Need advice: Two servo tilt/swivel mount.

Oldbitcollector (Jeff)

I have a "device" (approx: 4"x5", weight around 5 ounces) which needs to be mounted on my bot. It has a center bolt hole in the bottom.

I need it to tip upward and side to side. (picturing two servos here)

I could use some advice on something I could build from hardware store typical materials.
(My mechanical limitations are starting to haunt me here.)

OBC

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Propeller Feature Projects: PropellerPowered.com
Visit the: PROPELLERPOWERED SIG forum kindly hosted by Savage Circuits.

hover1

Jeff,

Don't know how much you want to spend, but I have used two of these so far, (why re-invent the wheel? Only Phil has the cool gadget for making his own [noparse]:)[/noparse] :

·http://www.servocity.com/html/spt200_pan___tilt_system.html

This one will handle up to 10oz and is a lot cheaper:

·http://www.servocity.com/html/spt100_pan___tilt_system.html

Note: Servos not included

Jim

John Abshier

Lynxmotion has one that uses regular servos and one that uses micro-servos if you are short on space. Have always shipped quick to me and delivery from IL will be fast for you.

http://www.lynxmotion.com/Category.aspx?CategoryID=61

John Abshier

Markov

other than buying a pan/tilt head meant for robots at most any internet shop--taking head off of used camera tripod would give you swivel at the base and 2-axis tilt platform (and probably of 'better' quality)--add your own servos--easy enough. can generally get good tripods cheap used and a reasonable one will have pretty good mechanical joints either a single ball (cheaper) or two-axis (might be easier to adapt to servos) mounted on a 'swiveling' flange that bolts down. Better (old-fashioned maybe) large format camera tripod heads tended to use a flange/bolts--others thread onto the leg assy otherwise --but all have some means of attaching to tripod legs that should be easily adaptable. you can buy new heads (only w/o legs--for better systems you choose the head you want for a set of legs you want. some rise on a column that, with clearances for such could also be adapted to a linear actuator giving you a height adj. Bogen makes a lot of good-enough stuff just for example and you can go all the way to top-of-the-line Reis (or other view camera tripods that are well machined but heavier) i suppose. one typically used for 4"x 5" cameras (typically a med. duty tripod was designed for 35mm to 4"x5" camera duty--would cover this). The size you mentioned would be covered easily of course--4x5 cameras weigh several to say 10 pounds and these heads have to account for weight imbalances (heavy glass lenses positioned off-center) so the weight is accounted for. You would just need to attach your servos--the head will have a thumbscrew/bolt to attach through the mounting plate to the bottom mount of (usually a camera)--you might have to adapt the size or else it might clamp to a plate that has a screw for this (this is such that various plates can be used). B&H Photo, Used Department or a host of other camera junk dealers--pawn shops. B&H Photo adapted to the changing world and is still on-line with their store in SOHO NY (fahion/art district--Lots of pro commercial photographers about and they have a lot of good used equipment--they tend to be matter of fact but generally known to be helpful if you don't call on the Jewish holidays. Search for others. Similar stuff is out there meant for other uses like surveying--Camera tripods are abundant though and typically much better deal?--particularly now that digital cameras are the rage and are much lighter--- sooo lots of good old movements laying around collecting dust.

schill

I've used the SPT200 from servocity with mixed success. It's well made and I was using high torque servos, but my load was a little too high. The tilt servo was doing a lot of work holding position unless the weight was directly overhead.

I replaced the tilt mechanism with another version from servocity: http://www.servocity.com/html/ddt540_direct_drive_tilt.html . It's much easier to balance the load with this one and the tilt servo isn't straining as much.

I use this to mount a video camera (actually, one of two cameras weighing 9 oz and 16 oz (without batteries)).

The mechanisms are not that complicated, but I've found that making anything but the simplest version takes me more time than I have available to make the parts precisely enough (matching sides, etc.). For me, this was a case where I decided to throw some money at the solution.

Oldbitcollector (Jeff)

@Hover1, Thanks! Picked up the (SPT100F) Direct Drive Pan & Tilt $19.99

Should work perfectly for what I have in mind!

