Serial Servo Controller
Pololu Micro Serial Servo Controller, from SparkFun Electronics
Since I am still waiting for my servomotors to arrive from across the ocean, I went ahead and assembled the servo controller. I decided to use the Pololu Micro Serial Servo Controller, which I ordered on Free Day from SparkFun electronics. I did not end up getting it for free, however, as I am too slow on the “reload” key. Nevertheless, I ordered it anyway, which is exactly what several Internet curmudgeons would rather I didn’t do- “don’t encourage them!” they claim. I like SFU, though, and I have to support my Colorado brethren. Maybe I will move back to Colorado one day and become a combined snowboard bum / electronics guru!
The Micro SSC, despite being the size of a postage stamp, is not the latest technology, and is being threatened with extinction itself by a slightly more expensive USB-connecting version. In fact, it implements the serial protocol from an even older controller, the SSC from Scott Edwards Electronics, which had it’s debut way back when “Nuts and Volts” magazine was in that weird large tabloid format. I used it successfully on several projects, mostly interfaced to an HC11 Miniboard (thank you Fred Martin and MIT Media Lab!) or a Basic Stamp BS1. It had a remarkably easy command structure, and you could string several of the boards together to get even more servos online. Neat!
The Pololu unit implements the old SSC interface, but also a much-improved interface of its own that has lots of nice features like travel limits and travel rates, etc., all of which make for a much nicer robot arm. I will probably start off using the old SSC language that I am familiar with, and then move to the new framework as I need the additional features (or as I break servos doing the usual stupid stuff…)
Next step is to set up the pendant for programming the robot. Ultimately, I am planning on integrating one of the several open source inverse kinematics frameworks available or path planning, but for now I am going to integrate a simple “do as I do” training system, using an old Playstation 2 joypad that I have sitting around. While I am waiting for the servos to come in, I will set that up- watch for a post on that topic in the next couple of days.
