R. I. T Multidisciplinary Senior Design Phase-Appropriate Feasibility Analysis Rochester Institute of Technology Mechanical Engineering Department Rochester, NY USA

R. I. T Multidisciplinary Senior Design Session Objectives Motivation: Risk Analysis, Metrics & Specs Assignment Examples EE CE ME

R. I. T Multidisciplinary Senior Design Session Objectives Motivation: Risk Analysis, Metrics & Specs Assignment Examples EE CE ME

R. I. T Multidisciplinary Senior Design Engineering Requirement Requirement = Metric + Specification Metrics = what measurement you are going to make to determine whether your design is successful Specification = the target (or minimally acceptable or ideal) value to achieve for that measurement Use preliminary feasibility here!

R. I. T Multidisciplinary Senior Design Project Risks Schedule risks Things take longer than expected to design, order, receive, build, test Personnel risks Staffing is insufficient, team member is unable to complete his or her work, team dynamics become an issue Resource risks Project is over budget, lack space, equipment missing, can’t get into machine shop, etc. Use preliminary feasibility here!

R. I. T Multidisciplinary Senior Design Technical Risks Risks associated with your design. Design is not feasible Specs are not feasible Components don’t perform to spec Components can’t be manufactured as designed Technology is not as developed as anticipated Expertise of team is overestimated Use preliminary feasibility here!

R. I. T Multidisciplinary Senior Design Session Objectives Motivation: Risk Analysis, Metrics & Specs Assignment Examples EE CE ME

R. I. T Multidisciplinary Senior Design Prepare for class: Give one question about your design that can be answered by phase-appropriate feasibility analysis Discuss this as a team ahead of time – do not duplicate effort between team members! Determine whether the question is best answered with analysis, benchmarking, or prototyping List assumptions, governing equations, materials, competitors, etc. as appropriate

R. I. T Multidisciplinary Senior Design Session Objectives Motivation: Risk Analysis, Metrics & Specs Assignment Examples EE CE ME

R. I. T Multidisciplinary Senior Design Power Supply Driving parameters… Rechargeable vs. single-use What is consuming power? How much? W (=VxA), hp, Btu/hr, ft-lb/sec Voltage requirements Physical size of battery Cost

R. I. T Multidisciplinary Senior Design Example from MSD - Analysis From P12015/6 Navigation Aid for Blind Person Preliminary feasibility question #1: can we power a device that has all the functionality our customer requires for the length of time our customer requires? Assumptions: Use some good candidate off-the-shelf components and an off-the-shelf battery. It takes 20 minutes at most for the user to move from one location to another, and this happens at most 10 times per day.

R. I. T Multidisciplinary Senior Design P12015: Power Calculations RFID Reader1.5796W*hr Motors W*hr MCU W*hr Magnetometer0.0913W*hr Keypad W*hr *Sum W*hr *For (10) 20 minute intervals of navigation

R. I. T Multidisciplinary Senior Design Hold on a minute! Significant figures… ????? Use datasheets and maintain significant figures That give us…

R. I. T Multidisciplinary Senior Design P12015: Better Power Calculations RFID Reader1.58W*hr Motors0.02W*hr MCU0.047W*hr Magnetometer0.09W*hr Keypad0.08W*hr *Sum W*hr *For (10) 20 minute intervals of navigation Math skills involved: Reading datasheets, multiplying voltage and current, maintaining significant figures. Value: High!

R. I. T Multidisciplinary Senior Design P12016: Power Calculations Total Power (mW/hr)Total (mW)Battery Life (%) Total hours of Life Assume battery is 3.7V, 1100mA*hr, 4.01W*hr Voltage Output: 3.3V For (10) 20 minute intervals of navigation Min Usage (mAh) =23.4Min Usage (mWh ) =77.2 Average (mAh) =239Average (mWh) =790 Worst Usage (mAh) =745Worst Case (mWh) =2460 Math skills: Reading datasheets Multiplying voltage and current Maintaining significant figures Estimating usage time Value: High!

R. I. T Multidisciplinary Senior Design Example from MSD – Analysis & Benchmarking From P12015/6 Navigation Aid for Blind Person Preliminary feasibility question #2: Is there a low cost microcontroller that will meet our onboard storage AND I/O needs? Assumptions: Building map will be stored onboard and will be the biggest memory hog. I2C or SPI interface required for peripherals.

R. I. T Multidisciplinary Senior Design Map representation Major considerations include the size of the map file (limited memory space on the board), the ASCII character set requirement spec, and the 1000 maximum tags spec Maps consist of: o tags, each with an ID (12 bytes) and X and Y coordinates in inches or centimeters (range: 0~4000); o map vertices (e.g., rooms, water fountains, bathrooms, hall intersections), each with X and Y coordinates; o walking paths between vertices, which include the start and end vertices o assumption that the device is currently only being used to navigate one floor of one building

R. I. T Multidisciplinary Senior Design Map representation (continued) Possible solution: use base64 notation (ASCII-safe but still small) o Tags, with their large ID fields, will likely comprise the largest part of the file o With base64 notation, tag IDs require 16 'digits' and the coordinates will use 2+2 'digits' = total of 20 bytes per tag o The MCU memory must be able to accommodate up to 1000 tags = 20KB minimum per map (restricts MCU choice!) Store the graph underlying the map of destinations and paths densely (low connectedness)

R. I. T Multidisciplinary Senior Design Microcontroller selection Selection: Arduino Nano (weak in clock speed, but sufficient in memory and I/O options, and can start programming quickly) with TI MSP430F5529 as a backup choice

R. I. T Multidisciplinary Senior Design Example from MSD - Prototyping P14042 – Una-Crutch Preliminary Feasibility Question: What type of design is going to be most appealing to users? Can we find out before spending lots of time doing detailed analysis and manufacturing planning? Approach: foam + PVC pipe models (non-load bearing) and user survey

R. I. T Multidisciplinary Senior Design Axilla Pads and Handles Prototypes Created

R. I. T Multidisciplinary Senior Design C B Frames and Connective Mechanisms Prototypes B, C, and G G

R. I. T Multidisciplinary Senior Design Cost Driving parameters vary widely by project! Some big ticket items can be: MCU with development board Precision motion equipment Highly accurate sensors Custom manufacturing (rapid prototyping, water jet cutting, thermoforming, some printed circuit boards) Materials with specific environment rating Vacuum, corrosive, medical

R. I. T Multidisciplinary Senior Design Standard format The problem to be solved Governing equation(s) What you know What you need to know/need to assume Justify assumptions Analyze