Best Mounting of Head Servo?
Best Mounting of Head Servo?
by TechnoBuff
Tue Jul 21, 2009 7:33 pm
What is the RN community consensus on the best way to physically mount the head servo?
I am using a standard HSR-8498HB in the 3R200 (sticker 9) configuration but with the shallow horn. Of course it has the full length wire harness. Mounting this in the chest cavity of a fully built RN has been a barrel of laughs:
1st - In order to slide the servo into the chest cavity, I had to cut away the upper center channel of the Front Body Frame (the section that projects forward.)
2nd - In test fitting the servo in the Top Body Frame with the removed piece of channel in place, I discovered that two thicknesses of frame metal forced the servo horn to ride too high on the servo shaft for a safe secure fit. This forced the decision to use the front servo hole in the top frame because cutting away the center of the top lip of the Back Body Frame seemed too difficult/dangerous that close to the installed Controller. (The two thicknesses of frame metal at the far end of the servo don't affect the mounting of the horne.)
3rd - Sliding the servo into the cavity disclosed that the two top mounting screws holding the shoulder servos to the Shoulder Back Universal Brackets projected too far into the cavity preventing the head servo from entering fully. So I removed these four screws.
4th - The head servo wire coming out the side of the servo also prevented the servo from fitting into the cavity. So I disassembled the back of the case and notched it so the wire comes out of the bottom of the case. I had to cut away the strain relief.
5th - By trying to push the unmodified servo into the cavity, I had worn away the insulation exposing the wires. Magnification showed three separate conductors with no shorts. So I applied two coats of rubber cement followed by some clear silicon cement to make a protective bead where the wire now exits the servo case.
6th - Everything finally reassembled. I connected the head servo atop the left arm in position 11 of the controller, wrote some code for center, half left and right, and full left and right positions. IT WORKS.
Clearly there must be a much better way. For one thing, the head is too far forward.
How do you all do this? Do you use different servos? Where have I failed?
I am using a standard HSR-8498HB in the 3R200 (sticker 9) configuration but with the shallow horn. Of course it has the full length wire harness. Mounting this in the chest cavity of a fully built RN has been a barrel of laughs:
1st - In order to slide the servo into the chest cavity, I had to cut away the upper center channel of the Front Body Frame (the section that projects forward.)
2nd - In test fitting the servo in the Top Body Frame with the removed piece of channel in place, I discovered that two thicknesses of frame metal forced the servo horn to ride too high on the servo shaft for a safe secure fit. This forced the decision to use the front servo hole in the top frame because cutting away the center of the top lip of the Back Body Frame seemed too difficult/dangerous that close to the installed Controller. (The two thicknesses of frame metal at the far end of the servo don't affect the mounting of the horne.)
3rd - Sliding the servo into the cavity disclosed that the two top mounting screws holding the shoulder servos to the Shoulder Back Universal Brackets projected too far into the cavity preventing the head servo from entering fully. So I removed these four screws.
4th - The head servo wire coming out the side of the servo also prevented the servo from fitting into the cavity. So I disassembled the back of the case and notched it so the wire comes out of the bottom of the case. I had to cut away the strain relief.
5th - By trying to push the unmodified servo into the cavity, I had worn away the insulation exposing the wires. Magnification showed three separate conductors with no shorts. So I applied two coats of rubber cement followed by some clear silicon cement to make a protective bead where the wire now exits the servo case.
6th - Everything finally reassembled. I connected the head servo atop the left arm in position 11 of the controller, wrote some code for center, half left and right, and full left and right positions. IT WORKS.
Clearly there must be a much better way. For one thing, the head is too far forward.
How do you all do this? Do you use different servos? Where have I failed?
by xx2747
Mon Jul 27, 2009 5:57 am
Oh
Are you going to use the standard supplied head?
Then I don't know how to mount it unless you make custom frames.
However, you could try different servos if you like. I used the HS-81 micro servo. I just turned it upside down and used a piece of aluminum with holes on it to mount it. I could give you the dimensions if you want.
I would post pictures but the Img thing won't work.
edit: So, here's a link to a site that has the pix in it. It's the 5th post of this page: http://forums.trossenrobotics.com/showthread.php?t=3230&page=5
Are you going to use the standard supplied head?
Then I don't know how to mount it unless you make custom frames.
However, you could try different servos if you like. I used the HS-81 micro servo. I just turned it upside down and used a piece of aluminum with holes on it to mount it. I could give you the dimensions if you want.
I would post pictures but the Img thing won't work.
edit: So, here's a link to a site that has the pix in it. It's the 5th post of this page: http://forums.trossenrobotics.com/showthread.php?t=3230&page=5
by TechnoBuff
Mon Jul 27, 2009 4:34 pm
xx2747, Thank you for your reply. I followed your link and saw that you have done some neat things with your robot.
