RoboSavvy Forum Robosavvy Forum: The largest online community of Humanoid Robot Builders 2016-05-06T15:09:06+01:00 http://forum.robosavvy.com/feed.php?f=1&t=14220 2016-05-06T15:09:06+01:00 2016-05-06T15:09:06+01:00 http://forum.robosavvy.com/viewtopic.php?t=14220&p=43701#p43701 <![CDATA[Re: XYZrobot A1-16 Review]]>
To do that we secured the 3 servos into a piece of MDF and tried to send the same command to all 3 (not a easy task as the BUS is not the same)

To do this we connected the output ports of the CM-530 to a input pin of the XYZ controller board to trigger the same action.

First we checked the speed on position control and then on wheel mode.

After that we went to test the A1-16 position control method with a payload, for that we used 1050g at 10cm and performed some tests.

Check the video for more details

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As you saw on the video the speed is very similar to a AX-12 on position control mode (turning 180º) but that on wheel mode it's faster.

Regarding position control is almost inexistent, let's start by the test 3 on the video.

Small increments in position with a payload, it seems that the servo is trying to go to the goal position but it does not move, what the hell were the firmware guys thinking about? If you do the same test with a ROBOTIS Dynamixel it will try to go to the goal position and will only fail if the payload is bigger than the specs.

On the test 4 you can see that with the exactly same payload but sending the command to move more it will actually move, this means that the servo is powerful enough for that payload just the firmware is badly designed...

After this tests we tried to check how much payload it will hold without trying to move. Unfortunately the horn is not powerful enough and with about 2.6kg at 10cm the plastic was the weakest part. As you can see on the image below the plastic horn should be a square with a trimmed corner and it's now more like a deformed square that rotates on the metal shaft.
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We would like to check what would be the maximum moving and holding torque for this servos but due to this issue we were not able to check it as the horn would rotate on the shaft. We performed those tests on the ROBOTIS Dynamixel AX-12A and AX-18A, check the results on this other forum post

Conclusion, there's some potential on the servos in terms of hardware but the bad position control and the very bad designed horn will make it very hard to use as you will have unexpected results.

Statistics: Posted by nunogato — Fri May 06, 2016 3:09 pm

]]> 2016-03-31T12:00:09+01:00 2016-03-31T12:00:09+01:00 http://forum.robosavvy.com/viewtopic.php?t=14220&p=43694#p43694 <![CDATA[XYZrobot A1-16 Review]]>
We just received 4 x A1-16 servos from XYZrobot to check the specs and to compare to what seems that they want to compete against the ROBOTIS Dynamixel AX-12/AX-18.

We only had time to make some photos where you can see how similar this servo is to a AX series from ROBOTIS

We are preparing some tests to see how it compares in terms of speed control, position control, torque and strength of the gears with ROBOTIS servos

For now here are the announced specs and some photos below

  • Operation voltage : 8 ~ 12 V
  • Maximum speed : 70 ± 10 rpm
  • Stall torque : 25.0 kg-cm max
  • Operation Degree : 330° effective position control and endless turn speed control
    Range in software is from 23 to 1001 where 512 is the center position, this gives a resolution of 0.337º
  • Protocol type : Duplex UART 5V TTL serial communication(8, N, 1)
  • Communication Speed : 9600, 19200, 57600, 115200(default)
  • Feedback Information : Position, Temperature, Current, Voltage, etc

ImageImageImageImage

To see the complete set of photos visit this Flickr album

Statistics: Posted by nunogato — Thu Mar 31, 2016 12:00 pm

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