Group 23: Gate 2

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Contents

Overview

Preliminary Project Review

Management Plan

Our original management plan has worked fairly well. All group members are completing given tasks on time and communicating well with each other. By assigning roles, each member knows what is expected of them for each part of the product. By beginning work on each gate early, there is adequate time to come up with solutions to any problems that come up. However, there have been some changes made to the original plan.

The major change that we have made in our management plan is the times of our meeting. In the past few weeks, our group members have had many exams and projects due, so it has been difficult to meet for extended periods of time during the school week. We have decided to meet at least one time during the week and then on Sunday afternoons in the Ellicott Complex. The meetings on Sundays are where a majority of the work requiring the product will be done. The meetings during the week either Monday or Wednesday after lecture will be used to plan out a work schedule for the rest of the week, work on the Wiki and compile the gates. Our communication liaison will text all members when an extra meeting is planned. The decision to change the meeting time was determined after a unanimous group vote.

Another small change that has been made to the management plan is that group members no longer have to be machine shop certified by the end of October. Taking apart the Barbie Dune Buggy does not require the use of the machine shop and dissection of this product can be completed in the dissection lab or the Ellicott complex. All members have proven to have the basic knowledge of tools required to take apart this product.

Work Proposal

The work proposal for the dissection of the Barbie Dune Buggy was also slightly altered once the dissection began. Before dissection began, we estimated the dissection of the product to take about two to three hours. The actual dissection time was closer to eight hours and required multiple group meetings. The group also changed the order in which parts were taken apart also differed from the original work proposal.

In our proposal we underestimated the complexity of this project and how interconnected the parts within the toy were. Once we actually began taking the product apart we saw connected the product was. For example, while trying to remove the steering wheel, we ran into problems trying to disconnect the axel because this required us to remove the two front tires from the car. Instead of following the original plan, we began to remove parts in the order in which they appeared to be connected.

Another issue that we hadn’t considered in our original work proposal was how long it would take to remove certain fasteners such as the lock washers on the steering wheel and tires. We tried multiple ways to remove these fasteners, but when it came down to it, removing the fasteners just took a lot of time and applying forces at different angles until the lock washers popped off. These techniques allowed us remove the fasteners, but it also distorted some of their shapes. This may become a greater factor later in the project.

Product Dissection Process

Table 1. Established Scale of Difficulty

Scale of Difficulty chartGROUP23yup.JPG

Table 2. Steps of Dissection

Below is the list of tools used in product dissection:

  • Small Philips head screw driver
  • Large Philips head screw driver
  • Small Flat head screw driver
  • Large Philips head screw driver
  • Hammer
  • Wrench
  • Needle nose pliers

The following table gives the step-by-step process by which the Barbie Dune Buggy Powerwheels was dissected.

