Analysis & Experimentation
Now that you have chosen the final concept, it is necessary to establish that critical subsystems will perform as required. In many cases, performance can be predicted by calculations using data obtained during the research phase. In others, experimentation will be required. The experimental setup may closely resemble the contemplated prototype (in which case it’s sometimes called a “breadboard” after the practice, in the early days of radio, of building the circuit up on a wooden board used for cutting bread). Or, it might be much simpler, simply containing the functional element to be tested. For example, a phase-change incubator will require testing to determine the optimal geometry and quantity of phase change material. It might be enclosed in plastic spheres of the intended size and number, or it might simply be contained in a laboratory beaker. The choice would depend on the information needed and the resources available. Another example might be a mechanical linkage. If linkage dynamics are important, an accurate breadboard would be necessary. If only kinematics are required, a Lego model, or even cardboard model might be sufficient.
Deliverable (Homework 15)
Each team member should choose a critical subsystem of your chosen concept and perform the necessary analyses and experiments to ensure that it can work according to specifications. Ideally, each person on the team should choose a different component or subsystem, but if there aren’t enough, independent work on the same component is acceptable. Present a summary of this work at the Ses #17 design review.
Once the performance potential of the critical subsystems is established, it is necessary to work out all the details that will make a workable prototype. This will vary greatly from project to project but includes aspects such as: dimensions and tolerances, material selection, kinematics of assemblies and sub-assemblies, and calculations of energy and power requirements. Every component of your project should be designed to best fulfill its purpose. Your first layout will not be your final one; continual refinement is possible until you run out of time, but the difference in quality from the first layout to the last can be enormous.
Keeping all these considerations in mind, start the process of producing technical drawings of your proposed design. Make sure to have all critical custom-made components drawn up either by hand or using computer programs such as SolidWorks, Pro/Engineer or AutoCAD (we don’t need drawings of screws, nuts, off-the shelf parts or banana leaves!). Also, with each drawing make a list of materials that you will need in order to fabricate the parts you have designed, a list of processes needed to fabricate each part and denote where they will be made (a small-scale machine shop, a large plastics factory, etc.).
Deliverable (Homework 15)
Each member of the team should choose a different component of the design and turn in the detail drawing and materials list for that part. Even though each team member turns in just one part, this process should be done for all parts of the design. Present this information at the Ses #17 design review.
Now it is time to turn your ideas into reality—generally one begins by building a proof of concept prototype. In this case, the parts are typically fabricated on an individual basis and may not be made in the same way, or of the same material, as the final product. A careful planning of this phase will save you valuable time, unnecessary waiting times for your raw materials or components, and stressful last-minute hard-work.
As a group, make a plan that outlines how you propose to complete your prototype during the next three weeks. Sketch out the main steps in a Gantt chart or timeline, including milestones. List all the materials you will need in the fabrication of your prototype, and make a preliminary budget detailing where you plan to obtain all your materials. Present this plan and the progress you have made to date at the Ses #17 design review.
Testing and Evaluation
Once you have built a prototype, it is necessary to test it and see if it does what it is supposed to do. Now is the time to go back to the design specifications outlined in the early stages of the design process and verify that the device works according to the given specifications. Devise techniques for measuring the performance of your device for each of your design specifications. As part of this exercise, think of how your device could be improved. Are there ways you can make it cheaper, faster, better? Try to lower the part count or remove material. Is it as simple as possible (but not simpler?) Not only should the technical performance of the device be tested, but also the human factors; test for usability and ergonomics. Have people try your device and get their feedback. Whenever possible, have the actual users try the device, if this is not feasible, try to find people with as close to the same background as possible. Have users try your device without as little instruction or guidance as possible, and analyze their interactions. You can observe how intuitive, easy and/or safe the device is to use.
Use all the information gathered at this stage to inform the next iteration of the design process. Consider revising the design specifications and the original ideal and desired values. Identify the subcomponents that need to be revisited or redesigned, and outline the goals for how to move the project forward.
Summarize the results of your tests and present them at the Ses #20 design review. Videos of people using the machine are an especially effective presentation technique. Include recommendations for moving forward with the project.