Симуляционная модель системы адаптивного управления сегментами составного зеркала космического телескопа и ее метрологическая аттестация

Abstract. Problem. Speed control systems are used to ensure road safety and improve vehicle efficiency by controlling traffic speed. The main purpose of the speed control system is to ensure road safety, increase vehicle efficiency and reduce the negative impact of transport on the environment by controlling the speed of traffic. Reducing speed allows drivers to react in time to unforeseen situations, stop at traffic lights, and reduce the distance to other vehicles. In this paper, we have carried out mathematical modeling of a vehicle speed control system. Goal. As a result of the analysis, the purpose of the study was highlighted: to carry out mathematical modeling of the car speed control system. Job tasks: to model the speed control system using a proportional regulator and a PID controller. Methodology. Initially, we considered a vehicle speed control system using a proportional regulator. In the process of synthesis, it was found that the use of a P-controller provides insufficiently good quality of the vehicle speed control system. It was decided to use a PID controller to synthesize the speed control system. Results. The result of the study is: optimized settings of the PID controller provide a given control time tp≈40 s with practically no overshoot, which is a completely satisfactory quality of this system. Originality. The originality lies in the fact that a PID controller with an NCD block was used to determine the transient function of the system with optimal settings. Practical value. The use of the proposed results indicates the possibility of using a PID controller to ensure the set parameters.

The utilization of a telescope with a large single aperture is limited by the manufacturing technique, cost, volume and weight of a monolithic mirror. In order to solve these problems, the technology of the segmented synthetic aperture was introduced. The primary mirror of a large segmented synthetic aperture telescope consists of several segmented mirrors, whose misalignment errors make the wavefront change drastically and influence the MTF of the optical system badly. The wavefront coding technology (WFC) is an innovative technology that joints the optical design and digital image processing together. By adding a phase mask close to the pupil of an optical system and modulating the wavefront, the WFC system becomes very insensitive to defocus and other aberrations based on defocus. The theoretical analysis of characteristics of the WFC system was done in the form of PSF. The application of WFC to a segmented three mirror anastigmat (TMA) was presented. A space telescope with an effective focal length as 40m, a F number as 10, a field of view as 0.5°x0.05° was designed, whose primary mirror consisted of seven segmented mirrors. The influence of defocus and misalignment errors on the telescope was discussed. The imaging process of the WFC system and following image restoration were simulated. As a result, sharp images were obtained and the large segmented synthetic aperture telescope had looser misalignment tolerance and extended depth of focus.

A novel scheme for remote alignment of adaptive optical systems is presented. In comparison to conventional methods where near-field measurements (in the form of near-field phase across the adaptive component or gaps between neighboring segments) are used for feedback control, Far-Field Optimization utilizes only the far-field intensity. A figure of merit based solely on the point spread function is used to iteratively configure the adaptive elements to optical alignment. In this review paper, we first describe the far-field optimization method and then discuss its application to three different adaptive optical systems - a deformable mirror, a segmented mirror and a multiple mirror telescope. The convergence, efficiency and robustness of the iterative far-field optimization are illustrated with computer simulations. Experimental validation of the novel technique for adaptive optics alignment is demonstrated with results from a laboratory test with a segmented mirror. Potential utility of far-field optimization for dynamic wavefront control (e.g. atmospheric turbulence compensation) is briefly discussed.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

With the aperture of telescope becoming larger, the mass of primary mirror and other relevant structures will become heavier as well. Therefore, lighting weight for large space-based telescope is necessary. This paper purposed a method based on Neural Network aims to build a math model for primary mirror of large space-based telescope, which can reduce weight of the telescope and smaller mirror deformation caused by gravity release effectively. In the meantime, it can also improve stiffness of structure and reduce thermal strain caused by on orbit temperature variation effectively. The model describes the relationship between the structure of primary mirror of large space-based telescope and corresponding deformation, and describes the optical performance of mirror by using Zernike Polynomial. To optimize the structure of primary mirror lightweight, we take the deformation of mirror and its optical performance into consideration. To apply the structures parameters and its corresponding deformations to Neural Network training, we use the combination samples of different mirror lightweight structure parameters and corresponding deformation which caused by gravity release and thermal condition. Finally, by taking advantage of the Neural Network model to optimize the primary mirror lightweight of 1-meter rectangle space-based telescope, which can make the RMS 0.024λ (λ=632.8nm)and areal density under 15kg/m². This method combines existing results and numerical simulation to establish numerical model based on Neural Network method. Research results can be applied to same processes of designing, analyzing, and processing of large space-based telescope directly.

