Hip Rotation
Hip Rotation
by daveski
Wed Feb 14, 2007 3:22 pm
Hi,
I'm new to the forums and must say, full of useful infomation.
My question is, has anyone come up with a practical method of hip rotation.
It seems that hip rotation makes a lot of differnce to the smoothness of movment and also increases the potental "can do" for the Robonova.
Any imput would be helpful.
I'm new to the forums and must say, full of useful infomation.
My question is, has anyone come up with a practical method of hip rotation.
It seems that hip rotation makes a lot of differnce to the smoothness of movment and also increases the potental "can do" for the Robonova.
Any imput would be helpful.
by DirtyRoboto
Wed Feb 14, 2007 6:17 pm
I was looking at combining the foot and ankle servos into the feet and that got me thinking if the same could be done to the hip and thigh servos... It can. This leaves a single servo at the knee and lots of room for a hip rotation servo above.
Not so. as the thigh servo becomes hip rotation servo and the new servo becomes the thigh servo.
I was also looking to perform a scale up of 1:1.25 in the RNs overall frame by creating custom fixings based on the originals but scaled up. Then I thought I may as well design my own bot if I am going to goto all that trouble.
I may buy a MANOI (or other second robot) if I can and when I do, the RN will be re-engineered.
Marcus.
Not so. as the thigh servo becomes hip rotation servo and the new servo becomes the thigh servo.
I was also looking to perform a scale up of 1:1.25 in the RNs overall frame by creating custom fixings based on the originals but scaled up. Then I thought I may as well design my own bot if I am going to goto all that trouble.
I may buy a MANOI (or other second robot) if I can and when I do, the RN will be re-engineered.
Marcus.
In servo's we trust!
by daveski
Wed Feb 14, 2007 9:31 pm
DirtyRoboto wrote:I was looking at combining the foot and ankle servos into the feet and that got me thinking if the same could be done to the hip and thigh servos... It can. This leaves a single servo at the knee and lots of room for a hip rotation servo above.
Not so. as the thigh servo becomes hip rotation servo and the new servo becomes the thigh servo.
How are you going to combine the 2 servos?
What kits at present have hip rotation?
Is it really that hard to create hip rotation for the RN.
Is it a case of reengineering the entire torso?
by hivemind
Wed Feb 14, 2007 9:50 pm
The HiTec HSR-8498HB (stock) servos do not have enough torque for hip rotation (either individual leg or waist rotation). Furthermore, the taller the legs are, the more give the servos have -which makes posing harder (as well as standing and moving in general). The problem comes when trying to have three degrees of freedom in one place (ie: hip). There is too much compliance.
I think that if you wait for the new HiTec servos to come out you will have more success.
-just my $.02 since I have tried before and it only worked somewhat (although he could ride a skateboard nicely
)
-Hive
I think that if you wait for the new HiTec servos to come out you will have more success.
-just my $.02 since I have tried before and it only worked somewhat (although he could ride a skateboard nicely
)
-Hive
by gdubb2
Thu Feb 15, 2007 12:48 am
I agree with Hive on this issue. I tried basically the same thing. I made some new brackets, moved servos 4 and 22 out of the torso to the top of the legs. Added new servos ( 5 and 23) to the torso to do the leg rotation.
It was easy enough to do, but as Hivemind mentioned, things became very unstable. The legs became longer which induced balance issues, and it seems like everything flexed too much. There was flexing in the servos, the servo horns, and to some small degree, in the brackets themeselves.
I returned it back to the stock configuration for now. After Robogames, I plan on trying it again, but with stronger servos, and making the legs shorter.(Hives idea)
Good Luck
Gary
It was easy enough to do, but as Hivemind mentioned, things became very unstable. The legs became longer which induced balance issues, and it seems like everything flexed too much. There was flexing in the servos, the servo horns, and to some small degree, in the brackets themeselves.
I returned it back to the stock configuration for now. After Robogames, I plan on trying it again, but with stronger servos, and making the legs shorter.(Hives idea)
Good Luck
Gary
by plingboot
Thu Feb 15, 2007 1:17 pm
Don't get as much time to lark about with the RN1 as i'd like, but still like to ponder on issues.
Would it be possible to take a KHR1-HV and 'transplant' the RN-1 brains into it - so you'd have an 'out of the box' 'tried and tested' hip rotation solution and the familiarity and (ehem) flexibility of the RN-1 pc interface?
I've toyed with the idea of mod'ing the RN-1 for hip rotation, but it strikes me - especially now i've read hive's post - that it's work, effort and coin which is simply a 'good hiding to nothing'.
So unless Hitec have either a crafty new swivel hips RN-1 (RN-2??) or an 'out of the box' hip rotation kit in the pipeline - the obvious route would be to frankenstein a KHR1-HV.
any thoughts?
Would it be possible to take a KHR1-HV and 'transplant' the RN-1 brains into it - so you'd have an 'out of the box' 'tried and tested' hip rotation solution and the familiarity and (ehem) flexibility of the RN-1 pc interface?
I've toyed with the idea of mod'ing the RN-1 for hip rotation, but it strikes me - especially now i've read hive's post - that it's work, effort and coin which is simply a 'good hiding to nothing'.
So unless Hitec have either a crafty new swivel hips RN-1 (RN-2??) or an 'out of the box' hip rotation kit in the pipeline - the obvious route would be to frankenstein a KHR1-HV.
any thoughts?
by plingboot
Fri Feb 16, 2007 10:29 am
err... no i'm not.
i'm david, graphic designer, panoramic photographer and p!ss poor triathlete.
it's all in the glasses - i wear oakley prescription yardsticks or doubledowns, jason bradbury doesn't.
i'm david, graphic designer, panoramic photographer and p!ss poor triathlete.
it's all in the glasses - i wear oakley prescription yardsticks or doubledowns, jason bradbury doesn't.
Last edited by plingboot on Fri Feb 16, 2007 7:08 pm, edited 1 time in total.
by plingboot
Fri Feb 16, 2007 7:06 pm
NO!
no offence to jason, but i'm happy being me, i don't care for the lookey-likey thing and seem to spend much of my time telling people i'm neither harry hill or jason bradbury - which is a royal PIA.
i only wish people would start telling these celebs they look like me and see how quickly they get told to "Foxtrot Oscar"
by daveski
Sat Feb 17, 2007 10:20 pm
plingboot wrote:i only wish people would start telling these celebs they look like me and see how quickly they get told to "Foxtrot Oscar"
Already done!
he emailed me back with this response:
That's very funny. You do like me - you lucky bastard!
I'll check the site.
Jason (the real one - unless of course I'm a robot and don't know it yet)
www.jasonbradbury.com
Why not?
by NewBreedWarrior
Thu Mar 01, 2007 6:38 am
What would be a good servo for the job? Hitec HS-5955? I am willing to re-work the entire frame, relocate the thigh servos and rebuild the body..this seems like a big step ( which is ) ....but it is whats needed to be done...to achieve the hip rotation....but opens a door to a whole new RN-1? more space....mods, greater stability and cg. It is understood that the HSR- 8498 will not support the hip rotation. I assume that a method of combining the 2 servos together as most bi-peds have worked well.
In the fell clutch of circumstance
I have not winced nor cried aloud.
Under the bludgeonings of chance
My head is bloody, but unbowed.
I have not winced nor cried aloud.
Under the bludgeonings of chance
My head is bloody, but unbowed.
