ROBOTIS e-Manual v1.29.00

Replacing Dynamixel(s)

Table of Contents


  1. A. Proper Installation of horn and bearing set.
    1. Installing the front horn
    2. Installing the bearing set
  2. B. Proper ID and baud rate setting

    1. Method A: You have a USB2 Dynamixel controller and a Robotis dedicated robot controller (CM-5, CM-510, or CM-700)
    2. Method B: You have a USB2Dynamixel controller but do not have a Robotis dedicated robot controller (CM-5, CM-510, or CM-700).
    3. Method C: You do not have a USB2Dynamixel controller nor a Robotis dedicated robot controller (CM-5, CM-510, or CM-700).

 

There may be an instance where you will need to replace a Dynamixel actuator due to failure. The following page will guide you on how to replace a Dynamixel actuator.

To replace an MX-28 on DARWIN-OP you need to complete the following procedures.

A. Proper installation of horn, bearing set to the new MX-28.

B. Proper ID and baud rate setting.

 

Please refer to the assembly guide for reference during replacement procedure.

 

A. Proper Installation of horn and bearing set.#

Every MX-28 on DARWIN-OP comes comes installed with the horn (front side of actuator). Some of the MX-28's come with the bearing set (rear side of actuator) installed as well. You will need a wrench for 2.5mm thick bolt (provided).

Installing the front horn#

Place the thrust horn washer into the actuator before inserting the horn

You must carefully align the horn to the actuator by aligning the dots.

Once alignment is properly done slightly push the horn into the actuator. Make sure not to misalign the horn washer as you tighten the bolt.

 

Installing the bearing set #

You may need to remove the bearing set from the previous actuator and reinstall it into the new actuator. The bearing set can also be purchased separately

For more information on the bearing set please click here. Note that the bearing set is for the RX-28, which will fit perfectly on the MX-28 as they both share the exact physical dimensions.

B. Proper ID and baud rate setting#

Method A: You have a USB2 Dynamixel controller and a Robotis dedicated robot controller (CM-5, CM-510, or CM-700)#

 

  1. Provide power to new MX-28. That is connect one TTL port from the MX-28 to the controller; then power on the controller.

  2. Connect the other TTL port of the MX-28 to the USB2Dynamixel dongle (Make sure to set the switch to "TTL" on the dongle).

  3. Connect the dongle to an open USB port in your PC. Run Dynamixel Wizard.

  4. Change the ID number from 1 to the proper number.

  5. Change the baud rate from 34 (576000 bps) to 1 (1 Mbps).

 

6) After replacement is done. Run DXL Monitor. and reset all Dynamixels.

 

 

For more information on Dynamixel Wizard click here.

 

Method B: You have a USB2Dynamixel controller but do not have a Robotis dedicated robot controller (CM-5, CM-510, or CM-700).#

 

Steps 2 through 5 from Method A remains unchanged. Step 1 needs to be modified for proper power supply.

You will need 2 separate 3-pin TTL cables (they come supplied with every DARWIN-OP). The following procedure is recommended:

 

1) Open the Interface panel of DARWIN-OP (back cover). Carefully remove the plastic back panel to prevent any damages to the interface board cables.

 

2) Disconnect both Interface Board cables.

3) Temporarily disconnect ALL currently connected cables. You can choose any TTL port. Do not disconnect the power cable from sub-controller to main controller. Doing so will not allow Dynamixel Wizard proper Dynamixel search.

 

 

4) Connect a spare TTL cable to any open port and the other end to the new MX-28.

 

5) Connect a second TTL cable to the other port of the MX-28. Connect the other end of the cable to the USB2Dynamixel controller. Afterwards connect USB2Dynamixel to the PC.

 

6) Turn the switch on on DARWIN-OP and let Ubuntu load (this process may take up to 2 minutes).

Note that the head LED will remain green and will not turn amber. The demo program will not run automatically.

 

7) Connect to DARWIN-OP and run Dynamixel Monitor.

Once Dynamixel Monitor is running all actuators will show as "fail" even with the new MX-28 connected. Do not exit Dynamixel Monitor. Leave the program running.

8) On Windows run Dynamixel Wizard.

Change address 4 (baud rate) from the default value of 34 to 1. You must perform this operation with Dynamixel Wizard as Dynamixel Monitor does not support this function currently. If you do not change the baud rate then Dynamixel Monitor will fail to scan the actuator.

Change address 3 (ID) from the default value of 1 to the desired value. You may also use Dynamixel Monitor to change ID as well.

 

Note that RoboPlus Manager does not currently support the CM-730 controller because it lacks the Serial Connector input.

 

Once the baud rate value is set to 1 you may return to Dynamixel Monitor and type scan to verify success on baud rate change (the first attempt may show the new actuator as "fail" if so type scan again until "OK" shows on screen).

 

Once all changes are made you still need to exit Dynamixel Monitor and shut DARWIN-OP down properly.

Once shut down and powered off replace the Dynamixel actuator and restore all connections.

Once connections are restored return to DXL Monitor and reset all Dynamixels.

 

If you are replacing 2 or more Dynamixel then you must perform this procedure again as Dynamixel Wizard will show errors when multiple Dynamixels with the same ID and same baud rate are connected.

 

Once the actuator has been replaced it is highly recommended that you update the firmware with Firmware Installer so that ALL Dynamixels are matched with the same firmware.

 

Method C: You do not have a USB2Dynamixel controller nor a Robotis dedicated robot controller (CM-5, CM-510, or CM-700).#

 

Ensure you perform proper horn installation and proper bearing set installation (if applicable).

