PDA

View Full Version : [Question(s)] Selecting servos for Camera-Gimbals



MathiasP
12-03-2012, 11:59 AM
I'm a little curious about the Dynamixel servos. Thinking if I could build a camera gimbal for a multi rotor with these. Model RC-servo does not have a high enough resolution to be able to compensate sufficiently good.
My question is, if so, is there anyone else who built this? Which model do you have in that case used or which would recomend?
The idea was to wear a Gopro camera or Nex5 or Nex7.
An awesome but expensive camera gimbal like this would be fun to build.
http://www.dji-innovations.com/products/zenmuse-z15/overview/

LuPalm
01-23-2013, 10:13 PM
Most cameras are light enough for AX-12s or AX-18s. Be sure to have a TTL serial port available from your microcontroller.

jwatte
01-24-2013, 12:02 PM
AX and RX servos don't have as good resolution as MX servos. You probably want the MX servos for the application you're suggesting. The AXs even have a "dead zone" where you get no feedback at all. The RX may have this, too, I don't know. The MX use a high-resolution magnetic encoder that gives readings at 360 degrees.

Another option is to limit the range of compensation. If you build a 4:1 lever mounting system, that will allow you to pan/tilt +/- 45 degrees from whatever you decide "center" is, which will give you 4x the resolution at 1/4 the speed.

tician
01-24-2013, 06:29 PM
The AX/DX/RX-series servos all have a mechanical potentiometer good for (at best) ~300 degrees connected to a 10-bit ADC on a 16MHz ATmega88. For some reason I'm thinking that the EX-series has an additional quadrature rotary encoder for better speed control, but not sure. The MX-series all have a 360 degree 12-bit magnetic encoder connected via SPI or I2C (can't remember) to a 72MHz STM32 (ARM Cortex-M3).