This paper performs extensive analysis of complete manoeuvres of nonlinear vehicle model developed using Multibody Systems Techniques (MBS). This analysis is aimed at the study of integrated vehicle motion control, the paper discusses the theoretical properties of resulting linearised models which embraces all aspects of vehicle motion (performance, handling and ride). It also addresses the implication of this modelling technique to integrated control systems design. In this sense, it provides an effective link between MBS vehicle models and Control Theory.
For this purposes it discusses the influence of the formulation and topology adopted in the MBS model on the resulting State space and Transfer function matrix representations of the system. This discussion includes the effects of the latter on the system structure such as eigenvalues, eigenvectors, and the elements of the A, B, C and D matrices. Also discussed are poles and zeros frequency response and the principal gains. Resulting system properties for analysis, control design and numerical stability purposes such as conditioning, controllability, observability and the respective gramians, etc.; will also be addressed. Based on these analysis, the application of System's Theory will be carried out in order to obtain an adequate realisation of the system for control design objectives. In this case, topics discussed include balancing, decomposition, model order reduction, etc. In order to check the validity of the use of linear approximations for control studies, the changes in system's structure with some parameter variation is studied and results of the linear simulation are compared with nonlinear ones.
While developing from an earlier work by the same authors [1], which describes the use of SD/FAST [6] and ACSL [7] as a MBS simulation environment, the present paper brings in the use of the computer package MATLAB [9] as a powerful tool for the analysis of the resulting linear system representation, as well as a development facility for linear control system design. The work as a whole, also emphasises the importance of package integration, a key concept, in the design stages of the production process. The possibility of having very powerful tools in their own areas efficiently integrating is a very desireable and atractive one.