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Team Vision for Integrated System Build & Test Phase
Our team's plan for this phase was:
- Order to PCB designed by team member Matt.
- Finish the foam mold of the board.
- Begin manufacturing of the rails once dimensions and sizes are verified.
- Complete a battery pack design and begin the assembly with verified output.
- Test the structural strength, threaded insert integration, and nylon weave pattern on the foam board.
- Complete the code.
- Have trucks either 3D printed or ordered from vendor.
- Continue using the schedule in order to foresee any problems that could arise.
Our team accomplished this phase:
Ordered all necessary PCBs and components for assembly.
Finished the draft poster.
Prepared to verify correctness of electronic design with code once assembled.
Created a new end goal and adjusted the schedule to fit.
Continued Toolpath Corrections for Deck Manufacturing
Optimized Deck Design for ease of Manufacture and COT truck installation
Optimized Truck Baseplate for Ease of Manufacture
Selected Material for Power Contact Design based on Deflection in the Elastic Range
Risk Management
Strike through - Items no longer applicable due to scope reduction
RED - Items that we have timed out of a contingency plan for
YELLOW - Items that we are close to passing the point of no return on
GREEN - items with feasible contingency plans still
| Risk Category | Risk | Cause | Effect | Risk Prevention | Contingency Plan | Period Until Switching to CP | Lead Time | Likelihood | Severity | Importance | Owner(s) |
| Technical | Deck can't fit all the Necessary Components | Too many large components in too thin of a body | Functions may have to be demonstrated on separate testbeds | Design subsystems with the intention of integration but on separate testbeds to prevent roadblocks | Subsystems stay on seperate testbeds | 7 weeks | N/A | 6 | 5 | 81 | Erik |
| Technical | Failure of Force Sensors | Damage to sensing surface or blocked transmission of force to sensing surface | Complete loss of motor control/unexpected motor response | Thoroughly test force sensor installation | Use remote to control motors | 2 weeks | 6 weeks | 3 | 9 | 27 | Matthew G. |
| Technical | 3D Printed Base Plate Failure | Does not meet stress/impact requirements | Does not meet stress/impact requirements | Simulate stress requirements using an FEA analysis in solidworks | Buying Trucks | 2 weeks | 2 weeks | Conner | |||
| Technical | Hanger Experiences Bending | Too much weight | Bending/Warping | Simulate stress requirements using an FEA analysis in solidworks | Buying Trucks | 2 weeks | 2 weeks | Conner | |||
| Technical | Truck design failure | Trucks don't work as designed | Danger to the rider of falling and hurting themselves | Conduct tests of trucks over full range of speeds with differing loads. Redesign Truck Assembly | Buying trucks that are stable | 2 weeks | 2 weeks | 3 | 9 | 27 | Tanvir M. Connor F. |
| Resource | PCB design does not work | Lack of experience with PCB design. | Non-functioning PCB. | Get Eric's friend to verify design and make sure design follows general design of VESC | Purchase a second turn of a new PCB design. | 2 weeks | 6 weeks | 3 | 9 | 27 | Matthew G |
| Technical | Product failure or part malfunctions | Miscalculations during design process | A non-functioning product | Mechanical Design Leads must be consulting each other | Consult with Mechanical Engineering Professor. | 2 weeks | N/A | 3 | 9 | 27 | Tanvir M. Connor F. Erik L. |
| Technical | Control system causing unexpected outputs (malfunction) | Incorrect inputs were put in the system | Incorrect Outputs/System Failure | Follow microchip whitepaper exactly and verify code on controller func | Have a micro-controller system expert look over the system | 0 weeks | N/A | 1 | 9 | 9 | Matthew G. |
| Technical | Electronic components protection | Exposure to external environmental factors (water,rocks, etc.) | Damage to the battery and other components | Ensure proper location and protection of electrical components. | Have a guide for a particular environment that must | 0 weeks | N/A | 1 | 3 | 3 | Kristin O. |
| Safety | Pinch points in the mechanism | Folding Mechanism | Damage to hands and fingers of riders. | Proper outlined guide for Hand Placement | Wear protection gloves | 0 weeks | N/A | 1 | 3 | 3 | Tanvir M. Connor F. Erik L. |
| Resource | Lack of additional funding (Budget) | The budget we were given was too low from the outset | Unable to finish design or a low quality product | Get budget increase | Cut costs where necessary and/or fund with personal funds | 3 weeks | N/A | 3 | 3 | 9 | Deirdre A. |
