Preliminary Detailed Design
Team Vision for Preliminary Detailed Design PhaseThe plan for this phase of the design process was to choose our most critical and potentially difficult systems and focus primarily on making significant progress on them. Through research and expert input, we wanted to be sure that the most difficult components of our design were solidified by the preliminary detailed design review.
Tasks Completed During this Phase
|Member||Tasks For This Phase|
New Gantt ChartWe switched to a new Gantt chart template made by Miguel Gutierrez (Team P18365). To see the working version of the new Gantt chart, click here.
Customer Meeting - Leah Talbot (3/26/2018)
- Overall, Leah is pleased with the progress we made and the projection of the project
- She worked with Wayne County Public Health to get a car seat donated to the team
- A update:
- Is back living with his biological parents, so the car will mostly be used at school now and not at home
- A is more right handed
- He is only able to use one hand at a time
- Gave us Kelly Gilroy’s email (emailed on
- She works with Step by Step (another physical therapy place in Henrietta) and specializes in children with disabilities
- We will be able to meet up with Kelly and her coworker Sara Strohmeyer (since they are located much closer than Leah) and test child control system, the finished car, etc with the kids
- In the final stages of setting up a meeting with
Kelly/Sara; just waiting on final parent consent
- The kid(s) we would be viewing have CP like A
Control Discussion - Leah Talbot (3/26/2018)
- Child control discussion:
- Really likes the idea of having different levels of control as A ages
- We shouldn’t have child controls which require the simultaneous use of both hands
- Leah is on board with using a joystick as part of the child controls because it would be a step towards introducing A to a powered wheelchair (which he will most likely use)
- Likes the idea of having a pedal-type control (like the accelerator in a car) for the hands so A can get used to pushing the pedal down more increases acceleration
- The PS4 controller might be a little too distracting with all of the different buttons – if we use this for the child controls we’d have to cover the unneeded buttons
Ergonomics Expert Meeting - Dr. Matthew Marshall (3/29/2018)
- Dr. Marshall recommended a few ideas in regards to
- Create multiple dummy controls for prelimenary motion testing.
- If budget allows create multiple control systems that can be swapped between on the final product.
- Test the active controls when possible.
Test PlanThere are multiple different child control options that we would like to test:
- Acquire the different child control types in toy
- Turn and Learn Driver (https://www.walmart.com/ip/Turn-Learn-Driver-trade/45079155)
- We’ve been in contact with Kelly Gilroy from
the Step by Step Pediatric Therapy Center in Henrietta
about observing some of this kids on her and her
colleague’s caseload playing with the different
- Kelly doesn't personally have any kids with CP on her caseload, but is in touch with her coworker Sara, who does have two kids with CP
- We are in the final stages of setting up a meeting with Sara/Kelly and the kids
- Bring in the joystick and Turn and Learn driver to
document which control types the kids prefer/are easier
for them to use
- Definitely keep track of the ages of the kids and toy preferences
- Take videos if possible (need parent permission)
- We've already made some decisions in relation to
- The controls will be able to be operable by one hand at a time, since simultaneous use of both hands in kids with CP is difficult
- There will be different control options that can be activated/deactivated as A ages
- Determine the control types to use after Kelly/Sara meeting
- Categorize control groups based on age so A can increase his level of control as he ages
- Make prototypes of the controls and re-visit the kids with CP to test
- Determine control mounting system (PS4 controller, design our own, etc)
- Source materials for control mounting system and controls themselves
Wiring Diagram for Existing Car
How to Power Microcontroller
- Input voltage: 11.5-30V,Output voltage: 5V
- Output Current: 2.5A MAX , can use for 2.5A current .
- power cable lenght : 1M ,micro usb output lenght : 2M
- Light compact, convenient to use and transport
- Short circuit protection: red DC +, black DC -, yellow, VCC .
