Newbie.....very new. Robotic help.
Whats up everyone!
Ive been doing alot of research for starting my very first robotic project, A humanoid. Im a bit excited and kinda need a lil bit of direction on if im choosing the right products for this project. I also wanted to know if theres anything else i should put into consideration for motions control purposes.
The hardware is already set up (1ft.tall, 2inch wide at waste, .5 inch width for legs and arms.)·andall thats needed is the servos, sensors, and anything else i decide to add on. I calculated 14 joints (knees, elbow, etc). for the joints i·plan on using· HI-TEK HS-50·servos·all thru out. the reason·i·chose these servos was because its small in size. i also have a few sensors in mind but that wont be added till lata on once i get this thing moving.
I want to be able to control the robot using a Playstation control wireslessly would anyone have any idea on which RF trans./receiver package would work for me?
And finally , would i be able to get this done using my BS2?
Its a pretty simple setup, just not sure if i covered it all.
ANY input would be greatly appreciated.
Thanx in advance.
Ive been doing alot of research for starting my very first robotic project, A humanoid. Im a bit excited and kinda need a lil bit of direction on if im choosing the right products for this project. I also wanted to know if theres anything else i should put into consideration for motions control purposes.
The hardware is already set up (1ft.tall, 2inch wide at waste, .5 inch width for legs and arms.)·andall thats needed is the servos, sensors, and anything else i decide to add on. I calculated 14 joints (knees, elbow, etc). for the joints i·plan on using· HI-TEK HS-50·servos·all thru out. the reason·i·chose these servos was because its small in size. i also have a few sensors in mind but that wont be added till lata on once i get this thing moving.
I want to be able to control the robot using a Playstation control wireslessly would anyone have any idea on which RF trans./receiver package would work for me?
And finally , would i be able to get this done using my BS2?
Its a pretty simple setup, just not sure if i covered it all.
ANY input would be greatly appreciated.
Thanx in advance.
Comments
1) You have 14 servos. Each one requires an I/O pin for control. The BS2 only has 16 I/O pins. That leaves only 2 I/O pins for other things.
2) A servo requires a control pulse approximately 0.5ms to 2.5ms in width, more typically 1ms to 2ms for about 180 degrees of motion. These pulses have to be repeated roughly every 20ms. With 14 of these, that's 35ms total width worse case ... not enough time since the Stamps can only do one thing at a time.
3) What I'm getting at is that a single Stamp will not do for what you want. You'll need either an external servo controller like the Parallax Servo Controller (and you'll need two of them for 14 servos) or you need to use a different microcontroller with more I/O pins and some parallelism (like the Propeller). An SX would also work for the servo controlling, but you might run out of processing capability once you add sensors and the RF link.
4) The Playstation controller uses a clocked serial protocol with some other signals as well. You can't use a plain RF receiver/transmitter for that. You'll need some kind of microcontroller at the Playstation end. For the RF link, I'd suggest using an xBee which provides a nice bidirectional asynchronous serial link with built-in error checking (see www.selmaware.com). You could use something as simple as an SX microcontroller at the Playstation end. A Stamp would sort of work, but you really need to do two things at once (read the Playstation controller and talk to the RF link).
The Propeller has its own language (SPIN) which is very similar to C. There's a growing library of contributed I/O drivers and other routines including a controller for up to 32 servos, a complete floating point package, drivers for various sensors, etc.
My personal bias is that the Propeller is a better investment in time and energy for any complex project. It's a bit harder to learn for someone unfamiliar with programming (mostly because the years of accumulation of tutorials, books, and other documentation available for the Stamps isn't there yet), but it's easier than most people think. There's a growing accumulation of documentation and examples (like the Propeller Education Kit tutorials). For your application, the best development board is probably the one from Wulfden (www.wulfden.org/PRC/index.shtml) which is designed for robot control use. It has lots of headers for attaching servos and sensors, but includes a small breadboard area for testing and development of new stuff. It's pretty small and easy to assemble. You'll need a USB adapter from Parallax. Either the USB2SER or the PropPlug will work if your computer has USB ports (you'll need to be using Windows XP or later). If you have "real" serial ports, Wulfden sells an adapter that works with that.
Wulfden also has keyboard/mouse/display adapters for this board that are really handy for debugging and development. The Propeller does all the work for the PS/2 keyboard/mouse and the TV or VGA display. Since the Propeller has 8 processors, you can dedicate 2 or 3 for debugging to "watch" other variables in the program and to allow you to set or change variables used by other parts of your program.