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DiverBob wrote: »
I don't know what the duty cycle is for the actuators but I'm not too worried about that in this application. My duty cycle should be fairly low since most of the time walking will be switching quite a bit between different legs so the motors will get plenty of rest!
The Pittman motors are nice motors, I bought about 10 new from Pittman several years ago and they work pretty well. They have a 120 rpm gearbox but I can stall the motor easily with my hand. I'd almost like to devise a way to use another linear actuator to control the swing motion but they are a bit large and it would require some redesigning to the swing mechanism. I was looking at several sites last night with hi torque gear motors, most of them cost at least a hundred bucks which isn't out of line considering how much I even found some linear actuators that could move 450 lbs at only $500 apiece! I've even looked at geared servos, the motor price is reasonable but they require additional control electronics which drives up the price considerably. I'd like to stick with brushed DC motors at 12v to be compatible with what I have done so far. Any suggestions are welcome. I'm sure some one else has had a similar problem and came up with a good solution!
GeckoKev wrote: »
Really impressive project!! Just curious, what do you use for CAD and CAM software?
erco wrote: »
This just in from Captain Obvious: Seems like you may need a larger gear or sector (half gear) for leg sweep (rotation), if you can shoehorn it in. More likely redesign. My guess is that double the current size would be the minimum, and even bigger is better. A spur gear pinion would drive that much more efficiently than the worm gear, and last longer.
RobotWorkshop wrote: »
You can pickup used ones for both books very inexpensively on Amazon. They are both worth having on hand.
cr0sh wrote: »
... cover of a future issue of Servo magazine!
Duane Degn wrote: »
I agree with others, this is an amazing project.
What about adding a way to sense the current to the motors. Wouldn't an obstacle cause the motor to draw more current? Of course you wouldn't be able to detect the object until after it had been hit. Current sensing might also be able to tell you when the leg is in contact with the floor since there would be more resistance to the motor's motion.
Thanks for taking time to document this. It's a lot of fun to follow along.
Ken Gracey wrote: »
DiverBob, is it practical with that Tormach CNC to add some flood coolant?
DiverBob wrote: »
It's fairly easy to add flood coolant. I got their stand and it has sloped sides and directs the runoff behind the stand where the reservoir tank, filters and pump would be located. I'm adding flood coolant soon but I want to build the full enclosure first using 80/20 aluminum extrusions to contain the coolant splashing.
Tormach also sells a flood coolant option but I'm going more with the home built version!