Passive Control Strategy Research Articles

Vibration Control for Rapid Attitude Stabilization of Spacecraft

A new vibration control strategy is presented to realize rapid attitude maneuvers and stabilization for a spacecraft with flexible appendages. This control strategy combines the command input shaping and the technique of passive vibration isolation for vibration sources. The analytical dynamic model of the spacecraft with control moment gyroscopes, passive vibration isolation system, and flexible appendages is constructed. Based on this analytical dynamic model and the proportion differentiation (PD) attitude control law, the modal parameters of the closed-loop system are calculated, and multiple mode input shapers are designed. Several simulations and comparative studies have shown that the combined active and passive vibration control strategy can not only improve the spacecraft motion performance, but also make the image quality of the optical payload better.

Using passive control by a pendulum in a portal frame platform with piezoelectric energy harvesting

This work presents a passive control strategy using a pendulum on a simple portal frame structure, with two-to-one internal resonance, with a piezoelectric material coupling as a means of energy harvesting. In addition, the system is externally base-excited by an electro-dynamical shaker with harmonic output. Due to internal resonance the system may present the phenomenon of saturation, which provides some nonlinear dynamical behavior to the system. A pendulum is coupled to control nonlinear behaviors, leading to a periodic orbit, which is necessary to maintain energy harvesting. The results show that the system presents, most of the time, as being quasiperiodic. However, it does not present as being chaotic. With the pendulum, it was possible to control most of these quasiperiodic behaviors, leading to a periodic orbit. Moreover, it is possible to eliminate the need for an active or semi-active control, which are usually more complex. In addition, the control provides a way to detune the energy captured to the desired operating frequency.

Passive Fault-tolerant Cooperative Control in an Offshore Wind Farm

The rapid growth in size and capacity of wind turbines together with harsh climate conditions and limited accessibility in offshore regions all result in higher failure rates and increased maintenance requirements and costs. Such difficulties motivate the use of advanced fault detection and diagnosis as well as fault-tolerant control schemes in wind farms to improve their reliability and availability. Given the importance of this issue, the current paper employs a fuzzy model reference adaptive control approach in a cooperative framework that is oriented to the design and development of a novel passive fault-tolerant cooperative control scheme in a wind farm. This scheme handles decreased power generation faults in a wind farm caused by turbine blade erosion and debris buildup on the blades over time. The effectiveness and performance of the proposed scheme is demonstrated by a series of simulations on an advanced large off-shore wind farm benchmark model.

Actively passive control of thermoacoustic instability

In this work, experimental studies of actively passive control of perforated liner with a bias flow on mitigating thermoacoustic instability are performed. For this, a well-designed Rijke-type thermoacoustic combustor with a perforated liner implemented is designed. A premixed propane-fueled flame is confined in the bottom half. A mean cooling flow (known as bias flow) generated from a centrifugal pump is forced to pass through the lined section. To maximize the damping capacity of the perforated liners, the bias flow rate is optimized by implementing a real-time tuning algorithm. The algorithm determines the optimum actuation signal to drive the centrifugal pump. On implementing the tuning algorithm, the unstable thermoacoustic combustor is successfully stabilized by reducing sound pressure level over 64 dB. To evaluate the off-design performance of the developed control approach, an extension tube is added/removed to the Rijke-type thermoacoustic combustor to give rise to the dominant unstable mode frequency being changed by approximately 17\%. It is found that the present actively passive control approach is able to mitigate the new limit cycle. And sound pressure level is reduced by about 41 dB. This confirms that the developed actively passive control scheme is sufficiently robust for use in real combustion systems.

Recent advances in vibration control of offshore platforms

Offshore platforms are widely used to explore, drill, produce, storage, and transport ocean resources and are usually subject to environmental loading, such as waves, winds, ice, and currents, which may lead to failure of deck facilities, fatigue failure of platforms, inefficiency of operation, and even discomfort of crews. In order to ensure reliability and safety of offshore platforms, it is of great significance to explore a proper way of suppressing vibration of offshore platforms. There are mainly three types of control schemes, i.e., passive control schemes, semi-active control schemes, and active control schemes, to deal with vibration of offshore platforms. This paper provides an overview of these schemes. Firstly, passive control schemes and several semi-active control schemes are briefly summarized. Secondly, some classical active control approaches, such as optimal control, robust control, and intelligent control, are briefly reviewed. Thirdly, recent advances of active control schemes with delayed feedback control, sliding model control, sampled-data control, and network-based control are deeply analyzed. Finally, some challenging issues are provided to guide future research directions.

Reduction of fluid forces and vortex shedding frequency of a circular cylinder using rigid splitter plates

This study investigates the fluid forces acting on a circular cylinder in a laminar flow regime while using a passive control strategy. Three cases including the cylinder with one, two or three rig...

