A two-stage calibration method for low-cost UAV attitude estimation using infrared sensor

2010 ◽  
Author(s):  
Long Di ◽  
Haiyang Chao ◽  
YangQuan Chen
Keyword(s):  
Low Cost ◽  
Calibration Method ◽  
Attitude Estimation ◽  
Infrared Sensor ◽  
Two Stage

scholarly journals A DCM Based Attitude Estimation Algorithm for Low-Cost MEMS IMUs

2015 ◽  
Vol 2015 ◽  
pp. 1-18 ◽  
Author(s):  
Heikki Hyyti ◽  
Arto Visala
Keyword(s):  
Kalman Filter ◽  
Extended Kalman Filter ◽  
Low Cost ◽  
Direction Cosine ◽  
Estimation Algorithm ◽  
Calibration Method ◽  
Attitude Estimation ◽  
Mems Sensors ◽  
Acceleration Sensors ◽  
Adaptive Extended Kalman Filter

An attitude estimation algorithm is developed using an adaptive extended Kalman filter for low-cost microelectromechanical-system (MEMS) triaxial accelerometers and gyroscopes, that is, inertial measurement units (IMUs). Although these MEMS sensors are relatively cheap, they give more inaccurate measurements than conventional high-quality gyroscopes and accelerometers. To be able to use these low-cost MEMS sensors with precision in all situations, a novel attitude estimation algorithm is proposed for fusing triaxial gyroscope and accelerometer measurements. An extended Kalman filter is implemented to estimate attitude in direction cosine matrix (DCM) formation and to calibrate gyroscope biases online. We use a variable measurement covariance for acceleration measurements to ensure robustness against temporary nongravitational accelerations, which usually induce errors when estimating attitude with ordinary algorithms. The proposed algorithm enables accurate gyroscope online calibration by using only a triaxial gyroscope and accelerometer. It outperforms comparable state-of-the-art algorithms in those cases when there are either biases in the gyroscope measurements or large temporary nongravitational accelerations present. A low-cost, temperature-based calibration method is also discussed for initially calibrating gyroscope and acceleration sensors. An open source implementation of the algorithm is also available.

scholarly journals A Fast Calibration and Compensation Method for Magnetometers in Strap-Down Spinning Projectiles

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4157 ◽  
Author(s):  
Dafeng Long ◽  
Xiaoming Zhang ◽  
Xiaohui Wei ◽  
Zhongliang Luo ◽  
Jianzhong Cao
Keyword(s):  
Low Cost ◽  
Experimental System ◽  
Calibration Method ◽  
Attitude Estimation ◽  
Attitude Measurement ◽  
Angle Error ◽  
Estimation Errors ◽  
Zero Bias ◽  
Launch Site ◽  
Spinning Projectile

Attitude measurement is an essential technology in projectile trajectory correction. Magnetometers have been used for projectile attitude measurement systems as they are small in size, lightweight, and low cost. However, magnetometers are seriously disturbed by the artillery magnetic field during launch. Moreover, the error parameters of the magnetometers, which are calibrated in advance, usually change after extended storage. The changed parameters have negative effects on attitude estimation of the projectile. To improve the accuracy of attitude estimation, the magnetometers should be calibrated again before launch or during flight. This paper presents a fast calibration method specific for a spinning projectile. At the launch site, the tri-axial magnetometer is calibrated, the parameters of magnetometer are quickly obtained by optimal ellipsoid fitting based on a least squares criterion. Then, the calibration parameters are used to compensate for magnetometer outputs during flight. The numerical simulation results show that the proposed calibration method can effectively determine zero bias, scale factors, and alignment angle errors. Finally, a semi-physical experimental system was designed to further verify the performance of the calibration method. The results show that pitch angle error reduces from 3.52° to 0.58° after calibration. The roll angle error is reduced from 2.59° to 0.65°. Simulations and experimental results indicate that the accuracy of magnetometer in strap-down spinning projectile has been greatly enhanced, and the attitude estimation errors are reduced after calibration.

scholarly journals Development and evaluation of low-cost walker with trunk support for senior citizen

2017 ◽  
Vol 51 (0) ◽  
Author(s):  
Paloma Hohmann Poier ◽  
Francisco Godke ◽  
José Aguiomar Foggiatto ◽  
Leandra Ulbricht
Keyword(s):  
Senior Citizens ◽  
Low Cost ◽  
Senior Citizen ◽  
Descriptive Study ◽  
The Body ◽  
Two Stage ◽  
Monitoring Time ◽  
Static Body ◽  
Study Development

Abstract OBJECTIVE Develop and evaluate a low-cost walker with trunk support for senior citizens. METHOD Two-stage descriptive study: development of a walker with trunk support and evaluation with fourth age senior citizens. RESULTS Twenty-three fourth age senior citizens were selected. The evaluated criteria were the immediate influence of the walker on the static stabilometry with baropodometer and the evaluation of gait with accelerometers monitoring time and amplitude of the hip movement. There was a significant decrease in the body oscillation of senior citizens with the use of the developed walker, and there were changes in the joint amplitudes of the hip, but they were not significant. CONCLUSION Using low-cost materials, it was possible to develop and equipment that met resistance and effectiveness requirements. The walker interfered in the balance of the senior citizens, reducing significantly the static body oscillation.

scholarly journals Superior Antireflection Coating for a Silicon Cell with a Micronanohybrid Structure

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Hsi-Chien Liu ◽  
Gou-Jen Wang
Keyword(s):  
Solar Cell ◽  
Silicon Solar Cell ◽  
Low Cost ◽  
Antireflection Coating ◽  
Light Spectrum ◽  
Two Stage ◽  
Liquid Diffusion ◽  
Pyramid Structure ◽  
Short Time ◽  
Structure Array

The object of this paper is to develop a high antireflection silicon solar cell. A novel two-stage metal-assisted etching (MAE) method is proposed for the fabrication of an antireflective layer of a micronanohybrid structure array. The processing time for the etching on an N-type high-resistance (NH) silicon wafer can be controlled to around 5 min. The resulting micronanohybrid structure array can achieve an average reflectivity of 1.21% for a light spectrum of 200–1000 nm. A P-N junction on the fabricated micronanohybrid structure array is formed using a low-cost liquid diffusion source. A high antireflection silicon solar cell with an average efficiency of 13.1% can be achieved. Compared with a conventional pyramid structure solar cell, the shorted circuit current of the proposed solar cell is increased by 73%. The major advantage of the two-stage MAE process is that a high antireflective silicon substrate can be fabricated cost-effectively in a relatively short time. The proposed method is feasible for the mass production of low-cost solar cells.

Gyro Drift Calibration in Low Cost Inertial System

1999 ◽  
Author(s):  
Zhong Zhao ◽  
Rong Ma ◽  
Weiguo Zhang
Keyword(s):  
Low Cost ◽  
Fuzzy Reasoning ◽  
Calibration Method ◽  
Inertial System ◽  
Time Varying ◽  
Dynamic Estimation ◽  
Gyro Drift

Abstract An intelligent gyro drift calibration method for low-cost inertial system is presented in this paper. This method based on fuzzy reasoning and dynamic estimation can calibrate time-varying gyro drift in the motion of vehicle. Experiments have been done on three strapdown inertial all-attitude systems constituted of piezoelectric rate gyros. The result shows that this method is effective by which the residual of piezoelectric gyro drift can be reduced to about one percent of its original drift value.

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