Optoelectronic Tracking Research Articles

Feedforward Control Based on Error and Disturbance Observation for the CCD and Fiber-Optic Gyroscope-Based Mobile Optoelectronic Tracking System

In the mobile optoelectronic tracking system (MOTS) based on charge-coupled device (CCD) and fiber-optic gyroscope (FOG), the tracking performance (TP) and anti-disturbance ability (ADA) characterized by boresight error are of equal importance. Generally, the position tracking loop, limited by the image integration time of CCD, would be subject to a non-negligible delay and low-sampling rate, which could not minimize the boresight error. Although the FOG-based velocity loop could enhance the ADA of the system, it is still insufficient in the case of some uncertain disturbances. In this paper, a feedforward control method based on the results of error and disturbance observation was proposed. The error observer (EOB) based on the CCD data and model output essentially combined the low-frequency tracking feedforward and closed-loop disturbance observer (DOB), which could simultaneously enhance the low-frequency TP and ADA. In addition, in view of the poor low-frequency performance of the FOG due to drift and noise that may result in the inaccuracy of the observed low-frequency disturbance, the FOG-based DOB was used to improve the relatively high-frequency ADA. The proposed method could make EOB and DOB complementary and help to obtain a high-precision MOTS, for in practical engineering, we give more attention to the low-frequency TP and full-band ADA. Simulations and experiments demonstrated that the proposed method was valid and had a much better performance than the traditional velocity and position double-loop control (VPDC).

Kinematic differences between children with obstetric brachial plexus palsy and healthy controls while performing activities of daily living

BackgroundResidual shoulder dysfunction and deformity impacts on functional performance in children with obstetric brachial plexus palsy. Clinical understanding of upper limb dynamic movement patterns is difficult with observation alone. This case-control study describes the significant kinematic differences between children with obstetric brachial plexus palsy compared to typically developing children while performing tasks of the modified Mallet Scale. MethodsEleven children with obstetric brachial plexus palsy (mean 10 years, range 7–15 years, Narakas group I-III) and 10 typically developing children (mean 9 years 9 months, range 6–15 years) completed three-dimensional upper limb motion analysis using the acromion method to track dynamic scapular movement. Kinematic data were captured by a 4-CODA cx1 optoelectronic tracking system. Participants performed three trials of the modified Mallet scale tasks. Local coordinate systems, segment and joint rotations were defined as recommended by the International Society of Biomechanics. FindingsJoint rotation angles against time of the glenohumeral, thoracohumeral and scapulohumeral joints were calculated. Kinematic findings demonstrated increased internal rotation in all postures, reduced glenohumeral excursion, habitual “trumpet” posture of glenohumeral abduction/elevation and variability in movement strategies. Scapulohumeral rhythm during abduction task was 1.88:1 in typically developing children and 1.04:1 in children with obstetric brachial plexus palsy. InterpretationChildren with obstetric brachial plexus palsy demonstrate deficient external rotation in all tasks. Despite increased postural internal rotation, ability to move through internal rotation range is compromised. The glenohumeral joint showed the greatest range deficit, contributing to abnormal scapulohumeral rhythm. Future sub-group analysis of Narakas Classification is recommended.

Robust adaptive integral backstepping control for opto-electronic tracking system based on modified LuGre friction model

This paper presents a robust adaptive integral backstepping control strategy with friction compensation for realizing accurate and stable control of opto-electronic tracking system in the presence of nonlinear friction and external disturbance. With the help of integral control term to decrease the steady-state error of the system and combining robust adaptive control approach with the backstepping design method, a novel control method is constructed. Nonlinear modified LuGre observer is designed to estimate friction behavior. Robust adaptive integral backstepping control strategy is developed to compensate the changes in friction behavior and external disturbance of the servo system. The stability of the opto-electronic tracking system is proved by Lyapunov criterion. The performance of robust adaptive integral backstepping controller is verified by the opto-electronic tracking system with modified LuGre model in simulation and practical experiments. Compared to the adaptive integral backstepping sliding mode control method, the root mean square of angle error is reduced by 26.6% when the proposed control method is used. The experiment results demonstrate the effectiveness and robustness of the proposed strategy.