| Resource | Team Members Being Absent | Exceptional Circumstances (Sickness, etc.) | Falling behind on deadlines and not being able to create longboard. | Make sure at least one person on the team has a good understanding of what the abstentee was doing, | Assign the another person the absentee's task depending on how important the task is | 3 weeks | N/A | 9 | 3 | 9 | All |
Problem Tracking
| Identifying & Selecting Problem PSP 1 | Analyzing Problem PSP 2 | Generating Potential Solutions PSP 3 | Selecting & Planning Solution PSP 4 | Implementing Solution PSP 5 | Evaluating Solution PSP 6 | ||
| Rating | R1 | R2 | R3 | Y4 | Y5 | G6 | |
| Motor Controller (Matt) | CRITICAL | PCB Design has incorrect outputs | Component Value is Incorrect/Connection made incorrectly | Consider Generating a Second Rev of Board and have it Looked over by two other individual | Generate a Second Rev of Board and have it Looked over by two other individual | New Boards are ordered | Test new motor PCBs on |
| Collapsing Mechanism (Erik) | Collapsing Mechanism Jams and Doesn’t Slide | Clear coat Resin on board is non uniform | Use CNC router to even out surface of the epoxy | Add post-machining to production process | post-machining tool paths are generated and executed | Does the collapsing mechanism move freely | |
| FSR (Matt) | FSRs aren't appropriately responsive to changes in weight distribution. | Identify the sensitivity of each sensor and generate plots of output vs force. | Simulate various calibrations using the data in PSPICE. | Determine the new resistors and/or DAC voltages that will be needed to implement the solution. Order any new capacitors and/or resistors that would be required. | Modify code and remove and/or replace the required components on the PCBs | Do FSRs respond appropriately? | |
| Jump Power Contacts (Tanvir) | MAJOR | The jump does not connect properly together to produce power. | Determine issues in the geometry of the jump and whether all dimensions are correct. | Consider purchasing custom made pins and sockets. | Determine if the jump properly connects. | Order custom pins and sockets. | Do they connect and distribute power? |
| Foam Board (Erik) | Only some foam boards are strong enough to handle the weight of the rider | Clear coat resin appears to be not full hardened in some spots | Experiment with different epoxy clear coat layering techniques and nylon weave wrappings | See if any of the new techniques consistently increase the structural stability of the foam long board deck | Implement new manufacturing techniques into board construction process | Determine if resulting boards following the manufacturing process update retain the same strength in stability that the test boards had | |
| Battery Pack (Deirdre) | ORDINARY | Battery Pack is assembled incorrectly. | Misunderstanding of how the battery back is assembled. | Consult with team members and other individuals to verify correct assembly of battery pack. | Fix any gaps in understanding or poor techniques. | Continue assembly with adapted plan. | Check for correct outputs once assembly is completed. |
| Cam Truck (Connor) | |||||||
| Latch Mechanism (Deirdre) | Latch Mechanism is not adequate for load needed. | Identify appropriate load needed. | Select new Latch Mechanism. Order and Re-work current latch mechanism. | Select and order a different latch mechanism as appropriate. | Order new latch. | Finite element analysis conducted on new latch. |
Material Selection
Power Contacts
Aluminum 6061 T4 has a yield strength of at least 110 MPA.
Aluminum 6061 T6 has a yield strength of at least 240 MPA.
Copper UNS C12000 has a yield strength between 69-365 MPA.
Aluminum 6061 T6 (43% IACS) is slightly more electrically conductive than T4 (40% IACS). Copper UNS C12000 has 95% IACS.
For our purposes, Copper UNS C12000 has a high electrical conductivity and high yield strength.
Designing for Manufacture
Deck
Truck Mounting Surfaces
In prior iterations of the longboard deck the mounting surfaces for the trucks were not level. Down the line this would have effected the steering characteristics of the trucks. It's because and one other flaw that the mold had to be remade for a third time.
(Prior Iterations)
(Current Version)
Addionally, the front mounting surface for the trucks was not long enough to accommodate our baseplate nor any other off-the-shelf truck. The current version of the longboard deck remedied this as well by extending the mounting surfaces to allow for the baseplate to fit with some room to spare.
