Electrical Engineering Department
BS in Mechanical Engineering
Long distance mountain bikers, bike-packers, and many bikers in developing countries rely on electrical devices for safety and communication. These specific groups of people operate in areas with little to no electricity, and often times have no power to sustain their devices. The purpose of this Cal Poly senior project, VeloElectric, was to design, build, and test a kinetic energy harvester for bicycles that can be used to charge common mobile devices via USB. This senior project team created a device that attaches directly to a bicycle and uses vibrations to generate energy, which in turn powers a variety of portable devices. The final product will be used by Professor Lynne Slivovsky on a bike ride from Canada to Mexico. This document contains information on the entire project during the 2014-2015 school year. The “Background” section summarizes research and case studies including dynamo chargers and an electromagnetic induction charger called the nPower PEG. The Pedl team used this information to generate initial design ideas such as using piezoelectrics and other kinetic energy harvesting devices. This research was also used to gain a better understanding of the current state of art for this type of product. The end of the background section provides details of the project management plan that was used through the course of the projects focusing heavily on the tasks completed during Spring quarter. Following the “Background” section is an explanation of the development of conceptual designs that lead to the final product. Conceptual designs included decision matrices to decide on a 3D printed exterior casing, Velcro straps for attachment, electromagnetic induction for energy generation, and a battery for energy storage. Diagrams, models and pictures of the end product are displayed and analyzed in the “Description of Final Design” section. This section shows the exterior casing that was created to house the inner casing, battery, and printed circuit board. The “Product Realization” section focuses on how a lathe was used to create the final inner casing, 3D printing for the exterior casing and inner casing caps, and simple soldering for the electrical components. The section also explains how the final prototype cost the team about $200, but through mass production could be lowered to about $45. The “Design Verification” section discusses how the final iteration was tested and includes test descriptions and photos while documenting the results of these tests. Example tests include weight, bike transfer time, USB compatibility, and vibrational tolerance. The document concludes by discussing the progress that was made on the project throughout the year and the recommendations that the design team has for possible future teams assigned to this task.