Servo travel issues

AntennaTracker
1

OK, I am building an antenna tracker somewhat similar to an Eagle Eyes Pan & Tilt. Similar in that it uses 2 gears to get ~360° yaw rotation. I am using Hitech HS-485HB servos on both pan and tilt. The yaw motion has a 2.16:1 gear ratio and using the servo’s max rotation of 190°, I should get ~ 410° of rotation. I am only getting about 285°. I have set the servo limits at 900 and 2200 on the servo test screen, and that is all I get for rotation. I could print a different gear set, but they are already getting big. When I check the physical limits of the servo, it goes about 180-190°, and when on the tracker I get a fair bit more than 360°, but that is physically rotating the tracker.

So I think I have 2 options:

  1. find a way to get the servo to go to 190° of rotation. Can Ardutracker do this?

  2. Go to a continuous rotation servo and redesign the gear set…

Other ideas

2

Ok, so quick update.
I pulled the specs for the HS-485HB servos.
190.5° max travel (out of the box)
0.102°/uSec (out of the box)

SO… 2200uS - 900uS =1300uS
1300 * 0.102 = 132.6° * 2.16 = 286.4°
2.16:1 is current gear ratio on the yaw movement

So it looks like if the min and max are locked at 900 and 2200, then I am stuck with only 286° of rotation, with current gears.

Can Ardutracker use a wider range? Say 1800uSec instead of the 1300uSec?

3

Usually the trick is to reprogram the servos (the digital ones) or change the potentiometer (in the analog ones)

4

Ugh…

I might just as well get a continuous rotation servo.

Thanks