Search results
21 – 30 of over 1000Mohd Ariffanan Mohd Basri, Abdul Rashid Husain and Kumeresan A. Danapalasingam
The purpose of this paper is to propose a new approach for robust control of an autonomous quadrotor unmanned aerial vehicle (UAV) in automatic take-off, hovering and landing…
Abstract
Purpose
The purpose of this paper is to propose a new approach for robust control of an autonomous quadrotor unmanned aerial vehicle (UAV) in automatic take-off, hovering and landing mission and also to improve the stabilizing performance of the quadrotor with inherent time-varying disturbance.
Design/methodology/approach
First, the dynamic model of the aerial vehicle is mathematically formulated. Then, a combination of a nonlinear backstepping scheme with the intelligent fuzzy system as a new key idea to generate a robust controller is designed for the stabilization and altitude tracking of the vehicle. For the problem of determining the backstepping control parameters, a new heuristic algorithm, namely, Gravitational Search Algorithm has been used.
Findings
The control law design utilizes the backstepping control methodology that uses Lyapunov function which can guarantee the stability of the nominal model system, whereas the intelligent system is used as a compensator to attenuate the effects caused by external disturbances. Simulation results demonstrate that the proposed control scheme can achieve favorable control performances for automatic take-off, hovering and landing mission of quadrotor UAV even in the presence of unknown perturbations.
Originality/value
This paper propose a new robust control design approach which incorporates the backstepping control with fuzzy system for quadrotor UAV with inherent time-varying disturbance. The originality of this work relies on the technique to compensate the disturbances acting on the quadrotor UAV. In this new approach, the fuzzy system is introduced as an auxiliary control effort to compensate the effect of disturbances. Because the proposed control technique has the capability of robustness against disturbance, thus, it is also suitable to be applied for a broad class of uncertain nonlinear systems.
Details
Keywords
As the land transport task, especially road is expected to increase significantly, by 2015, it would hardly be surprising that many policy makers will look to some form of urban…
Abstract
As the land transport task, especially road is expected to increase significantly, by 2015, it would hardly be surprising that many policy makers will look to some form of urban transport environmental control long before this date. One method is via the introduction of a set of operational environmental hurdles. This is not a new concept. However, this paper proposes a new environmental initiative for urban transport operations. The scheme which is simple for both operators and regulators proposes an effective and meaningful operational rating system which reflects the efforts an operator may go to in their internal fleet environmental policies in purchasing equipment, daily workload planning, waste disposals policies etc.
The three tiered environmental operator performance rating scheme, the E-plus scheme has three levels of operator segmentation. A good basic auditable level of environmental compliance, an E rating, an excellent rating E plus, and an exceptional rating would be an E double plus. Probably no fleets currently in Australia would earn a double plus rating at this time.
Why should there be a road transport operator environmental rating scheme? Firstly as a measurable benchmark for the community and the fleet operators themselves. Secondly and a factor of growing importance is for the customers who are the buyers of freight services. Already customers are specifying in their tender requirements that transport operator environmental competencies and capabilities be listed. This may aid the selection of an operator for a specific task. For example; food sensitive freight handling may require specific food certification scheme adoption such as the HACCP classification system. Similarly an urban courier contract may specify, environmental credentials which sit under an ISO 14000 framework. However, what more specific operator differentiation criteria can be requested by the customer? The E plus system is being designed for this very purpose. In Australia some regulators and teaching centres have begun to take an interest in this transport operator framework.
Shuangshuang Li, Xintian Liu, Xiaolan Wang and Yansong Wang
During the running of automobile, the stabilizer bar is frequently subjected to the impact of complex random loads, which is prone to fatigue failure and accident. In regard to…
Abstract
Purpose
During the running of automobile, the stabilizer bar is frequently subjected to the impact of complex random loads, which is prone to fatigue failure and accident. In regard to this, the purpose of this paper is to study and discuss fatigue life of automobile stabilizer bar.
Design/methodology/approach
Durability bench test shows that failure is located at the joint of sleeve and stabilizer bar body. Based on the collection and compilation of micro-strain load spectrum of the stabilizer bar, the strain-life model is studied considering the influence of average stress and maximum stress at failure area. Seven-grade strain-life curves of the stabilizer bar are established. According to the principle of linear damage accumulation, the relationship between fatigue life and damage is discussed, then the fatigue life of stabilizer bar is predicted. Fatigue life evaluation is carried out from three aspects: reliability analysis, static analysis and fatigue life simulation.
Findings
The results show that the reliability of the test sample is 99.9 percent when the confidence is 90 percent and the durability is 1,073 load spectrum cycles; the ratios of predicted and simulated life to design life are 2.77 and 2.30, respectively.
Originality/value
Based on the road load characteristics of automobile stabilizer bar, the method of fatigue life prediction and evaluation is discussed, which provides a basis for the design and development of automobile chassis components.
Details
Keywords
Ali Belhocine and Mostefa Bouchetara
The main purpose of this study is to analyse the thermomechanical behavior of the dry contact between the brake disc and pads during the braking phase.
Abstract
Purpose
The main purpose of this study is to analyse the thermomechanical behavior of the dry contact between the brake disc and pads during the braking phase.
