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New high-torque servo for the robotic arm
As you probably already read about, I got performance problems with my robotic arm.
The issue is the relatively high weight of the arm itself compared to the poor torque performance of the cheap servos that I used. So, last week I finally decided to buy new servos for my robotic arm:
I got them bidding on eBay. Basically I wanted to buy two Towerpro MG995R that is a compact but powerful servo, with metal gears that should be capable of 10 Kg/cm.
While looking for them, I saw also the Towerpro 9805BB that shows a great value of 20 Kg/cm of torque in its features.
As the price was really low (mostly because the bid was just started) I offered the minimum which was 11 euros.
Probably I was really lucky because nobody else bidded on it so I got it for 11 euro instead of the 25 of the "buy it now" price!
This powerful servo is amazing big compared to normal ones like the MG995R.
So, now I have 10+10 Kg/cm for the two MG995R and 20 Kg/cm for the 9805BB.
This way I'll have to chose whether to use the two small one for the shoulder and the big one for the elbow (most probably) or the reverse.
Unfortunately for using those new servos I need to build again several parts of the robot, at least the shoulder servo brackets, the arm and forearm.
Anyway, even if with lower priority than my new LCD multitouch display work, I hope to find time in the next weeks to design the new parts in order to have again a fully functional and more powerful robot arm, stay tuned!
The issue is the relatively high weight of the arm itself compared to the poor torque performance of the cheap servos that I used. So, last week I finally decided to buy new servos for my robotic arm:
I got them bidding on eBay. Basically I wanted to buy two Towerpro MG995R that is a compact but powerful servo, with metal gears that should be capable of 10 Kg/cm.
While looking for them, I saw also the Towerpro 9805BB that shows a great value of 20 Kg/cm of torque in its features.
As the price was really low (mostly because the bid was just started) I offered the minimum which was 11 euros.
Probably I was really lucky because nobody else bidded on it so I got it for 11 euro instead of the 25 of the "buy it now" price!
This powerful servo is amazing big compared to normal ones like the MG995R. So, now I have 10+10 Kg/cm for the two MG995R and 20 Kg/cm for the 9805BB.
This way I'll have to chose whether to use the two small one for the shoulder and the big one for the elbow (most probably) or the reverse.
Unfortunately for using those new servos I need to build again several parts of the robot, at least the shoulder servo brackets, the arm and forearm.
Anyway, even if with lower priority than my new LCD multitouch display work, I hope to find time in the next weeks to design the new parts in order to have again a fully functional and more powerful robot arm, stay tuned!
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| Multitouch Display: a plexiglas case for the LCD FTIR multitouch (part one) » |
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hello!
How is the actuation resolution (which is the smallest angle than can be obtain) for yours servos?
I use for my redundant planar robotic arm (4 degrees of freedom) 4 digital servos from Robbe FS 280 T because these servos allow to decrease very much the angular velocity (a big velocity produces vibrations). So, I want to use my robotic arm for follow a prescribed curve and the resolution for angles is cca 1/3 degree.
Thank you! a good day!
@Cornel
Hi, I didn't measured the angle resolution especially because mine is definitively a low precision application. In addition the servos are under heavy load and can't be so precise.
Theorically speaking there are the numbers to reach the resolution you need but most probably you need to use other hw to reach such accuracy. What about using stepper motors?
Nice work on the robot arm and on the display. I'm just snooping around looking for basic beginner robot stuff but your work is very impressive.
Great work, has anyone thought of using the AS5040 magnetic rotary encoder showcased on hackaday to make a robotic arm?
I guess using DC motors.
I wouldd like to make a robotic arm around 5-6 feet long, maybe 4 axis freedom, and possibly holding an object with a mass of no more than 5lbs with 5lbs of torque.
Can this be done?
What were the specs of that kitchen cleaning bot? lol