Teaching Undergraduate Kinetics Using A Lego Mindstorms Race Car Competition

Students often struggle with the fundamental concepts covered in a first course in rigid body dynamics. Difficulty visualizing the connection between homework assignments and real world situations and low motivation for solving seemingly contrived problems only compounds the problem of understanding and correctly applying the learned material. To add student motivation and increase interest in the study of kinetics, a course project has been developed at the United States Air Force Academy using the LEGO ® Mindstorms Project kit. The project involves the design and construction of a race car capable of competing in both a maximum speed as well as a hill climb competition with minimal configuration changes. Following introduction of the project, various homework problems were also developed and integrated into the project to increase the hands-on design, construction, and analysis components. Experimental determination of the mass moment of inertia of wheels and axles, analytical study of go cart dynamics, experimental determination of center of mass and other assignments are used to prepare the students for a detailed analysis of their race car. Students used these problems to analytically determine the maximum acceleration of their cars during a 50-foot race and the time required to complete a hill climbing contest. The stall torque of the car’s motor(s) is calculated using an incline test, then compared to the published motor torque of 0.276 in-lbs. If the students choose to use gearing or pulleys for their cars, they are required to calculate the effective output torque using appropriate gear ratios and estimated power losses. Using the determined values for the vehicle center of mass, the mass moment of inertia, and the motor torque, the students calculated the cars’ theoretical acceleration. As a final analysis, the calculated performance is compared to the actual acceleration of the car from timed races. Students seemed to enjoy building the cars, and really enjoyed the competitive races that are performed at the end of the project. The LEGO ® Mindstorms Car Competition provides a fun, real world problem that helps motivate students to learn rigid body dynamics.