Ground Hook Research Articles

Analysis of ride comfort and road friendliness of heavy vehicle inertial suspension based on the ground-hook control strategy

In order to comprehensively improve the ride comfort performance and the road friendliness performance of the heavy vehicles, an inertial suspension using ground-hook (GH) control is proposed in this paper, and the suspension performances are compared at different loading rates and driving speeds. Firstly, a half vehicle model of the inertial suspension of the heavy vehicle based on the GH control is established. Then, the key parameters of the GH inertial suspension are optimized by the genetic algorithm and the system simulations are carried out. By comparing to the conventional passive suspension, the root-mean-square (RMS) of the vertical acceleration of the body centroid is reduced by 4.87%, and the RMS of the dynamic tire loads of the front and the rear wheels are reduced by 16.19% and 10.02%, respectively. Results show that the GH inertial suspension can effectively coordinate and improve the ride comfort and road friendliness of heavy vehicles simultaneously.

Vibration Isolation of Railway Vehicle Car body using Semi-active Suspension

In the past, the magnetorheological (MR) suspension for railway vehicle has obtained great attention for the isolation of vibrations. This work presents a numerical approach to analyse skyhook and ground hook semi-active control methods for railway vehicle suspension. A 10 DoF model of the railway vehicle system is formulated for the comparative analysis between conventional passive and semi-active suspension control in the present study. The non-linear analysis is investigated in time and frequency domain for the sinusoidal excitations from the track.

Performance analysis of MR damper based semi-active suspension system using optimally tuned controllers

This study assesses the dynamic performance of the semi-active quarter car vehicle under random road conditions through a new approach. The monotube MR damper is modelled using non-parametric method based on the dynamic characteristics obtained from the experiments. This model is used as the variable damper in a semi-active suspension. In order to control the vibration caused under random road excitation, an optimal sliding mode controller (SMC) is utilised. Particle swarm optimisation (PSO) is coupled to identify the parameters of the SMC. Three optimal criteria are used for determining the best sliding mode controller parameters which are later used in estimating the ride comfort and road handling of a semi-active suspension system. A comparison between the SMC, Skyhook, Ground hook and PID controller suggests that the optimal parameters with SMC have better controllability than the PID controller. SMC has also provided better controllability than the PID controller at higher road roughness.

Research on Ride Comfort and Driving Safety under Hybrid Damping Extension Control for Suspension Systems

This paper is concerned with the conflicting performances of ride comfort and driving safety for semi-active suspension systems. To alleviate this conflict, a novel hybrid damping extension control (HDEC) method is proposed. This method adopts various control methods and the weights of each method are determined by extension theory. Firstly, body acceleration and tire dynamic transformation are selected to evaluate ride comfort and driving safety performance for the semi-active suspension system and their frequency responses of passive suspension, sky-hook control, ground hook control, and S-GH (sky-ground hook) control are analyzed based on a two degree-of-freedom (2-DOF) model. Secondly, extension theory is introduced and the extension control system, which contains three modes and corresponding control algorithms, is established. In addition, the low-frequency excitation and high-frequency excitation simulations are designed to determine the parameters of the extension control system. Finally, ve-DYNA vehicle suspension model simulation is applied to prove the feasibility and effectiveness of the extension control. The simulation results show that, based on the suspension state, extension control can improve the performance of ride comfort and driving safety.

An investigation on the impacts of passive and semiactive structural control on a fixed bottom and a floating offshore wind turbine

AbstractThe application of structural control to offshore wind turbines (OWTs) using tuned mass dampers (TMDs) has shown to be effective in reducing the system loads. The parameters of a magnetorheological (MR) damper modeled by the Bouc‐Wen model are modified to utilize it as a damping device of the TMD. Rather than showcasing the intricate design policy, this research focuses on the availability of the MR damper model on TMDs and its significance on structural control. The impact of passive and semiactive (S‐A) TMDs applied to both fixed bottom and floating OWTs is evaluated under the fatigue limit state (FLS) and the ultimate limit state (ULS). Different S‐A control logics based on the ground hook (GH) control policy are implemented, and the frequency response of each algorithm is investigated. It is shown that the performance of each algorithm varies according to the load conditions such as a normal operation and an extreme case. Fully coupled time domain simulations are conducted through a newly developed simulation tool, integrated into FASTv8. Compared with the passive TMD, it is shown that the S‐A TMD results in higher load reductions with smaller strokes under both the FLS and the ULS conditions. The S‐A TMD using displacement‐based GH control is capable of reducing the fore‐aft and side‐to‐side damage equivalent loads for the monopile by approximately 12% and 64%, respectively. The ultimate loadings at the tower base for the floating substructure are reduced by 9% with the S‐A TMD followed by inverse velocity‐based GH control (IVB‐GH).