Steps of Product Dissection
Step: Part Removal and Process Description: Difficulty Rating: Process Photograph:
1 The first step to disassembly of the Power Wheels was the removal of the vehicle’s seat. Four Philips head screws under the body of the power wheel were removed with a Philips head screwdriver with ease. Once the four screws were removed, two flat head screw drivers were used to pop-out the eight lock tabs holding the seat into the frame. Due to the design of the lock tabs, the seat was not intended to be removed after installation. 3
Image 1. Barbie Dune Buggy without seat
2 The roll bar was the next piece to be disassembled. Using a flat head screwdriver, six lock tabs were unfastened. The roll bar was also not intended to be removed after installation, because the lock tabs secure the roll bar to the body. Little challenge was meat during these processes. 3
Image 2. Seat and Roll bar removed
3 The next step was the removal of the hood on the vehicle. This was done by applying a pulling force from the hands. Tools were not needed for this part. The hood was intended to be removed because underneath lies the battery housing making it accessible for charging. 1
Image 3. Seat, roll bar, and hood removed
4 The next part to be disassembledwas the windshield. One Philips head screw was removed with a Philips head screwdriver. This screw connected the windshield to the body of the vehicle. The windshield was then removed by using a flat head screwdriver to pop the lock tabs. The windshield was not intended to be removed. Upon removal of the windshield, it was discovered that it is actually an accumulation of multiple parts. Eight Philips head screws, which connected the silver shield to the plastic securing frame, were removed with a Philips head screwdriver. The windshield system is semi-challenging to take apart, but it is not intended to be disassembled by the consumer. 4
Image 4. Windshield system removed and disassembled
5 The next step was to remove the dashboard console from the car’s body. Using a Philips head screwdriver, four Philips head screws were removed from the dashboard which connected it to the car’s body. After attempting to remove the dashboard by hand, it was discovered that the steering column was secured within the dashboard, thus making this step impossible for completion. Neither the dashboard nor the steering wheel column was meant to be removed. 5
Image 5. Removal of dashboard console
6 Five Philips head screws were removed from the underside of the steering wheel using a Philips head screwdriver. These screws connected the two halves of the steering wheel together. A flat head was used to attempt to pry apart these halves of the steering wheel. This proved unsuccessful and upon further analysis it was discovered that underneath a sticker on the steering wheel was one Philips head screw. A Philips head screwdriver was used to remove this last screw which connected the steering wheel through its central axis to the wheel. This was not intended to be removed by the consumer. When the two pieces separated, a black securing cap was revealed and was removed with pliers. Under the cap was a metal lock washer which secured the wheel to the steering column. Removal process for such washer was unknown so an unconventional approach was taken. 4
Image 6. Removal of steering wheel lock washer with needle nose pliers
7 After analysis of several tools to complete the task of removing the lock washer, it was decided that a hammer claw would work best due to the leverage force it creates. Using the claw, the lock washer was pried from the steering column.Much brute force was requiredfor this process. This is because the washer was intended to permanently secure the two components it held together oncefastened on. 5
Image 7. Removal of Steering wheel from steering column
8 The dashboard console was then removed by hand by sliding it over the steering column. This process was done with ease. 1
Image 8. Removal of dashboard and radio consoles
9 Two Philips head screws were removed from the rearview mirror which connected it to the windshield frame. The rearview mirror then slides off of the console. 1
Image 9. Rear view mirror unscrewed with Philips head screwdriver
10 The radio console was then removed from the dashboard. At first look it was unknown how to accomplish this. After examination it was found that front cover of the radio could be pried off and by hand and the radio/speaker slides out. This part is meant to be removed by the consumer. If ever an issue rose with the speakers, wiring, or battery, these components could be replaced. 1
Image 10. Dashboard console with radio removed
11 Using a Philips head screw driver, four Philips head screws were then removed from the transmission cover located below the seat of the car. Afterward, then the cover was removed by hand. This part is meant to be removed if wire repair is necessary. 2
Image 11. Transmission cover removed from body
12 The battery was then removed from the battery housing in the front of the car. This was done by hand, sliding the securing bar to the right and lifting the battery out. The connection was also unclipped by hand and the battery was set aside. The battery is intended for removal for charging purposes. 1
Image 12. Battery removed manually from battery cabin
13 The next part to be removed was the battery’s securing bar. This was done by removing the securing bar cover by hand and then using small flat head screwdrivers to remove the lock tabs. Afterward,needle-nose pliers were used to remove the lock washerdue to the hammer claw being unable to fit. Then the secure bar was slid out and two washers with a spring were removed by hand from the device. 3
Image 13. Secure Device disassembled
14 Using a Philips head screwdriver, four Philips head screws were removed from the base of the power wheels cabin. The most challenging part of this stage was finding a screw small enough to fit into the tight area. 2
Image 14. Four philips head screws removed from cabin
15 The plastic wire guard located in the center of the vehicle was then removed from the base of the car cabin. This was donethrough pulling it off by hand and with added force. 1
Image 15. Wire Guard removed from body
