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Journal Article

Robust Yaw Moment Control for Vehicle Handling and Stability

This paper presents a robust controller design method for improving vehicle lateral stability and handling performance. In particular, the practical load variation will be taken into account in the controller synthesis process such that the controller can keep the vehicle lateral stability and handling performance regardless of the load variation. Based on a two-degree-of-freedom (2-DOF) lateral dynamics model, a model-based Takagi-Sugeno fuzzy control strategy is applied to design such a controller and the sufficient conditions for designing such a controller are given in terms of linear matrix inequalities (LMIs) which can be solved efficiently using currently available numerical software. Numerical simulations are used to validate the effectiveness of the proposed control approach.
Technical Paper

Robust Active Roll Controller Design for Vehicles Considering Variable Speed and Actuator Delay

A robust controller design method for vehicle roll control with variable speed and actuator delay is presented. Based on a three-degree-of-freedom (3DOF) yaw-roll model, the H∞ performance from the steering input to the vehicle body roll angle is considered. The design approach is formulated in terms of the feasibility of delay-dependent matrix inequalities. By combining the random search of genetic algorithms (GAs) and the efficient solution of linear matrix inequalities (LMIs), the state feedback controllers can be obtained. The approach is validated by simulations showing that the designed controllers can achieve good performance in roll control.
Journal Article

H∞ Control of a Novel Low-Cost Roll-Plane Active Hydraulically Interconnected Suspension: An Experimental Investigation of Roll Control under Ground Excitation

In order to make the active suspension more affordable, a novel low-cost active hydraulically interconnected suspension is developed, assembled and tested onto a sport utility vehicle. H∞ roll control strategy is employed to control vehicle body's roll motion. The hydraulic suspension model used for deriving the H∞ controller is estimated experimentally from the testing data. The active suspension model is then combined with the half-car model through their mechanical-hydraulic interface in the cylinders. The weighting function design of the H∞ control is provided. On a 4-post-test rig, the active suspension with H∞ control is validated with several road excitations. The test rig and experimental setup are explained and the obtained results are compared. The effectiveness of the designed H∞ controller is verified by the test data, with a considerable roll angle reduction in the three tests presented.
Technical Paper

Experimental Vibration Simulation for Heavy Duty Vehicle Seat Suspension with a Multiple-DOF Motion Platform

This paper presents a study on experimental vibration simulation using a multiple-DOF motion platform for heavy duty vehicle seat suspension test. The platform is designed to have 6-DOF with the advantages of high force-to-weight ratio, high dexterity and high position accuracy. It can simulate vehicle vibrations in the x, y and z translational axis and in the roll pitch and yaw axis rotation. To use this platform to emulate the real vibration measured from vehicle seat base under real operation for vehicle seat suspension test in lab, an Inertial Measurement Unit (IMU) is applied to collect the acceleration data from a real vehicle. An estimation algorithm is developed to estimate the displacement from the measured acceleration. The estimated displacement is then used to calculate the length of each leg of the platform so that the platform can generate the motion similar to the measured one.
Journal Article

Experimental Investigation of a Hydraulically Interconnected Suspension in Vehicle Dynamics and Stability Control

Mainly motivated by developing cost-effective vehicle anti-roll systems, hydraulically interconnected suspension has been studied in the past decade to replace anti-roll bars. It has been proved theoretically and practically that hydraulic suspensions have superior anti-roll ability over anti-roll bars, and therefore they have achieved commercial success in racing cars and luxury sports utility vehicles (SUVs). However, since vehicle is a highly coupled complex system, it is necessary to investigate/evaluate the hydraulic-suspension-fitted-vehicle's dynamic performance in other aspects, apart from anti-roll ability, such as ride comfort, lateral stability, etc. This paper presents an experimental investigation of a SUV fitted with a hydraulically interconnected suspension under a severe steady steering maneuver; the result is compared with a same type vehicle fitted with anti-roll bars.
Journal Article

A Novel Method for Side Slip Angle Estimation of Omni-Directional Vehicles

The omni-directional vehicle is an innovative vehicle, in which the in-wheel steering motor and in-wheel driving motor are integrated into each wheel of the vehicle so that each wheel can be independently controlled to have traction, braking, and turning motions to improve the vehicle's mobility, handling and stability. To realize good performance, various control strategies have been proposed, like the active steering control and the direct yaw moment control, where the accurate slip angle information is critical to these control strategies. However, in practice, the side slip angle is hard or expensive to be measured for a passenger vehicle, therefore, different estimation methods have been proposed in the literature. In this paper, a novel side slip angle estimation method is proposed for the omni-directional vehicle that has four independent steering motors.