Modelling and robust controller design for an underactuated self-balancing robot with uncertain parameter estimation

A comprehensive literature review of self-balancing robot (SBR) provides an insight to the strengths and limitations of the available control techniques for different applications. Most of the researchers have not included the payload and its variations in their investigations. To address this problem comprehensively, it was realized that a rigorous mathematical model of the SBR will help to design an effective control for the targeted system. A robust control for a two-wheeled SBR with unknown payload parameters is considered in these investigations. Although, its mechanical design has the advantage of additional maneuverability, however, the robot's stability is affected by changes in the rider's mass and height, which affect the robot's center of gravity (COG). Conventionally, variations in these parameters impact the performance of the controller that are designed with the assumption to operate under nominal values of the rider's mass and height. The proposed solution includes an extended Kalman filter (EKF) based sliding mode controller (SMC) with an extensive mathematical model describing the dynamics of the robot itself and the payload. The rider's mass and height are estimated using EKF and this information is used to improve the control of SBR. Significance of the proposed method is demonstrated by comparing simulation results with the conventional SMC under different scenarios as well as with other techniques in literature. The proposed method shows zero steady state error and no overshoot. Performance of the conventional SMC is improved with controller parameter estimation. Moreover, the stability issue in the reaching phase of the controller is also solved with the availability of parameter estimates. The proposed method is suitable for a wide range of indoor applications with no disturbance. This investigation provides a comprehensive comparison of available techniques to contextualize the proposed method within the scope of self-balancing robots for indoor applications

Stratified heat transfer of magneto-tangent hyperbolic bio-nanofluid flow with gyrotactic microorganisms: Keller-Box solution technique

The purpose of the present investigation is to examine the heat, mass and microorganism concentration transfer rates in the magnetohydrodynamics (MHD) stratified boundary layer flow of tangent hyperbolic nanofluid past a linearly, uniform stretching surface comprising gyrotactic microorganisms as well as nanoparticles. The governing PDEs with relevant end point conditions are molded into a non-dimensional ordinary differential equation (ODE) form by means of the similarity transformation. The numerical solution of dimensionless problem is acquired within the frame of robust Keller-Box technique. The velocity, temperature, mass and motile microorganism density are investigated graphically within the context of different significant parameters. Numerical results have been inspected via plots and table (namely as the local Nusselt number, the local wall mass flux and the local microorganisms wall flux). This article proves that the energy, concentration and motile microorganism density reduce with increase in thermal, solutal and motile density stratification parameters. The asserted outcomes are beneficial to enhance the cooling and heating processes, energy generation, thermal machines, solar energy systems, industrial processes etc

Cross electromagnetic nanofluid flow examination with infinite shear rate viscosity and melting heat through Skan-Falkner wedge

This demonstration of study focalizes the melting transport and inclined magnetizing effect of cross fluid with infinite shear rate viscosity along the Skan-Falkner wedge. Transport of energy analysis is brought through the melting process and velocity distribution is numerically achieved under the influence of the inclined magnetic dipole effect. Moreover, this study brings out the numerical effect of the process of thermophoresis diffusion and Brownian motion. The infinite shear rate of viscosity model of cross fluid reveals the set of partial differential equations (PDEs). Similarity transformation of variables converts the PDEs system into nonlinear ordinary differential equations (ODEs). Furthermore, a numerical bvp4c process is imposed on these resultant ODEs for the pursuit of a numerical solution. From the debate, it is concluded that melting process cases boost the velocity of fluid and velocity ratio parameter. The augmentation of the minimum value of energy needed to activate or energize the molecules or atoms to activate the chemical reaction boosts the concentricity inclined magnetized flow, infinite shear rate viscosity, Brownian motion, 2-D cross fluid, melting process of energy, thermophoresis diffusion melting of energy.Campus Chiclay

Thermal growth in solar water pump using Prandtl-Eyring hybrid nanofluid: a solar energy application

