Preview-based techniques for vehicle suspension control: a state-of-the-art review

Abstract Automotive suspension systems are key to ride comfort and handling performance enhancement. In the last decades semi-active and active suspension configurations have been the focus of intensive automotive engineering research, and have been implemented by the industry. The recent advances in road profile measurement and estimation systems make road-preview-based suspension control a viable solution for production vehicles. Despite the availability of a significant body of papers on the topic, the literature lacks a comprehensive and up-to-date survey on the variety of proposed techniques for suspension control with road preview, and the comparison of their effectiveness. To cover the gap, this literature review deals with the research conducted over the past decades on the topic of semi-active and active suspension controllers with road preview. The main formulations are reported for each control category, and the respective features are critically analysed, together with the most relevant performance indicators. The paper also discusses the effect of the road preview time on the resulting system performance, and identifies control development trends

Adaptive predictive vibration control in vehicular rear view mirrors

Reduction in rear view mirror vibration has been identified as a research and development priority by large automotive mirror manufacturers, such as Schefenacker Vision Systems Australia Pty Ltd (SVS), the industrial partner of this project. Mirror vibration, particularly in luxury and heavy vehicles, has proved to be a major source of complaints received from the customers. Such vibration may result in image blurring and the loss of rear vision. This can adversely affect the driver, the control of the car, and the safety of the driver and the passengers. The vehicle mirror vibration is also generally perceived to indicate the poor quality of a vehicle. Mirror glass vibration is primarily caused by wind as the result of the motion of the vehicle. The structure-borne vibrations also contribute to vibration by affecting the mirror’s housing. The vibration intensity will depend on parameters, such as the roughness of the road, the engine speed, and wind intensity. Under some circumstances, the image provided by the mirror is not indicative of the true conditions behind the car, which can lead to incorrect perception and to driver misjudgement, resulting in the increased risk of an accident. The main focus of this thesis is to investigate the feasibility of developing an intelligent active vibration controller capable of maintaining a sharp reflected image under all driving conditions. An adaptive predictive controller is proposed. As an adaptive method, the proposed system can generate a control signal, according to the driving conditions, to cancel the vibration. The predictive characteristics of the approach can minimise the effect of delay between the measurement of the vibration signal and the generated control signal. An extensive review of the literature relevant to rear view mirrors, measurement techniques and active control of noise and vibration is carried out. The nature of the mirror vibration based on the road data is obtained empirically and statistically characterised. In order to develop and validate the vibration compensator, a number of experimental rigs are designed and developed. In a rigorous and systematic approach, a number of active vibration techniques are developed and validated through computer simulation and experimental work. The structure of nearly all of these algorithms is based on internal model control, where the actual disturbance signal is reconstructed analytically. The control structures include at least one variant of the FxLMS adaptive filter in different configurations. The results of modelling and validation are systematically recorded in the thesis. The results obtained show that the methodologies proposed in this study, outperform the conventional controllers in reducing vibration levels in rear view mirror

Model predictive control of low Earth-orbiting satellites using magnetic actuation

This paper presents a model predictive control approach for regulating the attitude of magnetically actuated satellites. Unlike other contributions in this area, a predictive control approach is developed which guarantees closed-loop stability of satellite configurations with unstable open-loop pitch dynamics. With the pitch axis being unstable, two magnetic dipoles are used exclusively for regulation of this axis. This allows the dynamics to be treated as a linear time-invariant system, and a simple proportional–derivative (PD) scheme is implemented. A model predictive controller is designed to regulate the lateral dynamics, with a Lyapunov function derived to guarantee asymptotic stability of the closed-loop system. The regulation of the lateral dynamics is achieved with a singe dipole moment, with a novel reformulation of the lateral dynamics also providing an explicit link between the two controllers. Simulations demonstrate the effectiveness and stability of the proposed algorithm when applied to the European Space Agency’s GOCE satellite

Trajectory planning based on adaptive model predictive control: Study of the performance of an autonomous vehicle in critical highway scenarios

Increasing automation in automotive industry is an important contribution to overcome many of the major societal challenges. However, testing and validating a highly autonomous vehicle is one of the biggest obstacles to the deployment of such vehicles, since they rely on data-driven and real-time sensors, actuators, complex algorithms, machine learning systems, and powerful processors to execute software, and they must be proven to be reliable and safe. For this reason, the verification, validation and testing (VVT) of autonomous vehicles is gaining interest and attention among the scientific community and there has been a number of significant efforts in this field. VVT helps developers and testers to determine any hidden faults, increasing systems confidence in safety, security, functional analysis, and in the ability to integrate autonomous prototypes into existing road networks. Other stakeholders like higher-management, public authorities and the public are also crucial to complete the VTT process. As autonomous vehicles require hundreds of millions of kilometers of testing driven on public roads before vehicle certification, simulations are playing a key role as they allow the simulation tools to virtually test millions of real-life scenarios, increasing safety and reducing costs, time and the need for physical road tests. In this study, a literature review is conducted to classify approaches for the VVT and an existing simulation tool is used to implement an autonomous driving system. The system will be characterized from the point of view of its performance in some critical highway scenarios.O aumento da automação na indústria automotiva é uma importante contribuição para superar muitos dos principais desafios da sociedade. No entanto, testar e validar um veículo altamente autónomo é um dos maiores obstáculos para a implantação de tais veículos, uma vez que eles contam com sensores, atuadores, algoritmos complexos, sistemas de aprendizagem de máquina e processadores potentes para executar softwares em tempo real, e devem ser comprovadamente confiáveis e seguros. Por esta razão, a verificação, validação e teste (VVT) de veículos autónomos está a ganhar interesse e atenção entre a comunidade científica e tem havido uma série de esforços significativos neste campo. A VVT ajuda os desenvolvedores e testadores a determinar quaisquer falhas ocultas, aumentando a confiança dos sistemas na segurança, proteção, análise funcional e na capacidade de integrar protótipos autónomos em redes rodoviárias existentes. Outras partes interessadas, como a alta administração, autoridades públicas e o público também são cruciais para concluir o processo de VTT. Como os veículos autónomos exigem centenas de milhões de quilómetros de testes conduzidos em vias públicas antes da certificação do veículo, as simulações estão a desempenhar cada vez mais um papel fundamental, pois permitem que as ferramentas de simulação testem virtualmente milhões de cenários da vida real, aumentando a segurança e reduzindo custos, tempo e necessidade de testes físicos em estrada. Neste estudo, é realizada uma revisão da literatura para classificar abordagens para a VVT e uma ferramenta de simulação existente é usada para implementar um sistema de direção autónoma. O sistema é caracterizado do ponto de vista do seu desempenho em alguns cenários críticos de autoestrad

Attitude control of magnetically actuated satellites with an uneven inertia distribution

This paper addresses magnetic attitude control of a satellite with one axis of inertia significantly lower than that of the other two. With onboard resources often limited, this paper considers the development of an effective control strategy that remains easy to implement. Often used in this type of application, the classical ‘torque-projection’ approach is shown to be unsuitable for satellites with an uneven inertia distribution. To tackle the weaknesses in this approach a new ‘weighted’ PD approach is proposed, with the control torque determined through minimization of a simple cost function. Through a similar philosophy, a feed-forward compensator is designed to supplement the feedback control and improve the disturbance rejection characteristics of the controller. Floquet analysis is used to verify stability of the control strategy for the nominal case and satellites with uncertainties. Simulations carried out on a high fidelity model demonstrate the effectiveness of the proposed control law and the significant performance benefits offered over existing approaches