216 research outputs found

    Design of One Dimensional Adjustment Platform Servo Control System Based on Neural Network

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    This paper designed a one dimensional adjustment of high precision servo control system, in order to provide individual comprehensive combat system high precision gun visual Angle. In servo control system hardware design based on DSP digital signal processing (DSP) chip as the CPU control circuit, in regard to algorithm, using the three layers BP neural network algorithm for PID integral gain and differential gain and intelligently adjusting proportion gain. On this basis, also analyzes the advantages and disadvantages of the traditional BP neural network algorithm, carries on the improvement. Vector using adaptive control, numerical optimization and introducing the steepness factor method, solve the contradiction between the stability and learning time, greatly improving the convergence speed and stability of the system performance, the static stability of the turntable accuracy is less than 3″, indicators reached the design requirements

    Disturbance observer based sliding mode control for a continuous stirred tank reactor (CSTR)

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    A continuous stirred tank reactor (CSTR) is typical of equipment found in the process control industry. The dynamics represent a wide class of second order nonlinear systems and thus as well as having specific industrial application, control of the CSTR is frequently used as a benchmark problem for application and testing of new control algorithms. Due to the high complexity of the CSTR system, the robust control design problem is challenging. This paper first establishes a mathematical model of the system. A disturbance observer is then designed to estimate the disturbance and a corresponding asymptotically stable sliding mode control is developed. Stability analysis is presented in terms of the Lyapunov method. Finally, based on experimental data, the proposed method is validated using simulation experiments

    Application of cell mapping to control optimization for an antenna servo system on a disturbed carrier

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    The cell-mapping method, due to its global optimality, has been applied to solve multi-objective optimization problems (MOPs) and optimal control problems. However, the curse of dimensionality limits its application in high-dimensional systems. In this paper, the multi-parameter sensitivity analysis is investigated to reduce the parameter space dimension, which broadens the application of cell mapping to MOPs in high-dimensional parameter space. A post-processing algorithm for MOPs is introduced to help choose proper control parameters from the Pareto set. The proposed scheme is applied successfully in the control parameter optimization of an adaptive nonsingular terminal sliding-mode control for an antenna servo system on a disturbed carrier. Moreover, as the existing global optimal tracking control with an adjoining cell-mapping method may generate tracking-phase differences, an optimal-sliding-mode combined-control strategy is proposed. By using the combined-control strategy, the azimuth and pitch angles of the antenna system are controlled to catch up to a target trajectory with the minimum cost function and to keep high-precision tracking after that.</p

    Preliminary Design of Robust Adaptive Control Laws for an Aerial Manipulator

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    One platform commonly used in modern control systems research is the quadcopter unmanned aerial vehicle (UAV). This platform finds many uses in both civilian and military aviation, such as aerial surveillance and imaging, search and rescue operations, and remote sensing. To perform these tasks, it is increasingly common to rely on autonomous UAVs to allow the vehicle to perform desired tasks without an operator. One weakness of the quadcopter UAV is its underactuation, since this vehicle has six degrees of freedom and only four control inputs. To overcome this complexity, it is proposed to actuate the vehicle propellers, creating a tiltrotor vehicle, in this thesis of the H-configuration. To this end, the equations of motion of the vehicle will be established, and an original robust model reference adaptive control law will be formulated to control the vehicle in the presence of disturbances. Another current goal in UAV research is in providing a method for the vehicle to manipulate its environment. In this thesis, a two-link robotic manipulator mounted on a cylindrical hinge will be used. This manipulator will have its own trajectory generation and control formulation for its end-effector, after which it will be mounted to the H-configuration tiltrotor. This combined aerial manipulator will be numerically simulated with the manipulator and tiltrotor control laws running simultaneously, demonstrating the feasibility of the combined system

