Abstract:

This work aims to present projects developed by undergraduate and graduate students around a single theme: the modelling and control of an autonomous electric small scale motorcycle. The object of research is interesting due to the complexity of interaction between its components, which allows to simultaneously study subjects such as system modelling, vehicle dynamics, gyroscopic effect, stability control, trajectory control and machine instrumentation. All systems were developed and built by students with different levels of knowledge in Pontifical Catholic University of Rio de Janeiro to aid the teaching, learning and research in Engineering, particularly on the Control and Automation, Mechanical and Mechatronics fields.

The first work developed was the computational modeling in SolidWorks of the system, in order to obtain the centers of mass and moments of inertia of the motorcycle’s components. The state model developed by Meijaard (2012) was used as a basis, which considers the two-wheeled vehicle a multi-body system composed of four bodies: the two wheels, the steering frame and the main frame, in which the driver is included. Later, the system’s center of mass data obtained by the computer simulation were confirmed by an experimental apparatus, also developed by the students of the Mechatronic System Development Laboratory (LDSM, in portuguese).

With regard to vehicle dynamics, a passive platform was designed to aid the initial tests of the autonomous motorcycle’s control algorithms. The platform should secure the motorcycle while not restricting the yaw and roll movement, which are crucial for its dynamics. The work is still in progress; early versions include a treadmill, driven by the vehicle's wheels, attached to a mobile platform whose movement tendencies are also brought about by the small scale motorcycle.

Another main dynamic phenomenon that occurs in two-wheeled vehicles is the gyroscopic effect, generated by the combination of angular velocity and moment of inertia of spinning bodies, which influences the equilibrium. In order to physically understand this phenomenon and develop its mathematical model, another passive platform was devised, focused solely on the front axle of the motorcycle. The device’s first prototype in LEGO was recently concluded, after an elementary theoretical foundation; still in a preliminary version, its objective was to test the concept and to correctly position the mobile base’s rotation axes in relation to the roll and yaw axes of the motorcycle, considering that only its steering system and front wheel are sufficient to generate the desired gyroscopic effects.

Since all motorcycle’s components have been individually studied and modelled, it is necessary to understand how they work together. To this end, an instrumentation system was implemented, which includes an inertial measuring unit (IMU), hall sensors to check the engine and rear wheel rotation and a potentiometer, to measure the handlebars’ steer angle. With all these sensors boarded in the vehicle, it is possible to develop and apply different control strategies to keep the motorcycle stable at any speed and trajectory.

Keywords:

Research and Educational Projects, Control Engineering, Motorcycle dynamics.