Mounting Holes
To make a commercial off the shelf backup for the cam-based trucks feasible, the deck needed to have hole patterns that matched both options. The easiest way to achieve this was to make sure that the cam based trucks shared the same hole pattern as the off-the-shelf ones. This prevented the drilling of extra holes into the deck.
Bottom Fillets
For aesthetic reasons the board has a large number of sharp curves. Unfortunately these are incredibly hard to machine into the negative cavity in a mold as the end mill is relatively wide. The try and make sure the model matched the part being produced, almost all of the sharp edges of the board that have to fit into the mold were given 0.25" fillets to represent the material left behind by a 0.5" ball end mill.
Trucks
Baseplate
To represent a realistic part after manufacturing fillets were added to the negative pockets in the baseplate as well. Additionally the boss for the o-ring was removed to allow for an easier machining process. This will be replaced by an independently made bushing.
Hanger
Battery Pack Configuration
The battery pack configuration was determined almost exclusively by the allotted space on the board. The board allowed for a hollowed out section of the dimensions 21.94" x 4.25" with a depth varying from 0.74" to 1.13". The lithium ion batteries used for the board have dimensions of 2.55" in length and a diameter of 0.72". As a result, the batteries could not be stacked in layers because only one battery could fit in the depth of the opening regardless of which side of the opening you are on. This left the only possibility of creating 8 columns of 5 rows of batteries. There was not a possibility of creating two long rows of batteries because similarly to the issue that occurred with the depth, the length of the battery - 2.55" - would not allow for two batteries to be set in two rows horizontally as the total length would be greater than 5" while the total available length is 4.25". The final battery pack configuration can be seen in the below image with the dimensions of the batteries themselves and the dimensions of the opening listed:
Figure 1. Configuration of batteries determined via the opening space available in the board. Figure does not represent a to-scale drawing but rather allows for understanding of the battery orientations and configuration.
Battery Pack Assembly
Assembling the Battery
The Battery Pack Assembly should be quite simple and free from issue. The battery pack needs to be assembled as a 10S4P, meaning that the battery pack requires 4 parallel sets of 10 series batteries. The assembly of this battery pack involves the following steps which will be completed prior to the due date of November 14th:
- Develop a PCB to protect the battery. Note that this step was completed at a significantly earlier date by Matt Gould.
- Arrange the batteries in the needed configuration determined previously and secure them in that configuration through utilization of battery spacers.
- Apply the initial flux and solder points to the lithium ion batteries.
- Positioning the nickel strip as necessary for the correct wiring of the batteries, solder the strips in place.
- Glue together the batteries for added security and to help deter from issues related to vibration of the batteries.
- Using high temperature tape, secure the battery pack together further.
- Conduct appropriate battery testing by using a multimeter to test and verify the assembly of the batter pack.
- Complete wiring of the battery pack to the electrical components.
Functional Demo Materials
Deck Mold (1st Iteration)
This first iteration of the mold had no square edges which made zeroing the part placed in it tricky. To make matters worse it was cut slightly too small so when we did eventually try and put the positive bottom of the board into the negative cavity in the mold it didn't fit.
Deck Mold (2nd Iteration)
Learning from prior mistake I made sure to do the tool path properly this time and cut the cavity to the proper dimension. Unfortunately I noticed after the machining was done that the back mounting face for the back truck was on an angle and that's when I realized the deck model might have a flaw.
Deck Mold (3rd Iteration)
After correcting the deck design, this is the model of the new mold for fixturing the board during the machining of its top surface.
Deck Bottom (1st Iteration)
This was the first test of my tool path for cutting out the positive bottom of the board. As mentioned earlier this didn't end up fitting in the mold and I also contained that slanted back surface so it was unusable.
Links
Link to the phase review presentation.
Link to the Bill of Materials.
Plans for next phase
Complete assembly of all electronic boards with proper components.
Have lightning talk slide finished and submitted to MyCourses.
Complete a team self-assessment with objective evaluation of successes and failures.
Have a completed wiki with all final products and testing results.
Be able to demo the hands-free board.
Decide on design for the trucks and have the material bought with the trucks manufactured.
Have board finished with coating.
Start and Finish technical paper for the project.
Finish poster with notes from draft submitted.
Test electronics for verification.
3 Week Plans
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