Passive and Active Control Strategies of a Leg Rehabilitation Exoskeleton Powered by Pneumatic Artificial Muscles

Nerve injury can cause lower limb paralysis and gait disorder. Currently lower limb rehabilitation exoskeleton robots used in the hospitals need more power to correct abnormal motor patterns of stroke patients’ legs. These gait rehabilitation robots are powered by cumbersome and bulky electric motors, which provides a poor user experience. A newly developed gait rehabilitation exoskeleton robot actuated by low-cost and lightweight pneumatic artificial muscles (PAMs) is presented in this research. A model-free proxy-based sliding mode control (PSMC) strategy and a model-based chattering mitigation robust variable control (CRVC) strategy were developed and first applied in rehabilitation trainings, respectively. As the dynamic response of PAM due to the compressed air is low, an innovative intention identification control strategy was taken in active trainings by the use of the subject’s intention indirectly through the estimation of the interaction force between the subject’s leg and the exoskeleton. The proposed intention identification strategy was verified by treadmill-based gait training experiments.

A strategy for passive control of natural roll-waves in power-law fluids through inlet boundary conditions.

A strategy for passive control of natural roll-waves in power-law fluids through inlet boundary conditions.

A Strategy for Passive Control of Natural Roll-Waves in Power-Law Fluids through Inlet Boundary Conditions

The paper investigates the influence of the inlet boundary condition on the spatial evolution of natural roll-waves in a power-law fluid flowing in steep slope channels. The analysis is carried out numerically, by solving the von Kármán depth-integrated mass and momentum conservation equations, in the long-wave approximation. A second-order accurate scheme is adopted and a small random white-noise is superposed to the discharge at the channel inlet to generate the natural roll-waves train. Both shear-thinning and shear-thickening power-law fluids are investigated, considering uniform, accelerated and decelerated hypercritical profiles as the unperturbed condition. Independently of the unperturbed profile and of the fluid rheology, numerical simulations clearly enlighten the presence of coalescence, coarsening and overtaking processes, as experimentally observed. All the considered statistical parameters indicate that the natural roll-waves spatial evolution is strongly affected by the unperturbed profile. Compared with the uniform condition, at the beginning of roll-waves development an accelerated profile reduces the growth of the roll-waves with a downstream shift of the non-linear wave interaction. The opposite behavior is observed if the roll wave train develops over a decelerated profile. The comparison with the theoretical outcomes of the linearized near wave-front analysis allows the interpretation of this result in terms of stability of the base flow. It is shown that once the coarsening process starts to take place, the roll-waves spatial growth rate is independent of the unperturbed profile. Present results suggest that an appropriate selection of the flow depth at the channel inlet may contribute to control, either enhancing or inhibiting, the formation of a roll-waves train in power-law fluids.

Passive Control Strategy for Mixing Ventilation in Heating and Cooling Modes Using Lobed Inserts

Mixing ventilation is commonly used to control thermal comfort in a room by means of air jets. The jet diffusers should distribute the fresh air and energy, for heating or cooling, in the entire occupied zone. Therefore, the design of the diffusers must aim, beyond aesthetic aspect, the ability to provide a good mixing between the jet and the ambient air. Enhancement of jet mixing with the ambient air by means of lobed inserts into a diffuser, was recently proposed in an European patent, as a promising and low-cost solution for improving the performance of HVAC systems. In this paper, an experimental investigation on thermal comfort generated by a classical multi-cone ceiling-mounted diffuser is proposed. Its performance is compared with the same diffuser equipped with lobed inserts. A simplified heated manikin simulates the presence of a human body in the test room. Thermal comfort was analyzed based on traditional pointwise measuring probes and on the standard ISO 7730. It is revealed that the thermal comfort was significantly improved using the lobed diffuser compared to the conventional one, without increase of pressure drop and sound pressure levels.

Flow around a semicircular cylinder with passive flow control mechanisms

Wind tunnel experiments were performed to study the effect of passive flow control strategies on the wake and drag of a semicircular cylinder of infinite aspect ratio. High-resolution planar particle image velocimetry was used to obtain flow statistics around the semicircular cylinder at Reynolds number \(Re\approx 3.2\times 10^4\) based on the cylinder diameter. The control mechanisms under consideration include rigid flaps of various lengths placed at the edges of the structure and a small slot along the symmetry plane of the cylinder. Mean velocity fields reveal the distinctive effects of each passive mechanism on the flow, such as velocity recovery, size of the recirculation bubble and location of the reattachment point. The distributions of turbulence kinetic energy and kinematic shear stress show the modulation of each passive control mechanism on the wake, including the onset and location of the maximum turbulence levels. Instantaneous and mean fields of swirling strength further highlight the role of the passive mechanisms in the vortex dynamics. Drag coefficient for the various cases was estimated indirectly from the flow measurements using a momentum balance. This approach shows that long flaps and slot were able to reduce drag with respect to the base case. The rigid flaps with length coincident with the diameter of the cylinder offered the best performance with drag reduction of \(\sim\)25\(\%\).

