Owen Accas - Dan Crossen - Rebecca Irwin - Madeline Liccione - Hao Shi

Double Stance Time Propagator (RK 4)

Single Stance a o

Current Prototype Parameter s Proposed System Parameters Units of Parameter Number of spokes 55Quantity Length of legs m Mass per spoke Kg Inertia per spoke Kg·m 2 Mass of inertia wheel Kg Inertia of inertia wheel Kg·m 2 k-value of spring 37N·m/rad

 10mm diameter aluminum  Assume no tension/compression or insignificant tension/compression  Shear modulus = 26 GPa  Area = Pi*(.01m)^2=pi*10^-4 m^2  Shear failure at ~204 million Newtons which is approximately 45.8 million lbs  This strength will more than account for the forces seen on the axle in shear

 Worst case: 1 plate rigid, 1 side has full torque  Full torque = (40 lbs/spring)*(2 springs)*1.5 in =120 in-lbs  Bending force on each brace =(120 in-lbs)/(14 inches)/(5 braces) =1.714 lbs/brace, therefore assume 2.5 lbs with a safety factor

 Shear Strength = 10,500 PSI  With 100 pounds, we would need a cross sectional area of in^2 or greater to avoid failure  With 2.5 lbs (calculated on previous slide), we would see no failure at all, as the pvc we are using has an area of.256 in^2  These will ad.172 kg to entire frame, but add.0217 kg-m^2 of inertia (about 20% increase)

 The core material we intend to use is Core- Cell Foam, a boat building and repair supply  Relatively inexpensive  Very strong  Readily attainable  Thin  Low density

 Balsa wood is also a popular core material for composites applications  Deemed to be more expensive  Not as strong  Similarly thin  Higher density than Core-cell

 SAE Boeing Carbon fiber is our selected coat  Incredibly strong, especially in tension and compression (along the weave)  Very thin  Very consistent  Aesthetically pleasing  Would be expensive (~34.99 per 50” x 30”) ◦ We have a free connection to needed amount

 Fiberglass was another option for our top coat  Less expensive than carbon, if we had to buy  Not quite as strong  Most fiber weaves are more random  Similar material properties, carbon is free

 2 Gyroscopes (L3GD20) – mA =.0462 W  1 Encoder (E5)– 5 50 mA =.25 W  Current Sensor (ACS714) – mA = ~negligible  Microcontroller = 0.246mW Total Power = 0.307W

 Requested Specs: <.5 Deg/Sec accuracy (doesn't make sense, since we will go through about 360 Deg in a second)  E5 Encoder: 1024 CpR=.35 Deg sensitivity  E5 Encoder: RPS maximum (300KHz max count frequency)

 Requested Specs: <.1 Deg/Sec accuracy  L3GD20: +/- 500 Deg/Sec and 400kHz sampling means resolution of deg  This is the same Gyro as is currently used in the prototype

 Using NiMH batteries for safety and for voltage matching (1.2V steps), as well as cost (<$3 per battery), ease of replacement, and rechargeablity.

 No specific specs provided  Sampling rate of 500 Hz depends upon processor  Using error of 2% as spec

 Amps  If this motor were on all the time, we would be looking at 61 W, and a cost of transport of approximately 3.36, way over our goal.  Therefore, we would like to estimate the CoT when our motor is only on for 1/10 th of a second  CoT =.358

 There are certain ways to obtain our goal of.05 CoT  We looked at getting a larger motor (increased performance & weight). This decreases the amount of time the motor must be active (1/40 th of a second) and increases the denominator of CoT equation.  Can rotate ¼ turn in.00625, but we are accounting for negating torque so we assume.02 seconds (max of 2500 RPMs)  CoT = (90 W*(.02 s)+.5)/(51 N*.5 m)=.9

Part nameQuantityCost/item ($/item)Total cost ($)Obtained Lead Times (estimated) Frame plate foam 1 – 44in x 88 in x 9.5 mm $77 Buy from Core-Cell1 week Carbon Overlay2 m^200RIT Baja1 day Resin Overlay1 gallon$65 Buy from Core-Cell1 week Hardener1 quart$23.50 Buy from Core-Cell1 week Mounting platesTotal of 1300Machine shop/self machined3 days Hollow axle1$0 - $20 May custom order or2 weeks Spring Pulley2$10$20Self machine/bearing from McMaster2 weeks Axle Pulley2$20$40Self machine/bearing from McMaster2 weeks Small, Solid Axle100Self machine/bearing from McMaster2 days Batteries 1 – 16pk of AA NiMH $38 Amazon2 weeks Gyroscope2$25$50Pololu2 weeks Current Sensor6$4$24Online (will update when known)2 weeks Encoder1$90.63 US Digital2 weeks

Part nameQuantityCost/item ($/item)Total cost ($)Obtained Lead Times (estimated) Microcontroller (PCB) 2$50 or free$60Advanced Circuits Decoupling components 10+$0.05$1+Digikey, Mouser Motor Isolation (PCB) 2$50$60Advanced Circuits Motor Isolation (components) 10+$0.05$1+Digikey, Mouser Electronic Storage1Unknown

Part nameQuantityCost/item ($/item)Total cost ($)Obtained Lead Times (estimated) Motor1$299 Teknic1 day – 4 weeks Motor Control Kit1$200 or free$200TI2 weeks Microprocessor220$40Not found yet1 week WiresVarious (a lot)~$0.00$10Hardware store/scrap2 days PVC Braces5Not found yet<$20Not found yet2 days Springs2<$20<$40McMaster Carr1 week StringApprox. 10 feetUnknown$0 - $5Hardware store2 days Voltage Sensor6Not found yet<$40Online (will update when known)2 weeks Bike wheel100 Member has unused bike to commandeer 1 week Various FastenersVarious $0 - $16.11hardware store/scrap/McMaster5 days Microcontroller Dev kit 1 up to $100 or free $100Texas Instruments TOTAL COST $ $ (this is with $200 learning MC Kit) TOTAL COST $ $928.24(w/o learning MC Kit)