Improved kernelized correlation filter algorithm and application in the optoelectronic tracking system

In order to improve the tracking accuracy and real-time performance of the optoelectronic tracking system, an improved kernelized correlation filter approach is developed to obtain precise tracking of a maneuvering object. The proposed strategy contains merits of adaptive threshold approach, kernelized correlation filter method, and Kalman filter algorithm. The adaptive threshold approach can choose the suitable threshold in accordance with the size of the target in the image to improve the tracking performance of the kernelized correlation filter method. When the change between previous position and current position is larger than the distance threshold, Kalman filter algorithm is used to predict the target position for tracking. The tracking accuracy of the proposed algorithm is improved by updating the prediction of the target position with a trusted algorithm. The experimental results on comparison with some state-of-the-art trackers, such as kernelized correlation filter; Tracking-Learning-Detection; scale adaptive with multiple features; minimum output sum of squared error; and dual correlation filter, demonstrate that the proposed approach has the effectiveness of tracking accuracy and real-time performance in tracking the maneuvering object.

Adaptive integral backstepping sliding mode control for opto-electronic tracking system based on modified LuGre friction model

ABSTRACTIn order to improve the control accuracy and stability of opto-electronic tracking system fixed on reef or airport under friction and external disturbance conditions, adaptive integral backstepping sliding mode control approach with friction compensation is developed to achieve accurate and stable tracking for fast moving target. The nonlinear observer and slide mode controller based on modified LuGre model with friction compensation can effectively reduce the influence of nonlinear friction and disturbance of this servo system. The stability of the closed-loop system is guaranteed by Lyapunov theory. The steady-state error of the system is eliminated by integral action. The adaptive integral backstepping sliding mode controller and its performance are validated by a nonlinear modified LuGre dynamic model of the opto-electronic tracking system in simulation and practical experiments. The experiment results demonstrate that the proposed controller can effectively realise the accuracy and stability control of opto-electronic tracking system.

Compensating Unknown Time-Varying Delay in Opto-Electronic Platform Tracking Servo System.

This paper investigates the problem of compensating miss-distance delay in opto-electronic platform tracking servo system. According to the characteristic of LOS (light-of-sight) motion, we setup the Markovian process model and compensate this unknown time-varying delay by feed-forward forecasting controller based on robust H∞ control. Finally, simulation based on double closed-loop PI (Proportion Integration) control system indicates that the proposed method is effective for compensating unknown time-varying delay. Tracking experiments on the opto-electronic platform indicate that RMS (root-mean-square) error is 1.253 mrad when tracking 10° 0.2 Hz signal.

Reliability of 3D upper limb motion analysis in children with obstetric brachial plexus palsy

Kinematics, measured by 3D upper limb motion analysis (3D-ULMA), can potentially increase understanding of movement patterns by quantifying individual joint contributions. Reliability in children with obstetric brachial plexus palsy (OBPP) has not been established.Objective: This study aimed to determine between session reliability and measurement errors of 3D-ULMA using the acromion method (AM) in children with OBPP.Approach: Ten participants (mean 10 years, range 7–15 years, Narakas classification I–III) completed 3D-ULMA on two occasions, mean interval of 8.6 d (±2.8 d). Kinematic data were captured by a 4-CODA cx1 optoelectronic tracking system. Participants performed three trials of the modified Mallet scale tasks. Local coordinate systems, segment and joint rotations were defined as recommended by the International Society of Biomechanics. The intraclass correlation coefficient (ICC 2,K) and standard error of measurement (SEM) were calculated for task duration, range and joint angle at point of task achievement (PTA).Main Results: Results indicated poor reliability for spatiotemporal parameters and range. Moderate to excellent reliability at PTA was observed in 19/60 variables (ICC: 0.77–0.98; SEM: 3.5°–10.4°). The Abduction Task had the highest (ICC: 0.79–0.98; SEM: 3.5°–10.3°) with External Rotation the lowest reliability. Glenohumeral and thoracohumeral elevation had the most consistent reliability. Scapular protraction/retraction had consistently poor reliability (ICC: 0–0.72; SEM: 3.5°–10.2°) with axial rotation also poor (ICC: 0.00–0.91; SEM: 6.3°–32.8°).This study determined inconsistent test–retest reliability of 3D-ULMA, using AM, to track dynamic performance of functional tasks in children with OBPP. It is the first study to outline measurement error in this population. This information permits more reliable interpretation of future studies of kinematic patterns in children with OBPP.

