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Gao X.-Y.,Beijing Institute of Technology | Gao X.-Y.,Ordnance Engineering College | Zhang Q.-M.,Beijing Institute of Technology | Wu B.,Air Force Armament Research Academy | Liu G.-Q.,Ordnance Engineering College
Beijing Ligong Daxue Xuebao/Transaction of Beijing Institute of Technology | Year: 2014

In order to acquire the attenuation law of different penetrator in soil for researching on detonating unexploded explosive ordnance with shape charge, the impact compression test was carried out with separated Hopkinson pressure bar and the overall process curves for stress-strain were gained. Results show that with the increase of soil density the impact stress peak of soil will rise, the impact stress peak of clay loam is comparative big and the rate of descent of impact stress is comparative slow; the water content of soil influences intensity on the clay loam in impact stress peak but the sand clay loam and the medium clay loam, the conclusion provides the foundation for researching attenuation law of different penetrator in soil.

Liu X.,Beihang University | Chen W.,Beihang University | Yin X.,Air Force Armament Research Academy | Xing X.,Beihang University
Advanced Materials Research | Year: 2012

In this paper we propose a control scheme of electromechanical actuator with optical encoder feedback. Controlled object is the simplified model of a DC motor while feedback device is an optical encoder. Encoder model is established after analyzing its principle and signal characteristic. Many velocity estimation methods have been compared and the least squares fit filter is selected for our design because of its simple algorithm and capability of predicting velocity and position. Using these predictions as feedback, a variable structure controller based on exponential approach law is adopted in the actuator close-loop control. The relationship between system performance and encoder resolution is exposed. This scheme can be implemented easily with low cost and convenient interface. Its validity is proved by simulation results.

Liu X.,Beihang University | Chen W.,Beihang University | Yin X.,Beihang University | Xing X.,Air Force Armament Research Academy
Advanced Materials Research | Year: 2012

An optical flow sensor is fabricated by using an optical navigation sensor as its core chip. The design process is detailed and an optical flow testing platform is designed to test its performance and calibrate its basic parameters. Then the optical flow sensor is introduced to the altitude-holding control loop of a cruise missile and a hardware-in-loop simulation is demonstrated. The simulation result verifies the sensor's effectiveness in the low-altitude penetration.

Qin T.,Beihang University | Chen W.,Beihang University | Xing X.,Air Force Armament Research Academy
Advanced Materials Research | Year: 2012

This paper presents a real-time optical flow algorithm for a vision-based guidance of an unmanned aerial vehicle (UAV). The optical flow algorithm detects a moving target, and obtains the optical position and optical flow vectors of the target from the image sequence. Then, a vision-based guidance of the UAV is designed to follow the moving target. Additionally, the control law of the imaging seeker uses visual information from the image sequence for target tracking. The method was tested on a 3 degree of freedom (3DOF) dual-rotor UAV with a video camera and the result proved the effectiveness of this method.

Liu X.,Beihang University | Chen W.,Beihang University | Xing X.,Air Force Armament Research Academy | Yin X.,The Aerospace Corporation
Beijing Hangkong Hangtian Daxue Xuebao/Journal of Beijing University of Aeronautics and Astronautics | Year: 2012

Several optical flow sensors were mounted dispersedly on a missile airframe. The airframe kinematics model in the vertical plane and the optical flow sensor measurement model were established. Discrete-time Kalman filters were used to fuse the optical flow data and rate gyroscope data, and estimate the altitude, attitude and velocity of the airframe. A very-low altitude-holding flight simulation was then implemented based on these estimations. The simulation results indicate that several optical flow sensors and a rate gyroscope can be used to estimate the altitude, vertical velocity, pitching angle, pitching angular velocity and attack angle exactly and real-time. These estimations can help to implement very-low penetration missions.

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