Senior design consists of two required courses, Design I and II. Design I is a three-credit hour course in which students are introduced to a variety of subjects. These include: working on teams, design process, planning and scheduling (time-lines), technical report writing, proposal writing, oral presentations, ethics in design, safety, liability, impact of economic constraints, standards, FDA, environmental considerations, manufacturing and marketing. Each student in Design I:
Selects a project to aid a person with disabilities or an industry sponsored after conducting an interview;
Prepares a project proposal;
Considers alternative solutions;
Selects an optimal solution and carries out a feasibility study;
Specifies components, conducts a cost analysis and creates a time-line using Microsoft Project for product completion in BME291;
Creates a paper design with extensive modeling and computer analysis;
Presents an oral report on Senior Design Day (first reading day before finals).
Design II is a three-credit hour course following Design I. This course requires students to implement their design by completing a working model of the final product. Prototype testing of the paper design typically requires modification to meet specifications. These modifications undergo proof of design using commercial software programs commonly used in industry. Each student in Design II:
Constructs and tests a prototype using modular components as appropriate;
Conducts system integration and testing;
Assembles final product and field-tests the device;
Writes final project report;
Presents an oral report using PowerPoint on Senior Design Day (first reading day before finals);
Gives the product to the person with disabilities after the person with disabilities or their guardian signs a waiver, or the industry sponsor.
Project Selection and Project Statement
The first phase of the Design I involves the student selecting a project.
Students interested in working on an industry sponsored project are provided a list of projects to select. Through a random drawing, student teams are assigned for each project.
Students interested in working on an NSF sponsored project to aid a person with disabilities (client) are provided a list of projects to select. Through a random drawing, student teams are assigned for each client.
For either type of project, the student team submits a project statement that describes the problem, including a statement of need, basic preliminary requirements, basic limitations, other data accumulated and important unresolved questions.
One of the most important parts of the design process is determining the requirements that the design project must fulfill. Before the design of a project, a statement as to how the device functions is required based on operational specifications. Specifications determine the device to be built, but do not provide any information about how the device is built. Specifications also include a technical description of the device, and contain, usually in tabular format, all of the facts and figures needed to complete the design project.
Prior to the design of a project, a statement as to how the device will function is required based on operational specifications. These specifications determine the problem to be solved. The operational specifications completely describe and define the project. Specifications are defined such that any competent engineer is able to design a device that will perform a given function. If several engineers design a device from the same specifications, all of the designs would perform within the given tolerances and satisfy the requirements; however, each design would be different. No manufacturer’s name or components are stated in specifications. For example, specifications do not list electronic components or even a microprocessor since use of these components implies that a design choice has been made.
If the design project involves modifying an existing device, the device is fully described in as much detail as possible in the specifications. In this case, it is desired to describe the device by discussing specific components, such as the microprocessor, displays, and electronic components. This level of detail in describing the existing device is appropriate because it defines the environment to which the design project must interface. However, the specifications for the modification should not provide any information about how the device is to be built.
Specifications written report qualitatively describes the project as completely as possible, and how the project will improve the life of the disabled person. It also provides motivation for carrying out the project in the specifications. The following issues are also addressed in the specifications:
What will the finished device do?
What is unusual about the device?
A table listing all electrical, mechanical, environmental, software specifications and other details are also provided.
Each student writes a proposal whose purpose is to motivate upper management to fund the project. The proposal introduces the project in layperson terms, examines the market place identifying existing products that have similar specifications, and presents a preliminary budget and timeline. Extensive research using previous NSF project publications, bmesource.org and ABLEDATA are carried out for completeness. The student presents the proposal using MS PowerPoint to the class. Following this, the student then presented the proposal to the client and/or client coordinator.
Paper Design and Analysis
The next phase of the design is the generation of possible solutions to the problem based on the specifications, and selecting the optimal solution. This involves creating a paper design for each of the solutions and evaluating performance based on the specifications. Since design projects are open-ended, many solutions exist, solutions that often require a multidisciplinary system or holistic approach for a successful and useful project. This stage of the design process is typically the most challenging because of the creative aspect to generating problem solutions.
