woah! thats a project that will keep you occupied for a long, long time! it looks cool, but I’m wondering what servos you are going to use… good luck and send pics and videos when you start!
Sam
If I’m reading my wieght chart correctly, it says that the arm will way an estimated 1.107 lbs TOTAL, thats all the hardware (WTF???). I don’t think thats write.
What about linear acutators for moving the leg up and down?
woah thats cool!!
Sam
I ran into the same problem looking for high torque output geraboxes, they were all 50kg and below. I think i would have to make a custom one for it, but I don’t know anything about drive trains, so I would have to invest a good amount of time into R&D.
I was thinking about a 110lb force actuator for the Trochanter to Femur, then 40lb for the rest.
But, if I scaled back, maybe to 2x the sixe of the spider, the leg would only be a total of 15 inches long. This would be manganable by the servos. Now for the 4x spider, Linear actuators are looking the way to be.
Ok, here’s the skinny. After about 5 hours, I pouned out a design for an actuated leg with a servo that will move it left an right.
It’s looking to be about 3lbs (no actuators or servo) be leg because so that it can handle the amount of force applied to it by the actuators.
I will post a picture once I get the design finalized to where I want it. Probably only take about 3 hours, I have to make a 3D model of the actuators for reference.
Wow… I hadn’t been keeping up on your hexapod progress, Matt.
You certaintly take things to a whole new level!!!
About them thar linear actuators…
Have you been coupling their outputs them to something like an anti-backlash ball nut to get rotary motion out of them (and thus use them just like we do servos)?
Or are you directly coupling them to the joint like a construction escavator’s boom joints are?
Man, so I have to design new brackets and legs for the actuators now that I have their lengths, the old one wouldn’t work, to much stuff in the way. Who knew R&D could be so painful, now I feel sorry for these folks.
I know that Hitec built the servo for Robo-One builders. The robots are only operated for a very short time in the competitions. This is no excuse for them not publishing this information. But it is the truth behind the situation.
Nice metal work! 
THAT THING IS AWESOME!!! r those micro servos?
I think they’re the aforementioned robot servos which can’t be used for more than a few minutes- hence the expensive paperweight comment!
that is realy cool!!! I want to do a hexapod now 
Well, I’ve almost completed rendering one of the legs.Just have to tweak the last 3 limbs then it’s a go for stress analysis, and what not.
I’ve modeled all the actuator’s I plan on using, and haven’t made them movable, that’s the next part.
Once that’s completed, it’s to move on to the grippers, fangs, and then the body. I’ll proabably have pic’s up either if I finish Monday or next weekend. Going mudding today, then helpin’ neighbor sunday, this weekend is shot.
http://i105.photobucket.com/albums/m208/The_Captain_2006/Robotics/Concept%20Pictures/ActuatedArm.jpg
Heres the pic of the actuated arm Im designing. In actuators go as follows farthest to closets.
200lbs of force - 4in stroke
165lbs of force - 3in stroke
165lbs of force - 3in stroke
200lbs of force - 4in stroke
165lbs of force - 2in stroke
It’s reach is 48" long, and 20" high
Estimated mass of arm in picture ~12kg
Right now, these are model from here. They are for moving TV screens and such. I’m also looking into modeling these.
The ones from Ultramotion I can get Linear POT in them.
As for Rotary Position Sensors, I never thought of that. So I got do some research. I hate research.
gonna be a lot of h-bridges in that baby.
Once I finish modeling the Spider to the point I can begin pricing out parts, I will release the files under GPL for others to few.
Just wondered if you’ve taken speed into any of your calculations. All the high power actuators you are using are around 1/3" per second stroke. That could make for a very slow spider. Go to 1.75" to 2" per second stroke and you have 28 to 40 lbs of force.
the mechanical advatage he has built in should speed it up,but at .7"per sec. still gonna take 6 sec. for a 4" stroke ,hmmm(sticks arm out straight in front and moves it up to 90*1 mississipi,2mississippi,3m,)
i think i could live with that,
I did look at the faster actuators, but when I did a torque problem, it was just barely enough. So that’s why I went to bigger actuators. Plus because they have move power, they can move faster because they have less load on them.