Team Vision for System-Level Design Phase
Throughout the Systems-Level Design Phase, Team BASE has worked to accomplish:
- A comprehensive functional decomposition of the system;
- Concept generation, identification of alternatives and concept selection; and
- Planning and execution of benchtop sensor feasibility testing.
A functional decomposition was generated in order to identify the major subsystems within the design.
Product BenchmarkingBenchmarking of current headphones on the market was performed in order to supplement concept generation and selection.
Our selected concept will definitely need to include Bluetooth 4.0, weigh no more than 10 oz. and retain a form factor consistent with social norms. The selected concept should attempt to be water resistant and have a battery life greater than 8 hours in order to be competitive with current devices on the market.
|Sensor||Metrics||Dimensions||Interface||Accuracy||Range||Current Consumption||Cost (per unit)|
|STMicroelectronics LIS2DHTR||3-Axis Accelerometer||2 x 2 x 1 mm||I2C or SPI||± 0.040g||± 16g||2-185 µA||$1.59|
|3-Axis Accelerometer||3 x 5 x 1 mm||I2C or SPI||± 16g||25-130 µA||$9.95|
|3-Axis Accelerometer and Gyroscope||2.5 x 3 x 0.83 mm||I2C or SPI||± 0.040g||± 16g||290-650 µA||$4.09|
|Temperature, Humidity, Pressure||40 x 20 x 15 mm||I2C or SPI||± 1hPa, ± 1°C, ± 3%||300-1100hPa, -40-85°C, 0-100%||0.4 mA||$17.00|
|Temperature, Humidity, Pressure||3 x 3 x 0.95 mm||I2C or SPI||± 3%||300-1100hPa, -40-85°C, 0-100%||8.9 µA|
|Temperature, Humidity, Pressure||2.5 x 2.5 x 0.93 mm||I2C or SPI||± 3%||300-1100hPa, -40-85°C, 0-100%||3.6 µA|
|Temperature||2.5 x 2.5 x 0.9 mm||I2C or SPI||± 0.3°C||0-65°C||6.6 µW|
|Temperature||4 x 4 mm||I2C||± 0.5°C||-40-105°C||2-210µA||$1.36|
|3-Axis Accelerometer and Gyroscope||2.5 x 3 x 0.83 mm||I2C or SPI||± 125-2000 dps||290-650µA||$4.09|
|3-Axis Gyroscope||3 x 3 x 0.95 mm||I2C or SPI||± 125-2000 dps||5 mA||$5.39|
|3-Axis Gyroscope||4 x 4 x 1.1 mm||I2C or SPI||± 205-2000 dsp||6.1 mA|
|UV Sensor||2 x 2 x 0.7 mm||I2C||± 20%||2300 counts/UVI||100-110 µA|
|UV Sensor||2.35 x 1.8 x 1 mm||I2C||5 µW/cm^2/st||100-250 µA|
Concept Development and SelectionIn order to determine the best design solution (in terms of ingenuity, feasibility, cost and time), various concepts were generated and systematically reviewed before choosing a solution.
A Morphological Table was developed by incorporating ideas gathered during benchmarking as well as unique ideas suggested by team members. The purpose of this exercise was to identify unique combinations of alternatives.
At this point in the design process, the sensors of interest had been researched and selected. Therefore, the only design challenge remaining revolved around the form factor. Three alternatives were chosen from the Morphological Table above, which included the occipital band, the necklace and the neckband. A Pugh Analysis was performed in order to choose the best form factor based off the customer and engineering requirements (selection criteria).
Ultimately, a decision regarding form factor will need to be postponed until sensor-location testing can be performed in the next Design Phase.
How much current will the device require?
Estimated Battery Life = (Battery Capacity/Current Consumption) x (0.70)
Estimated Battery Life = 9.5 hrs
How much storage do we need on the device?
|Metric||Rate (samples/min)||Data Generated (bytes/min)|
Total Storage Needed: 30 kb/hr
We need to integrate additional memory to store data. We would like to store for at least 2 days, requiring 1.4MB of memory.
What 3D-printable materials are available to use and meets requirements?
|Nylon||Strong, durable & flexible; 1mm minimum wall thickness; 10 layers/mm|
|ABS||Strong; 1mm minimum wall thickness; 3 layers/mm; solvent weldable & smoothable|
|PLA||Strong (less flexible than ABS); 1mm minimum wall thickness; 3 layers/mm|
|Ninjaflex/FilaFlex||Rubber-like; no support; earbuds/exterior casing with no support features|
A functional block diagram was developed in order to identify the function between input and output variables.
Based off the chosen design, the following risks were identified. Actions to minimize each risk were developed and will be implemented.
Design Review Materials
Plans for next phaseBy Design Review 3, Team BASE hopes to accomplish the following tasks:
- All sensors functioning, their accuracy and locations determined (RP: Terry, Tegan & Andrew)
- PCB layout completed and ordered (RP: Htet)
- BT module functioning (RP: Alex)
- External CAD models (RP: Byung)