Abstract:

The School of Engineering of the University of Bergamo offers a new curriculum in Mechatronics that combines traditional aspects of mechanical engineering with additional knowledge on electronics, automation and robotics. The study plan of this curriculum includes the course of Functional Design of Mechatronic Systems (6 ECTS) and an elective lab on Mechatronic Systems (17 ECTS), where all competences, acquired in several courses, are applied to a project that students must accomplish divided in small teams.

Team organization is left to the students, according to their skills and interests; generally, we see a task subdivision among mechanical design, mathematical/computer modeling and control, electronics setup. However, during project discussion, students must be able to answer questions about the whole project.

In the past years, several projects (including also an experimental part) have been proposed, such as inverse pendulum modeling and control, design and control of a cartesian plotter, design and control of an autonomous two wheeled vehicle following a marked path.

Motorsport is a topic that in general is very attractive and stimulating for the student, so we had the idea to add, as course project, the design of the tractive system of a competition electrical vehicle, according to the rules of formula SAE.

To simplify the project within the limits of a course project, we asked the students to design this tractive system considering only the acceleration test. The other tests that are planned in formula SAE Rules, such as lateral acceleration (skidpad), agility (autocross) and endurance , would require a more sophisticated modeling of the vehicle, taking into account, for example, suspensions, regenerative braking and battery pack cooling.

To avoid dispersion of ideas and to allow an easier comparison among the projects of the different teams, the tractive system layout has been predefined, consisting of four electric motors mounted on the wheel hubs.

This layout corresponds to the one used by the most representative teams; moreover, it allows more opportunities to develop further projects.

The assigned project consisted in the choice of the electric motors and transmissions taking into account vehicle characteristics (length, mass, center of mass position, aerodynamic properties) and tire road adherence, in order to minimize the time required to cover the acceleration track (75 m length).

Sensitivity analysis was also required to highlight the parameters that are more relevant to vehicle performance and are, therefore, more suitable to fine tuning.

Students highly appreciated this subject and, at the end of the course, a group of them proposed to kick off a University Team to participate, as a first step, to the static events of Formula SAE Electric.

Keywords:

Mechatronics, Teaching, Problem based learning, Formula SAE.