- Install Raspberry Pi OS
- Install Bluetooth Controller Driver
- Create simple app to communicate with controller
- Finalize DAC and PWM control Design
- Purchase motor controller
Child Restraint System and Mounting System
Final Mounting Design
Mounting System Materials
- 80/20 will be used as the back frame of the mounting system – its main purpose is to provide support for the back of the car seat (https://8020.net/shop/25-2525.html)
- An diamond tread aluminum plate will be mounted onto the chassis as the support for the bottom of the car seat (https://www.mcmaster.com/#aluminum-plates/=1ca5tqx)
- Square head bolts will be used to attach the aluminum plate to the car chassis (https://www.mcmaster.com/#square-head-specialty-bolts/=1ca5vfe)
- The latch system that comes with the car seat will be used to attach the seat to the aluminum plate and the 80/20 support frame
- U-Bolts will be mounted to the bottom of the aluminum plate so that the car seat latch system can be attached to the aluminum plate – this will allow the car sear to be removable/switched out for a new seat (https://www.mcmaster.com/#u-bolts/=1ca5w67)
Car Seat OverviewFeatures considered for choosing a car seat:
- Washable or wipeable material
- Available as forward facing
- Size of base & size of seat
- Easy to install
- Height measured from bottom to top of seat
- Head support/cushions available
- How much is the car seat angled up when forward facing
Car Seat Options
- Finish CAD model of the mounting system design
- Decide whether or not a prototype of the mounting system will be necessary
Current Steering Setup
Initial Steering Designs
Meeting with Gear Expert - Dr. Fuentes Aznar (3/28/2018)
- Presented the preliminary steering designs to get
technical input on the gear systems
- The curved rack and pinion design was presented as our favorite option
- A bevel gear design was also discussed as a potential solution
- Dr.Fuentes-Aznar told us that a curved rack and pinion design is very expensive and complex to design and manufacture
- He suggested instead of attempting to use the gears to facilitate the curved motion that the axle follows, we should try to find a different way to guide the axle
- He also wanted to know more about how the wheels were
attached to the axle
- This prompted us to take apart the plastic covering of the car to observe the wheel connection
- Another meeting with Dr.Fuentes-Aznar will be planned to present the most recent design
Iteration 2 of Steering Design
Meeting with Gear Expert - Dr. Fuentes Aznar (4/4/2018)
- Presented the pin and slot steering design
- Dr.Fuentes-Aznar said this design was a nice, simple, and cheap design
- He mentioned that the main would be ensuring we have enough torque from the servo motor
- Source materials for the pin and slot steering design
- Choose and source a motor to use in the pin and slot design
- Design a mounting method for motor to chassis
- Figure out how the motor will be powered
Bill of Materials (BOM)
To see the working version of the new BOM, click here.
Many tests, including seeing if vehicle tips over on a 15° incline plane when it is overloaded, driving toy into a step with a height of 50 mm and tipping over vehicle.
(ISO 8124-1:2014 Sections 4.15, 5.12.3, 5.12.4, 5.24.3, 5.24.4) (ASTM F963-17 Sections 8.7, 8.15, 8.21, 8.28)
Holes need to have a diameter smaller than 5mm or bigger than 13mm.
Sharp edges are tested with a piece of adhesive tape attached to a mandrel and rotated along sharp edge. Less than 50% of the tape should be cut after the test.
(ASTM F963-17 Section 4.18.1) (ISO 8124-1:2014 Sections 4.13.1, 4.13.2, 4.18.1, 4.39.3)
(ISO 8124-1:2014 Sections 4.6.3, 5.8)
|Tension and Torque Tests||
Apply a 0.45 Nm torque evenly for 5 second period and maintain for 10 seconds.
Apply a 70 N force parallel and perpendicular to the major axis of the test component evenly over a period of 5 seconds and maintain for 10 seconds.
(ISO 8124-1:2014 Section 5.24.5) (ASTM F963-17 Sections 8.8, 8.9)
(ISO 8124-1:2014 Section 5.24.6)
General safety requirements, including not exceeding maximum temperature ratings, no short-circuit conditions when tested, and no risk of fire.
Shall carry safety labeling consisting of the word “WARNING”, “RISK OF FIRE” and text that indications how to reduce the risk of injury.
(ASTM F963-17 Section 4.25, 8.18, 8.19)
(ASTM F963-17 Section 5.15)
If car is considered free wheeling (rolls down an 10° incline with a 50 kg mass), there must be a braking device that prevents it from moving more than 5 cm when tested on a 10° incline.
If car is more than 30 kg, a parking brake is necessary.
The switch (which turns on the vehicle) shall cut off power automatically when released.
(ISO 8124-1:2014 Sections 4.21, 5.16.1, 5.16.2)
(ISO 8124-1:2014 Section 4.21)
(ISO 8124-1:2014 Section 4.21)
Electrically driven ride-on toys shall have a maximum speed of 8 km/h.
(ISO 8124-1:2014 Sections 4.23, 5.17)
Design Review MaterialsInclude links to:
Plans for next phase (Very high level)
- Main focus
- finish choosing parts for the power steering system
- completely integrate the power, child controls, power steering, motors for forward motion, and microcontroller.
- Main deliverables
- schematics that show how every part will be powered, and how the various parts that need to be controlled will interface with the microcontroller
- preliminary programming flowchart, pseudocode, or both in order to illustrate the plans that are being made for the various control methods.
- Main focus
- design a mounting system for the child controls that is ergonomically effective and is able to interface well with the chosen controls
- source materials for slot and pin steering system and child controls mounting system
- Main deliverables
- CAD model of car seat mounting system, slot and pin steering system , and child controls mounting system
- Main focus
- continue to correspond well with the customer
- maintain the edge page better than in the past-constant improvement
- maintain the BOM, risk management information, and Gantt chart
- continue meeting with experts to get helpful critiques about the system