Abstract:

This contribution describes a setting where students in a course designed, built and tested a system for stable reversing of a car-trailer system.
The system was built in the project part of a 7.5 ECTS course that consists of three parts: theory, labs and a mini project.

In the project setting the task was to reverse a trailer. Reversing of a car-trailer system is a good project problem since it easy to visually see and verify when reversing is working and when it is not. To get it to work the students need to apply the fundamentals of Kalman Filtering, control techniques for stable reversing, vehicle kinematics, processing of sensor signals and programming embedded and distributed systems.

So, to support the mini project three labs were designed for the lab part of the course. The labs introduced Kalman Filtering, sensors in robotics, control and the embedded hardware connected to the car-trailer system. For the project planning a formal project steering model was used, that has a Design, Build, and Test approach. The project directive divided the group work into four distinct parts: the estimator, controller, teleoperator, and simulator. The estimator is the part that estimates state variables of the trailer system, for example the hitch angle – the angle between the trailer and the car. The controller is the part that reverses the car-trailer in a stable way. The teleoperator is basically a user interface for a human teleoperator that enables remote control the car-trailer system, and the last part is the kinematic simulator mimics the kinematics of the real car-trailer system. Four students formed each project group. The car-trailer is based on a 1:10 scale toy RC-car.

Each project member could have responsibility of one part.
The students have submitted reports and successfully presented a stable car-trailer reversing system that that were able to reverse stable in a desired direction. They also added a laser range finder to get external observations of the hitch angle to feed the Kalman Filter. Students worked both over distance and in university facilities. Canvas and Zoom are example of tools that enabled distance learning.

It can also be mentioned that the project was redesigned regarding the Covid19 situation that we have experienced in year 2020. I comparison to previous course settings more time was initially invested to write a good project directive that isolated the four important parts of the system. The students implemented the simulator and when they get a stable reversing in the simulator they moved to the RC-car trailer system. Students told it took a lot of time to get it to work properly on the real RC-car system. The outcome is valuable input for coming courses, since it shows that it is possible to give a project course over distance.

Keywords:

Project, Robotics, reversing a trailer, design-build-test.