I am most interested in how you used your HS-81 - not how you mounted it - but how you connected and controlled it. Where did you plug it into the controller? How did you code it?
I tried using an HS-56HB plugged into PWM Port 0, but I could not get it to move. Obviously, I am missing something somewhere in controlling anything other than the standard HSR-8498HB servos.
So, yes, I did use the original head on a servo in the chest cavity. But there has to be a better way.
Thanks again,
TechnoBuff
I am most interested in how you used your HS-81 - not how you mounted it - but how you connected and controlled it. Where did you plug it into the controller? How did you code it?
I tried using an HS-56HB plugged into PWM Port 0, but I could not get it to move. Obviously, I am missing something somewhere in controlling anything other than the standard HSR-8498HB servos.
So, yes, I did use the original head on a servo in the chest cavity. But there has to be a better way.
Thanks again,
TechnoBuff
by xx2747
Mon Jul 27, 2009 9:01 pm
Any pictures of your robot? I could probably help you more with them.
Anyway, I haven't actually programmed a move involving the movement of the head yet but I have tried several test runs using the real time servo control in robobasic. It's what you use to capture motions. Just connect the servo into any servo port and try messing with the real-time servo control. (you can just move the bars(?) that indicate a servo's rotation amount and the servo will move)
Also, if your servo starts to jitter when you plug it in, it's not a major problem - it will stop when it receives a command.
Wait, I'm not done yet - the easiest way to see if your servo works with your robot is to unplug an existing servo from the board and replace it with your new servo. Then initiate a move (hehe that sounds cool... sorry) that involves the movement of the original servo and see if the new servo moves.
http://forums.trossenrobotics.com/showthread.php?t=3420
Hope this helps
Anyway, I haven't actually programmed a move involving the movement of the head yet but I have tried several test runs using the real time servo control in robobasic. It's what you use to capture motions. Just connect the servo into any servo port and try messing with the real-time servo control. (you can just move the bars(?) that indicate a servo's rotation amount and the servo will move)
Also, if your servo starts to jitter when you plug it in, it's not a major problem - it will stop when it receives a command.
Wait, I'm not done yet - the easiest way to see if your servo works with your robot is to unplug an existing servo from the board and replace it with your new servo. Then initiate a move (hehe that sounds cool... sorry) that involves the movement of the original servo and see if the new servo moves.
http://forums.trossenrobotics.com/showthread.php?t=3420
Hope this helps
by TechnoBuff
Mon Jul 27, 2009 11:10 pm
xx2747 Thanks, friend, [where were you when I really needed you?] It looks like you were smart enough to ask the questions I should have asked before I started cutting metal.
I had been under the impression that analog servos could not be used on the digital ports. As soon as I can, I will try this. If I get it to work, I will swap the servos and save the expensive digital one for something more important. The real benefit will be getting the head centered front-to-back again.
Thanks, TechnoBuff
I had been under the impression that analog servos could not be used on the digital ports. As soon as I can, I will try this. If I get it to work, I will swap the servos and save the expensive digital one for something more important. The real benefit will be getting the head centered front-to-back again.
Thanks, TechnoBuff
by xx2747
Tue Jul 28, 2009 12:38 am
Thanks for the compliment - I'm glad I can help.
About your saving the expensive servo for later use - that's a good idea. You don't really need accuracy or catch and pose for the head anyway. When I figured out that I could use cheaper servos, I was very happy cause then I wouldn't have to buy $50 servos every time I need an extra DoF.
Oh, just a note, weight's a problem too as I am seeing right now on Robert - it has 2 more HSR-5498s on the arms and it'll fall more easily if pushed.
Also, I probably don't know much about robots than you do - I'm just a 14 year old kid who likes robots.
About your saving the expensive servo for later use - that's a good idea. You don't really need accuracy or catch and pose for the head anyway. When I figured out that I could use cheaper servos, I was very happy cause then I wouldn't have to buy $50 servos every time I need an extra DoF.
Oh, just a note, weight's a problem too as I am seeing right now on Robert - it has 2 more HSR-5498s on the arms and it'll fall more easily if pushed.
Also, I probably don't know much about robots than you do - I'm just a 14 year old kid who likes robots.
by TechnoBuff
Tue Jul 28, 2009 9:10 pm
xx2747:
Well, I am just a 70 year old kid who likes robots (and trains, planes, cars, fire engines, cameras, video and sound editing, anything technical, and singing.)
One thing I learned a long time ago is that one can learn from anybody. Only a stupid person can't. So your being 14 doesn't alter the equation. If, you are only one page ahead of me in the book, you know more than I do - and I'm a slow reader.
