Active Roll Control Research Articles

ACTIVE ROLL CONTROL DEVICE FOR VEHICLES EQUIPPED WITH HYDROPNEUMATIC SUSPENSIONS

This paper presents a new active roll control device. This device uses an original hydraulic actuator, based on two tandem pumps, designed to be used in addition of a reduced anti-roll bar. The actuator control strategy is also original. It is based on hierarchical and hybrid control with a supervisor, a feedforward and a feedback loop whose robust controller is synthesized thanks to the CRONE control methodology. Because of the severe specifications sheets in term of power consumption, the simulated performances are thus limited but interesting.

Active roll control of an experimental articulated vehicle

A new experimental articulated vehicle with computer-controlled suspensions is used to investigate the benefits of active roll control for heavy vehicles. The mechanical hardware, the instrumentation, and the distributed control architecture are detailed. A simple roll-plane model is developed and validated against experimental data, and used to design a controller based on lateral acceleration feedback. The controller is implemented and tested on the experimental vehicle. By tilting both the tractor drive axle and the trailer inwards, substantial reductions in normalized lateral load transfer are obtained, both in steady state and transient conditions. Power requirements are also considered.

HEAVY-DUTY VEHICLE ROLLOVER DETECTION AND ACTIVE ROLL CONTROL

The safety of road vehicles depends on the yaw-roll dynamics. A loss of roll stability results in a rollover accident. Mechanisms to warn against rollover threat and a rollover avoidance control methodology are crucial in designing a successful active safety warning/control system for heavy-duty commercial vehicles. A dynamic rollover metric, Time-To-Rollover (TTR), has become popular in rollover detection. In this paper, the TTR metric is further studied and two extended versions of TTR metrics are proposed for rollover detection. Based on the TTR rollover detection module, a prototype Active Roll Control (ARC) system is designed. Simulation results show that a heavy-duty vehicle's roll stability is considerably improved with the rollover detection and active roll control systems proposed. Heavy-duty vehicle

ROBUST YAW CONTROL DESIGN WITH ACTIVE DIFFERENTIAL AND ACTIVE ROLL CONTROL SYSTEMS

A simple robust yaw controller for the nonlinear single-track model is designed, making use of active differential and active roll control systems. Robustness is studied for uncertainties in several model parameters, namely the vehicle longitudinal velocity, the road adherence coefficients and the hand wheel angle. Constructive nonlinear dynamics are employed for the controller design. The controller parameters are selected by solving an optimization problem. Stability of the solution is guaranteed by constraints that ensure a minimal distance between the nominal operating point and a stability boundary in the space of uncertain parameters.

Rollover Stability Control for Heavy Vehicles by Using LPV Model

The paper is concerned with the use of active roll control systems employing active anti roll bars in order to improve the roll stability of heavy vehicles. Since the forward velocity of the vehicle changes in time, the combined yaw-roll dynamic model has a nonlinear structure. Selecting the velocity as a scheduling parameter, a Linear Parameter Varying (LPV) model is constructed. In the control design based on an LPV method, the changes in the forward velocity and both the performance requirements and the model uncertainties are taken into consideration. The control design is demonstrated in different situations.

Active Roll Control of Single Unit Heavy Road Vehicles

Summary Strategies are investigated for controlling active anti-roll systems in single unit heavy road vehicles, so as to maximise roll stability. The achievable roll stability improvements that can be obtained by applying active anti-roll torques to truck suspensions are discussed. Active roll control strategies are developed, based on linear quadratic controllers. It is shown that an effective controller can be designed using the LQG approach, combined with the loop transfer recovery method to ensure adequate stability margins. A roll controller is designed for a torsionally flexible single unit vehicle, and the vehicle response to steady-state and transient cornering manoeuvres is simulated. It is concluded that roll stability can be improved by between 26% and 46% depending on the manoeuvre. Handling stability is also improved significantly.

Achievable roll stability of heavy road vehicles

A general purpose numerical model, suitable for simulating the yaw—roll behaviour of torsionally flexible heavy goods vehicles with an arbitrary arrangement of vehicle units, is presented. A controllability analysis is then performed to examine the fundamental limitations in achievable roll stability of heavy vehicles with active roll control systems. It is established that it is not possible to control simultaneously and independently all axle load transfers and body roll angles. The best achievable control objective for maximizing roll stability is shown to be setting the normalized load transfers at all critical axles to be equal, while taking the largest inward suspension roll angle to the maximum allowable angle. The results of a simulation of a tractor—semitrailer vehicle with a full—state feedback active roll control system are presented. It is shown that the roll stability of the vehicle can be increased by 30-40 per cent for steady state and transient manoeuvres and that the handling performance improves significantly.