Example 1: replace the the right elbow (ID 5) with a new actuator without disconnecting the remaining actuators.

if so let's assume we need to replace the right elbow (ID 5) and already replaced the actuator before performing the software changes:

1) Run DXL Monitor You will see the following appear on screen

notice despite installing the new actuator replacement for ID 5 the software still displays as "fail." Now its time to make the proper changes.

2) Go to ID 1 by typing id 1 and temporarily assign a different ID number. You may assign numbers between 21 and 199 but refrain from numbers between 1 and 20.

let's say change to 39 so type wr 3 39.

Notice that the command prompt changed from ID:1 R_SHOULDER_PITCH to ID:39 UNKNOWN.

3) Return to the CM-730 command prompt by typing id 200.

4) Type scan and notice the "extra" ID on ID 39. You'll also notice that ID 1 and 5 failed.

5) Type the command wr 4 34 while remaining in ID 200. This means that the communications baud rate between the CM-730 and MX-28 switched from 1Mbps to 576000 bps.

6) Type scan and the following will appear onscreen

Notice that all actuators fail except ID 1 (remember that the default values on a new Dynamixel is ID 1 and baud rate 34). Notice that ID 39 does not appear anymore. No need to worry this is because ID 39 does not currently have a specific function in DARWIN-OP and the baud rate of said ID is 1 Mbps; whereas the current baud rate between the CM-730 and and MX-28 is 576000 bps.

7) go to ID 1 by typing id 1

8) The command prompt will change from ID 200 to ID 1

9) change the baud rate from 34 to 1 by typing wr 4 1

10) Once baud rate of the new actuator matches with the rest of the actuators return to to ID 200 by typing id 200

11) Change the baud rate between CM-730 and MX-28 back to 1 Mbps by typing wr 4 1

12) Return to ID 1 by typing id 1; change the ID from 1 to desired ID. In this case to ID 5 by typing wr 3 5.

13) Return to ID 200 and type scan. Notice that ID 5 has been set, but ID 1 still failed and there's ID 39. Go to ID 39 by typing id 39.

Remember that ID 39 is a temporary ID change for ID 1. Now its time to revert the change back.

14) Go to ID 39 by typing id 39. Restore ID 1 again by typing wr 3 1. Return to ID 200 and run scan.

15) Run reset all and all DARWIN-OP will be back to normal again.

 

Repeat the same procedure again if replacing more than 1 actuator.

 

Example 2: replace the the right elbow (ID 5) with a new actuator with less software manipulation.

 

Just like Method B disconnect all Dynamixels from the CM-730 but do not disconnect the power from CM-730 to Main Controller.

 

However in this case instead of the need for 2 3-pin TTL cables you'll only need 1.

1) Connect the new actuator to any TTL port.

2) Turn DARWIN-OP on and run DXL Monitor. Do not worry about setting DARWIN-OP in the kneeling position during this procedure as the demo program will fail to run automatically due to the disconnected Dynamixels. Please set DARWIN-OP in a stable position (either sitting or laying down on its belly).

3) Run scan and you will notice that all ID's will fail

4) Change the baud rate on ID 200 from 1 Mbps to 576000 bps by typing wr 4 34

5) Run scan again and you'll notice the OK on ID 1 (remember that all new Dynamixels have default values 1 for ID and 34 for baud rate).

6) Go to ID 1. Change the baud rate of ID 1 from 576000 bps to 1 Mbps by typing wr 4 1

7) Return to ID 200 and change the baud rate back to 1 Mbps

8) Return to ID 1 and make the ID change. In this case change to ID 5 by typing wr 3 5.

9) Return to ID 200.

10) The ID change is done. Shut down DARWIN-OP properly, power off. Perform replacement, restore all connections and turn DARWIN-OP on again. Remember to set DARWIN-OP in the kneeling position as all actuators are connected and the demo program will run automatically.

11) Perform the killall procedure to end the demo program. Run DXL Monitor and reset all Dynamixels.

 

For multiple Dynamixels you may only repeat steps 3 through 9. You can disconnect the actuator after step 9, connect the new Dynamixel and run from step 3 again.

 

Once done replacing Dynamixel(s) and settings set appropriately run Firmware Installer. Select option 2 and you are done. This is an important final step because it sets the angle limits on the joints.

DARWIN-OP is back to normal again.

 

Example 1 requires less hardware work but more programming work, as well as keeping careful track of changes made during programming and repeating the entire process for multiple Dynamixels.

Example 2 requires more hardware work (unscrewing/screwing disconnecting/connecting), but less on software work.

 

Pick the method that most convenient for you.

 

 

The reset all procedure at the end is necessary because DXL Monitor will set the angle limits on all Dynamixels. Setting angle limits is a robot safety mechanism to prevent joints from overextending, therefore preventing damage to the robot.

 

Pressing the reset button on DARWIN-OP will reset settings of the sub-controller CM-730 to default values. For example:

-If the CM-730 has the baud rate changed from 1 Mpbs to 576000 bps, pressing the reset button will change the baud rate back to 1Mpbs (default).

-If the eye LED has been changed from blue to orange, pressing the reset button will change the color back to blue (default).

 

Any further inquiries or issues regarding changing the MX-28 visit this page:

 

http://www.robotis.com/xe/?mid=memberIssueTracker&act=dispIssuetrackerViewIssue&milestone_srl=0&document_srl=73056

 

 



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