YangQuan Chen | University of California, Merced (original) (raw)

Papers by YangQuan Chen

Proceedings of the 16th IFAC World Congress, 2005, 2005

This paper investigates the synthesis of a non-linear spatial lookahead controller for path track... more This paper investigates the synthesis of a non-linear spatial lookahead controller for path tracking of Ackerman-steered autonomous vehicles. Controller tuning is performed using stability results and optimization techniques. Controller performance is analyzed when the vehicle follows different paths at different speeds. Finally experiments have been conducted using the ROMEO 4R autonomous vehicle.

$Research paper thumbnail of Stability of linear time invariant systems with interval fractional orders and interval coefficients$

This paper considers the stability of the fractional-order linear time-invariant systems with int... more This paper considers the stability of the fractional-order linear time-invariant systems with interval type uncertainties in both fractional orders and the relevant coefficients. It is an extension of our previous result on the robust stability analysis of the interval type uncertain fractional order LTI systems with crisply known fractional orders. We have proposed a stability check procedure for uncertain LTI

$Research paper thumbnail of Adaptive minimum energy cognitive lighting control: Integer order vs fractional order strategies in sliding mode based extremum seeking$

Mechatronics, Oct 1, 2013

To achieve comfortable illumination while minimizing the energy consumption in hybrid lighting, a... more To achieve comfortable illumination while minimizing the energy consumption in hybrid lighting, a minimum energy point tracking algorithm is developed to achieve the minimized energy usage despite of environmental variations in this paper. A hardware-in-the-loop prototype of an adaptive minimum energy cognitive lighting control is proposed, designed and built. A sliding mode based extremum seeking controller (SM-ESC) including integer order (IO) and fractional-order (FO) strategies is firstly employed to minimize energy usage in the lights, while a PID controller is applied to maintain a light level. The performance of the designed controller is compared with both fractional order and integer order controllers which are designed based the proposed lighting system. The hardware-in-the-loop experimental results are presented to demonstrate the practicality and effectiveness of the proposed cognitive lighting control scheme.

Nonlinear Dynamics, Dec 1, 2004

This paper attempts to present an expository review of continued fraction expansion (CFE) based d... more This paper attempts to present an expository review of continued fraction expansion (CFE) based discretization schemes for fractional order differentiators defined in continuous time domain. The schemes reviewed are limited to infinite impulse response (IIR) type generating functions of first and second orders, although high-order IIR type generating functions are possible. For the first-order IIR case, the widely used Tustin operator and Al-Alaoui operator are considered. For the second order IIR case, the generating function is obtained by the stable inversion of the weighted sum of Simpson integration formula and the trapezoidal integration formula, which includes many previous discretization schemes as special cases. Numerical examples and sample codes are included for illustrations.

The development of unmanned aerial vehicle (UAV) technology and the miniaturization of sensors ha... more The development of unmanned aerial vehicle (UAV) technology and the miniaturization of sensors have changed the way remote sensing (RS) is used, popularizing this geoscientific discipline in other fields, such as precision agriculture. This makes it necessary to implement the use of these technologies in teaching RS alongside the classical platforms (satellite and manned aircraft). This manuscript describes how The Higher Technical School of Agricultural Engineering at the University of Córdoba (Spain) has introduced UAV RS into the academic program by way of project-based learning (PBL). It also presents the basic characteristics of PBL, the design of the subject, the description of the teacher-guided and self-directed activities, as well as the degree of student satisfaction. The teaching and learning objectives of the subject are to learn how to determine the vigor, temperature, and water stress of a crop through the use of RGB, multispectral, and thermographic sensors onboard a UAV platform. From the onset, students are motivated, actively participate in the tasks related to the realization of UAV flights, and subsequent processing and analysis of the registered images. Students report that PBL is more engaging and allows them to develop a better understanding of RS.

This paper describes a data quality aware framework for developing a repeatable flight mission de... more This paper describes a data quality aware framework for developing a repeatable flight mission design for fugitive methane sniffing missions using fixed wing small unmanned aerial systems (sUAS) in rural areas. The design outlines general aircraft requirements & performance characteristics as well as overviews required sensors and their performance & data quality considerations. Using Gaussian plume models, atmospheric stability and detection experiments from previous works - we outline a mission design that focuses on detection of downwind plume using a two flux plane flight path. This mission design aims to aid future efforts in improving flux quantification accuracy, uncertainty and comparison between individual experiments.

Accurate and precise measurements of wind are important for understanding atmospheric transport, ... more Accurate and precise measurements of wind are important for understanding atmospheric transport, especially when trying to localize and quantify natural gas emissions from pipeline leaks. This work looks at the applicability of measuring wind speed and direction with mini ultrasonic anemometers onboard small unmanned aerial systems. The 'prop wash effect' from propeller air intake mixing of the wind is quantified through experiments for a multi-rotor platform in a low cost wind tunnel (LCWT). Trisonica and FT742SM sensors are compared through wind tunnel experiments for accuracy confirmation. The validation of measuring wind conditions onboard is compared with accepted estimation techniques for VTOL and fixed wing platforms.

