To expand on the other questions you posted to the new thread.
Yes you are likely going to exceed the fuse protection on the ez-b using 24 dynamixels. It's probably a good idea to breakout the power lines and run them back to the battery with their own fuse protection.
I'd say since you have 24 servos it'd probably be ok to breakout the power wires for 4 sets of 6 Dynamixel servos and run them back to the battery (with fuse protection of course).
Thanks Jeremie. I can easily get a higher voltage power supply.
You seem to know about dynamixels. Are they worth the expense? I need around 40 kg.cm to lift (tilt) and rotate (pan) each shoulder alone in my life size, six foot tall humanoid, but I don't need this much power in the neck, elbows, wrists, etc. Also, I want them to hold their position without requiring power.
I'm currently using Power HD 1235MG servos which can manage 40 kg.cm at 7.5v, but they are really loud, and they do not have failsafe holding brakes in them, so they overheat when there is no pulse as they try to maintain their position, then the arms come crashing down as soon as the power is cut. This also means the arms punch you in the face as soon as you turn the power back on. This can easily break your nose or kill a child.
I therefore need sensible servos that have holding brakes, or strong enough gearing to withstand gravity.
My i00600 Torxis servos have 115 kg.cm of torque, and these would probably jack up a car, but when combined as a tilt pan system they are the combined size of a large human head. No good for wrists, elbows, shoulders or anything human. But they do not rotate at all unless there is a pulse and power going to them. They are rock solid when there is no power or no pulse. This is vital.
The other problem of course is that all of these servos are rectangular, which makes me consider these servos but I don't know how to rig them to the ezb v4:
I called Trossen Robotics to ask about dynamixel servos and found out that they are manufactured by Robotis. Anyway, they told me that dynamixels do not hold their position, and do not plug into microcontrollers using PWM. This last part seemed like misinformation but I don't doubt they they will jitterheat or crash like all the other hobby servos Ive ever tested.
I wish someone would tell me how to achieve these essential tasks easily.
Does anyone know why car windows hold their position so well? Stepper motors don't have internal brakes, do they?
Zxen, Trossen Robotics has provided incorrect information regarding EZ-Robot product specifications. I believe they are unaware that the EZ-B v4 can control more than one type of servo. The EZ-B v4 controls Dynamixel v1/v2 and PWM servos simultaneously.
I do not know what Trossen Robotics meant by "They do not hold their position". All Dynamixel servos (or all servos for that matter) hold their position, which is what servos are meant to do. Whether PWM or serial communication, the servo is instructed to move into a position and that position until instructed to do otherwise.
As Jeremie had mentioned, ensure your robot has correct power source and Dynamixel is a great choice for high precision.
No prob, well I don't have much experience with six foot tall Humanoids lol but I can probably help with your decision making process a bit.
I don't feel that your Robot would benefit from Dynamixels in particular unless you are looking for a specific range of motion (greater than 180 degrees) and you want an extremely stream-lined wiring system with a single signal wire. Otherwise, you'll likely get much more for your money going with Large hobby servos. The Dynamixels that are more suited for large robots are quite expensive.
Budget is what usually constrains most of us on projects like these. I believe in the inMoov project uses large hobby servos attached to worm gears (and Boris even added springs) to hold appendages in position even after power down.
I don't believe that using Dynamixels (without modification) would allow for this type of feature, you would likely see the same result of the arms falling down after power is removed.
Electronic brakes are a great idea in concept but I believe they are very power hungry and would draw all kinds of power when activated. Not ideal if you want to move to a battery operated system one day.
A number of people in the ezrobot community (@Richard R, @bhouston, @D.cochran, @Aerius, @rentaprinta, and I'm likely forgetting many others) have a ton of life size Humanoid building experience so I think I'll have to defer to them to share their experiences with you.
@Jeremie has a point... look at the inMoov project to see how to do a life size humanoid... Especially @rentaprinta's and Bob Houston... I think they have the benchmark of inMoov's
To expand on the other questions you posted to the new thread.
Yes you are likely going to exceed the fuse protection on the ez-b using 24 dynamixels. It's probably a good idea to breakout the power lines and run them back to the battery with their own fuse protection.