Lynxmotion wanted to charge me $10 shipping for a $9.00 part. (blah!)
They weren't around to answer the phone today, so I'll try them next time.

Thanks guys! $25.00 well spent will save me a LOT of aggravation!

Looking forward to seeing this work!

OBC

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Propeller Feature Projects: PropellerPowered.com
Visit the: PROPELLERPOWERED SIG forum kindly hosted by Savage Circuits.

Phil Pilgrim (PhiPi)

The main thing I've learned from building my own pan/tilt platforms is not to overload them. Although a given servo may be capable of tilting a certain static load (horizontal panning isn't such an issue), there may still be resonances that lead to very jerky movement. The key is to keep as much mass as possible close to the tilt axis. The bigger your rotational moment of inertia is, the jerkier the motion will be.

-Phil

Oldbitcollector (Jeff)

My ServoCity order arrived this morning! Nice, fast shipping to NE Ohio.

Handed the package of candy they included in the box to the wife and daughter and heading down to the lab.
(With their blessing, it's women's day out today. [noparse]:)[/noparse]

This looks like it will fill the bill nicely! Thanks hover1

OBC

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Propeller Feature Projects: PropellerPowered.com
Visit the: PROPELLERPOWERED SIG forum kindly hosted by Savage Circuits.

hover1

@Phil

I know what you mean about keeping thing on balance, and within the cababilities of the servos. I designed a couple of Owl heads to meet the load limitations of the servos on the ServoCity SP200 Pan/Tilt. 2 Liter cup with 1.5 lb. pour foam around it..perfect, about 1.1 lbs.·Send it out to an artist to finish the facials..all of a sudden, there is is 1.25 lbs of epoxy putty on the front!·This is the second one. The first one was 2 lbs of putty on the front, the are going to learn how to sculpt out of foam!

Found a friend in the Owl's head today, Brown Recluse.·The head has·been sitting on the floor for about 3 weeks, guess it was a nice home. I have caught quite a few in the glue traps around the house, but the is the biggest and the first one I caught alive.·Being more deadly than a·Black Widow, he didn't make it into my petting zoo.

@OBC

Can we get pics or do we have to wait untill the expo?

Phil Pilgrim (PhiPi) said...
The main thing I've learned from building my own pan/tilt platforms is not to overload them. Although a given servo may be capable of tilting a certain static load (horizontal panning isn't such an issue), there may still be resonances that lead to very jerky movement. The key is to keep as much mass as possible close to the tilt axis. The bigger your rotational moment of inertia is, the jerkier the motion will be.

-Phil

Post Edited (hover1) : 6/13/2010 1:38:40 AM GMT

Phil Pilgrim (PhiPi)

hover1,

At the risk of hijacking OBC's thread -- but I assume he's just as curious -- you've got an owl wearing a pack or parachute. WT...? Enquiring Minds Want to Know!^TM

-Phil

hover1

Phil, should be on topic, I'm still talkin' Pan and Tilt [noparse]:)[/noparse]

Darn, I didn't know I posted the full body picture. It's a new drone that I have been working on for the military. I'm in trouble now!

Actually, it's an Owl that sits in a tree at a library. It has big eyeglasses and a little benie (got to get a propeller benie !) so it looks like a young nerdy student, (hence the backback). Pan and tilt movments on the head. 25 random mp3 files played from VMusic2 when triggered by PIR. Beak moves during the time the audio is output, but is not synched just yet. One wing flaps randomly.

This is going to be the second installation, just got to get the artists to think weight, (or lack of)!

Jim

erco

I·doubt if·these 8-gram servos are up to handling your 5-ounce payload, but I'll post this link here nonetheless. A VERY·light-duty pan & tilt for ~$20 delivered from Hong Kong. Might be OK for a PING or Micro DVR cam, anyway!

http://cgi.ebay.com/Servo-Motor-Assembly-Support-Two-DOF-Arduino-robot-/270588005025?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item3f004d4aa1



▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
·"If you build it, they will come."