Table of Contents
Team Vision for Detailed Design Phase
Review of ProjectDuring MSD I, P16045 was tasked with creating a feasible, concept design for a manual stander modification kit. The intent of the kit is to enable any secondary user(i.e. parent, physical therapist) to modify a manual stander to become a Motorized Pediatric Stander. Previous design iterations, especially the work completed by P15045, have helped guide the team in building upon work completed and documentation of changes and reasoning of these changes. However, previous iterations had several shortfalls that inhibit the stander from being fully functional for young children with physical and cognitive disabilities. The main shortfall, which has been seen through all of the iterations is the lack of control to go straight.
With the help and collaboration of Industrial Design and Business students, P16045 is tasked to fix these shortfalls by creating a design that will allow a child to interact in a more natural way with his/her surroundings and peers. Specifically, with the proposed design, the team is looking into creating a modular box to house the electronics, battery, motors/drive system, and environmental sensors that is to be placed along the front axle of any stander. Further, with the research and testing of various user control schemes, the secondary user may be able to pick which type of user controls best suit the ability of the child to be operating the modified stander. Below is a review of the Customer Requirements and Engineering Requirements, along with test plans for MSD II.
- Market Engagement Plans
- Steps to Market the Stander
- Various Control Schemes (i.e. buttons, joysticks, touchscreen app)
- 14045 Stander, 15045 Stander, and 16045 Prototype Board
At the completion of the challenge, the team was honored with winning first place, and accepted one of Dr. Destler's Banjos. The team, also, was able to talk with various visitor's that helped further the importance and understanding for technologies that enable movement and natural lifestyles of disabled person's. In specific, the group learned the following:
- The importance of this technology to be accessible to young children and their families. Several physical therapists and elementary school teachers discussed with multiple members of the group about how important it is to enable young children with physical disabilities to learn and develop in a similar manner to their peers.
- The impact of this technology to children with and without physical disabilities. Although the P16045 prototype was not allowed to be ridden, the P15045 and P14045 were. These prototypes allowed the team to see how children of all abilities gained joy in using the standers.
- From winning the first place prize of Dr. Destler's Challenge, the team was able to see how the design and collaboration from all disciplines lead to a successful prototype. Moving forward, the team is encouraged strongly to continue the work to create a functional final motorized pediatric stander.
MechanicalFor the final detailed design review, the mechanical revisited the motor calculations based on governing equations used to determine the necessary wheel torque for vehicles. The torque required to power a system is based on several different factors such as:
- Total Tractive Effort - the net horizontal force applied from the drive wheels to the ground
- Rolling Resistance Force - the force necessary to propel the vehicle over the given surface
- Grade Resistance Force - the force necessary to move the vehicle up an inclined surface
- Acceleration Force - the force required to accelerate, from stop, to maximum speed in a desired time frame
- Gross Vehicle Weight - the maximum operating weight of a vehicle that includes the weight of the vehicle's chassis, body, engine, fluids, fuel, accessories, passengers, and cargo
- Rolling Resistance of Surface - the energy lost due to a tire rolling over a surface
Finalized Motor Calculations
Above the calculations produce a range of required wheel torques for varying stander sizes and surface grades. The maximum user weight criteria, as rated by the manufacturer, for a given stander size is applied, but divided by 4. This assumes that the weight distribution of the stander load is even throughout, which was seen relatively in preliminary weight distribution testing with an applied load of 50 lbs. This assumption needs to be validated by the mechanical team as the design move forward, and is discussed later in the mechanical engineering team's test plans. It is seen for all stander sizes that the use of a stander within sand of all conditions causes the wheels to require the larges torques. These hand calculations provide evidence that the Parallax Motor Kit is suitable for the conditions that the stander are to be expected to perform in.
Kit Housing Design
As the design for motors and electrical components are solidifying, the focus is slowly shifting to housing for the motor kit. The mechanical team is working with the industrial design team to design a housing that is structurally stable, functional, and aesthetically pleasing. Initial research has shown that the use of aluminum 6061 fits many criteria that is needed for the housing. Above is a comparison chart of other aluminum 6061 and other alloys.
SchematicRefer to private folder
Remote Interface DesignContinuing to develop and understand the advantages and limitations of the Simblee app.
Use Case Diagram
Mechanical Test PlanMechanical testing is to occur during the first three weeks of MSD II, this coming fall. Specifically, the mechanical engineering team has identified the necessity to determine the dynamic stability, surface conditions, and weight distribution of the stander. The test matrices for each test, materials, procedures, and observations can be seen below. The overarching goal to complete these tests are: to determine the safety of the system as it moves along various inclined surfaces, to determine the actual motor effectiveness along changing surface conditions, and to determine the weight change of an unloaded to loaded system.
Software Test Plan
User Interface Test Plan
Bill of Material (BOM)
Current running budget and BOM for MSD II
MechanicalIn order to accomplish necessary tasks during MSD 1, the mechanical team has only required the need to purchase the Parallax Motor Kit, which was utilized by all three previous iterations. Other necessary parts to help bring the prototype test dolly to life were purchased and built through the industrial design team.
ElectricalRequired parts and quantities identified based on schematic. Sources for obtaining parts still need to be identified.
Risk AssessmentThe most current version of the risk analysis documents can be found here. During this phase, the team decided to split up the risk analysis chart into a mechanical and electrical team concerns. Moving forward this will allow for better mapping of each risk to designated teams and members. Further, this allows for each team to update the risk analysis chart based on problems that arise to their area of concern.
The live document can be found here
Mechanical Risk Assessment
During this phase, there were no added changes to the risks designated to the mechanical engineering team.