Mechanics and Construction > Mechanics and Construction
Servos
YAN-1:
Well I am considering finding a stronger servo for the shoulder and use this monster servo for the elbow. Do you know of any type of servo that can provide this torque? I would appreciate that a lot. Thank you very much.
Nichola V. Abdo
Admin:
Again, your only option is to do gearing. There are no servos any stronger.
Robotzone has this item that can multiply torque by x5 on the HS-805BB servo:
http://www.robotzone.com/customer/product.php?productid=186&cat=51&page=1
But personally its way over priced for a gear and some plastic hinges. Better if you copy and make it yourself.
But I still say worm gears are best. Just google worm gear box and find one to attach your servo to.
http://www.google.com/search?sourceid=navclient&ie=UTF-8&rls=GGLC,GGLC:1969-53,GGLC:en&q=%22worm+gear+box%22
Admin:
FYI, Hitec has come out with new 7.4V higher torque digital servos.
I am not sure if they are selling them yet, but the HSR-5995TG has 416.61 oz*in (30 kgcm)
YAN-1:
--- Quote from: Admin on March 25, 2006, 05:10:19 PM ---Again, your only option is to do gearing. There are no servos any stronger.
Robotzone has this item that can multiply torque by x5 on the HS-805BB servo:
http://www.robotzone.com/customer/product.php?productid=186&cat=51&page=1
But personally its way over priced for a gear and some plastic hinges. Better if you copy and make it yourself.
--- End quote ---
Well thanks a lot. I think I'm gonna use the HS-805BB for the shoulder with that gear box using a gear ratio of 4:1. This will give a tourque of about 97 Kg.cm, which is very safe. As for the elbow, I think I'll use the same combination but with a gear ratio of 2:1. The previous calculations, when done on the elbow joint, show that it needs to carry around 25Kg.cm in the horizontal position. This motor/gear combination will give it around 49 Kg.cm. But as for this gear box, can its input be easily attached to the servo and can its output connect to the arm easily as well?
And as for the servo itself, it says here: http://www.servocity.com/html/hs-805bb_mega_power.html that 'Operating Angle: 45 Deg. one side pulse traveling 400usec'. What does that mean? It only moves forwards and backwards within a range of 45 degrees? That's not enough! And won't this range be divided by the gear ration if I use the gearbox?! Also, what does '360 Modifiable: Yes' mean and how do I adjust it to rotate for 360 degrees?
Thanks a lot. I really appreciate your help.
Nichola V. Abdo
Admin:
You might be interested in this too:
http://www.servocity.com/html/hsr-5995tg_ultra_torque.html
I have never used that gear box, I couldnt tell ya if it is easy. The pic looks simple tho . . .
All servos will travel about 180 degrees, unless otherwise specified. Remember, if you do a 4:1 gearing, your full motion will be 180/4 = 45 degrees.
I am not entirely sure what Operating Angle means, I couldnt find the definition anywhere. My GUESS is that it is how many degrees your servo will travel with a single pulse of 400us.
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