From DDL Wiki

First Report

We received your report on the bicycle light generator, and we are impressed with your work. You have found some interesting opportunities, and we look forward to your ideas in the next report. Detailed comments follow:

• In our company (and in most companies that we know of) reports will contain an executive summary that typically outlines your conclusions, not just a summary of what topics will be discussed in the report. This would be helpful for us in the next report, since our executives typically do not have time to read the full report.
  • The executive summary has been added to the beginning of the report.
• A picture of the full assembly mounted on the bicycle with components labeled would be helpful in understanding the function of the product. In particular, it is important to understand the mechanical as well as the electrical properties. You have done some analysis of the electrical circuit, but we found it difficult to understand the full mechanical setup without a picture of the device in use. Also, labeling the components in the picture will help in understanding the functional description, and a free body diagram would also help.
  • Picture of full assembly has been added to help identify functional parts under section: Product Dissection.
• You have a good list of customer needs, but what about requiring low additional pedaling effort needed to run the generator?
  • Thank you for your suggestion, low additional pedaling effort has been added to customer needs.
• Is contact with the wheel of bicycle the only way to drive the generator? It seems that attaching the generator directly to the crank would be better for ensuring a more consistent input, since the crank is generally driven at a consistent cadence, whereas the wheel may travel very fast or very slow depending on conditions. Did you consider this?
  • We have considered different input sources to power the generator such as chain-mount, and wheel hub. However, we believe chain-mount, wheel hub, and crank shaft all required replacement of major parts of bicycle rather than being an add-on for the users like your orginal product. Keeping the product as an add-on not only ensures easy maintenance, but also lower costs
• You identified an important opportunity of the absence of light when the bicycle is stopped. If you move toward a design with a battery or capacitor to solve this problem, make sure you consider what happens if bike tires move backward?
  • Thank you for your concern. We will definitly look into this issue.
• Can you comment on the use of the generator in a bike with a suspension or a nonconductive bike frame?
  • Nonconductive bike frame has been addressed in FMEA. As of bike with a suspension, we believe this can be easily solved if customers has an option to choose between mounting bracket for bike with suspension or without suspension when purchasing.
• We found some typos in the report (rare instead of rear, for example)
• The circuit diagram was helpful. In the diagram, Vs is shown as an alternating current – is it alternating or direct, and how do you know? Also, where does the bike frame and bulb appear in the diagram, and what components create each? I assume Rload is the bulb? Do you have estimated values for these component parameters?
• Nice BOM, but what are your conclusions? Some pictures seem to be missing.
• We have some questions about the manufacturing processes you identified. For example, you listed the Indicator LED Circuit Board assembly as being stamped? Also, the generator roller you say is plastic but identify it as being stamped. This does not seem correct.
• Were you unable to disassemble the generator assembly? What components are contained in the assembly?
  • Generator assembly was impossible to taken apart without destroying the functionality of it.
• What did you conclude from your DFMA and DFE analysis? It seems that you don’t have any suggestions.
  • DFMA and DFE analysis have been updated
• We had an LOL moment at your “Failure Modes and Effective Analysis” title. You have outlined some good ideas for improvement, but we typically like to see an FMEA table for formal analysis and to address issues of severity, occurrence, and detection explicitly.
  • FMEA has been updated
• Also, please include a free body diagram with numerical analysis of the input/output speed and torque from the geartrain (did we pick the right gear ratios for the job), as well as a free body diagram of the device mounted on the bike and interacting with the wheel.

Additional Comments

It would be useful if some of your conclusions were drawn together into an executive summary.

Your simple circuit analysis is very good. However, it might be nice if you could explain what your results of mean in the context of the product. It might also help if your equations were a little easier to read.

Your FMEA seems a little lacking, and it might help if it were arranged in a more formal format.

Revision

We received your revised report 1, but we could not find responses to the comments we provided. It appears that you have addressed some of the issues in the report itself, but you did not provide a summary of responses on the discussion page, so it is difficult for us to assess. Please provide a summary. We also were unable to find the free body diagram and mechanical analysis requested.