Han Jun-wei

Harmonic cancellation for electro-hydraulic servo shaking table based on LMS adaptive algorithm

An electro-hydraulic shaking table which is based on acceleration control is studied here. A three-variable control scheme is applied to achieve robustness, disturbance suppression and sufficient frequency bandwidth. Its acceleration response contains harmonics corresponding to sinusoidal input because of nonlinearities in the system. To reduce harmonic distortion and improve control performance of the shaking table, a harmonic cancellation algorithm is developed. The weights of the proposed algorithm are on-line updated by the normalized LMS algorithm. The reference input with input frequency is filtered by the adaptive LMS filter. The output of the adaptive filter is a close harmonic replica and is added to the fundamental signal such that the output harmonic is cancelled leaving the desired signal alone, and the total harmonic distortion is greatly reduced. Experimental results demonstrate the efficiency and validity of the proposed control scheme.An electro-hydraulic shaking table which is based on acceleration control is studied here. A three-variable control scheme is applied to achieve robustness, disturbance suppression and sufficient frequency bandwidth. Its acceleration response contains harmonics corresponding to sinusoidal input because of nonlinearities in the system. To reduce harmonic distortion and improve control performance of the shaking table, a harmonic cancellation algorithm is developed. The weights of the proposed algorithm are on-line updated by the normalized LMS algorithm. The reference input with input frequency is filtered by the adaptive LMS filter. The output of the adaptive filter is a close harmonic replica and is added to the fundamental signal such that the output harmonic is cancelled leaving the desired signal alone, and the total harmonic distortion is greatly reduced. Experimental results demonstrate the efficiency and validity of the proposed control scheme.

RCP and RT control of 6-DOF parallel robot

In this paper, based on the rapid control prototype (RCP). real-time (RT) digital control of 6-DOF parallel robot system is developed. For the control of such a complex system, to bridge the LabVIEW and MATLAB/xPC Target can be a shortcut of low cost and high efficiency. Simulink, Real Time Workshop, xPC Target, and C compile are being exploited in the design. In order to realize RCP and RT control of 6-DOF parallel robot system, two computers are needed. One is the host computer, and the other is the target one. And some compatible data acquisition boards are required to communicate the software with the hardware controlled. In this environment, parameters such as control laws and inputs, which are running in the MATLAB/Simulink model on the target, can be easily changed real time in the LabVIEW GUI running on the host. Measured data can be both displayed instantaneously and saved for later analysis. This environment makes it easier to experiment with, develop and compare controllers with different control laws. Experimentation shows that this control method is feasible and has a good effect.

Research and modelling on performance database of flight management system

In order to investigate and exploit advanced flight management system with complete functions, provide applicable and reliable performance data for optimal trajectory search, data structure requirements of performance database of flight management system are presented, including the structure of aerodynamic data ,engine performance data and operation data. The whole authentic performance data is acquired by integrating the performance data of flight simulator in the second phase of 985 projects and the flight manual. Based on the former performance data, combining the thrust method, particle swarm optimization algorithm and the energy-state method, the performance data is transferred into equal energy-height curves which can be more applicable for optimal trajectory search. Based on the processed performance data, the performance model is built on the basis of Microsoft Visual C++ and MATLAB/SIMULINK. The running results of the flight management system program indicate the method used to exploit performance database of flight simulator prototype system is effective and feasible.

Three State Controller Design of Shaking Table in Active Structural Control System

The purpose of this paper is to develop an approach to improve the tracking characteristics of a small-scale shaking table actuation system, which is used in active structural control system. In this paper, firstly, the active control experimental system is described in detail. Then, the process of constructing analytical model of servo-hydraulic actuation system is presented. The proposed model, in the form of the total shaking table transfer function, accounts for the specific physical characteristics of the small-scale shaking table. Due to low natural frequency and small hydraulic actuator damping, the small-scale shaking table cannot meet the experimental requirement. Thus, three states feedback and three state feedforward control algorithm based on pole-assignment principle is applied for extending the acceleration bandwidth and improving system damping. Lastly, the shaking table experiments are tested and the experimental results indicate that the controller is effective.

