Team Vision for Detailed Design Phase
- The team set out to clinch sponsorship prospects explored in the previous phase as well as enhance the design materials produced in the previous phase with more detail. Sponsorships pursued included FUTEK for torque transducers and Volland for the drive motor. The team also aimed to finalize a bill of materials (BOM) for the project.
- FUTEK proposed a sponsorship, however the transducers were not offered to us for an acceptable discount, so acquiring the transducers from them is no longer an option. The options Volland provided were not feasible for the team due to budgetary constraints. As a result, the scope of the project was reduced. The reduction in scope allows for the use of torque sensing equipment and a smaller drive motor that are already in the team's possession. With those decisions, the detail items previously unknown have been examined and are shown in the following articles on this page. The BOM has been updated, and it is expected to be complete by the end of MSD I.
Prototyping, Engineering Analysis, Simulation
Controls & Data AcquisitionThe ADS1115 ADC that was proposed earlier, in conjunction with a Raspberry Pi, were tested. This is shown in the set up below.
The test bench used the following
- Arbitrary Waveform Generator
- Configured to 10Hz
- Square Wave
- 20% duty cycle
- 5V pk-pk
- 0V min, 5V max
- Digital Multimeter
- Probes monitoring differential voltage of DC Power Supply
- DC Power Supply
- Configured to output a small DC voltage around 50mV
Below is a screenshot of the code used to test the performance of the system.
The results of the code's performance is shown in the screenshot below, outputting each message as quickly as possible.
This test confirms the ability of the Raspberry Pi to log the pulse rate of the rotary encoders while also logging the analog voltage that will be output by the load gauges and the Tecat sensor.
Modal analysis of the chassis was calculated using the SolidWorks Simulation package, this is showing a resultant amplitude of 0.0005.
The chassis was loaded with the weight of the motor on the motor supports in this simulation. FEA simulated with Solidworks Simulation.
SolidWorks Simulation FEA of the motor bracket. Bracket loaded with the weight of the motor and fixed on the mounting locations. Max Stress 5ksi.
Drawings, Schematics, Flow Charts, SimulationsExample representation of vehicle Camber and Toe.
Below is revision 2 of the Electrical Block Diagram, updated to include the change from the Futek sensors proposed in the Preliminary Design Review. The system now includes the load gauge and Tecat strain-gauge based sensor, and two rotary encoders that will simply pulse once per revolution.
The control and data acquisition flow has not changed since the Preliminary Design Review. It is shown here again for convenience.
Bill of Material (BOM)Bill Of Materials
Risk AssessmentWhile some of the risks involving funding have been taken care of, the main concerns with the project are still budget related.
Risks the team has begun to address:
- Not having enough funds to complete the project
- Many sponsors have been contacted
- In house Tecat sensor and load cell to be used for torque measurement
- In house drive motor will be used
- Friction brake system using in house parts will suffice for load
- Misumi will sponsor a portion of the project
- Alternative designs have been developed to use cheaper items
- Timeline risks
- Lack of sensor and motor sponsorships inherently reduces lead time risks
- Knowing what resources are available without sponsorships lead to design decisions made that have reduced the risk of re-design
- Team member class scheduling has allowed for time during each week to work on the project
- Incompatibility with existing Baja designs
- CAD of current designs is being utilized in development of test rig
The lack of sponsorships attained had both positive and negative effects on the project. The conclusions drawn as a result of the efforts allowed progression on the more detailed design aspects of the project in both the electrical and mechanical systems. However, there are new concerns with the quality of the system, specifically in torque measurement accuracy and resolution. Overall, during this phase the risk to the project has been reduced, but the priorities of mitigation efforts have been shifted from cost savings to technical quality.
Plans for next phase
Preparing for Gate Review
- Solve issues brought up in Detailed Design Review
- Post all management and design docs to Edge main page
- Finalize Misumi order
- Prepare PO's for purchased components and materials
- Review budget
Preparing for MSDII
- Prepare purchase orders for rest of components
- Prepare prints for manufactured parts