I'd say since you have 24 servos it'd probably be ok to breakout the power wires for 4 sets of 6 Dynamixel servos and run them back to the battery (with fuse protection of course).
I thought this was removed in one of the latest updates , and only supported via a plug in?
Thanks Jeremie. I can easily get a higher voltage power supply.
You seem to know about dynamixels. Are they worth the expense? I need around 40 kg.cm to lift (tilt) and rotate (pan) each shoulder alone in my life size, six foot tall humanoid, but I don't need this much power in the neck, elbows, wrists, etc. Also, I want them to hold their position without requiring power.
I'm currently using Power HD 1235MG servos which can manage 40 kg.cm at 7.5v, but they are really loud, and they do not have failsafe holding brakes in them, so they overheat when there is no pulse as they try to maintain their position, then the arms come crashing down as soon as the power is cut. This also means the arms punch you in the face as soon as you turn the power back on. This can easily break your nose or kill a child.
I therefore need sensible servos that have holding brakes, or strong enough gearing to withstand gravity.
My i00600 Torxis servos have 115 kg.cm of torque, and these would probably jack up a car, but when combined as a tilt pan system they are the combined size of a large human head. No good for wrists, elbows, shoulders or anything human. But they do not rotate at all unless there is a pulse and power going to them. They are rock solid when there is no power or no pulse. This is vital.
The other problem of course is that all of these servos are rectangular, which makes me consider these servos but I don't know how to rig them to the ezb v4:
http://www.americanmotiontech.com/Products/ProductDetail.aspx?category=5&model=DCM50207D-1000
Then I could buy a failsafe brake for each servo like this one: http://www.alibaba.com/product-detail/dc-motor-electric-brake_1544631364.html?spm=a2700.7724838.8.29.zAXTzP&s=p
I hate to have to go to all this trouble to do what is absolutely essential in any robot. But nobody makes things properly.
What do you think? Would dynamixel adhere to most of these conditions?
I called Trossen Robotics to ask about dynamixel servos and found out that they are manufactured by Robotis. Anyway, they told me that dynamixels do not hold their position, and do not plug into microcontrollers using PWM. This last part seemed like misinformation but I don't doubt they they will jitterheat or crash like all the other hobby servos Ive ever tested.
I wish someone would tell me how to achieve these essential tasks easily.
Does anyone know why car windows hold their position so well? Stepper motors don't have internal brakes, do they?
I know why car windows hold their position.... Google worm gear....
Zxen, Trossen Robotics has provided incorrect information regarding EZ-Robot product specifications. I believe they are unaware that the EZ-B v4 can control more than one type of servo. The EZ-B v4 controls Dynamixel v1/v2 and PWM servos simultaneously.
I do not know what Trossen Robotics meant by "They do not hold their position". All Dynamixel servos (or all servos for that matter) hold their position, which is what servos are meant to do. Whether PWM or serial communication, the servo is instructed to move into a position and that position until instructed to do otherwise.
As Jeremie had mentioned, ensure your robot has correct power source and Dynamixel is a great choice for high precision
.
No prob, well I don't have much experience with six foot tall Humanoids lol but I can probably help with your decision making process a bit.
I don't feel that your Robot would benefit from Dynamixels in particular unless you are looking for a specific range of motion (greater than 180 degrees) and you want an extremely stream-lined wiring system with a single signal wire. Otherwise, you'll likely get much more for your money going with Large hobby servos. The Dynamixels that are more suited for large robots are quite expensive.
Budget is what usually constrains most of us on projects like these. I believe in the inMoov project uses large hobby servos attached to worm gears (and Boris even added springs) to hold appendages in position even after power down.
I don't believe that using Dynamixels (without modification) would allow for this type of feature, you would likely see the same result of the arms falling down after power is removed.
Electronic brakes are a great idea in concept but I believe they are very power hungry and would draw all kinds of power when activated. Not ideal if you want to move to a battery operated system one day.
A number of people in the ezrobot community (@Richard R, @bhouston, @D.cochran, @Aerius, @rentaprinta, and I'm likely forgetting many others) have a ton of life size Humanoid building experience so I think I'll have to defer to them to share their experiences with you.
@Jeremie has a point... look at the inMoov project to see how to do a life size humanoid... Especially @rentaprinta's and Bob Houston... I think they have the benchmark of inMoov's