Bar Balancing Cart

Date: November 2024 - December 2024

Role: Team Leader, Lead Programmer

My team was tasked with creating a cart which could transport an 1 foot long aluminum bar a specified distance between 5 and 10 feet as fast as possible while keeping the bar upright. In order to achieve this we used a DC motor which an encoder to read the motor’s position and velocity. This allowed us to create a closed loop control where the speed of the motor was determined both by its current speed and the amount it had already turned. An Arduino Uno was used to control the motor, the base of the cart was made out of plywood, and the wheels were 3D printed using our own custom designs. The limiting characteristic of how fast our cart could move while ensuring the bar remained upright was the linear acceleration of the cart. To determine the maximum theoretical acceptable acceleration, hand calculations were compared against a motion study performed in SolidWorks. The hand calculations and simulation both resulted in a theoretical acceleration of 32.17 inch/seconds^2, giving us confidence that this represented the upper limit of what we should test for our cart. This corresponded to a minimum time to move 10 feet and back of 7.72 seconds. However, the maximum velocity achieved by our cart in this scenario would exceed the velocity the motor was able to produce. To account for this, the triangular velocity profile was changed to be trapezoidal, resulting in a minimum theoretical time of 7.90 seconds. In reality, there were many external factors which necessitated that the actual acceleration we used in our code had to be lower based on numerous tests we performed. Aside from these technical aspects of the project, our team had to manage our time and work efficiently to accomplish all of the goals. My main contribution was creating the foundation for both the simulation and code, and since our team communicated well with each other, my colleagues were able to fix any mistakes and make everything fully functional. This led to our cart being able to successfully keep the bar upright and travel to within 6 inches of the specified distance before returning to its original position. Our fastest time to travel 10 feet and back while keeping the bar upright was approximately 25 seconds, and though this was somewhat slow, it showed we could accurately control our motor to achieve the goals set out for this project.