Date of final exam: 20/04/1999

E-mail: gentili@disp.uniroma2.it

Tutor: Prof.  S. Nicosia, Università di Roma ‘Tor Vergata’

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Modeling and Control of a Class of Constrained Mechanical Systems   ___________________________________________________________________________________________________________

Advisor:

Prof.  S. Nicosia, Università di Roma ‘Tor Vergata’

Co-advisor:

Prof.  A. Tornambe', Università di Roma Tre

Summary of the thesis

The dissertation is devoted to explore some issues which arise in the modelling and control of a class of mechanical systems subject to geometric and kinematic constraints. The class of mechanical systems under consideration includes several different types of wheeled vehicles which are characterised by unstable postural dynamics and by relevant dynamic couplings between steering (yaw) and leaning (roll) dynamics. The interest for dynamics and control of vehicles belonging to the previously mentioned class arises both in connection with the problem of drive control of common vehicles (such as bicycles and motorbikes) and also in connection with the design and control of prototypical vehicles for unmanned planet exploration missions.
The attention of this work is focused in particular on a two-body system referred in the sequel as the rider-vehicle system. Lateral displacements of the riders' torso, with respect to the vehicle instantaneous direction of motion are considered and the dynamics of the overall system, subject both to internal geometric constraints and to kinematic (rolling) constraints are derived by using the Lagrange-D'Alembert approach.
The problem of drive control for a rider-vehicle model system is studied in this dissertation, and its two main aspects, namely, posture equilibrium regulation and asymptotic tracking of a time parameterised ground-trajectory are considered.
After giving a formal statetement of the control problem to be solved, some properties of the non linear model of the overall system are highlighted and a feedback linearizing dynamic state feedback law is designed to attain the prescribed drive performance.
The problem of observer based output feedback design is addressed as a second step. The dynamics of the vehicle-rider system, after suitable output precompensation, are reduced to a system in observable form for which the design of an high gain observer can be performed.
Present work is dealing with the design of other observers for the system and with the inclusion of such observers within the control loop in order to obtain a dynamic output feedback controller.
 

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