An Adaptive Optic (AO) system is a fundamental requirement of 8m-class telescopes. We know that in order to obtain the maximum possible resolution allowed by these telescopes we need to correct the atmospheric turbulence. Thanks to adaptive optic systems we are able to use all the effective potential of these instruments, drawing all the information from the universe sources as best as possible. In an AO system there are two main components: the wavefront sensor (WFS) that is able to measure the aberrations on the incoming wavefront in the telescope, and the deformable mirror (DM) that is able to assume a shape opposite to the one measured by the sensor. The two subsystem are connected by the reconstructor (REC). In order to do this, the REC requires a “common language" between these two main AO components. It means that it needs a mapping between the sensor-space and the mirror-space, called an interaction matrix (IM). Therefore, in order to operate correctly, an AO system has a main requirement: the measure of an IM in order to obtain a calibration of the whole AO system. The IM measurement is a 'mile stone' for an AO system and must be done regardless of the telescope size or class. Usually, this calibration step is done adding to the telescope system an auxiliary artificial source of light (i.e a fiber) that illuminates both the deformable mirror and the sensor, permitting the calibration of the AO system. For large telescope (more than 8m, like Extremely Large Telescopes, ELTs) the fiber based IM measurement requires challenging optical setups that in some cases are also impractical to build. In these cases, new techniques to measure the IM are needed. In this PhD work we want to check the possibility of a different method of calibration that can be applied directly on sky, at the telescope, without any auxiliary source. Such a technique can be used to calibrate AO system on a telescope of any size. We want to test the new calibration technique, called “sinusoidal modulation technique”, on the Large Binocular Telescope (LBT) AO system, which is already a complete AO system with the two main components: a secondary deformable mirror with by 672 actuators, and a pyramid wavefront sensor. My first phase of PhD work was helping to implement the WFS board (containing the pyramid sensor and all the auxiliary optical components) working both optical alignments and tests of some optical components. Thanks to the “solar tower” facility of the Astrophysical Observatory of Arcetri (Firenze), we have been able to reproduce an environment very similar to the telescope one, testing the main LBT AO components: the pyramid sensor and the secondary deformable mirror. Thanks to this the second phase of my PhD thesis: the measure of IM applying the sinusoidal modulation technique. At first we have measured the IM using a fiber auxiliary source to calibrate the system, without any kind of disturbance injected. After that, we have tried to use this calibration technique in order to measure the IM directly “on sky”, so adding an atmospheric disturbance to the AO system. The results obtained in this PhD work measuring the IM directly in the Arcetri solar tower system are crucial for the future development: the possibility of the acquisition of IM directly on sky means that we are able to calibrate an AO system also for extremely large telescope class where classic IM measurements technique are problematic and, sometimes, impossible. Finally we have not to forget the reason why we need this: the main aim is to observe the universe. Thanks to these new big class of telescopes and only using their full capabilities, we will be able to increase our knowledge of the universe objects observed, because we will be able to resolve more detailed characteristics, discovering, analyzing and understanding the behavior of the universe components.

The cophase calibration system is applied for adaptive optical phasing with a large segmented telescope mirror, which commonly uses 3-DOF micro-position device with three micro-displacement actuators to drive segments in parallel, making the entire segmented mirror in phase at one time and obtaining the desired sensor readings accordingly. In order to run the active control system to make the segments cophase, it is necessary to calculate the coordinates of the three driving points correctly for segmented mirrors specially limited in geometric parameters, especially for the stability and sensitivity of the micro-positioning device. The mirrors will be supported on a massively parallel system of electrostatically controlled, interconnected microactuators that can be coordinated to achieve precise actuation Adjusting posture of each segment independently so as to obtain the co-phasing errors and to control them at a nanometer level. Several generations of individual actuators as well as parallel arrays of actuators with segmented mirrors have been designed. A mechanical model of the system has been constructed and simulated numerically to obtain the actual position of three actuators using the RPY angle describing means. A three-channel parallel control scheme has been developed and implemented on a segmented mirror array. A universal evaluating method for optimization is prompted and will be a good guide to the design optimization of micro-positioning device for each segmented mirror when the mirrors are groundbased horizontally.

