DESIGN APPROACH
You are beginning to develop knowledge of design, materials, and basic machine elements (e.g., power screws, bolted joints, bearings, gears). In addition, you are becoming skilled in CAD modeling, creating complex assemblies, animating linkage systems, and performing simple analysis of linkage motion. This project will focus on synthesizing a device that can provide human mobility. The problem statement is intentionally open-ended. It is expected that your device will provide the ability for a human to be in a seated position in one device configuration, navigate in space (across floors, down hallways, through doorways, etc.), and somehow reposition him/herself into a separate configuration to provide accessibility to previously inaccessible spaces and objects (bringing the person to the objects, not the objects to the person, as shown in the image above).
Course content on design, CAD modeling, linkage synthesis, and creating proper engineering drawings is the focus for this project. In terms of design, a logical starting point would be to define the design problem from your own perspective. What type of spaces/environments will your device operate? What age, size, and weight person would your device accommodate? What are the features, key geometries, and requirements of existing wheelchair designs? What surfaces would your device navigate? What spaces and objects would your device provide access to? Based on your custom-crafted problem statement, perform focused background research on possible existing design solutions. In thinking about your own new design, develop a list of specifications (i.e., metrics along with marginal and target values, with units as appropriate). For example, think about defining the basic range of motion, speed of operation, stability needs, etc.
Your next design activity could be to brainstorm many possible ideas. As with the first project, create clearly labeled hand sketches of at least the 5 best options (no CAD modeling necessary at this stage). Because the project focus is on linkage synthesize, ignore concerns about controls, buttons, motors, bearings, material choices, forces, etc. Focus on developing the structural aspects – the basic frame, wheels, and linkages. A decision matrix can be very useful to help down-select from your 5+ options. You can create a matrix to help select from the overall concepts or to help decide between certain sub-elements. For example, maybe you have a basic seat design in several brainstormed ideas, but the method by which the human changes to a more upright configuration might be different. You could develop a decision matrix to decide between alternative methods.
When you’ve decided on your best options for your design, develop good SolidWorks models. Ideally, a full assembly that can be manipulated manually or animated to demonstrate functional is the goal. It is required that you at least have a good linkage synthesis that can be animated to help perform an analysis and demonstrate functionality. One highly descriptive movie file will be required to be submitted. You should also perform a basic kinematic analysis of the linkage system to demonstrate graphically (with traces and/or labeled graphs) its operating envelope (position) and how quickly (velocity) the person is positioned from one configuration to the next. Report on the accelerations that would be experienced, focusing on peak accelerations.
PROJECT DELIVERABLES
Three key deliverables are required: (1) a design report; (2) a SolidWorks-derived movie file that shows an animation of your device in action; and (3) a manually operated proof-of-principle scale model that demonstrates basic functionality. More detail on each deliverable is given below:
Design Report
This formal document has no predetermined page limit. Use only the number of pages necessary to sufficiently convey a full description of your design concept. The reports are to be uploaded electronically (Microsoft Word or PDF format ONLY)and submitted in hard copy. Your report should contain the following:
• Title Page (including team member names and image of your CAD and proof-of-principle model)
• Problem Statement that your team developed for the project (a Problem/Needs Statement can typically be conveyed as two sentences; a sentence about the overall problem as it stands and a sentence that says “There is a need for…”)
• Background (description of focused research, such as geometry background on existing wheelchairs – remember to refer to specific reference material correctly)
• Design Concepts (show the specifications you developed and sketches of brainstormed ideas, with descriptions)
• Design Decisions (show decision matrices with accompanying descriptions on what choices were made in the creation of the matrices and interpretation of the results)
• Design Solution (show good shaded/labeled SolidWorks views of the device in relevant configuration, along with descriptions of the device and its operation)
• Design Assessment (show results of your basic kinematic analysis, extol the virtues of your design, and honestly assess the shortcomings)
• Appendix that contains engineering drawings (these should be complete and PRISTINE – each individual component displayed with appropriate views on drawing sheets using concise/correct title blocks, dimensioning and tolerancing applied using ANSI standards and proper drawing rules). In simple terms, the drawings should be of such high quality that they can be delivered to a shop for fabrication.
SolidWorks Movie File
Create an animation of a 4-bar linkage. In a like manner, create a clean, realistic animated model of your device and save it as a movie file; it will be uploaded to Trunk.
Proof-of-Principle Model
The goal of the proof-of-principle model is to convey the basics of the device operation (a physical counterpart to the SolidWorks movie file). It is not necessary to use the actual materials, the actual size, or electronics/motion control that the real device would use. A convenient scale might be 1:10 or shoebox size. Use everyday items as needed.