16 Using a Philips head screwdriver, two Philips head screws were removed from the base of the battery housing. 2
Image 16. Philips head screws removed from battery cabin
17 Removing the Philips head screwdriver thus freed the front wheel axel from the car’s body for removal. 1
Image 17. Front axle removed from body
18 The next part to be removed was the trunk cover. A flat head screwdriver was used to wedge the trunk cover off the car’s body. This in turn revealed the rear axle and two electric motors with gearboxes, each attached to one of the rear wheels. This trunk cover was intended to be removed by the owner if ever an issue arose with the motors or gears. 2
Image 18. Trunk cover removed
19 The white “VW” (Volkswagen) caps were then pried off the right rear wheel using a flat head screwdriver. 2
Image 19. VW caps removed from hubcap
20 Located underneath the white “VW” caps were similar black protecting caps. These were removed using a flat head screwdriver and a prying force. Located underneath was a lock washer that was removed with needle-nose pliers, a hammer, and physical force. Removing this lock washer was a great challenge clearly itwas not intended for removal. The rear axle was also not meant to be disassembled by the consumer. 4
Image 20. Removing lock washers from front wheel
21 The left white hub cap, left purple wheel, and left white wheel guard were removed easily by hand after the washer was removed. 1
Image 21. Wheel system disassembled(rear wheel)
22 The same process was used to remove the right VW cap, black cap, lock washer, white hub cap, right purple wheel and wheel guard. These parts are not meant to be removed and it was a challenge to get them off. 4
Image 22. Wheel system disassembled (front wheel)
23 Once the removal of both rear wheels was complete, the rear axle was pulled out by hand. 1
Image 23. Rear axle removal
24 The left and right side guards were removed from the blue body by removing two Philips head screws from each using a Philips head screwdriver. The side guards are not meant to be removed by the consumer, but are easily taken off. 2
Image 24. Right side guard removal
25 Four Philips head screws were removed from the front bumper using a Philips head screwdriver. This freed the front bumper from the car’s body to be removed by hand. 2
Image 25. Body without front bumper
26 Five Philips head screws were detached from the rear bumper using a Philips head screwdriver.This freed the rear bumper from the car’s body to be removed by hand. 2
Image 26. Rear bumper removed
27 Two flat head screws were removed from both the left and right gear box using a flat head screw driver in order to detach the motor from each. 2
Image 27. Interior of gearbox
28 A flat head screwdriver was used to release the lock tabs that hold the pedal into its housing at the base of the car’s cabin. 2
Image 28. Removal of pedal housing
29 One Philips head screw was removed from the pedal using a Philips head screwdriver. The pedal then slides out of the blue pedal holder, and the black spring box was slid through the blue plastic pedal holder. 2
Image 29. Pedal system
30 The next major step was the disassembly of the front axle. This was begun by prying off the black caps on the axle with pliers and removing the lock washers underneath with pliers as well. Like the rear axle, this also proved to be a challenge. 4
Image 30. Needle nose pliers
31 A wrench and a Philips head screw driver were used to remove a hex nut and a Philips head screw from both the left and the right of the front axle. The hex nuts connected the steering arm to the boot of the wheel. 2
Image 31. Removal of hex nut from front axle system
32 The steering column was removed by hand by sliding it through the base of the front axle. 1
Image 32. Steering column removed
33 The right white VW cap was removed using a flat head screw driver. Then the black cap was removed using a pair of pliers. The lock washer once again proved to be a challenge and took a great deal of time to remove using a hammer to pry and a pair of pliers. The right white hub cap was removed by hand, as was the right purple wheel and the right wheel guard. 4
Image 33. Disassembly of rear wheels
34 The right l axle was removed by hand from the right axle connection. 1
Image 34. Front axle system disassembled
35 The right white steering axle connection is not meant to be removed, so the bolt and washer that was permanently attached with a spread end secure. This system was removed using pliers to loosen the washer then the claw of the hammer was used to pry off the washer. The white steering boot was removed by hand and the bolt was removed using the claw of the hammer. 4
Image 35. Steering boot
36 The left white VW cap was removed using a flat head screw driver. Then the black cap was removed using a pair of pliers. The lock washer once again proved to be a challenge and took a great deal of time to remove using a hammer to pry and a pair of pliers. The left white hub cap was removed by hand, as was the left purple wheel and the left wheel guard. 4
Image 36. Flat head screw driver
37 The left white steering axle connection is not meant to be removed, so the bolt and washer that was permanently attached with a spread end secure. This system was removed using pliers to loosen the washer then the claw of the hammer was used to pry off the washer. The white steering boot was removed by hand and the bolt was removed using the claw of the hammer. 4
2011Group23 37.JPG
38 The two front axle support bars were removed by hand. 1
Image 38. Front steering system disassembled
39 Four Philips head screws were removed from the radio console using a small Philips head screwdriver. The radio and its components were removed from its plastic housing. A Philips head screw driver was used to remove one Philips head screw holding the battery plate on. The four AA radio batteries were removed. 2
Image 39. Radio console opened
40 The right gear box was opened by hand from the previous screw removal disassembly and four white gears were removed. This process was repeated for the left side. 1
Image 40. Gear box interior
41 Disassemble forward/reverse transmission box. Five screws were removed with a flat head screwdriver to take apart the box. Handle was popped out and unplugged from electric motor. 2
Image 41. Shifter component disassembled