Nowadays, with the advantages of nanotechnology and solar radiation, the research of Solar Water Pump (SWP) production has become a trend. In this article, Prandtl-Eyring hybrid nanofluid (P-EHNF) is chosen as a working fluid in the SWP model for the production of SWP in a parabolic trough surface collector (PTSC) is investigated for the case of numerous viscous dissipation, heat radiations, heat source, and the entropy generation analysis. By using a well-established numerical scheme the group of equations in terms of energy and momentum have been handled that is called the Keller-box method. The velocity, temperature, and shear stress are briefly explained and displayed in tables and figures. Nusselt number and surface drag coefficient are also being taken into reflection for illustrating the numerical results. The first finding is the improvement in SWP production is generated by amplification in thermal radiation and thermal conductivity variables. A single nanofluid and hybrid nanofluid is very crucial to provide us the efficient heat energy sources. Further, the thermal efficiency of MoS2-Cu/EO than Cu-EO is between 3.3 and 4.4% The second finding is the addition of entropy is due to the increasing level of radiative flow, nanoparticles size, and Prandtl-Eyring variable

A comparative entropy based analysis of Cu and Fe3O4/methanol Powell-Eyring nanofluid in solar thermal collectors subjected to thermal radiation, variable thermal conductivity and impact of different nanoparticles shape

The efficiency of any nanofluid based thermal solar system depend on the thermophysical properties of the operating fluids, type and shape of nanoparticles, nanoparticles volumetric concentration in the base fluid and the geometry/length of the system in which fluid is flowing. The recent research in the field of thermal solar energy has been focused to increase the efficiency of solar thermal collector systems. In the present research a simplified mathematical model is studied for inclusion in the thermal solar systems with the aim to improve the overall efficiency of the system. The flow of Powell-Eyring nanofluid is induced by non-uniform stretching of porous horizontal surface with fluid occupying a space over the surface. The thermal conductivity of the nanofluid is to vary as a linear function of temperature and the thermal radiation is to travel a short distance in the optically thick nanofluid. Numerical scheme of Keller box is implemented on the system of nonlinear ordinary differential equations, which are resultant after application of similarity transformation to governing nonlinear partial differential equations. The impact of non dimensional physical parameters appearing in the system have been observed on velocity and temperature profiles along with the entropy of the system. The velocity gradient (skin friction coefficient) and the strength of convective heat exchange (Nusselt number) are also investigated. Keywords: Entropy generation, Powell-Eyring fluid, Nanofluids, Partial slip, Thermal conductivity, Thermal radiation, Particle shap

Mathematical model for thermal and entropy analysis of thermal solar collectors by using Maxwell nanofluids with slip conditions, thermal radiation and variable thermal conductivity

In the present research a simplified mathematical model for the solar thermal collectors is considered in the form of non-uniform unsteady stretching surface. The non-Newtonian Maxwell nanofluid model is utilized for the working fluid along with slip and convective boundary conditions and comprehensive analysis of entropy generation in the system is also observed. The effect of thermal radiation and variable thermal conductivity are also included in the present model. The mathematical formulation is carried out through a boundary layer approach and the numerical computations are carried out for Cu-water and TiO2-water nanofluids. Results are presented for the velocity, temperature and entropy generation profiles, skin friction coefficient and Nusselt number. The discussion is concluded on the effect of various governing parameters on the motion, temperature variation, entropy generation, velocity gradient and the rate of heat transfer at the boundary

Gain-scheduled proportional integral derivative control of taxi model of unmanned aerial vehicles

