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trolley car
February 12, 2021

Trolley project delivers crash course in mechanical engineering

Written By: Adam Malecek


In ME 201: Introduction to Mechanical Engineering, first-year students learn valuable skills that prepare them for success in their mechanical engineering major at UW-Madison and beyond.

Throughout the semester, the students learn the basics of key software, mathematical and design tools, such as the 3D solid modeling program SolidWorks, as well as some fabrication skills, which they then apply to a hands-on design project.

 Kristofer Dressler
Kristofer Dressler

“Every new mechanical engineering student takes ME 201, which helps foster a real sense of community among students in the department and also shows them the many possibilities in mechanical engineering,” says instructor Kristofer Dressler.

And that’s the case, even during a pandemic. In the fall 2020 semester, Dressler debuted a new project: the students worked in teams, safely, in person, to design and build small, semi-autonomous trolley cars.

To start, Dressler gave each group a kit containing a few basic building supplies for their trolleys—a piece of fiberboard for the chassis, a small electric motor suitable for a toy-sized car, four CDs to serve as the wheels, some wires and a couple of battery packs. Then, it was up to the students to develop the design of their trolley, create any additional components, write the code to control its driving, and, ultimately, to build a working trolley.

Students used SolidWorks to design custom trolley components such as gears, mounts for the motor and batteries, and a body for their car, which they 3D printed in the college’s Makerspace, the Grainger Engineering Design Innovation Laboratory.

“It was really important for me that the students get into the college’s TEAM Lab and the Makerspace as part of the project,” Dressler says. “Learning how to use that equipment is a crucial skill for hands-on design work and provides a strong foundation for students’ engineering education.”

As students progressed through the iterative design process, many teams encountered problems with their trolleys while testing their designs. These missteps, Dressler says, are important because they spark powerful learning opportunities for students.

“My approach to teaching engineering is to savor the mistakes,” Dressler says. “In my experience, you learn a lot more from the failures than the things that go right the first time. A crucial skill that students learn in this course is troubleshooting—being able to figure out why something isn’t working and what can be done to fix it.”

While many university courses in fall 2020 were virtual due to the COVID-19 pandemic, students in ME 201 say the ability to work in person with their teammates on a tangible project greatly enriched their educational experience.

“The failures that we faced with our trolley while going through the design process were what really helped us learn, and many of those experiences wouldn’t have been possible if the class was only virtual,” says student Maggie Meissner. “The hands-on activities let us work through problems by allowing us to see how things worked, or didn’t, so we could find the best solutions as a team.”

And the different aspects of the trolley project—such as coding, design, building and troubleshooting—allowed students to gain a range of skills and also discover areas of interest.

“I began with no coding experience but quickly fell in love with software,” says student Caleb Starfeldt. “The trolley project provided a purpose and incentive to learning the Arduino version of C++. I’m now fascinated by the workings of computer software and excited to continue learning about it.”

The project culminated in a competition in which students put their trolleys to the test, driving around a track that Dressler assembled in the lobby of the Mechanical Engineering Building. For the competition, the students’ trolleys were supposed to drive around the track behind a school bus without crashing into the bus. Collisions resulted in a time penalty, and the team with the fastest time won.

However, Dressler had programmed the bus to stop, start, speed up and slow down at various points as it completed its circuit, creating a real test for each trolley’s adaptive cruise control.

To enable that feature, students installed sensors on their trolleys that detect the distance of nearby objects. With the code they wrote for controlling their trolleys, the students aimed to have their trolleys adapt their driving, in real time, in response to the bus’s movements and, like real-life vehicles, to hopefully avoid crashes.

Dressler says students enjoyed the competition and the opportunity to see how their trolleys fared in a real challenge.

“The students worked hard throughout the semester and persevered through setbacks, so it was great to see their eyes light up with excitement when their trolley made it around the track and avoided rear-ending the bus—they’d say, ‘Holy cow, we actually built this thing!’” Dressler says.

For students, the course offered an excellent introduction to collaborative engineering projects and illuminated the many ways that mechanical engineers can make a difference in a wide variety of areas and industries.

“This project was just an incredible first impression of engineering to a first-year mechanical engineer, and this course and the project helped me and many of my classmates confirm that we are in the right major for us,” says student Elena Moore.