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Mathematical Modelling for Ride Control of a Multi-Degree of Freedom Vehicle
Technical Paper
2004-05-0112
Sector:
Language:
English
Abstract
Simulating the modal response of a seven-degree-of-freedom (DOF)
vehicle model has been the main objective behind the work presented
in this paper. An independent front suspension, and a dependent
rear suspension SUV vehicle has been the model analyzed throughout
the study. Starting from the Kinematics and Kinetics of the 7DOF
vehicle model, the seven equations of motion describing the model
have been developed through Lagrange mathematical approach. The
study goes on through transforming the equations of motion to the
linear time invariant (LTI) form yielding fourteen state-space
equations.
The analysis has been conducted using a MATLAB® script
specifically developed to perform a parametric analysis on the
vibration response in the time domain of a 7DOF vehicle relative to
the variation of several chassis parameters. Throughout the study,
the dynamic response of the baseline design has been demonstrated
relative to the inputs at the road-tire interface. The second stage
of the study has been to investigate ways to enhance the ride
quality, stability, and occupant safety by surveying the role of
chassis parameters such as the anti-roll bar, weight distribution
ratio, vehicle dimensions, suspension stiffnesses and damping
factors.
The uniqueness of this research is the implementation of
classical mechanics and modern dynamics systems using state-space
formulation, which is appropriate for a Multi-Input Multi-Output
(MIMO) system. The effect of Roll motion on ride quality is also
investigated. The input data is a realistic SUV data. The research
shows that choosing the appropriate fitness between weight,
location of C.G., weight distribution, stiffnesses and dimensions
are affecting the ride quality significantly, and there is a need
to satisfy some magic numbers in the design cycle of a motor
vehicle on the highway for good ride performance.