Heather Beam Thomas Bean Megan Chapman Steven Geiger Kimberly Keating
Confirm Customer Needs and Engineering Specifications Review System Decomposition Review Concepts Introduce preliminary calculations and assumptions Cross-disciplinary review to generate further ideas Receive approval from customer to select and purchase a stander
Work Breakdown Structure (1 min) Project Background (1 min) Customer Needs (3 min) Engineering Specs (3 min) Needs vs Specs (2 min) Functional Decomposition (5 min) Concept Generation (5 min) Concept Screening Matrices (30 min) Speed and Tipping Forces (10 min) System Architecture (13 min) Risk Assessment (5 min) Project Schedule(2 min) Questions (10 min)
Megan Chapman-Project Leader ◦ Construct schedule, monitor budget, distribute workload ◦ Assist Heather with Mechanical Engineer work Heather Beam-Lead Mechanical Engineer ◦ Design motorized wheel system, mounting mechanisms, raise/lower system Steven Geiger-Lead Controls Engineer ◦ Design user interface, control system, and Trainer Mode Kimberly Keating-Systems Engineer ◦ Develop safety tests, help with budget, conduct safety tests Thomas Bean-Controls Engineer ◦ Design sensor integration, assist Steve with control system programming, design Trainer Mode
Mobilize a Pediatric Stander to increase independence and mobility for user ◦ Add ≤ 20 lbs. ◦ Incorporate Training Mode ◦ SAFETY ◦ Versatile Controls Risks ◦ Components will not be compatible ◦ Device will not be stable/safe ◦ Sensors will interfere with each other
Field Goal Head Array Joystick Accept pt User Input Push Button Switch Touch Screen (iPad) Tongue Switch Bluetooth Wire Connection Accept pt Trainer ner Overri rride de Wifi Motorized Wheels Move User Safely ly Treads Contact Switch Infrared Sensor Detect ct Hazard rd Laser Rangefinder Thermal Imaging Sensor Ultrasonic Sensor Hydraulic Adjustable Pneumatic Adjustable Adjust st Height Power Adjustable Rifton Dynamic Stander Snug Seat Gecko Standing Frame Stande der Sung Seat Rabbit Mobile Stander
We wanted to find a happy medium between a stopping distance and a stopping time. Luckily, we figured out that even at a speed of 6 mph stopping in 250 mm, we were safe from an acceleration perspective. According to the International Association of Amusement Parks and Attractions, sneezing subjects the body to approx. 2.5g's, or 22.5 m/s^2, noticeably more than our top speed/shortest distance calculation.
The spreadsheets on the following slides show the stopping times that would be associated with speeds from 3-5mph at certain distances. These values do not account for user reaction time as well as hardware reaction times. These times would have to be added to the values calculated. ◦ Human reaction time is approximately 250ms. However, because of the nature of our user, our time will be larger than that. ◦ Hardware reaction time should be under 100ms, but this is highly dependent on the hardware we end up choosing.
There are two options for speed control ◦ Our first option is potentiometers leading to the motors ◦ Our second option is to set software limits to govern speed.
A physics analysis was completed to evaluate the tipping force. We assumed that the force was impacting one corner at the top and the center of gravity was on the bottom in the middle of the stander. Force Stander Center Of Gravity
Max Speed: 5 mph 𝑤 𝑗 = 5𝑛𝑞ℎ 𝑤 𝑔 = 0𝑛𝑞ℎ Stop in less than one second. For this calculation, t=0.22 ◦ This time corresponds to stopping in .25m at 5mph 𝑤 𝑔 = 𝑤 𝑗 + 𝑏 ∗ 𝑢 0 = 5 + .2 ∗ 𝑏 𝑏 = − 22.73𝑛𝑞ℎ = −10.16 𝑛 𝑡 2 𝑡𝑓𝑑
Mass of Stander(Rabbit)=75kg Mass of User=40kg Total Mass=75+40=115kg 𝐺 = 𝑛𝑏 115 ∗ 10.16 = 1168.4𝑂 For the stander not to tip, the torque of the weight needs to be greater than or equal to the torque of the applied force.
𝑈𝑝𝑠𝑟𝑣𝑓 = 𝑔𝑝𝑠𝑑𝑓 ∗ 𝑠𝑏𝑒𝑗𝑣𝑡 𝑈𝑝𝑠𝑟𝑣𝑓 𝑝𝑔 𝑏𝑞𝑞𝑚𝑗𝑓𝑒 𝑔𝑝𝑠𝑑𝑓 = 1168.4𝑂 ∗ .5715𝑛 𝑠𝑏𝑐𝑐𝑗𝑢 = 667.74𝑂𝑛 𝑈𝑝𝑠𝑟𝑣𝑓 𝑝𝑔 𝑋𝑓𝑗ℎ𝑢 = 115 ∗ 9.81 ∗ .61595 𝑠𝑏𝑐𝑐𝑗𝑢 = 694.88𝑂𝑛 694.8 > 667.74 This tells us that in a realistic case, our stander shouldn’t tip.
Recommend
More recommend
