2,382 research outputs found
State of the art of control schemes for smart systems featuring magneto-rheological materials
This review presents various control strategies for application systems utilizing smart magneto-rheological fluid (MRF) and magneto-rheological elastomers (MRE). It is well known that both MRF and MRE are actively studied and applied to many practical systems such as vehicle dampers. The mandatory requirements for successful applications of MRF and MRE include several factors: advanced material properties, optimal mechanisms, suitable modeling, and appropriate control schemes. Among these requirements, the use of an appropriate control scheme is a crucial factor since it is the final action stage of the application systems to achieve the desired output responses. There are numerous different control strategies which have been applied to many different application systems of MRF and MRE, summarized in this review. In the literature review, advantages and disadvantages of each control scheme are discussed so that potential researchers can develop more effective strategies to achieve higher control performance of many application systems utilizing magneto-rheological materials
Active Vibration Cancellation of a Free-Piston Linear Generator Engine
A free-piston linear generator engine (LG) is a device that couples a free-piston combustion engine with a linear electric generator. The engine is consisted with a part called piston-rod assembly (PRA), where two pistons are connected by a rod attached with permanent magnet. During the operation of LG, PRA will linearly reciprocate between two internal combustion chambers on the opposite sides. However, when the PRA is on one side of the engine, an unbalanced impact force is created. The unbalanced forces provide an undesirable impact force acting on the engine block, causing the engine to vibrate. The control of vibration for the LG becomes crucial, because proper vibration controls maintain a consistent electricity output and maximize the efficiency of the engine. Current work proposed using a linear motor (LM) to create an anti-phase momentum into the system to counter the impact forces created by PRA. The works are based on analytical modeling with MATLAB used for simulation. Simulation shows the system instability characteristics, the time and frequency responses for LG. The results showed the existence of a real pole at the right hand side of complex plane which contribute to the system instability. The non-proportional damped time response obtained using state-space approach shows the overall interaction between mass forcer and PRA decreased with respect to time. The frequency responses showed that with the application of active vibration cancellation, the resonance can be delayed and the magnitude of the resonance can be reduced. A lumped-mass quarter car suspension model is used for validation. Case study is carried out to decide the best available driven forces that drive the LG. The conclusion of current study showed that with proper vibration control for the LG, the vibration level of LG can be reduced to a desirable level while maintaining the optimum operating conditions
Discrete-time Robust PD Controlled System with DOB/CDOB Compensation for High Speed Autonomous Vehicle Path Following
Autonomous vehicle path following performance is one of significant
consideration. This paper presents discrete time design of robust PD controlled
system with disturbance observer (DOB) and communication disturbance observer
(CDOB) compensation to enhance autonomous vehicle path following performance.
Although always implemented on digital devices, DOB and CDOB structure are
usually designed in continuous time in the literature and also in our previous
work. However, it requires high sampling rate for continuous-time design block
diagram to automatically convert to corresponding discrete-time controller
using rapid controller prototyping systems. In this paper, direct discrete time
design is carried out. Digital PD feedback controller is designed based on the
nominal plant using the proposed parameter space approach. Zero order hold
method is applied to discretize the nominal plant, DOB and CDOB structure in
continuous domain. Discrete time DOB is embedded into the steering to path
following error loop for model regulation in the presence of uncertainty in
vehicle parameters such as vehicle mass, vehicle speed and road-tire friction
coefficient and rejecting external disturbance like crosswind force. On the
other hand, time delay from CAN bus based sensor and actuator command
interfaces results in degradation of system performance since large negative
phase angles are added to the plant frequency response. Discrete time CDOB
compensated control system can be used for time delay compensation where the
accurate knowledge of delay time value is not necessary. A validated model of
our lab Ford Fusion hybrid automated driving research vehicle is used for the
simulation analysis while the vehicle is driving at high speed. Simulation
results successfully demonstrate the improvement of autonomous vehicle path
following performance with the proposed discrete time DOB and CDOB structure
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
Integrated Flywheel Technology, 1983
Topics of discussion included: technology assessment of the integrated flywheel systems, potential of system concepts, identification of critical areas needing development and, to scope and define an appropriate program for coordinated activity
An investigation of multibody system modelling and control analysis techniques for the development of advanced suspension systems in passenger cars
The subject of this thesis is the investigation of multibody system modelling
and control analysis techniques for the development of advanced suspension
systems in passenger cars. A review of the application of automatic control to
all areas of automotive vehicles illustrated the important factors in such
developments, including motivating influences, constraints and methodologies
used. A further review of specific applications for advanced suspension systems
highlighted a major discrepancy between the significant claims of theoretical
performance benefits and the scarcity of successful practical implementations.