Low-noise and high-gain Brillouin optical amplifier for narrowband active optical filtering based on a pump-to-signal optoelectronic tracking.

We implement and characterize an optical narrowband amplifier based on stimulated Brillouin scattering with pump-to-signal relative frequency fluctuations overcome thanks to an active pump tracking. We achieve a precise characterization of this amplifier in terms of gain and noise degradation (noise figure). The performances of this stable selective amplification are compared to those of a conventional erbium-doped fiber amplifier in order to highlight the interest of the Brillouin amplification solution for active narrow optical filtering with a bandpass of 10MHz. Thanks to the simple optoelectronic pump-to-signal tracking, the Brillouin active filter appears as a stable and reliable solution for narrowband optical processing in the coherent optical communication context and optical sensor applications.

一种提高光电跟踪设备捕获概率的搜索方法

一种提高光电跟踪设备捕获概率的搜索方法

光电跟踪转台的控制模型辨识

光电跟踪转台的控制模型辨识

Integrated design method of control loop in optoelectronic tracking system

Integrated design method of control loop in optoelectronic tracking system

一种提高光电跟踪设备捕获概率的搜索方法

一种提高光电跟踪设备捕获概率的搜索方法

Mean-shift跟踪算法及其在光电跟踪系统中的应用

Mean-shift跟踪算法及其在光电跟踪系统中的应用

最小节拍组合控制方法在光电跟踪系统中的应用

As the minimal prototype control system has fast response,smaller overshoots and smaller stable errors,it is suitable for a photo-electric tracking system to capture targets.Therefore,this paper designs a minimal prototype control system for a photo-electric tracking frame and also performs simulation and experimental tests。The experiments show that the simulation results are coincident with that of experiments well,which not only demonstrates that the minimal prototype control system is a linear system in the certain region of tracking signal,but also indicates the influences of a correction part and a front filter.This control method reduces overshoot and adjusting time,inhibits the jitter effect of system.These all show that minimal prototype control method can be used to acquire fast targets in digital guiding and is valuable in the project application for opto-electronic tracking systems.

Study on Robust Control Technology of Opto-Electronic Tracking System

Classic control algorithm can improve dynamic performance of opto-electronic tracking system, but the tracking system often has little robust performance. From the standpoint of inproving robust performance, modern robust control technology was adopted to design the controller of opto-electronic tracking system in this paper. On the basis of considering the system tracking precision requirement and main disturbance, the mathematical model of the system augmented objict was established. By repeatly testing, the suitable weighted functions were selected. Finally, the robust controller of opto-electronic tracking system was designed by synthesis method of modern robust control theory. The simulation result shows that the adjusting time of the system is 0.3S, and it can satisfy the requirements of the tracking speed. Robust controller has improved the system dynamic response characteristics and makes the system fast and no overshoot, and the opto-electronic tracking system has stronger robust stability and robust performance.

光电跟踪系统纯角度滤波器的设计

To improve the precision of an opto-electronic tracking system without installing new equipment,an assistant tracking with surplus angle information was carried out and a filter tracking only by angle information was designed.Firstly,the working principle of the opto-electronic tracking system with a laser-infrared detector was introduced,and a target model based on the current statistical model was established in a globe-coordinate.Considering the complex noise interference in the high frequency image series in a angle track process,the set-membership estimation was introduced to repair the maneuvering model,then a self-adjusted ellipsoidal bounding filter whose tracking was only by angle was designed.Finally,a simulation on the course tracking to enemy targets was performed by the opto-electronic system on the ship.The comparison results show when the laser detector probability decreases to fifty percent,the filter designed by ellipsoidal bounding algorithm could track the maneuvering target stably with a Room Mean Square Error(RMSE) of target angle less than 0.6 mrad.The filter could overcome the effect of non-white noises and has some practical values in engineering.

