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Liu X.,Beihang University | Chen Z.,Beihang University | Chen W.,Beihang University | Xing X.,Air Force Armament Research Academy
2016 IEEE International Conference on Mechatronics and Automation, IEEE ICMA 2016 | Year: 2016

Optical flow sensors (OFSs), with characteristics of small size, light weight, low cost, little power consumption, fast response and no radiation, are suitable for miniature aerial vehicles (MAVs) to detect the environment around them. According to our recent works, besides the velocity and the flight height above the ground, many other flight states can also be obtained using optical flow sensors and rate gyros, including attack angle, sideslip angle, MAV's Euler angles and so on. In this paper, a placement scheme of OFSs on a MAV is proposed. After establishing the measurement equations, an Unscented Kalman Filter (UKF) is applied to estimate the flight states of the MAV. Simulation results show that the flight states can be estimated accurately and quickly. The initial error between the true values and the estimations will be distinguished in about 4 seconds. Using the estimations as feedbacks, the autopilot can control the MAV effectively. Optimal placement scheme of OFSs is also discussed. © 2016 IEEE.


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 | 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.


Xiaoming L.,Beihang University | Jiali G.,Beihang University | Wanchun C.,Beihang University | Xiaolan X.,Air Force Armament Research Academy | Xingliang Y.,The Aerospace Corporation
IEEE Transactions on Aerospace and Electronic Systems | Year: 2012

We present a real-time error-compensation method which is used to improve the measurement precision of a Scheimpflug range sensor. Based on this method a Scheimpflug range sensor is fabricated. It only takes 3.21 ms to complete one distance measurement in a hardware test. Furthermore, by using this range sensor, an altitude-holding application is performed on a proof-of-concept flight test platform in the lab environment. The hardware-in-loop (HIL) simulation result shows that approximately 10 mm control accuracy is achieved by implementing the error compensation. © 2011 IEEE.


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.


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

An optical flow sensor, which is fabricated by our laboratory, was mounted on a unmanned aerial vehicle (UAV) to implement terrain following and autonomous landing tasks by using optical flow as feedback. The performance of the optical flow sensor was tested and the UAV model was built. Control algorithm for terrain following based on optical flow was developed and landing strategies using optical flow as feedback was proposed. Mathematical simulations and hardware-in-loop tests show optical flow information can be used in a relatively simple form to control both the flying speed and altitude at the same time to ensure the safety of flying missions for the UAV. The optical flow sensor is proved available for flight control by the hardware tests.


Qin T.,Beihang University | Chen W.-C.,Beihang University | Xing X.-L.,Air Force Armament Research Academy
Yuhang Xuebao/Journal of Astronautics | Year: 2012

A new guidance law is presented for the impact angle control problem. It can achieve zero miss distance and any desired impact attitude angle simultaneously. The guidance law does not require a time-to-go estimation and information of the range to the target. It attains a perfect intercept (zero miss distance and zero impact angle error) against nonmaneuvering targets under certain ideal conditions. In addition, it is shown that the acceleration command converges to zero at the impact time, which is beneficial to the weapon systems with penetrator warheads. The simulation results show that the new guidance law performs better compared with other two laws from the literatures for the impact angle control problem.


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.


Li M.,Air Force Armament Research Academy | Sun Z.,National University of Defense Technology | Gong E.,National University of Defense Technology
Procedia Engineering | Year: 2014

One approach based on AC20-128A is presented in order to assess the risk caused by uncontained engine rotor failure (UERF). In this approach, the risk assessment procedure includes hazard identification and hazard quantification. In the step of hazard identification, the catastrophic functional hazards, derived from the functional hazard analysis (FHA) results for the airplane, are used as the top events to construct the fault trees. The minimal cut sets (MSCs) of the fault trees are the hazards to be identified exactly. In the step of hazard quantification, the probability of one hazard triggered by some uncontained debris is evaluated. After the probabilities of all the identified hazards are quantified, the risk assessment of the airplane is completed. And the assessment result is compared with the design specifications to show compliance with the safety design. A small example is introduced to illustrate the rationality and accuracy of the aforementioned method. © 2014 The Authors. Published by Elsevier Ltd.

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