Pedal Power: Harnessing the Power of Kinetic Rotation
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Pedal Power is a bicycle energy generator that will allow both commuter and avid cyclists to charge their devices by converting the kinetic energy of a moving bicycle into usable electrical energy. The device design takes into account the needs of both cycling groups, including durability, weight and size, and universal compatibility. The complete Pedal Power product (Fig. 1) and generator mounting assembly (Fig. 2) are shown below. Complete prototype drawings are detailed in Appendix I. Two competitors manufacture a similar device, but those products do not adequately address the customer need to charge different electronics. Several design constraints were considered, which include: battery, costs, and the device form factor. Quantitative specifications were developed to meet the objectives and customer needs discussed above. Engineering calculations were performed early on to ensure that the engineering specifications can be met and to prepare for prototype development. Engineering calculations proved the validity of the design. Results determined that a generator shaft speed of approximately 10,000 RPM is enough to open the charging circuit and charge the battery (Appendix H, Table 1). Proof of concept (POC) testing proved that at 12 MPH, 0.5- 0.75A can be generated at 8V. POC testing also revealed contact issues between the roller and rim, as well as charging circuit lag, thus influenced the springloaded generator-mounting hinge design and capacitor addition to the circuit. Specifications were determined, and four primary functions and their respective sub-functions were identified to aide in prototype designing. The electronics pack was designed to secure all electronic components and connections. The generator mounting assembly ensures constant and reliable contact with the rear wheel and also includes a disconnect function. The components shown above were individually machined using 6061 Aluminum (with the exception of the prefabricated hinge and universal clamp). Component assembly was completed by hand. The electronics pack components were secured with silicon adhesive, and the generator assembly was fastened together with stainless steel screws. Thorough testing took place after the assembly process to ensure that Pedal Power met the customer expectations and design specifications. A testing summary is shown in Table 3, Prototype Testing and Result at the end of the report.