Hiroyuki Urabe

Enhancements in vehicle stability and steerability with slip control

To enhance both vehicle stability and steerability, vehicle dynamic parameters such as vehicle side slip angle, road friction coefficient and tire side forces were precisely estimated in real time. Utilizing four wheel slip control, a logic for optimizing vehicle dynamics was formulated. Tests on ice- and snow-covered roads demonstrated the effectiveness of the control, and confirmed the validity of the logic.

Design of Automotive Torsion Beam Suspension Using Lumped-Compliance Linkage Models

This paper presents a new method for efficiently and accurately modeling the elasto-kinematic behaviors of torsion beam suspension systems and of other similar classes of mechanical systems, and a design method utilizing the models. The torsion beam is represented as a linkage of lumped mass joined by nonlinear springs, bending and torsion, whose stiffness are identified via off-line computational experiments using nonlinear finite element simulations. A number of such computer experiments are conducted off-line for representative dimensions of torsion beams, and the results are stored in surrogate response models. During design iterations, these surrogate response models are utilized to automatically construct a lumped-compliance linkage model of a torsion beam and integrate it into a multi-body suspension system model that can be simulated using commercial software. Comparison with a nonlinear finite element analysis demonstrates much improved accuracy of the proposed model over commercial flexible multi-body simulation software, with comparable computational speed. Finally, an example is presented on the multi-objective optimization of the cross section of the torsion beam using the developed surrogate response models.

Simultaneous Robust Optimization of Suspension and Active Control System of Road Vehicles for Handling Improvement

This article proposes a simulation-based simultaneous robust design procedure of a suspension system and a vehicle dynamics controller. The aim of the procedure is designing a road vehicle that can maintain high stability and handling at the limit manoeuvering region even if the vehicle parameters and/or road conditions are varied. The system robustness is evaluated by the probabilities of unacceptable vehicle behaviour subject to the variations in uncertain vehicle parameters and steering/brake input patterns. The design problem is formulated as an optimization problem of suspension kinematics and controller parameters using a stochastic performance function. Numerical simulation results are presented to illustrate the effectiveness of the proposed procedure.