KRG-2 Gyro Stabilizer

[limor]

> From: Joe Greco
> Sent: Wednesday, April 06, 2005 3:05 AM
> To: Limor Schweitzer
> Subject: RE: gyro
>
> Hi Limor,
>
> I didn't realize that
> for full motion control, you need two gyro's. One for side to side,
> and the other for front to back. I was about to order the second when
> I noticed that you had translated documentationon your site. Thank
> you I noticed on the last page that when using the gyro for
> controlling the front to back motion you need to reverse the #16 servo
> using the 01018 ICS-PC interface(if I'm reading it correctly) If
> that's the case, I need to order that also, but if I'm reading it
> wrong, I don't want to order something I don't need. Do you know if
> this is correct? If it is and I do need it, is this part number the
> same as the servo programming cable that you sell?
>
> The Servo Manager software that I've seen was for the red servo's
> which I don't have, so I want to make sure I'm getting the right
> things.
>
> Thanks so much!
>
> Joe
>
> p.s. I joined your forum this evening. There's a lot of good
> information out there!
>




>From Limor Schweitzer on 6 Apr 2005:
> Hi Joe,
>
>
> It appears that in order to stabilize the two symmetrically opposed
> servos controlling backwards and forwards movements (such as the lower
> legs on channels 16 and 22), you need to change a parameter in the
> servo using the ICS PC interface or, according to one
> Japanese source, the Wireless control unit.
>
> Judging by the translated manual, you can test the gyro without the
> need for reversing a servo for the feet servos (channels 23 and 17).
>
>
> Regards,
>
> Limor Schweitzer
> RoboSavvy
>
> -----Original Message-----





From Joe Greco on 6 Apr 2005:
Hi Limor,

Well, I just verified that using the gyro to control front to back motion using servo's 16 & 22, the gyro does compensate servo 16 in the wrong direction. I'm still not sure wether the servo needs to be reversed, or if the gyro needs to be reversed to correct this. I just ordered the ICS-PC interface (for the servo's), so I'll verify which one needs to be adjusted once I receive that.

Aside from that, I tested the gyro on the side to side motion (using servo's 17 & 23) and was quite impressed with the results. I think once I have both gyro's installed, it will be tough to knock this guy over.

Joe

[Meltdown]

You can also reverse the gyro with it's own free software.
No need to reverse servo 16 with the optional pcs hardware/software.

[OnItsWay]

Hi guys, I'm new to this site. My robot is on its way!! can't wait to get it. Have you guys installed both gyros and how well do they work? Meltdown, i know you have had yours for a while now, what do you think of the gyros? do they work well?

[Meltdown]

Concrats "OnItsWay"!
You'll love it.

The verdict on the gyros isn't out yet. Had to little time to really test them yet due to a mechanical modification im doing.
My robot is in pieces right now.
This mod will make my KHR 10 times more stable and will take the slop out.
I will report on the gyros when done.

[OnItsWay]

Thanks Meltdown. I was really hoping you tried the gyros. I can't find any discussion anywhere (in english) about them. If somebody could point me in the right direction I would appreciate it. I'm very interested in your results.

What joints did you find to be weak? I am guessing the shoulders and hips? I have been wondering about that. I have been coming up with my own Ideas on adding bearings. I came up with a cool plan to add rotation to the legs like you did, a different method though. does your walk in circles better with that mod?

Thanks!!

[se7en]

I decided to officially join the forum. I posted earlier in this thread as "OnItsWay"

limor, I would really like to hear from you to about your gyro experience, especially the reversing thing. did you have to buy that cable?

Meltdown mentioned you can reverse the gyro with its software. does this mean you can revers the gyro corrections for 1 of the servos? I would think reversing the gyro would reverse the corrections for both servos.

[Meltdown]

You can reverse one channel at the time with the gyro soft.
Each gyro has 2 independant channels.
You always need the special pcs adapter/cable to acces the servo or gyro software.
One advantage is that you don't have to change the servo (nr16) itself.

I can walk in circles now with the two extra servos in the legs.
Interesting i'd like to know how you will do the legs mod differently?

first mod:
I found a way to really secure the servo horns and keep them from stripping out when fastened to much.

Second mod:
Also my legs, arms and schoulders don't have any play anymore.

In the future i will replace the hips and ankles with the 20Kg servos.
These seem to need the most power.

Now i'm building a servo pan/tilt system to be able to use my webcam as head.

[se7en]

Well I hope somebody out there describes how to make that cable for the servos and gyro. It cost 100 dollars here in the states. thats pretty expensive for what i see in the picture. whats on the disc? is it the same software i can download for free on the site?