Challenges of Dissection

  • The first challenge that was faced during the disassembly of the Barbie Dune Buggy was it was initially unknown how to remove the lock tabs that secured the roll bar and the seat to the body of the buggy. This step was important in the initial transport of the product to the disassemble site. The lock tabs were not meant to be removed once they are installed, so this was the first challenge faced. Removal was first tried using human force, but the lock tabs secured the roll bar and the seat to the body. In order to detach the lock tabs it was determine that a tool must be used that can slide in between the body and the tab to release it. Two flat head screw drivers ended up being the tools that successfully released the lock tabs. The method of using flat head screwdrivers to release the lock tabs was continually used throughout the disassembly process.
  • When the disassembly of the dashboard console began, the four Philips head screws were removed and a challenge was immediately discovered. The steering wheel axle and steering wheel went through the dashboard, making removal of the dashboard impossible at this point. It was discovered that the removal of the steering wheel must occur before the removal of the dashboard.
  • During the disassembly process it was unknown how to remove the steering wheel and specifically the center steering wheel cap. After the Philips head screws were removed from the underside of the steering wheel, flat head screwdrivers were used in attempt to pry apart the top and bottom halves of the steering wheel. This was an unsuccessful method. At this point, the steering wheel disassembly became a challenge. An outside look on the challenge was requested of another team member and it was discovered that there were two Philips head screws under the center VW sticker holding the steering wheel system together. Under the VW cap was a lock washer which removal was a large challenge. This challenge is outlined in the following bullet.
  • A major challenge throughout the whole disassembly process was the removal of the lock washers. The first lock was discovered with the disassembly of the steering wheel. Under the VW cap was a lock washer which is not intended to be removed. It can be easily installed on the metal axles and bolts, but is very difficult to remove. Many tools were used to try to remove the lock washer, such as pliers, and flat head screw drivers. In the end the claw end of a hammer was used to pry the lock washer off of the steering axel. During the disassembly process there were eight lock washers that needed to be removed. Each time the each lock washer proved to be a very large challenge. The same removal method could not be used each time due to space constraints or different orientations. Different removal methods include: hammering the axle out, prying the lock washer off with pliers, prying the lock washer off with the hammer claw, or removing with a flat head screwdriver and hammer force. All lock washer removals took at least ten to twenty minutes.
  • Another challenge that was faced was the removal of the trunk cover that covers the cabin that holds the motors. Initially it was unknown how to remove this cover. Removal by hand was not possible, because it was secured in the body. This challenge proved to be easily overcome by prying different sections of the trunk cover out with a flat head screw driver.

Post-Dissection Assessment of Subsystems

Figure 1. Functional Model of System

Flow ChartGROUP23.JPG

Table 3. Subsystems of the Barbie Dune Buggy

Subsystems of Barbie Car.JPG

What systems are connected?

The four major subsystems of the Barbie Dune Buggy are the electrical, steering, chassis and powertrain system. The fifth subsystem of the Barbie Dune Buggy is the radio system. The electrical system, steering system, powertrain system and radio system are all held within or supported by the chassis. The electrical system is also connected to the powertrain system. The motors of the electrical system are connected to rear wheels if the powertrain system. The steering system can also be seen as being connected to the powertrain system because when the rear wheels move, the front wheels will also move. The vehicle will then go in the direction that has been set by the steering wheel.

How are they connected?

The electrical system is connected to the powertrain system by signal, energy and physical connections and signals. When the user wants to move the car they must apply energy and push down on the pedal. When the pedal is compressed, it sends a signal to the battery. Chemical energy in the battery is then converted to electrical energy. The electrical energy is then transferred to the motors through the wires that connect the battery and the motors. In the motor energy is converted from electrical energy to rotational and translational energy. The motors are physically connected to the rear tires of the Barbie Dune Buggy. The wheels on the Barbie car turn and motion is achievable.

The powertrain system is connected to the steering system by energy and physical connections and signals. Energy provided by the powertrain system causes the rear wheels to spin which the causes the front wheels to spin. Both the rear wheels and the front wheels are physically connected to the chassis, so if the car is on a constant surface the spinning of the rear wheels will cause the front wheels to rotate. This allows motion of the car.

The chassis holds and supports all of the other subsystems of the Barbie Dune Buggy. The radio system is held in the front of the chassis in what would be considered the dashboard of an actual vehicle. The electrical system is held with in various parts of the chassis. The battery is located in the front of the chassis and then is protected under the hood. Wires then run throughout the chassis which connects the battery to the motors. The steering wheel column of the steering system runs through the front of the chassis. Both the rear and front wheels are connected to their axels which run through the chassis.

Why are they connected?

All of the subsystems of the Barbie Dune Buggy must be connected in order for the product to function properly. Without these connections there wouldn’t be proper energy flow and the function of transportation would not be achieved by the toy. The electrical system has to be connected to the powertrain system to convert the chemical energy of the battery to electrical energy which I then converted to rotational and translational energy in the motors. This energy can be used to rotate the wheels and cause the car to move. The powertrain and steering system be connected to assure that the intended direction of motion is achieved. Without the steering system there would be no way to control the motion of the vehicle. Lastly all the systems are connected to the chassis. This provides protection and support for all the subsystems.