This discrepancy was the result of idealistic analytical studies producing
unrealistic solutions with little regard for practical constraints. The
predominant application of prototype testing methods in implementation studies
also resulted in reduced potential performance improvements.
This work addressed this gap by the application of realistic modelling and
control design techniques to practical realistic suspension systems. Multibody
system modelling techniques were used to develop vehicle models incorporating
realistic representations of the suspension system itself, with the ability to
include models of the controllers, and facilitate control analysis tasks. These
models were first used to address ride control for fully active suspension
systems. Both state space techniques, including linear quadratic regulator and
pole placement and frequency domain design methods were applied. For the
multivariable frequency domain study, dyadic expansion techniques were used
to decouple the system into single input single output systems representing
each of the sprung mass modes. Both discretely and continuously variable
damping systems were then addressed with a range of control strategies,
including analytical solutions based on the active results and heuristic rule-based
approaches. The controllers based on active solutions were reduced to
satisfy realistic practical limitations of the achievable damping force. The
heuristic techniques included standard rule-based controllers using Boolean
logic for the discretely variable case, and fuzzy logic controllers for the
continuously variable case
Aerospace medicine and biology: A continuing bibliography with indexes (supplement 320)
This bibliography lists 125 reports, articles and other documents introduced into the NASA Scientific and Technical Information System during January, 1989. Subject coverage includes: aerospace medicine and psychology, life support systems and controlled environments, safety equipment, exobiology and extraterrestrial life, and flight crew behavior and performance
Proportional-integral state-feedback controller optimization for a full-car active suspension setup using a genetic algorithm
The use of active car suspensions to maximize driver comfort has been of growing
interest in the last decades. Various active car suspension control technologies have been
developed. In this work, an optimal control for a full-car electromechanical active suspension
is presented. Therefore, a scaled-down lab setup model of this full-car active suspension is
established, capable of emulating a car driving over a road surface with a much simpler approach
in comparison with a classical full-car setup. A kinematic analysis is performed to assure system
behaviour which matches typical full-car dynamics. A state-space model is deducted, in order
to accurately simulate the behaviour of a car driving over an actual road prole, in agreement
with the ISO 8608 norm. The active suspension control makes use of a Multiple-Input-Multiple-
Output (MIMO) state-feedback controller with proportional and integral actions. The optimal
controller tuning parameters are determined using a Genetic Algorithm, with respect to actuator
constraints and without the need of any further manual fine-tuning
Advanced robust control strategies of mechatronic suspensions for cars
Two novel mechatronic suspensions for road vehicles are studied in this thesis: the Series Active Variable Geometry Suspension (SAVGS) and the Parallel Active Link Suspension (PALS). The SAVGS and the PALS complement each other in terms of the vehicle categories they serve, which range from light high-performance vehicles (the Grand Tourer) to heavy SUV vehicles, respectively, based on the sprung mass and the passive suspension stiffness. Previous work developed various control methodologies for these types of suspension. Compared to existing active suspension solutions, both the SAVGS and the PALS are capable of low-frequency chassis attitude control and high-frequency ride comfort and road holding enhancement. In order to solve the limitation of both SAVGS and PALS robustness, mu-synthesis control methodologies are first developed for SAVGS and PALS, respectively, to account for structured uncertainties arising from changes to system parameters within realistic operating ranges. Subsequently, to guarantee robustness of both low-frequency and high-frequency vehicle dynamics for PALS, the mu-synthesis scheme is combined with proportional-integral-derivative (PID) control, employing a frequency separation paradigm. Moreover, as an alternative robustness guaranteeing scheme that captures plant nonlinearities and road unevenness as uncertainties and disturbances, a novel robust model predictive control (RMPC) based methodology is proposed for the SAVGS, motivated by the promise shown by RMPC in other industrial applications. Finally, aiming to provide further performance stability and improvements, feedforward control is developed for the PALS. Nonlinear simulations with a set of ISO driving situations are performed to evaluate the efficiency and effectiveness of the proposed control methods in this thesis.Open Acces
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