Problem. The article proposes a developed construction of a suspension – shock absorber, which made it possible to install a hydraulic hammer as a working equipment, simultaneously isolating it from vibrations.
 A mathematical model of the system was developed, the basis of which is a suspension – shock absorber for attaching a hydraulic hammer to an excavator, which includes modeling of its mechanical system. Goal. The goal is the development and research of a sub-axle - shock absorber for the attachment of hydraulic hammer equipment (hydraulic hammer) to an excavator. Methodology. The solution of the set problems involved the creation of a mathematical model of the vibration system and its implementation using the MathCAD application program. Originality. It is proposed to transform the differential equations of the mathematical model of the vibration system by the method of decreasing order and as a result obtain the displacements, velocities, and accelerations of individual elements and obtain the nature of the change in the disturbing force of the vibrating hammer. Using the MathCAD program, a study of the dynamics of the system, which includes a hydraulic ham a shock absorber and an excavator, was performed, as well as the frequencies of free oscillations of the system in question were determined. Practical value. The obtained results of scientific research on vibration protection of excavators, which are operated with attached shock devices (hydraulic hammers), with the use of the MathCAD mathematical program, can be successfully used in the development, as well as in the determination of dynamic loads of similar vibration protection systems used in industry.

Future large aperture space telescopes may use lightweight correctable active mirrors. The Naval Postgraduate School's Segmented Mirror Telescope (SMT) test bed uses 1-meter silicon carbide (SiC) active mirror segments to form a sixsegment deployable 3-meter telescope. The active segments suffer from residual surface errors after a correction is applied. A deformable mirror is added at the SMT pupil plane to improve this residual error. The large active SMT segment represents the woofer, and a small continuous micro-electro-mechanical system (MEMS) deformable mirror represents the tweeter. A global influence matrix and closed loop constrained least squares controller command the active segment and additional deformable mirror as a single device. An interferometer measures the surface error and provides feedback to the controller. Simulation and experimental results demonstrate a significant improvement in wavefront error compared to a 2-step sequential woofer-tweeter constrained least squares control approach.

In this paper, we introduce an approach for a fast assessment of the dynamic characteristics of system frequency during the period of cold load pickup following a large-scale blackout. The approach is developed based on a load model and a model of generation control system: the load model con-siders the unique time-dependent characteristic of inrush power surges during the period of cold load pickup, while the model of generation control system mimics the characteristics of various governors that are crucial to the determination of the key variables including initial rate of frequency change, frequency nadir and settling frequency. With the proposed linearization and estimation methods, the model of generation control system can be quickly constructed to offer a great amount of flexibility and simplicity for the study of the impact of cold load on frequency response. The proposed approach allows system operators to quickly evaluate many different options for system restoration. The application of the proposed approach is demonstrated in a case study based on the IEEE 39-bus system. The differences between the results obtained using the proposed approach and those obtained from complete PSS/E simulation are very small, which suggests that the linearized model of generation control system is fast, and accurate enough to address the major concerns of cold load pickup in system restoration.

The aim of the work is to develop a mathematical model of the control system of the pump unit with a neurocontroller. In the process of work the research of separate circuits of the control system of the pump unit was carried out. As a result of the research the following was obtained: computer model of pump unit control system; structure of neural regulator. The effectiveness of the model lies in the possibility to conduct research of different modes of operation of pump units at different connection options.