The specifications previously described are the criteria for selecting the best design solution. In many projects, some specifications are more important than others and trade-offs between specifications may be necessary. In fact, it may be impossible to design a project that satisfies all of the design specifications. Specifications that involve some degree of flexibility are helpful in reducing the overall complexity, cost and effort in carrying out the project. Some specifications are absolute and cannot be relaxed whatsoever.
Most projects are designed in a top-down approach similar to the approach of writing computer software by first starting with a flow chart. After the flow chart or block diagram is complete, the next step involves providing additional details to each block in the flow-chart. This continues until sufficient detail exists to determine whether the design meets the specifications after evaluation.
To select the optimal design, it is necessary to analyze and evaluate the possible solutions. For ease in analysis, it is usually easiest to use computer software. For example, PSpice, a circuit analysis program, easily analyzes circuit analysis problems and also allows printed circuit board fabrication. Other situations require a potential design project solution be partially constructed or breadboarded for analysis and evaluation. After analysis of all possible solutions, the optimal design selected is the one that meets the specifications most closely.
Construction and Evaluation of the Device
After selecting the optimal design, the student then constructs the device. The best method of construction is to build the device module by module. By building the project in this fashion, the student is able to test each module for correct operation before adding it to the complete device, composed of previously tested modules. It is far easier to eliminate problems module by module than to build the entire project, and then attempt to eliminate problems.
Design projects are analyzed and constructed with safety as one of the highest priorities. Clearly, the design project that fails should fail in a safe manner, a fail-safe mode, without any dramatic and harmful outcomes to the client or those nearby. An example of a fail-safe mode of operation for an electrical device involves grounding the chassis, and using appropriate fuses; thus if ever a 120-volt line voltage short circuit to the chassis should develop, a fuse would blow and no harm to the client would occur. Devices should also be protected against runaway conditions during the operation of the device, and also during periods of rest. Failure of any critical components in a device should result in the complete shutdown of the device.
After the project has undergone laboratory testing, it is then tested in the field with the client. After the field test, modifications are made to the project, and then the project is given to the disabled person. Ideally, the design project in use by the disabled person should be periodically evaluated for performance and usefulness after the project. Evaluation typically occurs, however, when the device no longer performs adequately for the disabled person, and is returned to the university for repair or modification. If the repair or modification is simple, a university technician will handle the problem. If the repair or modification is more extensive, another design student is assigned to the project to handle the problem as part of their design course requirements.
Throughout the design process, the student is required to document the optimal or best solution to the problem through a series of required written assignments. For the final report, documenting the design project involves integrating each of the required reports into a single final document. While this should be a simple exercise, it is usually a most vexing and difficult endeavor. Many times during the final stages of the project, some specifications are changed, or extensive modifications to the ideal paper design are necessary. BME Design requires the final report be professionally prepared using desktop publishing software. This requires that all circuit diagrams and mechanical drawings be professionally drawn. Illustrations are to be drawn with Visio .
WWW Based Approach
To facilitate working with sponsors, a WWW based approach is used for reporting the progress on projects. Students are responsible for creating their own WWW sites that support both html and pdf formats with the following elements:
Introduction for layperson
Weekly activities in BME Design I consist of lectures, student presentations and a team meeting with the instructor. Technical and non-technical issues that impact the design project are discussed during team meetings. Students also meet with clients/coordinators at scheduled times to report on progress.
Each student is expected to provide an oral progress report on his or her activity at the weekly team meeting with the instructor, and record weekly progress in a bound notebook and on the WWW site. Weekly report structure for the WWW includes: project identity, work completed during the past week, current work within the last day, future work, status review and at least one graphic inserted into the report. The client and/or client coordinator uses the WWW reports to keep up with project so that they can provide input on the progress. Weekly activities in BME Design II include team meetings with the course instructor, oral and written progress reports, and construction of the project. As before, the WEB is used to report project progress and communicate with the sponsors.