Table of Contents
P09007: Pedal Driven Auxiliary Power: User Interface - Mechanical System
Mechanical Engineer: Matt Sennett
Lucas Sienk (EE), Jeremy Tosh (EE), Matt Sones (ME), Derek Horton (ME), Donald Palmer (ID)
This section will describe the design process of the mechanical side of the user interface system.
The overall project is composed of three main systems: the mechanical system designed to transfer mechanical energy from the stationary bike to electrical energy, an electrical system to manipulate the output signal to a useful current and voltage, and a user interface system designed to withstand human interactions and output power statistics. A full description of the overall project can be found at the main page here.
However, this page is designed to convey (and thus will mostly contain) system-specific information pertaining to the mechanical aspects of the user interface system.
Throughout the project planning stages, customer communication is extremely important. Discussions with the customer is an iterative process, each time a little more of what the customer requires is finalized. After this process a final list of customer requirements is compiled.
The next step is taking the customer requirements and transforming them into a set of engineering specifications, which are metrics that once the design is completed, can be physically measured and checked off one by one to ensure compliance with customer requirements.
Based on the results of this process, designs were sketched up as shown, each brought to the customer, who in turn provides feedback, and the process is repeated.
This iteration keeps the customer informed of most design decisions, and ensures that the important requirements are being kept in mind and will be met by the final design.
System Level Design
Several major components of the design that must be met, as outlined by the customer and based off feedback from the previous design sketches, include:
- Two-post stand, to prevent vibration and increase stability
- Electrical enclosure to house electrical items, protect internal components from external hazards as well as user from internal hazards
- Enclosure will provide mounting for Ipod dock, USB connection, some restraint system for non-Ipod devices, LCD Screen, cooling fan
- Ease of adjustment of the assembly to accommodate many different users of varying heights and physical characteristics
From discussions of the design with the customer, several key functions of the mechanical user interface design became clear. The system must:
- House all electrical components securely and safely, both from external hazard, and protecting user from internal damage
- Provide mounting for all user interface items (Ipod dock, LCD, etc), as well as be able to withstand repeated user interaction
- Adjust easily for users of different heights or physical characteristics. Two degrees of freedom were required by the customer: height adjustment and angle adjustment
Two things that must also be considered at the system design level include risk assessment, which shows which areas of the design may run into problems (and list contingency plans) and a feasibility assessment, which shows how reasonable a design is, taking into account such factors as budget, lead time on ordered parts, likelihood of meeting all specifications and requirements. These assessments are shown here.
System Level Design Review
Finally a design review of the system level is held, with customer and other important personnel present to potentially find design flaws, ensure customer needs are being met, and things of this nature. For the user interface mechanical system, the following was presented to the customer during the design review.
The customer provided feedback on all aspects of the design, and a link to the feedback is provided here.
From the feedback provided from the system level design review a new revised concept sketch of the system is created, as shown:
During the detailed design phase, all the nitty-gritty details are thought out and planned in preparation of prototype construction.
The detailed design review is held for several reasons, including:
- Show all aspects of the design
- Identify design flaws before construction begins
- Ask for feedback on design challenges or decisions
- Prove readiness to begin prototype construction, or identify what is left to be completed before beginning construction
The following document was presented at the detailed design review pertaining to the mechanical aspect of the user interface system
Feedback from the customer and other personnel are included here.
The major components that must be purchased for the system include:
- Electrical enclosure
- Ipod dock
- Cooling fan & accessories
- Mounting Plate for electrical enclosure
Here are pictures of various aspects, components, and details of the mechanical portion of the user interface.
Electrical Enclosure Front Face
Electrical Enclosure Interior
Connection to Mechanical Box
Mount Plate/Angle Adjustment
The documentation for the final project review, held 2/25/2009, is shown here.
All of the major design components as requested by the customer are accounted for in the design. Some areas of improvement include a more rigid connection of the mechanical system to the bike, a better system to replace the velcro strap/tray system, and to find more aesthetically pleasing materials and connections.
An Industrial designer was brought in to show what could possibly be done without the budgetary and time constraints we were under, should the design ever be brought to production or if it were desired to be marketed to the public. Below are pictures of what he came up with.