Road-Holding-Oriented Control and Analysis of Semi-Active Suspension Systems

The most important function of a vehicle suspension system is keeping the tires on the road surface, imposing requirements on the road-holding performance. As is well known, a semi-active suspension can improve road-holding performance, but little effort has been made to build road-holding-oriented semi-active suspension controllers (RHSAC). This study improved four model reference controllers (MRCs) as RHSAC, including the road-Hook (RH), inverse ground-Hook (IGH), sky-Hook (SH), and ground-Hook (GH). These MRCs have optimal performances in different frequency ranges, and their working principle is analyzed from an energy perspective. To combine the advantages of different MRCs, a mixed control strategy is proposed to enhance the road-holding performance of the MRCs. By mixing SH and RH, the mixed SH–RH performs almost as well as a finely tuned model predictive controller, which outperforms any single MRCs. Based on CarSim-matlab cosimulations, the effectiveness of the mixed RHSAC controller is verified by various real road tests.

Analysis and Prediction of Performance of MR Damper at Different Currents and Control Strategies for Quarter Suspension System of a Roadway Vehicle

Ride comfort and vehicle handling are the two major issues to be dealt in the design of suspension systems of automobiles. With passive systems offering contrariety on these two parameters, the alternative systems are being in study. Magnetorheological (MR) damper, a most feasible semi-active device, is one such alternative, which will offer the advantage of dealing with both these issues overcoming contrariety. In this study, the suspension system of a car using MR damper is analysed at 5 different currents viz., 0A, 0.25A, 0.5A, 0.75A, 1A, using 2DOF quarter car model and 4DOF half car models for ride comfort and handling and the comparisons of these are done with same suspension system equipped with regular passive damper. A MR damper is built-up using MR fluid consisting of carbonyl iron powder and silicone oil added with additive. Further, the characteristic of this damper is established by conducting experiments, which in turn is used to identify the parameters of Spencer model for MR damper. Using Spencer model of MR damper, at 5 different currents, the quarter car and half car models of vehicle suspension system are simulated by implementing a semi-active suspension system for analysing the resulting displacement and acceleration in the car body. The ride comfort and vehicle handling performance of each specific vehicle model with passive suspension system are compared with corresponding skyhook, ground hook and hybrid based semi-active suspension systems. The simulation and analysis are carried out using Matlab/Simulink.

항공기용 MR 댐퍼의 스카이-그라운드 훅 제어기 설계

In this paper, a semi-active magnetorheological (MR) damper is proposed that can be applied to main landing gear suspension system of the aircraft. For the modeling of MR damper, a damping force in the annular orifice and an air force in the damper strut are derived. A MR damper with two magnetic cores is designed to control the damping force with sufficient dynamic range. After modeling the damper, its structural design with the annular type bypass for fast tension speed is determined considering the characteristics of the landing situation of the aircraft. In addition, through the magnetic field analysis of two magnetic cores, controllable yield force of MR fluid is proposed, designed by the magnetic intensity considering the input current. Next, superior performance of the semi-active damper is demonstrated by calculating the aircraft landing efficiency of passive and semi-active dampers by the damper excitation and aircraft drop simulations. To maximize the landing efficiency of drop simulation, the sky-ground control logic is established. The sky hook and ground hook coefficients can be adjusted by tuning the sky-ground hook weighting factor. After calculating the sky-ground hook force with the best-tuned sky hook and ground hook coefficients, the damping force of the MR damper is controlled by the calculated input current. Consequently, the optimized efficiency plot was obtained in comparison with controlled and passive dampers.

