PDA

View Full Version : Stabilization



bigbearchopper
01-28-2008, 07:28 AM
I am new at the Propeller chip and just starting to read about how to program it. My main reason to switching to the Propeller chip from the Basic Stamp PX is I have an application where I have two motors that control a pointer that needs to be stabilization on a rolling vehicle. To give an idea of the size I am talking about the motors have 400 in/lb of torque and run through a 50 to 1 worm gear. The pointer has a camera on the end and I need to stabilize this pointer so the camera can be viewed while driving. I do not know 'specs' to say what the stabilization needs to be, but it needs to be fairly fine. So, can the Propeller chip handle such a task, and how big of task is it going to be to write the program?

Thank you for helping a beginner at this.

RinksCustoms
01-28-2008, 11:19 AM
I think I understand what your getting at, and I can suggest to keep the main program sweet and short would be to use a digital helicopter gyro controlling a digital coreless servo (http://www.futaba-rc.com/radioaccys/futm0807.html), using a pwm signal from the prop for the cameras pointing. The gyro (on one axis) will stabalize the camera once calibrated corectly. Ex.- if you setup the gyro to stabalize the Y axis, then it should all but eliminate the verticle bumps from your viewpoint.

However if you have a 3 axis camera stability system in mind, would require a dynamic suspension system either mechanically or electronically. Electro-mechanical approach would probably require the camera be mounted to a 3-axis motorized arm or table using 3 stepper motors, a 3-axis accelerometer, and a bit of creative programming to dynamically stabalize the camera.

The mechanical route would involve some very careful selecting of suspension springs and also devising a way to dampen the springs so that your image is stable over bumps yet not over-dampened so that your image is still jumpy.

Still a bit fuzzy here with details, but nothin for nothin, any motor going throught a 50:1 gearbox is going to do little in the way of image stabalization. Perhaps you could get away with using a few brushless digital·servos (http://www.gpdealera.com/cgi-bin/wgainf100p.pgm?I=FUTM0551)used for hobby? Each of these feature a rating of 210 oz-in & 0.13 sec/60deg @ 6.0V. Stack two together or facing one another (one signal reversed) and you have 420oz-in & 0.13 sec/60deg with each servo weighing about 2oz.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
E3 = Thought

http://folding.stanford.edu/ (http://folding.stanford.edu/)·- Donating some CPU/GPU downtime just might lead to a cure for cancer! My team stats. (http://vspx27.stanford.edu/cgi-bin/main.py?qtype=teampage&teamnum=78528)

grasshopper
01-28-2008, 12:43 PM
As far as i understand it the propeller can do anything. It is going to be up to the supporting hardware to do the work of the motors you mention.

bigbearchopper
01-28-2008, 05:25 PM
Can someone direct me to some sample programs that may be a good direction to start with for the stabilization?

ANy more suggestions on type of gyro and accelerameter to use that would be of high enough quality for this?