A multiobjective control strategy for energy harvesting in regenerative vehicle suspension systems

ABSTRACTA significant amount of energy induced by road unevenness and vehicle roll and pitch motions is usually dissipated by conventional shock-absorbers. In this paper, a novel active multiobjective control design methodology is proposed which explicitly includes, besides the usual control objectives on ride comfort, road handling and suspension stroke, the amount of energy to be harvested as an additional, though conflicting, control objective and allows the designer to directly trade-off among them depending on the application. An electromechanical regenerative suspension system is considered where the viscous damper is replaced by a linear electrical motor which is actively governed. It is shown that the proposed control law is able to achieve remarkable improvements on the amount of the harvested energy with respect to passive or semi-active control strategies while maintaining the other objectives at acceptable levels. Simulative studies undertaken via CarSim are also reported that confirm the potentiality and flexibility of the proposed control design strategy.

Data-driven approach to design of passive flow control strategies

An approach to designing passive devices for control of unsteady flows is presented. The method requires only snapshots of the flow to be controlled as inputs. A temporal correlation based on proper orthogonal decomposition of both fluctuating velocity and nonlinear forcing serves to identify the spatial locations in which the forcing drives the different unsteady flow features. The installation of a passive device in these spatial locations inhibits the fluctuating motion. The potential of the methodology is demonstrated via the suppression of vortex shedding in flow past a square cylinder, paving the way to the control of more complex flows using passive devices. Connections in agreement with previous studies targeting the same flow using different passive flow control strategies are provided.

Approaches for reducing structural vibration of the carbody railway vehicles

Reducing the weight of the railway vehicles stands as a decisive rule in their design, entailed by higher velocities, the need to consume less energy and lower the manufacturing costs, along with the maximization of the use of loads on the axle. Once complied with this rule, the vehicle flexibility increases and leads to an easy excitation of the structural vibrations in the carbody, with an impact upon the ride comfort in the railway vehicle. For a better ride comfort in lightweight railway vehicles, both vibration isolation approaches and structural damping approaches have been introduced. The paper herein submits a brief review of the main structural damping approaches aiming to reduce the amplitude in the carbody structural vibrations, based on the use of the piezoelectric elements in passive control schemes. The paper outcomes show the potential of the presented methods concerning the reduction of the flexible vibrations in the carbody and the ride comfort improvement.

Seismic response control of benchmark highway bridge using passive hybrid control systems

In this study, the seismic response of a benchmark highway bridge is investigated with passive hybrid systems consisting of high damping rubber bearing (HDRB) and linear and nonlinear viscous fluid damper (VFD). The Phase I problem of the benchmark highway bridge is considered for this study. The ground acceleration is applied at all supports of the bridge. A comparative study is performed among the passive control strategies for seismic response control of the highway bridge by calculating various evaluation criteria as mentioned in the benchmark highway bridge problem. A parametric study has been conducted to find different parameters of VFD and HDRB. The optimum damping coefficient and velocity exponent are found for VFD and optimum isolation time period and optimum damping ratio are found for HDRB. The passive hybrid control system consisting of HDRB and nonlinear VFD gives better performance for reduction of base shear, overturning moment, displacement at midspan, bearing deformation and displacement at abutment of the bridge. Hence, it can be deduced that the performance of passive hybrid control system consisting of HDRB and nonlinear VFD is better than individual VFD and HDRB control systems.

Active Vibration Damping in Hydraulic Construction Machinery

Hydromechanical systems are prone to significant oscillations, due to the ability of hydraulic oil to store potential energy. This is extremely important when considering mobile hydraulic machinery, especially those machines which handle large loads. Oscillations can negatively affect the stability of the payload, the comfort of the operator, and the overall safety of the system. For the particular case of earthmoving machines, several systems have been designed in order to alleviate these oscillations and increase machine operability. These systems include both passive and active designs which attempt to utilize the motion of the payload in such a way as to cancel out the effect of machine vibrations.This paper seeks to assess the potential advantages of active oscillation control strategies with respect to current state of art passive strategies. A reference case vehicle (wheel loader) is presented and analyzed in order to determine its typical vibrational behavior. A simulation model for the reference machine is developed and used in assessing machine performance. The effectiveness of the current passive vibration damping approach with respect to reducing the vibrations perceived by the operator in the cabin, as well as those affecting the payload, is presented. Then, an active (electrohydraulic) control structure is presented using both acceleration and pressure feedback, including an adaptive controller constructed using an extremum-seeking algorithm. To quantitatively compare the relative performances of these various systems, an appropriate objective function is defined. Simulation results are presented for each of the considered control strategies, and their performances are compared. The simulation indicates a performance of active vibration control systems roughly equivalent to that of currently implemented passive control strategies. In some cases, the active control performance is actually two to three times as effective as the passive control.