$Research paper thumbnail of Matrix approach to discrete fractional calculus II: Partial fractional differential equations$

Journal of Computational Physics, May 1, 2009

A new method that enables easy and convenient discretization of partial differential equations wi... more A new method that enables easy and convenient discretization of partial differential equations with derivatives of arbitrary real order (so-called fractional derivatives) and delays is presented and illustrated on numerical solution of various types of fractional diffusion equation. The suggested method is the development of Podlubny's matrix approach (Fractional Calculus and Applied Analysis, vol. 3, no. 4, 2000, 359-386). Four examples of numerical solution of fractional diffusion equation with various combinations of time/space fractional derivatives (integer/integer, fractional/integer, integer/fractional, and fractional/fractional) with respect to time and to the spatial variable are provided in order to illustrate how simple and general is the suggested approach. The fifth example illustrates that the method can be equally simply used for fractional differential equations with delays. A set of MATLAB routines for the implementation of the method as well as sample code used to solve the examples have been developed.

American Society for Photogrammetry and Remote Sensing eBooks, 2019

Fractional Calculus and Applied Analysis, Oct 1, 2016

Dear readers, in the Editorial Notes we announce news for our journal, anniversaries, information... more Dear readers, in the Editorial Notes we announce news for our journal, anniversaries, information on international meetings, events, new books, etc. related to the FCAA ("Fractional Calculus and Applied Analysis") areas.

IFAC-PapersOnLine, 2016

Abstract: The remarkable development of small unmanned aerial systems (sUAS) and imaging payloads... more Abstract: The remarkable development of small unmanned aerial systems (sUAS) and imaging payloads have made it easier to monitor the crops with higher spatial resolution and temporal resolution images. As a crop based water status index, stem water potential (SWP) has been widely accepted in field practice to monitor the water status of almond trees. This study aims to research the relationship between SWP and vegetation index extracted from the high spatial resolution images. A circle mission was conducted to evaluate the effects of bidirectional reflectance distribution function (BRDF) on canopy NDVI mean. It indicated that the importance of BRDF calibration to infer SWP from canopy normalized difference vegetation index (NDVI) mean. In addition, it was demonstrated that a strong linear relationship exists between canopy NDVI mean and canopy NDVI variance under different view angles. Further analysis of images identified a non-normalized difference vegetation index (NNDVI) based on ground-truthed measurements of three weeks showed a more significant relationship with SWP than canopy NDVI mean.

Journal of Intelligent and Robotic Systems, Mar 7, 2017

With water shortages and drought affecting many regions of the world, it becomes urgent to increa... more With water shortages and drought affecting many regions of the world, it becomes urgent to increase water use efficiency (WUE) by optimizing irrigation schedule. Proper irrigation scheduling, which includes integrating of soil moisture monitoring, surface evapotranspiration loss calculation, and plant based measurements is required for high WUE. Stem water potential (SWP) has become one of the more common methods to measure water status. It is, however, labor intensive and time consuming, and adoption has been slow. This study aims to build the link between SWP and canopy normalized difference vegetation index (NDVI) based on aerial multi-spectral images and ground-truth measurement of an almond orchard. Data suggests that the correlation between SWP and canopy NDVI can be improved by tuning canopy NDVI threshold, as indicated by the coefficient of determination (R 2). Also, NDVI shows good correlation with SWP in different growing stages-fruit development and postharvest. Finally, it is demonstrated canopy NDVI distribution from different missions are significantly different, even if the interval between two flights is less than one hour. This poses the challenge that further calibration is needed to conduct quantitative measurement in long flight missions. Meanwhile, quantitative consideration of characteristic of bi-directional reflectance distribution function makes it necessary to obtain stable performance of canopy NDVI.

$Research paper thumbnail of Adaptive fractional-order switching-type control method design for 3D fractional-order nonlinear systems$

Nonlinear Dynamics, May 13, 2015

ABSTRACT

This paper presents the results of system identification (system ID) of a small fixed-wing low-co... more This paper presents the results of system identification (system ID) of a small fixed-wing low-cost unmanned aerial vehicle (UAV). The system ID estimates the aerodynamic coefficients of the linear longitudinal equations of motion using batch least squares enhanced with an Error Filtering Online Learning (EFOL) scheme. EFOL estimates the state derivatives using filtering without taking the derivative, making the least squares more robust. Thus, this method of system ID only requires flight data of the states and not the state derivatives. This is advantageous due to the limitations of low-cost sensors including GPS-aided INS systems. The derivation and benefits of least squares with EFOL are briefly described here in. The main contribution of this paper is the identification of the aerodynamic force and moment coefficients for the linear longitudinal model of the UAV. The error between the flight data and the model response are also presented. The identified model shows good correlation to the training data. The model predicts well the short period flight characteristics of the fixed-wing UAV but does not fully capture the long period dynamics. Solutions to this issue are presented and discussed.