FAQ about RC Servos

I have AMC1280USb and want to make a small 6DOF stewart platform with mini servo's.

On dropbox there's an example with a pololu serial servo controller. I have bought the newer version - micro meastro 6 channel usb servo controller - and wonder if I can use it instead. Looking at the specs of both boards, the main difference is the supply current/curretn consumption : for the serial servo controller it's 5mA and for the micro meastro it's 30mA (http://www.pololu.com/product/207 and www.pololu.com/product/1350/specs).

I also have a question regarding the pin header (not sure how it's called) In the dropbox folder "connection diagrams" there's a picture with a header on pin S2 (https://www.dropbox.com/sh/641qkq11p3prar1/AAD8-wC_f60334oZiaHNmNM3a/Connection%20Diagrams/Connections%20to%20miniservos%20(mini%206DOF%20platform)/IMG_20140611_102747_931.jpg?dl=0) while in the folder 'photo's of AMC1280USB - new mini servo" there's a picture with a header on pin S (https://www.dropbox.com/sh/641qkq11p3prar1/AAAUI6yDlS2pAnjxpf2FzE_Ba/Photos%20of%20AMC1280USB/new%20mini%20servo%206DOF%20platform/IMG_20140130_074451_423.jpg?dl=0) ?

Thx in advance

Xa4

Hey Mitch,

TY for very much for your reply, very helpful ... I'll buy and use the #207.

I'm a civil engineer and know little or nothing about electronics. I read a lot about arduino and others, but never actually used them, so everything is very new to me. I have a lot of other questions (probably stupid ones) and hope I'll be able to ask them here without being regarded as annoying ... I guess other electronic noobs could be helped by them.
Also worth mentioning, my goal is to make a full scale platform with AC motors and inverters (or maybe clearpath motors ?) and combine it with the Oculus Rift.

Here are a few other questions :
* I have six pololu servo motors HD-1501MG (http://www.pololu.com/product/1057). According to the datasheet they pull 500mA at no load and 2500mA at locked (both at 6V). Now I wonder what kind of power adapter I need. 2.5(A) x 6(V) x 6 (motors) = 90 Watt @ 6 Volt .... is this correct ?
* regarding the jumpers and dip switches : there is little information about them. Is there a overview of what the s1-s4 jumpers and 1-4 dip switches are for (and when to use them)
* lots of other questions about a full scale platform regarding ac motors vs crearpath motors, motor position, dimensions, ... but I'll ask them once I'm finished with the scale model and post them in the appropriated thread.

xa4

Hi guys - I'll help out with what I can!

I'm using HS-322HD servos because I already had them kicking around - I would imagine the current draw is similar to what you're using and there is really never any load on the platform. I'm using an AC to DC converter that puts out 5V 2000mA (which I also had left over from some long gone piece of electronic equipment) and it seems to work fine for me.

Originally before I bought the AMC1280 I used an Arduino Uno as a stand alone controller and also tied into buttons and accelerometers of a Wii nunchuck for input. It was fun little project and got me familiar with inverse kinematics and how it applies to this platform, as well as noise filtering for the accelerometers. I had the top and bottom plates laser cut at a local plastic shop - I had two sets made at the same time because it cost almost the same (which was really cheap). The finish was really good and only took a little modification to make it work. Its a good thing I had a spare set because I cracked and broke one of the top plates while trying to attach something to it and tightening a screw too much. I bought the high angle rod ends from a local RC hobby shop in a pack of 12, and they came with screws and nuts and spacers. The only trouble I had was finding arms - and had to cut a package of longer arms down to size and drill new holes (~1" spacing), as well as put a z kink into the arms to get full travel (due to the odd spacing from the servo to the arms I used).

The #207 is basically a translator - it takes serial communication from the AMC1280 and turns it into a something the servo motors can deal with... PWM or Pulse Width Modulation. Check out:  www.servocity.com/html/how_do_servos_work_.html#.VASl9fldVK8

WRT to dip switches, check this out from the AMC1280 user manual:

DIP Switch Buttons :

-DIP SW1: ON position, enables LCD menu and realtime values on the LCD. OFF position, Disables LCD menu and allows the controller to do even more calculation per second. Its recommended to set this Dip Sw1 to OFF position after you done tuning or changing configuration values.

-DIP SW2: ON position, Sets Serial speed 125000bps OFF position, Sets Serial speed 250000bps

-DIP SW3: ON position, Sets Unidrive method where the analog output signal provides both direction and speed OFF position, Sets Bi-directional method that is most common for VFD inverters.

-DIP SW4: ON position, enables the DC motor PWM outputs. (6DOF ext is disabled) OFF position, enables the 6DOF extension board outputs


Good luck!
-Mitch