Design/methodology/approach
The simulation strategy is based on computer code ANSYS11. The modeling of transient temperature in the disc is actually used to identify the factor of geometric design of the disc to install the ventilation system in vehicles. The thermal‐structural analysis is then used coupling to determine the deformation and the Von Mises stress established in the disc, the contact pressure distribution in pads.
Findings
The analysis results showed that temperature field and stress field in the process of braking phase were fully coupled.
Originality/value
The results are satisfactory when compared with those of the specialized literature.
Details
Keywords
Abstract
Details
Keywords
Abstract
Details
Keywords
Mohd Sabirin Rahmat, Khisbullah Hudha, Zulkiffli Abd Kadir, Noor Hafizah Amer, Muhammad Luqman Hakim Abd Rahman and Shohaimi Abdullah
The objective of this paper is to develop a fast modelling technique for predicting magneto-rheological fluid damper behaviour under impact loading applications.
Abstract
Purpose
The objective of this paper is to develop a fast modelling technique for predicting magneto-rheological fluid damper behaviour under impact loading applications.
Design/methodology/approach
The adaptive neuro-fuzzy inference system (ANFIS) technique was adopted to predict the behaviour of a magneto-rheological fluid (MRF) damper through experimental characterisation data. In this study, an MRF damper manufactured by Lord Corporation was used for characterisation using an impact pendulum test rig. The experimental characterisation was carried out with various impact energies and constant input currents applied to the MRF damper.
Findings
This research provided a fast modelling technique with relatively less error in predicting MRF damper behaviour for the development of control strategies. Accordingly, the ANFIS model was able to predict MRF damper behaviour under impact loading and showed better performance than the modified Bouc–Wen model.
Research limitations/implications
This study only focused on modelling technique for a single type of MRF damper used for impact loading applications. It is possible for other applications, such as cyclic loading, random loadings and system identification, to be studied in future experiments.
Original/Value
Future researchers could apply the ANFIS model as an actuator model for the development of control strategies and analyse the control performance. The model also can be replicated in other industries with minor modifications to suit different needs.
Details
Keywords
Francisco Villarreal-Valderrama, Carlos Santana Delgado, Patricia Del Carmen Zambrano-Robledo and Luis Amezquita-Brooks
Reducing fuel consumption of unmanned aerial vehicles (UAVs) during transient operation is a cornerstone to achieve environment-friendly operations. The purpose of this paper is…
Abstract
Purpose
Reducing fuel consumption of unmanned aerial vehicles (UAVs) during transient operation is a cornerstone to achieve environment-friendly operations. The purpose of this paper is to develop a control scheme that improves the fuel economy of a turbojet in its full operating envelope.
Design/methodology/approach
A novel direct-thrust linear quadratic integral (LQI) approach, comprised by an optimal observer/controller satisfying specified performance parameters, is presented. The thrust estimator, based in a Wiener model, is validated with the experimental data of a micro-turbojet. Model uncertainty is characterized by analyzing variations between the identified model and measured data. The resulting uncertainty range is used to verify closed-loop stability with the circle criterion. The proposed controller provides stable responses with the specified performance in the whole operating range, even with after considering plant nonlinearities. Finally, the direct-thrust LQI is compared with a standard thrust controller to assess fuel economy and performance.
Findings
The direct-thrust LQI approach reduced the fuel consumption by 2.1090% in the most realistic scenario. The controllers were also evaluated using the environmental effect parameter (EEP) and transient-thrust-specific fuel consumption (T-TSFC). These novel metrics are proposed to evaluate the environmental impact during transient-thrust operations. The direct-thrust LQI approach has a more efficient fuel consumption according to these metrics. The results also show that isolating the thrust dynamics within the feedback loop has an important impact in fuel economy. Controllers were also evaluated using the EEP and T-TSFC. These novel metrics are proposed to evaluate the environmental impact during transient-thrust operations. The direct-thrust LQI approach has a more efficient fuel consumption according to these metrics. The results also show that isolating the thrust dynamics within the feedback loop has an important impact in fuel economy.
Originality/value
This study shows the design of an effective direct-thrust control approach that minimizes fuel consumption, ensures stable responses for the full operation range, allows isolating the thrust dynamics when designing the controller and is compatible with classical robustness and performance metrics. Finally, the study shows that a simple controller can reduce the fuel consumption of the turbojet during transient operation in scenarios that approximate realistic operating conditions.
Details
Keywords
Fangwei Xie, Erming Ding, Rui Xuan, Xinxing Zhang, Yixian Feng and Jie Zhu
The purpose of this paper is to study the influence rules of geometric parameters on deformation of valve slices.
Abstract
Purpose
The purpose of this paper is to study the influence rules of geometric parameters on deformation of valve slices.
Design/methodology/approach
Based on the theory of flexural deformation of elastic thin slice, differential functions of deformation for both single and multi-slices are given and derived in detail. Furthermore, the effects of geometric dimensions on deformation are analyzed particularly by using Matlab/simulink.
Findings
The results indicated that the deformation decreases with the increment of fixed ring radius ra, slice thickness h, and its number n. Meanwhile, the deformation increases with a rise of slice radius rb, throttle position rk, the radius ratio λ1 and thickness ratio λ2 of slices.
Originality/value
This research can provide some theoretical supports for the parametric and optimal design of adjustable damping shock absorber.
Details
Keywords
G.J. DAVIES, D.R. EASTHAM and B.J. EASTWOOD
This paper is concerned with three types of bearing applications: