November 15, 2018, 12:01:38 pm
Welcome, Guest. Please login or register.

Author Topic: Antweight drive system help  (Read 191 times)

minorthreat

  • Roboteer
  • *
  • Posts: 1
    • View Profile
Antweight drive system help
« on: April 25, 2018, 04:23:17 pm »
I am designing by first 1lb antweight robot, and I could use some advice.
I plan to use the pololu 30T track set, two fingertech goldspark motors 50:1 ratio, and a 3 cell/11.1 V lipo battery
https://www.pololu.com/product/3033
I was calculating speed and pushing power, and I am not sure if they are reasonable values for the weight class or if I did them right. All the values are from the product description pages.

Speed: 9100 max rpm X 1/50 gear ratio X 1min/60sec X 4.838in/rev X 1 foot/inch = 1.2 feet/sec

Max pushing force [oz] = stall torque [oz-in] X .5 (estimate for max torque) X wheel radius [in]
           =.64 oz-in X .5 X .77in X 1lb/16oz = .0154lb pushing force (not good!)

Another option I was thinking of is using fingertech silver spark motors. Would those be overkill for the weight class or even viable with a 3 cell/11.1 battery? Are there any other important factors or calculations I should be looking at for the drive?
I know i

MikeNCR

  • Near Chaos Robotics
  • Administrator
  • Roboteer
  • ****
  • Posts: 297
    • View Profile
    • nearchaos.net
Re: Antweight drive system help
« Reply #1 on: April 26, 2018, 09:59:01 am »
I'd strongly suggest the silver spark over the gold spark, the geartrain is much more robust and better suited to combat. The motors will handle 3s lipo fine. You'll also likely want more speed than the 50:1's will give you. The 20 or 30:1s will likely leave you much happier. I'd be inclined to go 20:1 were I building it, but I also generally favor having the option of higher top speed. One nice thing is that you can buy the gearboxes separate, try both, and see which you prefer- https://www.fingertechrobotics.com/proddetail.php?prod=ft-Sspark16-gb

On the pushing force math, I think you forgot to include the gearing, as on 3s with the 50:1 box the output torque should be 48.46oz-in per the chart on the fingertech site.