Song Chunlei

Applications of zero-velocity detector and Kalman filter in zero velocity update for inertial navigation system

Zero velocity update (ZUPT) is an inexpensive and effective method for error control of inertial navigation system (INS). Detecting the stopping time interval is important for ZUPT methods. The ZUPT method based on Kalman filter has a higher degree of precision compared with the ZUPT method based on curve fitting and the ZUPT method based on maximum likelihood estimation, but the modeling of Kalman filter is critical for the performance of INS. In this paper, three kinds of zero-velocity detectors and a linear discrete Kalman filter model are applied in ZUPT for INS. Simulation results show that the three kinds of zero-velocity detectors are effective, and the ZUPT method based on the linear discrete Kalman filter model makes the positioning accuracy of INS significantly improved.

Online calibration method based on dual-axis rotation-modulating laser gyro SINS

Traditional calibration methods require a three-axis high precision turntable, which is unable to meet the demands of online calibration. Hence, based on the structural features of dual-axis rotation modulation laser strap-down inertial navigation system, this paper proposes an online calibration method by taking the velocity errors and the position errors as measurement information. In this paper, the error model of inertial navigation system is established, and a 30-dimension Kalman filtering model is derived in which the state variables include the gyro constant error and the gyro scale factor error and the gyro installation error angle, the accelerometer constant error and the accelerometer scale factor error and the accelerometer installation error angle. In order to identify error parameters comprehensively, an appropriate calibration route is designed. According to the route, the simulation shows that all error parameters of laser gyros and accelerometers can be identified and calibrated precisely. This method satisfies the demands of online calibration and has a great engineering significance.

The indoor positioning algorithm research based on improved location fingerprinting

It is the key point of the final precise of positioning that whether the positioning fingerprint database created by location fingerprinting can accurately reflect the mapping relationship between the position and the fingerprints signal. In order to improve the accuracy of indoor positioning, the mean smoothing algorithm is used to process the collected data during the building of WLAN indoor fingerprint database rather than mean value. Eliminating the gross error is necessary before processing data with mean smoothing algorithm. Meanwhile, this paper proposes an improved KNN algorithm, which is to weigh the difference of the test point and the reference point, then choose the appropriate value of α. The algorithm is based on the constructing indoor wireless network with wireless routers and collecting the signal strength of the five wireless routers. Through the comparison with the accuracy of the commonly used indoor positioning algorithms, the results show that the positioning accuracy of the error distance within 3.6m can reach 90%, and within 4.8m can reach 97%.

Design of longitudinal control system for target missiles based on fuzzy adaptive PID control

To achieve a better robustness and get a static response of a certain target missiles in longitudinal control, a mathematical model of target missiles is established. The uncontrolled trajectory, the predetermined trajectory and the requirements of the predetermined trajectory are analyzed next. Then the trajectory instruction angle is designed to ensure the stable flight of the target missiles system. To solve the problem that the PID controller cannot adjust parameters online and the output is easy to be disturbed by external noise, the fuzzy adaptive PID control is designed. It enhanced the robustness of the target missiles by fuzzy control, and also has a good response by using PID control. The simulation experiments show the fuzzy adaptive control system can track the predetermined trajectory rapidly and smoothly, and the static error and overshoot were significantly reduced. When the system are affected by noise, the fuzzy adaptive PID control can achieve a good robustness than traditional PID controller.

The research and error analysis of attitude solution algorithm for guided munitions based on MR sensor

The attitude solution is a vital index in the research of guided munitions. In order to better understand the attitude solution algorithm, the initial alignment and the error analysis, we study the attitude parameters. For the initial alignment requirement of the guided munitions integrated navigation, we use the attitude solution algorithm based on using the MR sensor. This algorithm uses magnetic sensor to measure the magnetic field signal. And in the premise of knowing the head angle, we tend to calculate the other two attitude angles. In addition, this paper proposes three algorithm errors, and the result is showed with the simulation and analysis using MATLAB. The simulation results show the algorithm is advisable in the attitude solution. It can be considered using this algorithm for guided munitions.

The application of R-T-S smoothing algorithm in the post-processing of the integrated navigation

Integrated navigation system usually uses Kalman filter to make it possible for error compensation. In order to improve the precision of navigation and the stability of data, we introduce the R-T-S (Rauch-Tung-Striebel) optimal fixed-interval smoothing into the post-processing of data. On the basis of the forward Kalman filter, we add the backward information filter to the system and use the measured data to verify the algorithm. The results show that compared with the traditional Kalman filter, the R-T-S optimal fixed-interval smoothing can not only improve the precision of the position and posture but can also improve the precision of navigation significantly in case of lock-lose, making it possible as an effective way of data processing.

An improved binocular visual odometry for high-speed automotive applications

In this paper, we present an improved motion estimation method by adding extra information for binocular visual odometry (VO) which is especially suited for improving high-speed pose change estimation. The extra information is obtained by structured object detecting, taking lane line detection as an example. We can get an accurate position information by calculating the interval of each dotted lane line and counting the number of the dotted line which can be fused with the pose information obtained from visual odometry. The outlier rejection of the VO is also improved, making it adapt to highway situation. In the fusion process, a Kalman filter is adopted to estimate the motion and location information for a high speed vehicle. The experimental results show that the approach proposed is valid and can increase the positioning accuracy significantly compared with ordinary visual odometry.

Application of correlation detection in rotation-modulation north-seeking based on MEMS gyroscope

MEMS gyroscope has been recently the hotspot in inertial measurements applications, because of its advantage of low costs, micro size, and low power consumption, etc. But it is considered that MEMS gyroscope cannot be used in north-seeking because of its drift and noise. This paper has proposed a feasible rotation-modulation north-seeking method, in which correlation analysis is used to detect the modulated wave phase to give the relative direction to true north. Self-correlation detection, cross-correlation detection and Least Squares are presented in detail consisting of the systemic correlation detection approach. With the help of correlation detection, experimental results show that the rotation-modulation north-seeking method proposed in this paper gives impressive precision of north-seeking.

Design and Simulation of Trajectory Generator

Trajectory generator is necessary in many inertial navigation research fields. The paper gives the design method of a trajectory generator, and deduces the control equation in detail, then classifies the flight track into four fundamental stages. The trajectory generator resolves the flight track, generates specific force, angular velocity and position signals etc. To check the trajectory generator, the paper designs a navigation solution program. At last, a simulation is demonstrated; the data such as position information generated by trajectory generator and navigation solution equation is compared. Simulation shows that the design is correct and the precision of the trajectory generator is very high.