    United Technologies Robotic Tool for Aircraft Rim Cleaning

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    Conventional systems for cleaning aircraft split rims waste millions of dollars in water and electrical resources annually. Team B.E.E.M. was tasked by the United Technologies Research Center (UTRC) in East Hartford, CT, with developing an alternative method for cleaning aircraft rims. To suit the needs of operation facilities under United Technologies Aerospace Systems, the product must reduce annual waste, maintain the current cleaning cycle time, and avoid damaging the anodized coating on the wheel rim’s surface. These design requirements are to be met with a fully automated system that implements laser ablation. Laser ablation is a no-contact process that vaporizes targeted materials, eliminates the use of water, and significantly reduces electrical wattage. The system design consists of a 1.0 KW Yttrium-fiber laser coupled with a collimator and galvanometer on the head of a robotic arm. The galvanometer aims at a rotating wheel to ablate the entire surface. Scaled testing with a 20-watt laser and five varying mixtures of dirt, grease, and carbon dust proved that an ablation system can clean up to 95% of the targeted dirt surface. A half-scale model of the loading system was developed to simulate the laser trajectory across the surface of the wheel rim and proved to be capable of reaching all surfaces, including the bolt and spoke holes. This report presents design specifications for the project, as well as research on optic technology and contamination found on an aircraft wheel rim. The team proposed 120 concepts as alternative methods for cleaning aircraft split rims, which were judged by the ability to satisfy parameters in a Quality Function Deployment analysis set by the United Technologies Research Center. Engineering analysis is provided for theoretical energy requirements for vaporizing contamination, the dynamics and structural integrity of the turntable, and the trajectory algorithm for the robotic manipulator. The design and production of the half-scale model are documented, along with additional redesign features. The laser parameters were verified through scaled tests at IPG Photonics in Oxford, Massachusetts, and the half-scale model was tested for covering the entire surface of the wheel rim. A financial analysis of the project proved to significantly reduce operation costs after a high initial cost. The Laser Ablation Robotic Rim Intensive Cleaner (LARRIC) has exceeded all design specifications outlined throughout this report. The LARRIC successfully met design considerations throughout the prototyping phase of product development. Further design considerations are provided in this report to optimize the system design and laser trajectory

    Unknown dynamics estimator-based output-feedback control for nonlinear pure-feedback systems

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    Most existing adaptive control designs for nonlinear pure-feedback systems have been derived based on backstepping or dynamic surface control (DSC) methods, requiring full system states to be measurable. The neural networks (NNs) or fuzzy logic systems (FLSs) used to accommodate uncertainties also impose demanding computational cost and sluggish convergence. To address these issues, this paper proposes a new output-feedback control for uncertain pure-feedback systems without using backstepping and function approximator. A coordinate transform is first used to represent the pure-feedback system in a canonical form to evade using the backstepping or DSC scheme. Then the Levant's differentiator is used to reconstruct the unknown states of the derived canonical system. Finally, a new unknown system dynamics estimator with only one tuning parameter is developed to compensate for the lumped unknown dynamics in the feedback control. This leads to an alternative, simple approximation-free control method for pure-feedback systems, where only the system output needs to be measured. The stability of the closed-loop control system, including the unknown dynamics estimator and the feedback control is proved. Comparative simulations and experiments based on a PMSM test-rig are carried out to test and validate the effectiveness of the proposed method

    An Integrated Platform to Increase the Range/Endurance of Unmanned Helicopters

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    Class I (kg) autonomous helicopters are becoming increasingly popular for a wide range of non-military applications such as, surveillance, reconnaissance, traffic monitoring, emergency response, agricultural spraying, and many other eye in the sky missions. However, an efficient landing/takeoff platform with refueling/recharging capabilities has not yet been developed to increase the endurance and decrease the cost for Class I helicopters. This dissertation presents a three-prong approach for increasing the range and endurance of Class I autonomous helicopters, which will then spur demand by non-military organizations wanting to take advantage of such capabilities and, therefore, drop their price. The proposed Intelligent Self-Leveling and Nodal Docking System (ISLANDS) is developed as a mobile refueling/recharging station, which is one part of a three-pronged approach. ISLANDS is an electro-mechanical system that provides a safe landing surface for helicopters on gradients of up to 60%. ISLANDS operates off the grid and, therefore, must provide its own energy sources for the refueling/recharging tasks it performs. A method for determining ISLANDS\u27 energy needs for refueling/recharging of gas and/or electric helicopters for an arbitrary number of days is provided as the second part of the three-pronged approach. The final step for increasing autonomous helicopter endurance is a method for determining placement of ISLANDS nodes in the area to be serviced ensuring that the helicopters can achieve their mission goal. In this dissertation all aspects of the three-pronged approach are presented and explained in detail, providing experimental results that validate the proposed methods to solve each of the three problems. A case study using Commercially Off The Shelf (COTS) components that shows how all the parts of the proposed three-pronged solution work together for increasing the endurance of Class I helicopters is provided as a conclusion to the dissertation

    The 24th Aerospace Mechanisms Symposium

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    The proceedings of the symposium are reported. Technological areas covered include actuators, aerospace mechanism applications for ground support equipment, lubricants, latches, connectors, and other mechanisms for large space structures
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