Study of vibration control using laboratory test rig of wind turbine tower-nacelle system with MR damper based tuned vibration absorber

Abstract Wind turbine tower dynamic stress is related to the fatigue wear and reliability of the whole wind turbine structure. This paper deals with the problem of tower vibration control using a specially designed and built laboratory model. The considered wind turbine tower-nacelle model consists of a vertically arranged stiff rod (representing the tower), and a system of steel plates (representing nacelle and turbine assemblies) fixed at its top. The horizontally aligned tuned vibration absorber (TVA) with magnetorheological (MR) damper is located also at the top of the rod (in nacelle system). Force excitation sources applied horizontally to the tower itself and to the nacelle were both considered. The MR damper real-time control algorithms, including ground hook control and its modification, sliding mode control, linear and nonlinear (cubic and square root) damping, and adaptive solutions are compared to the open-loop case with various constant MR damper input current values and system without MR TVA (i.e., MR TVA in “locked” state). Comprehensive experimental analyses and their results are presented.

Design of a Road Friendly SAS System for Heavy-Duty Vehicles Based on a Fuzzy-Hybrid-ADD and GH-Control Strategy

Semiactive suspension (SAS) system has been widely used for its outstanding performance in offering competent ride quality, road holding, and handling capacity. However, the road friendliness is also one of the crucial factors that should be attached in the design of the SAS system for heavy-duty vehicles. In this study, a fuzzy controlled hybrid-acceleration driven damper (ADD) and ground hook- (GH-) control strategy is proposed for SAS system of heavy-duty vehicles. Firstly, a quarter-vehicle model with SAS system is constructed. Then, aiming to improve the ride quality and road friendliness, a hybrid-ADD and GH-control strategy is proposed under the coordination of the fuzzy controller. Numerical results show that the ride quality and road friendliness of the SAS system with the proposed control strategy outperform those with traditional hybrid-sky hook and ground hook-control strategy. It is also verified that the proposed strategy is superior to the sole ADD approach and sole ground hook approach in improving the vehicle overall performance.

Tire Force Control Strategy for Semi Active Magnetorheological Damper Suspension System Using Quarter Heavy Vehicle Model

This paper proposed semi active controller scheme for magnetorheological (MR) damper of a heavy vehicle suspension known as Tire Force Control (TFC). A reported algorithm in the literature to reduce tire force is Groundhook (GRD). Thus, the objective of this paper is to investigate the effectiveness of the proposed TFC algorithm compared to GRD. These algorithms are applied to a quarter heavy vehicle models, where the objective of the proposed controller is to reduce unsprung force (tire force). The simulation model was developed and simulated using MATLAB Simulink software. The use of semi active MR damper using TFC is analytically studied. Ride test was conducted at three different speeds and three bump heights, and the simulation results of TFC and GRD are compared and analysed. The results showed that the proposed controller is able to reduced tire force significantly compared to GRD control strategy.

Ground Semi Active Damping Force Estimator (gSADE) for Magnetorheological Damper Suspension System Using Quarter Heavy Vehicle Model

This paper proposed semi active controller scheme for magnetorheological (MR) damper of a heavy vehicle suspension known as Ground Semi Active Damping Force Estimator (gSADE), where it was modified from Semi Active Damping Force Estimator (SADE) algorithm. A reported algorithm known as Groundhook (GRD) was developed where its aim to minimize tire road forces and hence reduce road damage. Thus, the objective of this paper is to investigate the effectiveness of the proposed gSADE algorithm compared to GRD and SADE. These algorithms are applied to a quarter heavy vehicle models and the simulation model was developed and simulated using MATLAB Simulink software. Ride test was conducted at three different speeds and three bump heights, and the simulation results of gSADE, SADE and GRD are compared and analysed. The results showed that the proposed controller is able to reduced tire force significantly compared to GRD control strategy.