Seismic response control of benchmark highway bridge using passive hybrid control systems

In this study, the seismic response of a benchmark highway bridge is investigated with passive hybrid systems consisting of high damping rubber bearing (HDRB) and linear and nonlinear viscous fluid damper (VFD). The Phase I problem of the benchmark highway bridge is considered for this study. The ground acceleration is applied at all supports of the bridge. A comparative study is performed among the passive control strategies for seismic response control of the highway bridge by calculating various evaluation criteria as mentioned in the benchmark highway bridge problem. A parametric study has been conducted to find different parameters of VFD and HDRB. The optimum damping coefficient and velocity exponent are found for VFD and optimum isolation time period and optimum damping ratio are found for HDRB. The passive hybrid control system consisting of HDRB and nonlinear VFD gives better performance for reduction of base shear, overturning moment, displacement at midspan, bearing deformation and displacement at abutment of the bridge. Hence, it can be deduced that the performance of passive hybrid control system consisting of HDRB and nonlinear VFD is better than individual VFD and HDRB control systems.

Perturbation observer-based adaptive passive control for nonlinear systems with uncertainties and disturbances

In this paper, a perturbation observer-based adaptive passive control scheme is developed to provide great robustness of nonlinear systems against the unpredictable uncertainties and disturbances therein. The proposed scheme includes a high-gain perturbation observer and a robust passive controller. The high-gain perturbation observer is designed to estimate online the perturbation aggregated from the combinatorial effect of system nonlinearity, parameter uncertainty, unmodelled dynamics and fast time-varying external disturbances. Then the robust passive controller, using the estimated perturbation, can produce the minimal control effort needed to compensate for the magnitude of the actual current perturbation. Furthermore, the convergence of estimation error of the high-gain perturbation observer and the closed-loop system stability are analyzed theoretically. Finally, two practical examples are given to show the effectiveness and advantages of the proposed approach over the accurate model-based passive control scheme and the linearly parametric estimation-based adaptive passive control scheme.

State of the Art of Non-Linear Devices and Strategies for Vibration Control

Modern structures undergo considerably large responses when subjected to external loading owing to the tall, lighter and flexible nature of these structures. Due to this and the instability that may be induced, any vibrating system either civil or mechanical has the disability of being utilised to its maximum efficiency. This necessitates the response control of such structures and systems for many reasons. Different methods have been used for this response control from the past, which includes passive, active and hybrid control devices and strategies. Linear procedures and models used in this context have their own limitations since all real systems are basically nonlinear. This has been understood well in advance and hence, many control techniques have been devised to cater for non-linear behaviour from early mid-19th century. Predicting the post-yield behaviour of civil engineering structures as well as controlling their vibrations using non-linear systems are ever challenging problems, especially when subjected to random excitations such as wind and earthquake. This paper presents the state of the art of non-linear devices and strategies for vibration control of structures and systems. It briefly discusses the control strategies and devices used in practise emphasising the merits and demerits of each of them. The use of control devices with linear plus cubic spring, hyperbolic sine spring, Belleville non-linear softening spring in parallel with viscous damper for the control of vibration is presented. The use of frequency energy dependence in the design of absorber and the use of power absorption ratio and kinetic energy of non-linear oscillator for the design of non-linear absorber, which is vastly explored in the recent years are outlined. A newer but efficient method in modelling non-linear system by the use of nonlinear targeted energy transfer is also discussed.

Passive control strategy for mixing ventilation in heating mode using lobed inserts

The main purpose of ventilation systems is to satisfy the need of occupants in terms of thermal comfort and air quality. In the case of mixing ventilation, based on the use of jets from one or from multiple diffusers placed in the room, the fresh air and the thermal loads should be distributed in the entire occupied zone. Therefore, the design of the diffusers must aim, beyond aesthetic aspect, the ability to provide a good mixing between the jet and the ambient air. Enhancement of jet induction by means of lobed inserts into a diffuser, was recently proposed in an European patent as a promising and low-cost solution for improving the performance of HVAC systems. In this paper, an experimental investigation on jet characteristics and thermal comfort generated by a classical multi-cone ceiling-mounted diffuser is proposed. Its performance is compared with the same diffuser equipped with lobed inserts. A simplified heated manikin simulates the presence of a human body in the test room. Airflow pattern from the diffuser and its interaction with the manikin were analyzed with whole-field PIV technique. Thermal comfort was analyzed based on traditional pointwise measuring probes and on the standard ISO 7730. It is revealed that the thermal comfort was significantly improved using the lobed diffuser compared to the conventional one, without increase of pressure drop and sound pressure levels.