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1 – 10 of 302Shuangshuang 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.
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THE twenty‐sixth annual meeting of the Institute of Aeronautical Sciences was held, as usual, in the Sheraton‐Astor Hotel, New York. The papers delivered during the week covered…
Abstract
THE twenty‐sixth annual meeting of the Institute of Aeronautical Sciences was held, as usual, in the Sheraton‐Astor Hotel, New York. The papers delivered during the week covered the widest range of subjects to date, including gravity, and anti‐gravity, hypersonic aerodynamics, space propulsion and earth satellites, to name only an exotic few. It is obvious that any one observer can give a coherent summary of (or even attend) only a limited number of lectures, and this report is concerned only with the rotary wing sessions.
The paper presents results of a pilot project on technological innovation of main flexible components for automotive suspension systems, that are coil springs and stabilizer bars…
Abstract
The paper presents results of a pilot project on technological innovation of main flexible components for automotive suspension systems, that are coil springs and stabilizer bars. Current technology has been described and related problems have been outlined. In order to fulfil features such as compactness, lightness and environmentally conscious design, solutions based on new forms, materials and manufacturing processes have been proposed. Improvements in weights, dimensions, noiselessness, corrosion and fatigue strength, environmental effects, have been all assessed, keeping a quite low project cost (around $3 million).
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RICHARD A. EVANS and G.W. FOSDICK
A SIGNIFICANT NUMBER of the helicopters presently in the US Army inventory are inherently unstable and use pressurised hydraulic fluid in the hydromechanical flight control…
Abstract
A SIGNIFICANT NUMBER of the helicopters presently in the US Army inventory are inherently unstable and use pressurised hydraulic fluid in the hydromechanical flight control system. The development of a hydrofluidic stability‐augmentation system which can be integrated into the helicopter primary control system, offering promise of improved reliability, maintainability, and reduced cost over conventional electromechanical stability augmentation systems, has been accomplished.
Jinwu Xiang, Tong Shen and Daochun Li
Obstacle and wind field are common environmental factors for mini unmanned helicopter (MUH) flight. This paper aims to develop a trajectory planning approach guiding MUH to avoid…
Abstract
Purpose
Obstacle and wind field are common environmental factors for mini unmanned helicopter (MUH) flight. This paper aims to develop a trajectory planning approach guiding MUH to avoid static and dynamic obstacles and to fly in steady uniform or boundary-layer wind field.
Design/methodology/approach
An optimal control model including a nonlinear flight dynamics model and a cubic obstacle model is established for MUH trajectory planning. Radau pseudospectral method is used to generate the optimal trajectory.
Findings
The approach can plan reasonable obstacle-avoiding trajectories in obstacle and windy environments. The simulation results show that high-speed wind fields increase the flight time and fluctuation of control inputs. If boundary-layer wind field exists, the trajectory deforms significantly and gets closer to the ground to escape from the strong wind.
Originality/value
The key innovations in this paper include a cubic obstacle model which is straightforward and practical for trajectory planning and MUH trajectory planning in steady uniform wind field and boundary-layer wind field. This study provides an efficient solution to the trajectory planning for MUH in obstacle and windy environments.
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Seongpil Kim, Agus Budiyono, Jang‐Ho Lee, DooHyun Kim and Kwang Joon Yoon
The purpose of this paper is to conduct the design, development and testing of a controller for an autonomous small‐scale helicopter.
Abstract
Purpose
The purpose of this paper is to conduct the design, development and testing of a controller for an autonomous small‐scale helicopter.
Design/methodology/approach
The hardware in the loop simulation (HILS) platform is developed based on the nonlinear model of JR Voyager G‐260 small‐scale helicopter. Autonomous controllers are verified using the HILS environment prior to flight experiments.
Findings
The gains of the multi‐loop cascaded control architecture can be effectively optimized within the HILS environment. Various autonomous flight operations are achieved and it is demonstrated that the prediction from the simulations is in a good agreement with the result from the flight test.
Research limitations/implications
The synthesized controller is effective for the particular test‐bed. For other small‐scale helicopters (with different size and engine specifications), the controller gains must be tuned again.
Practical implications
This work represents a practical control design and testing procedures for an autonomous small‐scale helicopter flight control. The autonomous helicopter can be used for various missions ranging from film making, agriculture and volcanic surveillance to power line inspection.
Originality/value
The research addresses the need for systematic design, development and testing of controller for a small‐scale autonomous helicopter by utilizing HILS environment.
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ADVANCED technology components for the international automotive industry were displayed by the Rugby‐based AE group at the 1986 Society of Automotive Engineers Congress in…
Abstract
ADVANCED technology components for the international automotive industry were displayed by the Rugby‐based AE group at the 1986 Society of Automotive Engineers Congress in Detroit, USA, recently.
A. McClements and S/Ldr. A. Armitage
UNDER the stimulus of military interest helicopter development went ahead (notably in America and Germany) during the war years and helicopter production resulted which, while…
Abstract
UNDER the stimulus of military interest helicopter development went ahead (notably in America and Germany) during the war years and helicopter production resulted which, while very modest, was on a scale never previously approached.
Hardian Reza Dharmayanda, Agus Budiyono and Taesam Kang
The purpose of this paper is to design a model‐based robust controller for autonomous hovering of a small‐scale helicopter.
Abstract
Purpose
The purpose of this paper is to design a model‐based robust controller for autonomous hovering of a small‐scale helicopter.
Design/methodology/approach
The model is developed using prediction error minimization (PEM) system identification method implemented to flight data. Based on the extracted linear model, an H∞ controller is synthesized for robustness against parametric uncertainties and disturbances.
Findings
The proposed techniques for modelling provide a linear state‐space model which correlates well with the recorded flight data. The synthesized H∞ controller demonstrates an effective performance which rejects both sinusoidal and step input disturbances. The controller enables the attitude angle follow the reference target while keeping the attitude rate constant about zero for hover flight condition.
Research limitations/implications
The synthesized controller is effective for hovering and low‐speed flight condition.
Practical implications
This work provides an efficient hovering/low‐speed autonomous helicopter flight control required in many civilian UAV applications such as aerial surveillance and photography.
Originality/value
The paper addresses the challenges of controlling a small‐scale helicopter during hover with inherent modelling uncertainties and disturbances.
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Khadeeja Nusrath T.K., Lulu V.P. and Jatinder Singh
This paper aims to build an accurate mathematical model which is necessary for control design and attitude estimation of a miniature unmanned rotorcraft and its subsequent…
Abstract
Purpose
This paper aims to build an accurate mathematical model which is necessary for control design and attitude estimation of a miniature unmanned rotorcraft and its subsequent conversion to an autonomous vehicle.
Design/methodology/approach
Frequency-domain system identification of a small-size flybar-less remote controlled helicopter is carried out based on the input–output data collected from flight tests of the instrumented vehicle. A complete six degrees of freedom quasi-steady dynamic model is derived for hover and cruise flight conditions.
Findings
The veracity of the developed model is ascertained by comparing the predicted model responses to the actual responses from flight experiments and from statistical measures. Dynamic stability analysis of the vehicle is carried out using eigenvalues and eigenvectors. The identified model represents the vehicle dynamics very well in the frequency range of interest.
Research limitations/implications
The model needs to be augmented with additional terms to represent the high-frequency dynamics of the vehicle.
Practical implications
Control algorithms developed using the first principles model can be easily reconfigured using the identified model, because the model structure is not altered during identification.
Originality/value
This paper gives a practical solution for model identification and stability analysis of a small-scale flybar-less helicopter. The estimated model can be easily used in developing control algorithms.
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