Vibration control of wind turbine tower-nacelle model with magnetorheological tuned vibration absorber

Wind turbine tower dynamic load is related to the fatigue and reliability of the structure. This paper deals with the problem of tower vibration control using specially designed and built numerical and laboratory model. The regarded wind turbine tower-nacelle model consists of vertically arranged stiff rod (representing the tower), and a stiff body fixed at its top representing nacelle assembly that is equipped with horizontally aligned tuned vibration absorber (TVA) with magnetorheological (MR) damper. To model tower-nacelle dynamics, Comsol Multiphysics finite element method environment was used. For time and frequency domain numerical analyses (including first and second bending modes of vibration) of system with TVA and MR damper models, MATLAB/Simulink environment was used with Comsol Multiphysics tower-nacelle model embedded. Force excitation sources applied horizontally to the nacelle, and to the tower itself were both considered. The MR damper real-time control algorithms, including ground hook control and its modification, sliding mode control, linear and nonlinear (cubic and square root) damping, and adaptive solutions are compared to the open-loop case with various constant MR damper input current values and system without MRTVA (i.e. MRTVA in ‘locked’ state). Comprehensive numerical analyses results are presented along with Vensys 82 full-scale tower-nacelle model validation. Finally, preliminary results of laboratory tests are included.

Tyre force control strategy for semi-active magnetorheological damper suspension system for light-heavy duty truck

A semi-active controller scheme for magnetorheological (MR) damper of a light-heavy vehicle suspension known as Tyre Force Control (TFC) is proposed. The effectiveness of the proposed TFC algorithm is compared with Groundhook (GRD) control. A simulation model was developed and simulated using MATLAB Simulink software. The performance of the semi-active MR damper using TFC is analytically studied. Ride test was conducted at three different speeds and two different bumps, and the simulation results of TFC and GRD are compared and analysed. The results showed that the proposed controller is able to reduce tyre force significantly compared to GRD control strategy.

A204 二慣性共同免震台上の二棟ビルモデルと簡易パッシブMRダンパの評価(OS4 スマート構造システム)

This paper presents seismic evaluation of double building models by a double inertia type common seismic stage, and presents performance evaluation of a simple passive MR damper. Notch property of double inertia seismic stage could decrease the major peak of double building. The method of resistance force measurement which links between the virtual fixed ground and the upper inertia of seismic stage, suggests the fixed ground hook damper.

Semi-active fuzzy control of a wind-excited tall building using multi-objective genetic algorithm

In this study, a multi-objective optimal fuzzy control system for the response reduction of a wind-excited tall building has been proposed. A semi-active tuned mass damper (STMD) is used for vibration control of a 76-story benchmark building subjected to wind load. An STMD consists of a 100kN magnetorheological (MR) damper and its natural period is tuned to the first-mode natural period of vibration of the example building structure. The damping force of the MR damper is controlled by a fuzzy logic controller. A multi-objective genetic algorithm is used for optimization of the fuzzy logic controller. Both the 75th floor acceleration response of the structure and the stroke of the STMD have been used as the objective functions for this multi-objective optimization problem. Because a multi-objective optimization approach provides a set of Pareto-optimal solutions, an engineer is able to select an appropriate design for the specific performance requirement. For a comparative study, a sky–ground hook control algorithm is employed for control of the STMD. Based on numerical results, it has been shown that the proposed control system can effectively reduce the STMD motion as well as building responses compared to the comparative sky–ground hook control algorithm. In addition, the control performance of the STMD controlled by the optimal fuzzy controller is superior to that of the passive TMD and is comparable to an active TMD, but with a significant reduction in power consumption.

Semi-Active Steering Damper Control in Two-Wheeled Vehicles

This work presents the design of innovative control strategies for a semi-active steering damper aimed at improving two-wheeled vehicles steering stability by controlling the weave and wobble modes. The proposed control strategies arise from a parallelism between steering and vertical dynamics of a motorcycle. According to this parallelism, the Sky-Hook (SH) and Ground-Hook (GH) damping concepts are adapted to the control of steering dynamics. A detailed analysis of the two approaches shows that a tradeoff arises between the damping of wobble and weave mode. It is then shown that the tradeoff can be solved by mixing the SH and GH strategies according to a frequency-range selector. The closed-loop stability properties are investigated via passivity theory. Further, both a multibody simulator and experimental data are employed to validate both the modeling phase and the control strategies performance.