Investigation of robust roll motion control considering varying speed and actuator dynamics

This paper presents the design of an active roll controller for a vehicle and an experimental study using the electrically actuating roll control system. Firstly, parameter sensitivity analysis is performed based on the 3DOF linear vehicle model. The controller is designed in the framework of lateral acceleration control and gain-scheduled H ∞ control scheme considering the varying parameters induced by laden and running vehicle condition. In order to investigate the feasibility of an active roll control system, experimental work is performed using a hardware-in-the-loop (Hil) setup which has been constructed using the devised electrically actuating system and a full vehicle model with tire characteristics. The performance is evaluated by experiment using the devised Hil setup under the conditions of steering maneuvers and parameter variations. Finally, in order to enhance the control performance in the transient region, a hybrid control strategy is proposed.

Real-Time Fault Identification in an Active Roll Control System

SUMMARYThis paper describes a method for generating analytic redundancy amongst vehicle dynamics sensors which are kinematically related. This facilitates consistency checking between sensors. A fault diagnosis strategy is developed based on a residual vector with elements normalised to allow reliable use in a wide range of operating conditions. The technique is tested by using experimental data, modified to simulate sensor faults. The method forms part of a safety system being developed to monitor an Active Roll Control suspension in an experimental heavy vehicle constructed by the Cambridge Vehicle Dynamics Consortium (CVDC).

Robust roll control of a vehicle: Experimental study using a hardware-in-the-loop set-up

This paper presents a simcopy IMulation and experimcopy IMental study of a vehicle with an electrically actuated roll control system. The controller is designed in the framework of an output feedback H∞ control scheme based on the three-degree-of-freedom linear vehicle model. Various parameters which affect the roll dynamics are considered for robust stability and disturbance rejection. In order to investigate the feasibility of the active roll control system, its performance is evaluated by simcopy IMulation in a full vehicle model with non-linear tyre characteristics. After that, an electrically actuated roll control system is devised, which imcopy IMproves the high frequency isolation during inoperative periods. Finally, its performance is investigated by experimcopy IMental work using a hardware-in-the-loop set-up with the devised control system.

Improving vehicle performance using adaptive control techniques

This paper reviews a collaborative research programme aimed at improving vehicle performance using adaptive control techniques. Initially the design of active suspension systems is considered, and the benefits of using a non-linear controller model with an adaptive control scheme are discussed. Adaptive schemes for active roll control are then considered, and the merits of incorporating a Smith predictor to accommodate for system delays are high-lighted. Preliminary research in adaptive cruise control and collision avoidance is discussed and plans for further developments are outlined.

A centralized hydraulic system for passenger cars

The majority of passenger vehicles use separate hydraulic circuits to drive and control high-power components such as the braking and steering systems. While this approach is acceptable, it is possible for significant improvements in effficiency to be achieved using a centralized system. In order to establish the advantages and disadvantages of the distributed and centralized approaches, a simulation-based feasibility study of the pressure, flow and power requirements of the individual engine cooling, anti-lock braking system (ABS), semi-automatic transmission, active roll control and power assisted steering subsystems was carried out. Using a realistic drive and load cycle together with simulation models accounting for component non-linearities and dynamics, the flow requirements of an integrated hydraulic system were established. It was shown that the steering and roll control suspension requirements were complementary. The steering system requires high flow at low forward speeds, while the suspension requires high flow during conditions of high speed. In addition it was shown that, although the peak flow requirements of an integrated system were high, the mean flow was moderate and the high demands could be met using small accumulator units, suggesting that the system would be feasible for use in passenger cars. Finally, an energy efficient integrated hydraulic circuit including some degree of safety back-up is proposed.

The Development of an Active Roll Control System for Heavy Vehicles

SUMMARYThis paper describes the development of an active roll control system for a tractor semi-trailer. The design of the roll control system hardware and software are detailed. Simulations of the yaw-roll response of the vehicle show that the system will provide significant improvements in rollover stability.

An Experimental Study of a Prototype Active Anti-Roll Suspension System

SUMMARY Active roll control is known to offer substantial improvements in ride and handling performance over the most sophisticated passive suspension systems. However although many different active suspension systems have been discussed and analysed through simulation little information regarding experimental performance data from a prototype active roll control system has been published. This study focuses on the design, development, commissioning and experimental evaluation of a roll control suspension based on active anti-roll bar actuation. In tests, the prototype vehicle demonstrated excellent steady state and dynamic roll cancellation within the lateral acceleration range of 0.5g. Subjective assessments of the system confirmed the benefits of a level ride together with the added benefit accrued from the elimination of roll dynamics.