How are the connections implemented?

Each subsystem in the Barbie Dune Buggy Power Wheels is connected in one of a few different ways. The various components of the electrical system are generally interconnected through wires and electrical junctions. This allows for the transportation of electrical signals and energy to and from the components, which is critical for the operation of the product. For example, the wires connecting the battery to the motor are crucial as they allow for the electrical energy in the battery to transfer to and power the motor. The radio system, too, is connected through electrical wires and junctions so that when a button was pushed, electrical signals would cause the music to start playing. The steering system is connected by somewhat simpler, mechanical means. The components of this system are interconnected using various screws and fasteners. They hold the parts, such as the steering column and the front axle, together. Thus, when human energy was exerted on one part, causing it to move, it would also move the other parts to which it was fastened. The chassis was connected in a similar way, with screws, fasteners, and plastic joints. The powertrain subsystem, which consisted of components of the electrical system as well as the back axel and wheels, was connected throughout by both electrical and mechanical methods. Electrical wires and fasteners connected the battery to the motor, which was attached to the back wheels and axel using screws and fasteners so that the wheels would rotate and turn with the motor.

Table 4. Influence of Global, Societal, Economic, and Environmental Concerns
Factor: Influence:
Global Concerns * The connections are influenced by the availability of specific screws and plastic connections on the global market. It is easier to sell the product globally if repair parts are sold globally as well.
  • Connection type is also influenced by the climate of which the product is sold, because if there are large temperature changes, over a few years the integrity of the connection may be significantly reduced, especially if it is made of plastic. This could result in breakage.
  • This product is meant for usage of flat, and preferably paved area, not rugged land.
Societal Concerns * Because this product is meant for children, the connection type must consider the safety of the rider. Small pieces or connections with sharp edges should not be used, nor should any connection be apparent to the passenger, where they may try to take it apart
Economic Concerns * The cost of production of specific connection parts must be considered in the selection of connection, because a higher cost of production would yield a higher cost to the consumer, so the designers must find a balance between quality and production cost of the connection.
  • Designing the product with as few screws as possible without compromising safety is important in keeping cost due to the connections lower.
  • The large plastic parts are an economic design concern, because large plastic parts are cheaper parts and also there are less parts to put together, therefore assembly is a shorter process.
Environmental Concerns * The environmental effect of the lifecycle of the plastic connections must be considered. The environmental effects of production can be harsh, and at the end of the products life, they must be recycled.
Performance Concerns * Connections that promote maximum energy transfer should be considered in the product design, so as little energy as possible is lost. An example would be the selection of good electrical conductors for the transmission of the energy from the battery to the motors.
  • Connections also must be strong and sturdy enough to handle the maximum load. Performance must not be compromised too much if the passenger is under the maximum load stated, so both the connection type and maximum load must be determined.

What is the arrangement of subsystems?

The Barbie Dune Buggy Power Wheels has many subsystems arranged in the fashion of a traditional vehicle. The arrangement of these subsystems is for the optimum running of the Dune Buggy. The foot pedal is placed near the floor of the car so the driver can utilize their hands for steering. Once pressed the foot pedal subsystem sends signal to the motor in the rear of the vehicle. This signal creates rotational energy from the battery and transfers it to the wheels subsystem. From the rear wheels, power is created and the car begins to move forward. Toward the front of the body lies the steering subsystem, which controls the direction of the vehicle. The steering and rear wheels cannot be adjacent to each other, for it would create poor control of the vehicle’s direction. The battery subsystem and the motors should not be adjacent either, these two parts are the heaviest subsystems in the car and placing them close would offset the equilibrium of the vehicle. The radio system needs to be placed adjacent to the steering system so that the user is able to easily control the sound without taking their hands off the wheel for an extended period of time.

The steering system is located at the front of the car. The steering wheel which is the piece that the user interacts with is located inside the cabin, along with all of the other pieces that involve user interaction. The pieces are located here because that is where the user sits. The steering columnattaches to the front wheels, the reason it attaches to the front not the back ones is that since it is a solely mechanical system the more direct the transfer between human signal and physical reaction the better. The electrical system is stretched throughout the chassis.The acceleration pedal is located in at the base of the cabin in similar way to a real car. When it is pushed it sends a signal to the battery which in turn sends power to the motor. The battery is located under the hood of the car. This is because that is where there was the most unused space and it is easy to access. The motors are attached to the rear wheels making the car a rear wheel drive car. By doing this it allows each set of wheels to only perform one function which simplifies how the car works.