Abstract
To reduce cost, increase resolution, and reduce errors due to changing light intensity of the VIS SPEC, a new technique is proposed which applies the Kalman algorithm along with a simple hardware setup and implementation. In real time, the SPEC automatically corrects spectral data errors resulting from an unstable light source by adding a photodiode sensor to monitor the changes in light source intensity. The Kalman algorithm is applied on the data to correct the errors. The light intensity instability is one of the sources of error considered in this work. The change in light intensity is due to the remaining lifetime, working time and physical mechanism of the halogen lamp, and/or battery and regulator stability. Coefficients and parameters for the processing are determined from MATLAB simulations based on two real types of datasets, which are mono-changing and multi-changing datasets, collected from the prototype SPEC. From the saved datasets, and based on the Kalman algorithm and other computer algorithms such as divide-and-conquer algorithm and greedy technique, the simulation program implements the search for process noise covariance, the correction function and its correction coefficients. These components, which will be implemented in the processor of the SPEC, Kalman algorithm and the light-source-monitoring sensor are essential to build the Kalman corrector. Through experimental results, the corrector can reduce the total error in the spectra on the order of 10 times; for certain typical local spectral data, it can reduce the error by up to 60 times. The experimental results prove that accuracy of the SPEC increases considerably by using the proposed Kalman corrector in the case of changes in light source intensity. The proposed Kalman technique can be applied to other applications to correct the errors due to slow changes in certain system components.
Highlights
The VIS SPEC applies Beer-Lambert law to find the substance concentration [1]
With the spectral intensity plot, the horizontal axis presents the step unit corresponding to the scanning steps of the stepper motor instead of wavelength unit or number wavelength unit which can be changed among them by using Equation (1)
The recorded data are collected under unchanging and slightly changing working conditions to simulate the unstable factors as mentioned in the Introduction which can lead to slight changes in light intensity
Summary
The VIS SPEC applies Beer-Lambert law to find the substance concentration [1]. Sensitivity and accuracy of a SPEC depend on several factors, one of these is, firstly, the analog-to-digital converter (ADC) which is responsible for digitalizing the measured analog signal from the sensors and providing resolution to the spectrometer [2]. Another important factor that affects the accuracy are the system stability factors such as light intensity, voltage regulator, ambient and operating temperature. To increase the SPEC’s sensitivity and to reduce the cost, an ADS1252 [6] and BPW-34 [7] are chosen
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
