Concept Finialization

In order to choose out of the ideas that we both had for the project we needed to make a weighted objectives table to really weed out the best design possible for our car. This helped us seed each of the faults in certain ideas, and the relative strengths of others and choose what our final concept of the car will look like.

Powertrain Design Table	Pull Back Geared Design	Traditional Lever Arm and String Design
Cost - How much each design would cost	Cost of a mouse trap as well as gear set to match the desired ratio from the spring to the wheels	Cost of the mouse trap as well as the string to attach it to the axel
	1 + 10 = 11$	1 + 2 = 3$
Time – How long would it take to develop	Modeling the design of a pullback toy car. No clear instructions or design. Might have to order parts online	Clear instruction and videos online explaining how to do this design. Time tested and proven
	Estimation:2-5 days	Estimation:1-2 days
Safety – How safe would it be for the customer	If implemented properly user should just have to pull back car since wheels are directly connected to spring	User will have to be able to set mouse trap which could be dangerous if user in not careful or is strong enough. To get around this we might have develop something else to set and release the spring for safety.
	Most 5 year olds	Most 8 year olds
Durability – Probability that the design would fail	Mousetrap spring may be too strong for gear system. Not very well tested. May cause failure.	Well tested. Not very likely to fail if previous designs followed.
	Durable excepting failure	Durable
Effectiveness – How effectively does it complete the challenge	If implemented properly spring will have enough power to get there and since the spring is directly driven will also brake car too. To control distance vary amount person pulls back car.	Not system for braking. Vary distance by changing length of lever arm.
	Meets the challenge, precise control	Meets the challenge, average control at best
	Time is a huge concern in this project, so the traditional design seems that it would fit us best. Although with a very meticulous schedule the other design might also be pulled off with great success as it does have more features that are going for it. Even so, I think something that is time tested and proven, and is also simple might be better for what this project demands because it meets all the requirements. Recommendation:  Traditional Lever Arm and String Design

Chassis Design Table	Wood - Frame from mouse trap	ABS Plastic – Lego Pieces
Cost - How much each design would cost	Included in cost of trap that is needed for project regardless. Counted as zero as to not be counted twice	Using personal set of Lego pieces which is a donation from me, or in other words free.
	0$	0$
Durability – Probability that the design would fail	After considerable uses, wood in trap might be strained to the point of braking. Will withstand drops from 5 feet.	After a lot of use stress of use plastic may stretch and deform but won’t break. Will withstand drops form 5 feet
	Durable till wood gives out	Durable
Safety – How safe would it be for the customer	Possibility of split wood or splinters	Unlikely that Legos will break and become hazardous Broken Legos don’t make sharp edges
	Most 8 year olds	Most 5 year olds
Effectiveness – How effectively does it lend itself to the challenge	Acts as a place to mount other parts of the car. Already can support spring	Acts as a place to mount other systems of car. Need to build support for spring
	Has been used effectively	Has been used effectively
Adjustability/Usability – How can it be adjusted	To mount systems to the chassis you need to drill into the wood or mount with wood screws. Threads may strip	Can slide along the pre made holes in Lego. Already have smooth holes for axels to go through, as well as other attachments
	Is adjustable but it only limited	Is fully adjustable to extent of holes
	This decision seems to lean in favor of a plastic Lego construction chassis due to its durability, and its pre-built adjustability. Recommendation:  ABS Plastic – Lego Pieces

Drivetrain (Wheels and Axels)	CDs	Lego Wheels
Cost - How much each design would cost	Cost of CDs (Might have to by a pack) and Axels.	Using personal set of Lego pieces which is a donation from me, or in other words free.
	13$	0$
Time – How long would it take to develop	Need to account for how to attach CD’s to axel and make them straight	Premade spaces and everything fits together nicely because it’s a kit
	Estimation:2-3 days	Estimation:1/2 a day
Durability – Probability that the design would fail	CDs likely to break under small stress	After a lot of use stress of use plastic may stretch and deform but won’t break. Will withstand drops form 5 feet
	Durable till wood gives out	Durable
Effectiveness – How effectively does it complete the challenge	CDs have been used in the past but effectiveness at least according to different online videos is less than suitable due to low friction and wobble of wheels.	Has lots of traction, can go straight, and is really adjustable
	Effective but less than would be optimal	Meets the challenge with added bonuses in implementation
	This decision is fairly easy because there is nothing going in favor of the CDs. Recommendation: Lego Wheels