coupled device (CCD) and rate sensor is proposed. A high bandwidth velocity closed-loop constructed by a fiber-optic gyroscope is utilized to provide a robust controlled plant for the Smith predictor controller. Usually, due to the mechanical resonances and time delay induced by a low CCD sampling rate, the tracking performance of FSM system is insufficient when suffering uncertain input command. Therefore, the Smith predictor control, which is famous for its delay-free characteristic and suitable for regulating systems with an excessively long time delay, is recommended to compensate for the CCD time delay. However, the classical Smith predictor is sensitive to plant parameter variations, which could deteriorate the stability of the control system. Thus, in order to make a robust Smith predictor, a cascaded dual closed-loop including a high bandwidth velocity inner loop is introduced to reduce the influence of plant parameter variations. The low sensitivity to parameter variation of this method shows the significant improvement of the conventional Smith predictor control. Simultaneously, the analysis of tracking accuracy and the bandwidth of the FSM system is also presented. A series of comparative experimental results demonstrate that the tracking performance of the FSM control system can be effectively improved by the proposed approach.

MEMS Inertial Sensors-Based Multi-Loop Control Enhanced by Disturbance Observation and Compensation for Fast Steering Mirror System.

In this paper, an approach to improve the disturbance suppression performance of a fast steering mirror (FSM) tracking control system based on a charge-coupled device (CCD) and micro-electro-mechanical system (MEMS) inertial sensors is proposed. The disturbance observation and compensation (DOC) control method is recommended to enhance the classical multi-loop feedback control (MFC) for line-of-sight (LOS) stabilization in the FSM system. MEMS accelerometers and gyroscopes have been used in the FSM system tentatively to implement MFC instead of fiber-optic gyroscopes (FOG) because of its smaller, lighter, cheaper features and gradually improved performance. However, the stabilization performance of FSM is still suffering a large number of mechanical resonances and time delay induced by a low CCD sampling rate, which causes insufficient error attenuation when suffering uncertain disturbances. Thus, in order to make further improvements on the stabilization performance, a cascaded MFC enhanced by DOC method is proposed. The sensitivity of this method shows the significant improvement of the conventional MFC system. Simultaneously, the analysis of stabilization accuracy is also presented. A series of comparative experimental results demonstrate the disturbance suppression performance of the FSM control system based on the MEMS inertial sensors can be effectively improved by the proposed approach.

Application of MEMS Accelerometers and Gyroscopes in Fast Steering Mirror Control Systems.

In a charge-coupled device (CCD)-based fast steering mirror (FSM) tracking control system, high control bandwidth is the most effective way to enhance the closed-loop performance. However, the control system usually suffers a great deal from mechanical resonances and time delays induced by the low sampling rate of CCDs. To meet the requirements of high precision and load restriction, fiber-optic gyroscopes (FOGs) are usually used in traditional FSM tracking control systems. In recent years, the MEMS accelerometer and gyroscope are becoming smaller and lighter and their performance have improved gradually, so that they can be used in a fast steering mirror (FSM) to realize the stabilization of the line-of-sight (LOS) of the control system. Therefore, a tentative approach to implement a CCD-based FSM tracking control system, which uses MEMS accelerometers and gyroscopes as feedback components and contains an acceleration loop, a velocity loop and a position loop, is proposed. The disturbance suppression of the proposed method is the product of the error attenuation of the acceleration loop, the velocity loop and the position loop. Extensive experimental results show that the MEMS accelerometers and gyroscopes can act the similar role as the FOG with lower cost for stabilizing the LOS of the FSM tracking control system.

