Maneuvering targets state prediction based on robust H ∞ filtering in opto-electronic tracking system

In this paper, an adaptive sliding mode control algorithm based on friction compensation utilizing neural network (NN) is designed for an opto-electronic tracking system under the circumstance of friction and external disturbance. Since neural networks can approximate any nonlinear function, the developed NN controller can approximate the nonlinear friction which is integrated into the adaptive sliding mode control system in the Lyapunov framework. The adaptive sliding mode controller with friction compensation can effectively reduce the effects of nonlinear friction and external disturbance of the opto-electronic tracking system utilizing neural network approximations. The stability of the proposed method is guaranteed according to Lyapunov criterion. Simulation and experimental validation results for a nonlinear LuGre dynamic model of the opto-electronic tracking system are provided to validate the effectiveness of the proposed control method.

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

The servo control system of the optoelectronic tracking equipment usually is a kind of SISO. When the fast moving target is tracked, the over-tune of the servo system is the main representation for the dynamic tracking error. As the result, the tracking ability may be improved by limiting the over-tune. We put forward a method, the advanced position compensation (called as APC in short), which is to check the speed-overtune by applying the advanced position information. For the large accelerate target, small over-tune tracking is achieved, but it lowers the ability for tracking the sine signal at low frequency area. While the dynamic high-type can improve the tracking precision for the sine signal at low frequency area, we work out a brand-new method, which combines the advantages of the both. It increases the tracking precision in the whole frequency band at large scale for the optoelectronic tracking system. The simulation results show that when the target moves with the largest accelerate 120°/s², 120°/s, the maximum static tracking error is about 0.6".

To enhance the wide-band measurement performance of magnetohydrodynamic angular rate sensor (MHD ARS) in precision optoelectronic tracking systems, accuracy fusion with an inertial measurement unit (IMU) is essential. This paper presents a Kalman filter with magnitude–frequency response attenuation ratio (MAR)-enhanced adaptive process noise covariance, which effectively improves the signal-to-noise ratio (SNR) and reduces scale factor degradation in the fused output caused by differences in sensor frequency responses. First, this paper proposes a frequency band discrimination method based on MAR, which iteratively calculates the MAR parameter from the sensor measurements to determine the signal's frequency band. Second, the process noise covariance is adaptively adjusted based on the MAR discrimination result to optimize the Kalman gain. Finally, the proposed algorithm is implemented on an embedded platform, and attitude is resolved, achieving high-precision measurement across the full frequency band. The fusion performance was validated through angular velocity, angular velocity dynamic tracking, and angular position response experiments, demonstrating significant improvements in tracking accuracy and SNR within the tested bandwidth. In the 0.1–300 Hz angular position test, the fused output exhibited a maximum amplitude ratio fluctuation below 0.04 and a maximum phase difference fluctuation below 13° relative to a precision laser reference. This study provides a novel sensor fusion solution for wide-band high-precision line-of-sight (LOS) stabilization in optoelectronic tracking systems on highly dynamic platforms under vibration environments.

The optoelectronic tracking system has a strong coupling between the tracking platform and the satellite platform when rapidly capturing and precisely tracking targets. The high-precision coordinated pointing control between the two platforms is a key technology in the fields of space laser communication, debris monitoring, and astronomical observation. Firstly, a multi-level coupled dynamics model of spacecraft with two-dimensional (2D) motion platforms is derived based on the principles of momentum and angular momentum. Secondly, the coupling effects between the motion platform and the satellite platform are theoretically analyzed, highlighting the impact of platform orientation, configuration, mass properties, and motion characteristics on the coupling. Finally, a multi-level platform cooperative control strategy is proposed, and the model and control strategy are validated through mathematical simulations. The results show that the model is consistent with simulation results from ADAMS software, and the satellite attitude accuracy under the cooperative control strategy can be improved by 80%.

A new variable-structure IMM method for maneuvering target tracking using current statistical model is presented. The maximum acceleration - a design parameter in current statistical model, is used to design various motion models. The model set adaptation logic according to the maximum acceleration variety is also proposed in the paper. Simulation shows that the performance of new method is superior to the fixed structure IMM algorithm when target maneuver is intense.