Experiment and Study of Control Loading System in a Flight Simulator Based on RCP

Control loading system is one of the important components for a flight simulator. It provides fidelity force simulation to pilot and belongs to passive force control system. According to the flight control systems principle of boeing737-300, this paper gives the simulation principle in flight simulator. Three channels Primary Control Loading system (PCL) hydraulic driven actuators were developed. The mathematical model was derived for the PCL. By means of rapid control prototyping technology, the passive force control system based on industrial personal computer is developed. Experiments demonstrate that the system has less than 4% error between computed force and actual force and good tracking performance. The PCL has been applied to flight simulator prototype system.

Computing of flight envelope using modified particle swarm optimization algorithm

A novel method, modified particle swarm optimization algorithm, is proposed to compute flight envelope in this paper. According to the principle of thrust method, the problem of solving flight envelope is converted into searching the optimal solution by the particle swarm optimization algorithm (PSO). Combined with adaptive inertia weight factor, the standard PSO algorithm is modified. Applying the modified PSO algorithm, the flight envelope is solved. Numerical simulations results illustrate that the search algorithm is feasible and efficient for solving flight envelop.

Analysis of Coupling Effects on Hydraulic Controlled 6 Degrees of Freedom Parallel Manipulator Using Joint Space Inverse Mass Matrix

This paper presents an analysis of the coupling effects between degrees of freedom of a hydraulic controlled six DOF parallel manipulator. Based on the singular value decomposition to the properties of its joint space inverse mass matrix, the method is put forward to analyze coupling effects between degrees of freedom using a transformation matrix, the product of transposed Jabobian matrix and an orthogonal unitary matrix, of which each element represents decoupled modal space coordinates with respect to physical task space frame. The simulation results in frequency domain prove the theoretical analysis right. The analysis will provide useful information to mechanism and controller designer, to asses from concept the coupling effects between DOF in respect of the requirement for a particular application and also for the study on decoupling control strategies.

A low-cost PC-based flight simulator development

Flight simulator is a large-scale simulation system. Because of the limitation by computer powers, only special computers ever were used to realize flight dynamics simulation and image generation in full flight simulator in the past. With the development of computer powers, high-performance computation and simulation can be realized applying by PC. While the need to reduce costs in every aspects of flight simulator become very important. A PC-based prototype system was implemented according to the architecture of flight simulator featuring a generic double engine airplane. Commercial-off-the-shelf (COTS) software components were use to reduce costs and improve developing efficiency. The detailed process was proposed. The integrated system shows that the feasibility of design based on PC.

Hybrid Realtime Simulation of the Space Docking Process

In order to test the space docking mechanism on the ground, the docking process of two spacecrafts must be simulated. The hybrid simulation (hardware-in-loop simulation) is a preferred method for its great applicability to different spacecrafts. Therefore, a space docking hybrid simulation (SDHS) prototype system is established. In this system actual spacecrafts are replaced by virtual ones and the docking dynamics model is built according to moment of momentum equations of the spacecrafts. Then a distributed realtime computer system is used for calculating the relative motion of the spacecrafts and driving a Stewart platform to implement this motion. Adopting an imitated docking mechanism in the experiment, the whole process of space docking is simulated successfully. On the basis of this system, a SDHS system using for testing actual docking mechanisms can be constructed in the future

Development of 3D sound simulation system for flight simulator

For the purpose of acquiring the immersion and reality of flight simulation, there is a necessity to reproduce 3D sound field of aircraft cockpit. In this paper, a 3D sound simulation system which is integrated into flight simulator used for training pilots is developed. After determining the sound events which will be simulated in flight simulation, spectrum analysis and time-frequency analysis are used to analyze original recordings for finding out the sound features of each part of an aircraft. And then sound sources which will be used in simulation can be extracted by using LMS adaptive filtering and other basic signal processing methods. Based on system integration and performance consideration, a new component of sound simulation system is presented and the object-oriented software development is used to develop the software part for matching this component. Two key technologies are particularly discussed in software realization: real-time sound synthesis and sound spatialization. The 3D sound simulation system meets development requirements after many flight tests and works reliably in a Boeing 737-800 flight simulator which is developed in our lab.