My leg mod will be placing a bearing between joints 13 and 14, 19 and 20 so the legs can spin. i want to mount the extra servos behind joints 13 and 19 and connect to the bottoms of the legs with a linkage or gears, whatever i can find. this will give the robot a butt. i just think that would be funny.

[se7en]

Meltdown, can i just install servo 16 backwards, then i will not need to reverse it or reverse the gyro, so i don't need to buy that expensive cable? In your opinion, do i need that cable to make this robot function correctly?
Thanks!

[Meltdown]

Interesting idea with the links. It may be hard to get the slop out.
You need ball-raced linkages for that and they are expensive.
Normal rc linkages have either to much slop or are so hard to turn it will:

1) Eat up your battery in no time.
2) Put extra strain on the servos electronics and gears.
But you're free to try, everything goes with robot building.
It's a large part of the hobby and fun to try to improve and discover things
dont take my word for it

I agree the cable is expensive but:
The special cable contains micro (smd) electronics i.e. a few (5) resistors, a
capacitor and 2 transistors on a small pcb. The software is the same one you can download.

You could install the servo backwards but the problems like balance, unsemitrical legs etc you face in return
may be hard to solve. Not worth it imho.

[se7en]

I am trying to reverse my gyro with the downloaded software and the ICS Servo cable. The instructions are in Japanese and I can't get it to work by following the pictures. I plug into a serial port, plug the other end of the cable into one channel of my gyro, then launch the software (I have version 1.0 and 1.1). At the bottom of the software I switch to COM1 and it detects. Then I click the picture that looks like a chip with an arrow exiting it. I expected this to read the gyro into the software. I just get a big red X every time I click it. Hmm. The ICS Servo cable splits into two leads. The instructions show one lead connecting to the gyro, and the other lead says "DC 4.5v~6.5v". Am I supposed to supply power? Do I plug this lead into RCB1 somewhere? If anybody has successfully accessed the gyros could you please list the steps? I am mainly interested in reversing channel 16 and playing with the gains. Thanks!!

[se7en]

I figured it out. I wanted to reverse channel 16 on the gyro. I just left everything on the gyro connected to the robot except the connector that attaches to the ics-servo cable. Channel 16 of the gyro gets powered through channel 22 when I switch on the robot. After that the software is quite simple. I still wish I knew what the 3 gains are for as well as the filter and the limit. I am having a friend take the instructions to her Japanese friend that translates software manuals for a living (what a lucky find). Maybe I'll have a good translation to post.

A note on the gyros' performance. They work well but really need to be tuned. Currently they send my robot into a resonant oscillation that ends in a fall. The gyros have an external gain adjustment which helps but seems to affect my home position also. I set my home position with the gyros on the robot. I probably should not have done that.

[Meltdown]

The gyros need to re-calibrate after an adjustment.
When you adjust the gyro and the home position changes, take the power
off and connect again. You will see that the home position will be adjusted automatically.

[se7en]

That's good to know, thanks meltdown! Do you have any information on the settings inside the gyro manager? The Gyro has an external gain adjustment using a screwdriver. It also has 3 different gain adjustments, a limit slider, and a digital filter on/off , all of which are adjustable in the software. I don't think I can count on getting the translation I mentioned above, so anybody please post what you know.

Another note on the gyros performance. They really work well once I changed some settings. The main problem was they were all compensating in the wrong direction! I installed them just like the instructions showed. Each gyro had reversing set to "on" for both channels which I didn't expect out of the box. Reversing one and physically inverting the other made the robot super stable. While testing, it was really hard to see what direction the feet moved for a certain input. The solution was to hold the gyro in my fingers and turn it instead of the whole robot. This allowed me to immediately see what it did to the feet and identify the reversing needs.

[Meltdown]

So it's good you bought the configuring cable as wel
I'm struggling with the settings myself. And boy do i know about the oscillation
It seems that to much gain will result in oscillation.

I'm not clear about one thing:
Do both the feet have to turn in the same direction (opposite to the gyros axes off-course)
Or do they have to turn opposite from each-other?
Illogical as it sounds but at one point i had them turn opposite and it seemed that the robot stabilized instantly that way without any oscillation at any gain.

I wrote to Kondo about providing some decent English documentation for all their software but as expected they never responded.
Kondo is seriously lacking in this department.
This is where Hitec will have an advantage when they launch their robot.
English documentation won't be a problem for them.

What we need is a Japanese user of this forum willing to translate the documents. Anyone?