Spring 2018 3DoT Hexy: Resource Report (Cost, Power, Mass)

By: Raymundo Lopez-Santiago (Mission, System, and Testing)

Verified by: Eduardo De La Cruz (Project Manager and Manufacturing Engineer)

Approved by: Miguel Garcia (Quality Assurance)


This blog post covers 3DoT Hexy’s Resource Report which include cost, power and mass.Values for the battery and 3DoT board were initially estimated based on the final blog post of 3DoT David. Values for each component or device are updated as the project is further developed.

Resource Reports (Updated March 15, 2018)

Mass Report Fig. 1: Mass Report 

For the mass report, the allocated mass for 3DoT Hexy is 450 grams. This is determined using different weights until the robot operated at 3.7V is no longer able to operate. See blog post (Mass Allocation Post). Most parts/components are measured, but values will be updated as needed. A small home digital scale is used to measure all mass for each part.

Power Report 

Fig. 2: Power Report 

For the power report, the allocated current comes from the battery used in this project which is 1100mA. This value is around 85% of the max current able to be supplied from the RCR123A battery. Values are initially estimated based on datasheets for minimum and maximum current draw f

or each device used. The maximum current draw is assumed to be worst case scenario and that is what is used for power estimates for each component. A section is included to compare the total expected current draw obtained from datasheets and total measured current draw. All measurements for current draw are done using a breakout current sensor.

Cost Report 

Fig. 3: Cost Report 

For the cost report, based on customer requirement our project allocation cost is $250.  At the moment we have got approval from the customer to allocate a max of $300 if needed. Most parts are already purchased, but values will be updated as needed. This table is covers all cost per part as well as provides links to all parts. A section added is to include parts covered by company stock. Even though some parts are provided, an expected price for those parts are included in the case someone else needs this information to know the total cost to build this robot. Total cost is broken up into cost covered by The Robot Company and expected cost from purchased parts.


Based on all spreadsheets presented in this blog post, we are in good shape to not exceed any parameters defined for each the cost, power and mass allocation. One recommendation is to start filling out all spreadsheets as soon as possible. Keeping up-to-date documentation will save a lot of time.


  1. https://www.sparkfun.com/products/14451
  2. https://www.parallax.com/product/28015
  3. https://www.digikey.com/product-detail/en/dfrobot/FIT0481/1738-1261-ND/7087158
  4. https://www.sparkfun.com/products/12829
  5. https://www.adafruit.com/product/1981
  6. https://www.arxterra.com/2016-spring-3dot-david-final-project-blog-post/
  7. https://www.frys.com/product/5016445?source=google&gclid=Cj0KCQiA2snUBRDfARIsAIGfpqGw6ov6eExenZ0MzyByUMZLA4PL2T_D5V22oT1b9NsDdywbOCx8tOcaAuw_EALw_wcB
  8. https://www.amazon.com/gp/product/B00V66YJQI/ref=ox_sc_act_title_1?smid=A2KD6YPQW2NHJU&psc=1