A theoretical investigation of a prototype active roll control system

This paper describes a simulation study conducted as part of the development of a hydraulic active roll control suspension. The system is based upon roll bars with integral closed loop position controlled hydraulic rotary actuators supplied with flow by a single proportional valve. A theoretical analysis of the fundamental characteristics of the system is presented together with the simulation implementation. System performance is examined, parameter sensitivity studies are undertaken and a number of practical measures to enhance performance are considered. The roll control system was largely insensitive to hydraulic system changes, control valve bandwidth being the most important parameter. Speed dependent gain scheduling of the forward path actuation system roll moment controller was shown to partially overcome the problem of vehicle dynamics which change with forward speed. A comparison of actuator displacement and actuator differential pressure feedback systems demonstrated that while the roll control performance of the former system was superior, the ride performance was inferior.

Development and Simulation of a Novel Roll Control System for the Interconnected Hydragas® Suspension

SUMMARY The design of passive suspension systems using conventional springs and dampers is limited by the need to compromise between vehicle ride and handling functions. The Interconnected Hydragas Suspension fitted to the current Rover 100 series partially allays this compromise by reducing the vehicle pitch stiffness witfiout affecting the bounce and roll stiffnesses. However, the vehicle body is still subject to roll during cornering manoeuvres. This paper outlines the development and simulation of a sealed low bandwidth active roll control suspension based on the existing Interconnected Hydragas System. Following a brief explanation of the Hydragas suspension operating principle die paper outlines the design of a fluid displacer or ‘shuttle’. This shuttle enables control over body roll during manoeuvres by displacing fluid from one side of the car to the other. Care is taken to ensure low power consumption whilst the sealed nature of the fluid based suspension units guarantee reliable operation without leakage. Using computer simulation, the system performance is predicted and compared with experimental measurements. It is shown that roll during manoeuvres can be reduced or eliminated using a minimum of hydraulic components with only moderate power consumption and cost.

Active Roll Control of Articulated Vehicles

SUMMARY This paper describes an investigation into active roll control of articulated vehicles. The objective is to minimise lateral load transfer using anti-roll bars incorporating low bandwidth hydraulic actuators. Results from handling tests performed on an articulated vehicle are used to validate a nonlinear yaw/roll model of the vehicle. The methodology used to design lateral acceleration controllers for vehicles equipped with active anti-roll bars is developed using a simplified linear articulated vehicle model. The hardware limitations and power consumption requirements of the active elements are studied. The controller is then implemented in the validated articulated vehicle model to evaluate the performance of an articulated lorry with active anti-roll bars. The simulation results demonstrate the possibility of a significant improvement in transient roll performance of the vehicle, using a relatively low power system (10 kW), with low bandwidth actuators (5 Hz).

Optimal Roll Control of a Single-Unit Lorry

Lateral acceleration control and linear quadratic regulator (LQR) theory are used to design active roll control systems for heavy goods vehicles. The suspension consists of a limited bandwidth hydraulic actuator in series with an anti-roll bar. The procedure used to determine suitable controller gains is described. The simulation results show that roll control of a single-unit lorry requires an actuator bandwidth of 6 Hz and mean power of approximately 17 kW for a ‘worst case’ random steering input. The static roll-over threshold of this vehicle is increased by 66 per cent when compared with the same vehicle with passive suspensions and the r.m.s. lateral load transfer is reduced by 34 per cent for a typical random steering input.

Active roll control and roll distribution control for ground vehicle Soo-Min Hwang (Daewoo Motor Co./Korea), Youngjin Park (Kaist/Korea), pp. 337–342, 11 figs., 1 table, 10 refs.

Active roll control and roll distribution control for ground vehicle Soo-Min Hwang (Daewoo Motor Co./Korea), Youngjin Park (Kaist/Korea), pp. 337–342, 11 figs., 1 table, 10 refs.

An Investigation of Active Roll Control of Heavy Road Vehicles

SUMMARY This paper describes an investigation of active roll control of heavy road vehicles. Results from handling tests performed on an articulated vehicle are used to validate a nonlinear simulation of the vehicle. A simple linear model of the vehicle is used to investigate three strategies for active roll control. The strategies are then implemented on the validated nonlinear model.