Load sharing in stabilized spinal segments was evaluated using sequential injury and stabilization with a posterior instrumentation system under an in vitro flexibility protocol. To analyze the partitioning of applied loads between anatomic and implanted structures of lumbar functional spinal units stabilized with a posterior instrumentation system. To identify surgical indications for which the risk of fixator breakage in vivo is high. Relatively few groups have experimentally measured the in vitro and in vivo forces and/or moments supported by posterior instrumentation systems, and no analysis, of the load sharing in these systems has been performed. This information will provide novel insight into implant fatigue life, and the degree to which the spinal anatomy is shielded from the applied load and will allow the verification of mathematical models for new injury scenarios. Specimen kinematics were determined using an optoelectronic tracking system. Intradiscal pressure and the forces and moments supported by the implants were measured using, respectively, a needle-mounted pressure sensor and strain gauges mounted on the spinal implants. A large majority of the applied moments were supported by an equal and opposite force pair between the intervertebral disc and fixator rods in flexion and extension and an equal and opposite force pair between the left and right fixator rods in lateral bending. Torsional moments were shared approximately equally between the posterior elements, intervertebral disc, an equal and opposite shear force pair in the transverse plane between the right and left fixators and internal fixator moments. When posterior instrumentation devices are used to stabilize severe anterior column injuries, they are at risk of fracture secondary to reversed bending moments.

For multi-target tracking, the IMM (interactive multiple model) algorithm has been proposed. The IMM is expected to reduce tracking errors for both nonmaneuvering and maneuvering targets. However, the IMM requires a heavy computational burden, because it utilizes multiple Kalman filters in parallel. On the other hand, the Kalman filter with a turning acceleration estimator, which can adapt a maneuvering target, has been proposed. The Kalman filter with a turning acceleration estimator is a single two-stage type filter and has a problem of setting threshold for the maneuver detector. In this paper, we propose the hybrid filter with a constant-velocity (CV) filter and a turning acceleration estimation filter. The proposed filter does not require a maneuver detector, because it integrates the outputs of two filters using the likelihood of each filter. And its computational requirement is smaller than the IMM, since it consists of only two Kalman based filters. The proposed method can prevent deteriorating tracking accuracy by reducing the risk of maneuver misdetection when a target maneuvers. We evaluate the performance of the proposed filter by computer simulation, and show the effectiveness of the proposed filter, comparing with the conventional Kalman filter and the two-stage Kalman filter.

Control of impact time of missile to target has a great importance in applications such as Cooperative Attack of Multiple Missiles or Anti-Ship Missiles. This paper presents sliding mode control based guidance law against maneuvering targets with impact time constraints. Using nonlinear engagement dynamics, appropriate switching surface has been selected and sliding mode control has been designed using Lyapunov stability theorem. The sliding surface has been selected such that both the line of sight range and the error of the time remaining to target become zero to guarantee impacting the target at the desired time . By considering the non linear dynamic equations of maneuvering target , the proposed method can achieve the desired impact time against maneuvering target . In the proposed method , there is no need to consider small impact angle and non maneuvering target . Using the simulation model, the effectiveness of the proposed method in different scenarios (static and maneuvering) and taking into account different times for the impact time and its efficiency and its superiority as compared to other methods is shown.

It has been recognized by several researchers that a guidance algorithm effective against maneuvering targets is the one that drives the heading error rapidly to zero and then maintains a zero heading error for the remainder of the flight. We have referred to this guidance algorithm as nonlinear guidance (NLG) as its implementation generally requires some nonlinear features. There are may ways in which NLG can be put into practice. We examine a new way of applying NLG that does not require knowledge of line-of-sight rate, or target acceleration. However, information on the target aspect angle is required. The new guidance law is derived using the Lyapunov optimizing feedback control method. We make some performance comparisons with augmented proportional navigation. Not only do we maintain the performance advantage previously demonstrated in our earlier applications (2000) of NLG (requiring line-of-sight rate and target acceleration) but we also obtain a dramatic improvement in performance in the presence of measurement noise.

Unscented fuzzy-controlled current statistic model and adaptive filtering for tracking maneuvering targets

Moving target tracking in marine aerosol environment with single photon lidar system

Radial acceleration estimation of multiple high maneuvering targets

Three-dimensional guidance law with precise control of attack time and constraints on attack angle.

In order to decrease the error of pose estimation based on image sequences, a filtering method for pose angles based on CS-STF-IMM was proposed. Firstly, current statistical (CS) model was used to establish state space model of pose transformation, which reflects the maneuver of target pose more truly. Then, strong tracking filter (STF) was introduced to overcome the shortcoming that Kalman filter can hardly track sudden maneuver. A parameters determination method based on least square fitting was proposed, which improves the performance of STF further. Based on these, CS-STF-IMM algorithm was established, which obviously improved the precision of pose estimation. Simulations showed that the proposed method has better overall performance, which is a feasible scheme for pose angles filtering.