He Flaps like a Bird: Destructive Resonation in Robot's Arms

[tempusmaster]

Thank you tempumaster.
by the way, do you mean COG is Center of Gravity?

Yes, exactly

sorry, a bit confused

No problem.

Here's a post that I put together about a year and half ago that you might find useful.

KHR-1: Learning How to Walk

If you compare what's happening with your robot versus the one in the post then you could get some idea of where your setup or home position is off, or if there is some other problem.

The video is the stock Kondo footage (at least at the time I put the tutorial together) but my KHR-1 performed exactly the same way, without gyros, once I got the home position setup properly.

By the way, I may not be checking the forum for the next couple of days since I leave tomorrow for Takamatsu. I'll be back by Monday night (Japan time) though.

[ryann2k1]

Thanks tempusmaster
Good luck with your journey

cheers,

ryann2k1

[RobotServicesGroup]

We hate to dredge up a really old forum post, but we need some help. We recently acquired a KHR-1, the original, not a 1HV, and we have encountered the same servo shaking problem mentioned in this thread. The shaking occurs on all servos, using either the motions provided on the CD, or on the Kondo website. We've got the KRS786 red servos, and we've tried H2H v1 and v1.4. The initial position and home positions look good compared to the manual, and all servos can be moved with no issues using the slider bars in H2H (no mis-wired servos).

So the solution proposed in this thread is to use the Servo Manager software to connect to the servos and change the Damping value to 1 instead of 2 on all servos. Of course, in order to do this, you need the special cable to connect from the PC to the servos. Robosavvy shows what appears to be a picture of this cable here in the Servo Manager, Gyro Manager and RCB Commander sections.



On the Kondo website, they list the software as "servo manager for2346REDVersion" and even mention "In order to connect, KOPROPO products ICS-PC interface is required". See here. Unfortunately, this product is listed under the Discontinued Items as part number 01018 from Kondo. Shown here

So now on to the fun part. Where can we get this special cable so that we can fix the servos and enjoy our wonderful new KHR-1?

Will this USB product do the same thing as the part that has been discontinued? We are hopeful because the Robosavvy description specifically mentions Servo Manager and damping. Product link



Any help provided would be greatly appreciated!

[tempusmaster]

We hate to dredge up a really old forum post, but we need some help.

No problem.

We recently acquired a KHR-1, the original, not a 1HV, and we have encountered the same servo shaking problem mentioned in this thread. The shaking occurs on all servos, using either the motions provided on the CD, or on the Kondo website. We've got the KRS786 red servos, and we've tried H2H v1 and v1.4. The initial position and home positions look good compared to the manual, and all servos can be moved with no issues using the slider bars in H2H (no mis-wired servos).

This was a fairly common problem with the KHR-1, but not common enough for Kondo to incorporate the servo characteristics setting into H2H.

They addressed the problem with the RCB-3 and RCB-3J (KHR-2HV, KHR-1HV, and the MANOI AT01, PF01) by including the functionality in the controller firmware and H2H3.

The shaking is oscillation, and although it may appear to be in all servos, it is normally triggered by the upper body/arm servos which don't have a heavy load and hence don't have much damping. The controller tries to bring the servo to the right position, it overshoots slightly (either from momentum or geartrain play), the controller tries to correct, and the servo goes into oscillation.

So the solution proposed in this thread is to use the Servo Manager software to connect to the servos and change the Damping value to 1 instead of 2 on all servos.

Usually changing the upper arm servo characteristics is enough.

Of course, in order to do this, you need the special cable to connect from the PC to the servos. Robosavvy shows what appears to be a picture of this cable here in the Servo Manager, Gyro Manager and RCB Commander sections.



On the Kondo website, they list the software as "servo manager for2346REDVersion" and even mention "In order to connect, KOPROPO products ICS-PC interface is required". See here. Unfortunately, this product is listed under the Discontinued Items as part number 01018 from Kondo.

With the phase-out of the original KHR-1, the servo manager became obsolete.

There are three options.

1) Find someone that has some still in stock, or can get one for you. I would suggest starting with Limor on this forum. If he can't help you, then contact RT Corp. Last time I visited their shop a couple weeks ago they still had some KHR-1 kits on the shelf, and might have the servo manager as well, and they speak English.

2) If you go back through the historical posts on this forum you'll find other threads about the same problem. I seem to recall that someone fabricated the required cable.

3) Upgrade the KHR-1 to use the RCB-3. That's the route I took with my KHR-1, and allows me to use both the original KHR-1 motions (after conversion) and the KHR-2HV motions also. It's a simple and pretty straight forward change. There are posts describing it, and the motion conversions, on Robots Dreams.

Shown here

So now on to the fun part. Where can we get this special cable so that we can fix the servos and enjoy our wonderful new KHR-1?

Will this USB product do the same thing as the part that has been discontinued? We are hopeful because the Robosavvy description specifically mentions Servo Manager and damping. Product link

From the description, it appears so - if you also get the software that's mentioned in the description. Limor can confirm it for you, and tell you whether or not they have it in stock.

[RobotServicesGroup]

Thanks for the info. Any new robot we purchase, we like to subject to our Human Emulation testing using the original equipment provided by the manufacturer. So we would prefer to get the robot working with the RCB-1 before considering the upgrade to RCB-3.

Fortunately, with a little more searching, it appears that the cable connection we need is also available in the USB radio control unit shown here. Product link. We were going to need some kind of remote control anyway, so this might just work out fine.

We just need someone to confirm that the package includes the cable we need to run the software to dampen the servos before spending that much money.

[limor]

We still have one of the original KHR1 radio control units in stock.
please send an email to sales@robosavvy.com
As for the USB ICS programmer.. I believe it should work with the 786 servos but need to confirm this with Kondo.

[RobotServicesGroup]

We just finished our Build Report on the KHR-1. We were able to successfully eliminate the shaking servos, thanks in large part to the information in this thread.

We documented the process to fix the shaking servos here

We've even got a video showing before and after the fix. Video

For our full Build Report on the KHR-1, check here

[limor]

Excellent work!
It is a shame Kondo discontinued the original KHR1 kit. IMHO they should have invested in licensing the kit to a toy company or just invest in Internationalization and safety/materials certification and made a batch of 10000 units with plastic brackets at a cost of 100$/robot targeted at APAC and US market markets that could have reached stores back in 2007 at $400 retail.
Don't know if you had noticed but we have quite a lot of info related to KHR1 on the left side of this page (Main Menu -> KHR-1) including the history and assembly.
RoboSavvy (UK) was the first ever company to export a bunch of these kits out of Japan in 2004.