So keep on offering help to people based on your experience; it reinforces what you know. Just imagine the projects you will work on when you are 70.
And the secret to surviving to 70 when age and treachery beat out youth and enthusiasm? While you're young, always treat your elders with enormous amounts of respect and deference, always call us sir or ma'am, always give us your place in line and your seat on the subway, and always listen carefully to all our well meant advice.
Then ignore most of us and live your life your way.
Thanks again, and help stamp out quicksand - TechnoBuff
Well, I am just a 70 year old kid who likes robots (and trains, planes, cars, fire engines, cameras, video and sound editing, anything technical, and singing.)
One thing I learned a long time ago is that one can learn from anybody. Only a stupid person can't. So your being 14 doesn't alter the equation. If, you are only one page ahead of me in the book, you know more than I do - and I'm a slow reader.
So keep on offering help to people based on your experience; it reinforces what you know. Just imagine the projects you will work on when you are 70.
And the secret to surviving to 70 when age and treachery beat out youth and enthusiasm? While you're young, always treat your elders with enormous amounts of respect and deference, always call us sir or ma'am, always give us your place in line and your seat on the subway, and always listen carefully to all our well meant advice.
Then ignore most of us and live your life your way.
Thanks again, and help stamp out quicksand - TechnoBuff
by ProblemChild
Wed Jul 29, 2009 10:52 am
I'm shooting straight from the Hip here, but how about using one of those miniature 4 ish Gram servos which would almost fit in the original head!!
I think you should be able to "loose" it in the RN's body then connect it via a Rod back to the Head.
I would like to have a go @ this my self but I have no real time for a month or more !
What are people's thoughts on this?
John
I think you should be able to "loose" it in the RN's body then connect it via a Rod back to the Head.
I would like to have a go @ this my self but I have no real time for a month or more !
What are people's thoughts on this?
John
by ProblemChild
Wed Jul 29, 2009 4:33 pm
I was thinking something like this little beasty!
http://www.dealextreme.com/details.dx/sku.20084
Either then hacking the plastic off and hiding it in the head and screw the horns on to the head's original mounting point. Making a bigger head and doing same...
The reverse Idea of putting the little servo body in to the RN body and attaching the head to the servo horn ??
What do people think of that ?
I presume no one really needs a massive torque to move a toy head around!
John
http://www.dealextreme.com/details.dx/sku.20084
Either then hacking the plastic off and hiding it in the head and screw the horns on to the head's original mounting point. Making a bigger head and doing same...
The reverse Idea of putting the little servo body in to the RN body and attaching the head to the servo horn ??
What do people think of that ?
I presume no one really needs a massive torque to move a toy head around!
John
by xx2747
Wed Jul 29, 2009 10:26 pm
Yes, that is very much possible.
However, do you like the original robonova head? It seems quite small compared to the rest of the body (that's why I gave Robert a new, bigger, head)
As for the servo in the head, I've thought about it before and here's a model in Sketchup that I made for Robert's future head. The HS 81 or any other micro servo would fit in it and it will be attached to the top part with servo tape.
For the servo in the body, that's the simplist way. Although you would have to make custom frames to mount the servo.
My head design: http://forums.trossenrobotics.com/showthread.php?t=3230&page=5
However, do you like the original robonova head? It seems quite small compared to the rest of the body (that's why I gave Robert a new, bigger, head)
As for the servo in the head, I've thought about it before and here's a model in Sketchup that I made for Robert's future head. The HS 81 or any other micro servo would fit in it and it will be attached to the top part with servo tape.
For the servo in the body, that's the simplist way. Although you would have to make custom frames to mount the servo.
My head design: http://forums.trossenrobotics.com/showthread.php?t=3230&page=5
by ProblemChild
Wed Jul 29, 2009 10:46 pm
Ok Looked at your head Thread on Trossen and at a basic level it's just like I was trying to describe except you haven't tried to re use the original mount and just stuck a replacement plate on ...(probably a better Idea!!)
With regards to the RN head I he reminds me of the Hunter with the shrunken head in Beetlejuice ...I agree it's totally out of proportion.
I wanted to sneak a phone camera into the head which is very doable and maybe with the Roboard do the vision processing with open CV.
i suppose you also need to jam a Laser in there for no reason other than it's BORG like
Let us al know how you are getting on with your head!
With regards to the RN head I he reminds me of the Hunter with the shrunken head in Beetlejuice ...I agree it's totally out of proportion.
I wanted to sneak a phone camera into the head which is very doable and maybe with the Roboard do the vision processing with open CV.
i suppose you also need to jam a Laser in there for no reason other than it's BORG like
Let us al know how you are getting on with your head!