We have developed a simple mathematical model of the human motor control system, which can generate periodic motions in a musculoskeletal arm. Our motor control model is based on the idea of a central pattern generator (CPG), in which a small population of neurons generates periodic limb motion. The CPG model produces the motion based on a simple descending command—the desired frequency of motion. Furthermore, the CPG model is implemented by a spiking neuron model; as a result of the stochasticity in the neuron activities, the motion exhibits a certain level of variation similar to real human motion. Finally, because of the simple structure of the CPG model, it can generate the sophisticated muscle excitation commands much faster than optimization-based methods.

In astronomy and microscopy, distortions in the wavefront affect the dynamic range of a high-contrast imaging system. These aberrations are either imposed by a turbulent medium such as the atmosphere, by static or thermal aberrations in the optical path, or by imperfectly phased subapertures in a segmented mirror. Active and adaptive optics (AO), consisting of a wavefront sensor and a deformable mirror, are employed to address this problem. Nevertheless, the non-common-path between the wavefront sensor and the science camera leads to persistent quasi-static speckles that are difficult to calibrate and which impose a floor on the image contrast. In this paper, we present the first experimental demonstration of a novel wavefront sensor requiring only a minor asymmetric obscuration of the pupil, using the science camera itself to detect high-order wavefront errors from the speckle pattern produced. We apply this to correct errors imposed on a deformable microelectromechanical segmented mirror in a closed loop, restoring a high-quality point spread function and residual wavefront errors of the order of ∼10 nm using 1600 nm light, from a starting point of ∼300 nm in piston and ∼0.3 mrad in tip–tilt. We recommend this as a method for measuring the non-common-path error in AO-equipped ground based telescopes, as well as an approach to phasing difficult segmented mirrors such as on the James Webb Space Telescope primary and as a future direction for extreme AO.

BACKGROUND: To maintain the required temperature range of electrical components of electric vehicles, it is necessary to use thermostating systems. The developing mathematical model of the temperature control system allows, even at the design stage of the vehicle, to determine the necessary parameters of the temperature control system, select algorithms for controlling the system, and calibrate the developed algorithm to ensure the necessary heat removal from electrical components. AIMS: Creation of a mathematical model of the electric motorcycle thermostating system, aimed at determining the potential possibilities of optimizing the system by organizing the air flow through the radiator. METHODS: The mathematical model is implemented in the AVL Cruise software environment. The characteristics of the components included in the model were obtained as a result of laboratory studies and supplemented with power equilibrium equations at the inputs and outputs, taking into account their efficiency. RESULTS: Using the developed model of the radiator of the thermostating system, the temperature graphs of the electric motor and inverter of the electric motorcycle during the driving cycle were obtained. It is noted that the applied temperature control system allows to maintain the temperature of electric components in the specified range. CONCLUSIONS: The mathematical model of the radiator of the thermostating system proposed in this paper allows to carry out calculations of the system at the stage of design of electric vehicles. The model also allows for further development in order to more fully determine the parameters of the thermostating system, including the thermal efficiency.

In article the multilevel hierarchical control system is considered. There is a necessity of replacement or updating of elements of the given system periodically. For realization of an estimation of expediency of such actions the mathematical model of an adaptive hierarchical control system is developed. This model is a system of the kinetic differential equations of the second sort with saturation. Researches of dynamics of the answer of a control system on external influences such as threats or noise are lead.

Switched reluctance motors have complex problems such as strong nonlinear characteristics, variable given speed, and large load disturbances. Aiming at the problem that the switched reluctance motor cannot adapt to the changing speed and large disturbance under the traditional PI control, this paper combines the fuzzy control and the PI control to form the fuzzy-PI controller, which constitutes the fuzzy adaptive speed regulation system of the SRM. Using fuzzy control to correct system parameters in real time can improve the situation that the traditional PI direct torque control system cannot effectively control the strong nonlinearity of SRM. By accurately establishing the nonlinear model of the SRM, and using the finite element simulation software to calculate the static characteristics of the motor's flux linkage, inductance and torque, the mathematical model of the SRM speed control system is established. Then it is shown by MATLAB/Simulink simulation, compared with the traditional PI control algorithm, the fuzzy-PI control algorithm can make the SRM system achieve better control effect in the case of variable speed and large load disturbance, improve the dynamic response of the system, reduce the overshoot, and enhance the robustness.