That gripper is working well. As I've said before my gripper stinks and has been the Achilles heel of my arm. My current thinking is the electromagnet picking up foam blocks with a washer glued to the top, but that is backed up behind CNC machine completion.
Are you planning to do inverse kinematic transforms using a co-processor, canned motion scripts, or something else?
Ted: Sure, here's a pic for you to hold you over until your next Robot magazine arrives! It's a quickie slam build, CA gluing servo to servo and aluminum tube. It's beauty lies in its simplicity & low cost. The whole robot costs ~$50 if you know where the deals are! At that price, it's not currently controlled by a Parallax product, but it will be at some point.
This thing is a hoot! More accurate than I dare hoped, with light loads anyway. Everybody oughtta build one of these, they're lots of fun to play with. Er, I mean, scientifically calibrate and empirically determine the coefficients of dynamic performance.
It will be in the next issue of ROBOT magazine (May/June). Just sent to the publisher, probably on the newsstand in 4-6 weeks.
TTYTT, I used three generic 9-gram servos costing ~$2 each from Ebay China, but since the servos are glued directly together, I would recommend using HXT-900 servos from Hobby King. They are barely more expensive at $2.69, but supposedly much more robust. A better gamble for a one-time installation.
Good prices, bad response time. Allow 3+ WEEKS for delivery. Sometimes it takes a week to get an "order acknowledged and sent to warehouse" verification!
It's fun to see it stack those blocks. You could add some blocks with numbers and have it keep track of the time.
We were given a little calendar that uses two blocks for the date. All the possible days of the month could be made with two blocks with numbers on their sides. It does require the "6" of some dates be used as a "9" for other dates.
I just noticed the HXT900 servos are back in stock. I should be posting pictures soon of my recent 18-servo project (using these small servos).
Hexapod, I'm guessing? Burning thru your supply of popsicle sticks with wild abandon? 3 of ten fingers still superglued together?
You're right about the hexapod.
My superglue was all dried up so I'm using Polymorph. I'm also using some M2 nuts and bolts to hold some things together.
None of my 9.9 fingers (table saw claimed 0.1 of them) are currently glued together (which isn't alway the case). ( I've also had my eye glued shut before. I now always wear safety glasses when using CA.)
I have been burning through my popsicle sticks but my box of 1000 (aka craft sticks) looks like it still has over 900 left so I should have enough to finsish this bot.
I sure hope there's no Altoids tin in your design.
That's a great idea! An Altoids tin is just the right size for a chassis.
Or, not. The main body will likely be one popsicle stick wide and two popsicle sticks long. I had initially tried to make it just one popsicle stick long but then the legs were too close together to move. Not that they are moving at all now. Who would have thought getting 18 servos to move in a coordinated manner would be a trick?
I just noticed the HXT900 servos are back in stock. I should be posting pictures soon of my recent 18-servo project (using these small servos).
I just got my first HXT servos from Hobby King yesterday (took a MONTH to get here, sheesh). Supposedly stronger gears than my generic HK $2 servos. They feel smoother. Best thing is that they rotate ~190 degrees, whereas my HK servos are more like 170 degrees. Worth the extra dollar, but waiting that month was painful.
Comments
Are you planning to do inverse kinematic transforms using a co-processor, canned motion scripts, or something else?
No co-processor for me. That's cheatin'!
For now, canned scripts, ultimately will use an IR teach pendant. Will try several different processors on this arm. BS2 HW board shown here.
@
So are roboticists...
One more late night and it's headed for an article in the next ROBOT magazine.
What kind of wire are you using in your linkage?
Amanda
PAPER CLIPS, of course! Plentiful, strong and easy to bend. Large wire paperclips.
Arrrr... forgot all about those. Even have a box of them sitting on my desk! :-|
Have to sort through mine tho'. Some of them have little crimp marks so you can't bend them without breaking. What a lame idea =that= was!
@
I think it's great. Form follows function. I would love to see plans/instructions on the gripper design.
Took your suggestion, ordered some 9 gram servos from ebay.
Looks like a fun build.
Keep us posted on what issue of SERVO your article appears in, I’ll pick up a copy.
TTYTT, I used three generic 9-gram servos costing ~$2 each from Ebay China, but since the servos are glued directly together, I would recommend using HXT-900 servos from Hobby King. They are barely more expensive at $2.69, but supposedly much more robust. A better gamble for a one-time installation.
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=662
Good prices, bad response time. Allow 3+ WEEKS for delivery. Sometimes it takes a week to get an "order acknowledged and sent to warehouse" verification!
I took a gamble and got the ones below. 4 @ $10.80 delivered
http://www.ebay.com/itm/4x-TP-SG90-mini-servo-800g-Torque-Helicopter-Cat-Boat-S-/120651545973
It's fun to see it stack those blocks. You could add some blocks with numbers and have it keep track of the time.
We were given a little calendar that uses two blocks for the date. All the possible days of the month could be made with two blocks with numbers on their sides. It does require the "6" of some dates be used as a "9" for other dates.
I just noticed the HXT900 servos are back in stock. I should be posting pictures soon of my recent 18-servo project (using these small servos).
Hexapod, I'm guessing? Burning thru your supply of popsicle sticks with wild abandon? 3 of ten fingers still superglued together?
You're right about the hexapod.
My superglue was all dried up so I'm using Polymorph. I'm also using some M2 nuts and bolts to hold some things together.
None of my 9.9 fingers (table saw claimed 0.1 of them) are currently glued together (which isn't alway the case). ( I've also had my eye glued shut before. I now always wear safety glasses when using CA.)
I have been burning through my popsicle sticks but my box of 1000 (aka craft sticks) looks like it still has over 900 left so I should have enough to finsish this bot.
That's a great idea! An Altoids tin is just the right size for a chassis.
Or, not. The main body will likely be one popsicle stick wide and two popsicle sticks long. I had initially tried to make it just one popsicle stick long but then the legs were too close together to move. Not that they are moving at all now. Who would have thought getting 18 servos to move in a coordinated manner would be a trick?
OR, simply use one servo and one motor for all 6 legs.
http://www.youtube.com/watch?v=LsTKAtBBkfU
I just got my first HXT servos from Hobby King yesterday (took a MONTH to get here, sheesh). Supposedly stronger gears than my generic HK $2 servos. They feel smoother. Best thing is that they rotate ~190 degrees, whereas my HK servos are more like 170 degrees. Worth the extra dollar, but waiting that month was painful.