Horizontal Trajectory Tracking System Based On Rotating Mirror

abstract Target track is an important research dot in weapon performance testingfiled, to stable track the flying target in optical detection system and testing instrument, horizontal trajectory tracking system based on rotating mirror was researchedin this paper.A horizontal trajectory tracking method was proposed for the tracking problem in the process of the projectile flight, the design of rotating mirror was analyzed and designed;the calculation method of the rotating mirror tracking system were derived, and the influence factors were studied and analyzed, the rotating mirror rotation control algorithm without considering effect of gravity flight targetwasanalyzed and the angular displacement and angular velocity of the rotating mirror were given in the effective tracking range. Through experiment and calculation, the results show that the tracking system can achieve stable tracking of flying target

200kW 타워형 태양열발전시스템의 헬리오스타트 필드 운영 알고리즘 개발

Heliostat field in a tower type solar thermal power plant is the sun tracking mirror system which affects the overall efficiency of solar thermal power plant most significantly while consumes a large amount of energy to operate it. Thus optimal operation of it is very crucial for maximizing the energy collection and, at the same time, for minimizing the operating cost. Heliostat field operational algorithm is the logics to control the heliostat field efficiently so as to optimize the heliostat field optical efficiency and to protect the system from damage as well as to reduce the energy consumption required to operate the field. This work presents the heliostat field operational algorithm developed for the heliostat field of 200kW solar thermal power plant built in Daegu, Korea. We first review the structure of heliostat field control system proposed in the previous work to provide the conceptual framework of how the algorithm developed in this work could be implemented. Then the methodologies to operate the heliostat field properly and efficiently, by defining and explaining the various operation modes, are discussed. A simulation, showing the heat flux distribution collected by the heliostat field at the receiver, is used to show the usefulness of proposed heliostat field operational algorithm.

A Simple Approach in Estimating the Effectiveness of Adapting Mirror Concentrator and Tracking Mechanism for PV Arrays in the Tropics

Mirror concentrating element and tracking mechanism has been seriously investigated and widely adapted in solar PV technology. In this study, a practical in-field method is conducted in Serdang, Selangor, Malaysia, for the two technologies in comparison to the common fixed flat PV arrays. The data sampling process is measured under stochastic weather characteristics with the main target of calculating the effectiveness of PV power output. The data are monitored, recorded, and analysed in real time via GPRS online monitoring system for 10 consecutive months. The analysis is based on a simple comparison of the actual daily power generation from each PV generator with statistical analysis of multiple linear regression (MLR) and analysis of variance test (ANOVA). From the analysis, it is shown that tracking mechanism generates approximately 88 Watts (9.4%) compared to the mirror concentrator which generates 144 Watts (23.4%) of the cumulative dc power for different array configurations at standard testing condition (STC) references. The significant increase in power generation shows feasibilities of implying both mechanisms for PV generators and thus contributes to additional reference in PV array design.

基于旋光-双反射结构的星载量子密钥分发精跟踪系统控制算法研究

The polarization of reflected light was studied when the polarimetry-double reflection structure was used as a fine tracking system in the satellite based quantum key distribution terminal.The polarization variation of reflected light caused by the inconformity of two light plans(which was confirmed by incident light and reflected light)was analyzed.The quantum bit error rate was calculated.Base on the characteristics of this reflection structure,the relationship between the normal directions of two mirrors and the vectors of incident light and reflected light was given.The control algorithm was presented when this reflection structure was used as a fine tracking mirror.

Strapdown Mirror Control Technology

This paper has described the status and role of the strapdown mirror control technology. It has analyzed the emphasis and difficulty in the study. In order to achieve higher system reliability and improve performance and eliminate all kinds of error of strapdown stable platform process what are stabilization while reducing the volume. In-depth analysis of the swing ship is on strapdown platform and mirror effect. The boat rocking and the sight stabilization mathematical model of mirror rotating. A study on the simulation what uses the MATLAB. By establishing the model of boat rocking, what analysis of the swings influence on the mirror steady accuracy and tracking accuracy. The existing stable servo control and principle has been detailed analysis. Through the simulation studies what compared their advantages and disadvantages. Also it has studied the coning error compensation method and the kalman filtering what influenced on the accuracy of strapdown mirror control system.