Unmanned aerial vehicles (UAVs) are extensively used for defense and surveillance applications. To ensure desirable performance under all conditions, a UAV requires an appropriate control strategy. For the design of control law, a complete understanding of the model is necessary. The present research proposes and develops a control strategy for a three-wheeled UAV while it is in taxi phase. This necessitates conducting a control-oriented analysis on the UAV to determine the most efficient input channel for controlling a specific output. A control structure is then designed to control the outputs using the control input of nose-wheel steering angle and rudder. In this regard, a proportional integral derivative (PID) controller offers a preliminary solution. To cater for the highly nonlinear nature of the taxi model, we propose a solution that employs a gain-scheduled PID (GS-PID) controller to cover the entire operating range of the UAV during taxi phase, where speed of the UAV is a scheduling variable. The values of the controller parameters are continuously updated according to the current UAV speed. Simulation results in the form of trajectory tracking in the presence of disturbances demonstrate efficiency of the proposed control law

Taxi model of unmanned aerial vehicle: Formulation and simulation

Unmanned Aerial Vehicles cannot work efficiently without a control system. Before any form of control is applied to it, modeling of the system is necessary. This work focuses on the development of a Taxi model of UAV. The reformulated model has been developed and simulated in Simulink and Simscape. Three scenarios have been considered in Simulation: Normal conditions with no wind, head and tail wind of 15 m/s and steering angle of 1 radian. The key objective of this model is to include all the necessary dynamics of UAV when it is in taxi phase. This has been done by modifying the vehicle body model in Simscape to fit to the specifications of the UAV and moreover integrating it with an undercarriage model from previous literature to include the forces

Entropy and heat transfer analysis using Cattaneo-Christov heat flux model for a boundary layer flow of Casson nanofluid

A numerical investigation of Casson nanofluid flow, heat transfer and entropy generation over a horizontal porous stretching surface is carried out in the present research. The simplified flow model includes the effect of Lorentz forces, Cattaneo-Christov heat flux, thermal radiation and non-uniform stretching of porous surface. Similarity technique is employed to reduce the governing nonlinear partial differential equations to a set of nonlinear ordinary differential equations. The resulting set is then solved using finite difference numerical scheme to approximate the solutions for the velocity, temperature and the entropy profiles. Furthermore, the skin friction factor and the heat exchange rate at the boundary have been computed and explored graphically. The numerical computations are carried for Cu-H2O and TiO2-H2O nanofluids. The significant findings of the study are the negative impact of Lorentz forces on the nanofluid motion within the boundary layer and the increase in temperature due to increase in non-Newtonian parameter, thermal radiation parameter and the sheet convection parameter. Moreover Cu-H2O nanofluid is detected as superior thermal conductor than TiO2-H2O nanofluid. Keywords: Casson nanofluid, Cattaneo-Christov heat flux model, Thermal radiation, Entropy generatio

Mathematical model for thermal solar collectors by using magnetohydrodynamic Maxwell nanofluid with slip conditions, thermal radiation and variable thermal conductivity

Solar energy is the cleanest, renewable and most abundant source of energy available on earth. The main use of solar energy is to heat and cool buildings, heat water and to generate electricity. There are two types of solar energy collection system, the photovoltaic systems and the solar thermal collectors. The efficiency of any solar thermal system depend on the thermophysical properties of the operating fluids and the geometry/length of the system in which fluid is flowing. In the present research a simplified mathematical model for the solar thermal collectors is considered in the form of non-uniform unsteady stretching surface. The flow is induced by a non-uniform stretching of the porous sheet and the uniform magnetic field is applied in the transverse direction to the flow. The non-Newtonian Maxwell fluid model is utilized for the working fluid along with slip boundary conditions. Moreover the high temperature effect of thermal radiation and temperature dependent thermal conductivity are also included in the present model. The mathematical formulation is carried out through a boundary layer approach and the numerical computations are carried out for cu-water and TiO2-water nanofluids. Results are presented for the velocity and temperature profiles as well as the skin friction coefficient and Nusselt number and the discussion is concluded on the effect of various governing parameters on the motion, temperature variation, velocity gradient and the rate of heat transfer at the boundary. Keywords: Solar energy, Thermal collectors, Maxwell-nanofluid, Thermal radiation, Partial slip, Variable thermal conductivit