Fuzzy Hybrid Control of Vibration Attitude of Full Car via Magneto-rheological Suspensions

A magneto-rheological(MR) semi-active suspension system with the controllable damping forces has received more attention in reducing the vibration of a vehicle. However, many control strategies only discussed one or two vibration states of the vehicle based on a quarter-car model or a half vehicle model via MR suspensions. They cannot provide a satisfying whole-vehicle performance on a road test. Hence, a full car vibration model via an MR suspension system is proposed. To reduce the heave, pitch and roll motion of the vehicle body and the vertical vibration of four wheels, a fuzzy hybrid controller for vibration attitude of full car via MR suspensions is proposed. First, a skyhook-fuzzy control scheme is designed to reduce the heave, roll and pitch motion of the vehicle body. Second, a revised ground hook control strategy is adopted to decrease the vertical vibration of the wheels. Finally, a hybrid control scheme based on a fuzzy reasoning method is proposed to tune the hybrid damping parameter, which is suitable for coordination the attitude of the vehicle body and the wheels. A test and control system for the vibration attitude of full car is set up. It is implemented on a car equipped with four MR suspensions. The results on random highway and rough road indicate that the fuzzy hybrid controller can decrease the vibration accelerations of the vehicle body and the wheels to 65%–80% and 80%–90%, respectively. It reduces the automotive vibrations of heave, roll and pitch more effectively than a passive suspension and an MR suspension with a traditional hybrid control scheme so that it achieves better ride comfort and road holding concurrently. This paper proposes a new fuzzy hybrid control(FHC) method for reducing vibration attitude of full car via MR suspensions and develops a road test to evaluate the FHC.

The craft of the Caman; A notational analysis of the frequency occurrence of skills used in Hurling

Hurling is a native sport to Ireland with limited scientific research. It is played using a Caman (hurling stick) and Sliotar (ball). Notational analysis is a means of providing reliable feed back on sporting performance. The purpose of the study is to determine the frequency of occurrence of selected skills providing information to refine current skill training. Four high level championship games were analyzed using defined criteria; the method was determined to be reliable. Descriptive statistics used for analysis. The aerial strike is the highest occurring skill. Jab lift is the most prominent method for possession gain. Taking steps most common method of travel. Non occurrence of ground hook was observed. Prevention of jab lift could reduce opponents in possession striking by 44.67% This method of striking accounts for 77.8% of all in play striking meaning a significant impact could be made. 18% of dispossessions did not register due to set criteria. 70% of possession striking skills occurred after traveling 4 or more steps. A higher level of performance can be attained through a focus on preventing opponent from jab lifting and increasing own proficiency with jab lift and aerial strike while moving.

Survey suggests numerous petroleum plays in the eastern Gulf of Mexico

Glyn Roberts and Kjell Finstad of GGS-Spectrum discuss the implications of a recently acquired 2D seismic survey off western Florida in the eastern Gulf of Mexico, an area that has been off limits to E&P operations in recent years. Owing to a drilling moratorium imposed on the oil industry, very little modern seismic has been acquired in the eastern GOM prior to a recent survey by GGS-Spectrum. The 2D seismic survey (West Florida WF-05 survey) covered a section east and southeast of the original Sale 181 area in the eastern Gulf of Mexico (GOM), running SSE along the Florida Escarpment towards the Dry Tortugas and the EEZ boundary (Fig.1) and covering OCS protraction areas: De Soto Canyon, Florida Middle Ground, Lloyd Ridge, The Elbow, Vernon Basin, and Howell Hook. Its eastern margin is approximately 125 miles from the West Florida coast. Water depths vary from 200 m to 3200 m and the present day bathymetry is dominated by the Florida Escarpment. The seismic data was acquired with an 8000 m streamer, 13 seconds record length and a fold of 107. An environmental impact assessment (EIA) was undertaken prior to survey start up and both marine mammal observers (MMOs) and a passive acoustic monitoring (PAM) system were deployed to assess and mitigate any effects of the survey on marine mammals. The eastern GOM area is one of the last remaining US petroleum frontier areas, and analysis of the results of this survey are intended to allow oil companies and regulatory authorities to more accurately identify potentially commercial volumes of oil and gas and to consider their future development.