A Chattering Free Discrete-Time Global Sliding Mode Controller for Optoelectronic Tracking System

Aiming at the uncertainties including parameter variations and external disturbances in optoelectronic tracking system, a discrete-time global sliding mode controller (DGSMC) is proposed. By the design of nonlinear switching function, the initial state of control system is set on the switching surface. An adaptive discrete-time reaching law is introduced to suppress the high-frequency chattering at control input, and a linear extrapolation method is employed to estimate the unknown uncertainties and commands. The global reachability for sliding mode and the chattering-free property are proven by means of mathematical derivation. Numerical simulation presents that the proposed DGSMC scheme not only ensures strong robustness against system uncertainties and small tracking error, but also suppresses the high-frequency chattering at control input effectively, compared with the SMC scheme using conventional discrete-time reaching law.

车载光电跟踪系统跟踪转台的初始标定

An initial turntable calibration method based on coordinate transformation was proposed to improve the target tracking precision of a vehicle-borne tracking system.First,according to the coordinate transformation theory,a precise turntable calibration model was established and a transformation matrix for the turntable calibration was obtained.Then,an approximate calibration approach based on the practical need was derived with reasonable analysis and careful approximation.Finally,a combined calibration method by using both approximate calibration and precise calibration was implemented in the turntable initial calibration process for a practical vehicle-borne opto-electronic tracking system.Experimental results show that the combined calibration method can improve the efficiency of turntable initial calibration.After precise calibration,the tracking error of the turntable is smaller than 0.1° for a remote target larger than 10 km away,which completely satisfies the precision requirements of the vehicle-borne opto-electronic tracking system.This calibration method has been successfully used in several vehicle-borne opto-electronic tracking systems.

Design of Motion Control Card on PXI Bus

The article introduces the design scheme of a motion control card on PXI bus. A detailed description of PCI interface module, FPGA module, DSP module, serial transceiver module and analog acquisition module is also given in this paper. Tests of data transfer rate between host and motion control card are adopted, the results suggest that the PXI local bus can get a high-rate communication. The motion control card is applied to control the two-dimensional turntable of an optoelectronic imaging and tracking system. The experiments indicate that the motion control card based on PXI can meet the requirements of real-time control. The performance of control is also acceptable.

Resistance of the sheep skull after a monocortical cranial graft harvest

IntroductionCranial bone grafts are commonly used for preimplant or facial reconstructive surgery. However, removing bone may weaken the parietal bone and lead to a loss of strength. This loss has never been quantified. Bone harvest site reconstruction is being carried out more frequently than in the past, but its effect on the strength of the donor site is unknown.The aim of our study is to quantify the loss of strength due to a monocortical cranial bone graft harvest in sheep. Materials and methodsThirty-four fresh sheep cadaver heads were used for the study. We performed a monocortical bone graft harvest on the posterior part of the right frontal bone. We used a surgical navigation system with optoelectronic tracking to measure bone thickness.To evaluate the resistance of the skull to an impact we developed a pendulum Charpy impact testing machine. The impact force hit a defined target frontal area. ResultsThe total thickness on both sides ranged from 3 mm to 10 mm with a mean of 6 mm (SD = 1.4 mm).The loss of strength between the intact left side and the harvested right side varied with a mean of 49% (SD = 17%) and was significant (p = 6.10−10). ConclusionThis study has demonstrated that there is a loss of strength in the skull on the side where a bone graft has been harvested.Reconstruction of the harvested site using biomaterials reduces the poor aesthetic outcome due to depression at the site, but we do not know its effects on strength. This kind of study cannot be performed in humans for ethical reasons.Data obtained from this study will allow us to carry out a study in sheep to evaluate strength of the frontal area of a skull with a harvest site reconstructed with hydroxyapatite cement.