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kamondelious
05-05-2011, 02:10 PM
Introducing RCMP (Royal Canadian Mechanized Police). :p This one is getting flashing Red & Blue LEDs. :D

Woodstock was fun and a great learning experience. I love the idea of biped Mechs. I'm hoping to vastly improve things in this new project.

I think the biggest problem with most biped robots (and Mechs especially) is that they are way to top heavy. Not an easy problem to alleviate since the robot only has 2 legs to support the weight and the obvious direction to build is up. With this in mind, I aimed to greatly lowered the COG and maximize carrying capacity over Woodstock while leaving potential to look cool. :p

I have been intrigued by all the PLM designs coming out over the past year, their strength & stability is fantastic. I didn't pursue a PLM design at the time, as I was happy with the leg design I had and opted to develop it further. For this project, I've merged the two design concepts into what I hope will be a competitive biped.


http://forums.trossenrobotics.com/picture.php?albumid=101&pictureid=639


Here's a closeup of the ball linkage I used.


http://forums.trossenrobotics.com/picture.php?albumid=101&pictureid=640


I kept the overall design of the 3DOF foot I came up with on Woodstock as I found it to be way more stable to balance on. So far the new variation seems better, but I haven't been walking on them yet. The front toes might have too much flex to them, but I'll know for certain soon enough.


http://forums.trossenrobotics.com/picture.php?albumid=101&pictureid=641


Here's a closer look at the hip/turret section in it's current state. I'm not sure how useful the turret rotation will be just yet. My thinking is that it will primarily be to keep the video image parallel to the ground, but may also help with balance (while shifting weight) once the guns are mounted on the bottom.


http://forums.trossenrobotics.com/picture.php?albumid=101&pictureid=642


I have mounted the batteries since taking these pictures, they are on the rear of the lower leg and blend in very well. I really didn't like the look the batteries on Woodstock's legs, but it was the only place I found to effectively place them on the leg to keep him from getting too top heavy.

Insanity? Probably. Fun? Absolutely!

More soon!

Cheers!

:D

elaughlin
05-05-2011, 02:20 PM
Are there 21 servos in there? That thing is a beast. Can't wait to see it walk.

Looks like some sort of sci-fi creature with the long backwards legs, and then then torso head hangs down in front. Pretty cool design, I hope it works out.

Xevel
05-05-2011, 02:26 PM
To be honest, my first thoughts when the image popped up: WTF? :eek:

It looks like a very interesting project, I'm really looking forward to seeing what can be done with such a design, in term of movements, payload, stability, etc.
Also very curious about how the toe+heel foot will turn out.

tician
05-05-2011, 06:21 PM
One of the first things to come to my mind was this (http://www.vgcats.com/comics/?strip_id=198) :rolleyes:. Very cool looking bot.

Definitely a compliment, my mind just goes some weird places sometimes... most times actually.

Stobs
05-05-2011, 07:38 PM
[On Woodstock it seemed that the foot design was stable, but that there wasn't much lift elevation; if that was the case will that be addressed with RCMP (cool name btw, reminds me of Fon Davis's Morav project)?] What variant of AX-12's are they? Darn fun looking project kamondelious! :)

kamondelious
05-05-2011, 08:26 PM
Are there 21 servos in there? That thing is a beast. Can't wait to see it walk.

Looks like some sort of sci-fi creature with the long backwards legs, and then then torso head hangs down in front. Pretty cool design, I hope it works out.

hehe, I considered beast as a name. There are 22 servos actually.
Thanks I hope it works too.



To be honest, my first thoughts when the image popped up: WTF? :eek:

It looks like a very interesting project, I'm really looking forward to seeing what can be done with such a design, in term of movements, payload, stability, etc.
Also very curious about how the toe+heel foot will turn out.

hahaha, when I first sketched this design up my first impression was, "that is absurd".
The PLM legs really seem to lift with solidly, I'll have to do some weight lifting test (caught on video) and get a feel for what it can do. The leg is 7DOF, so mobility should be pretty good providing I can do the balancing right. The heel + toe seemed pretty effective on my previous project, but was prone to sudden fall-overs if weight shifted too suddenly to the heel. I think I've improved the design enough that that will be less of an issue, but I definitely need to take care with that.


One of the first things to come to my mind was this (http://www.vgcats.com/comics/?strip_id=198) :rolleyes:. Very cool looking bot.

lol, thanks, I think. I might have to put a diaper on it and take a picture.



[On Woodstock it seemed that the foot design was stable, but that there wasn't much lift elevation; if that was the case will that be addressed with RCMP (cool name btw, reminds me of Fon Davis's Morav project)?] What variant of AX-12's are they? Darn fun looking project kamondelious! :)

Woodstock's foot was actually posed about 1" off the ground for his walking gait. The lack in elevation in his step was all gear backlash. This should less of an issue on RCMP as the PLM design helps eliminate some of that. I'd very much like to make a generation 3 police MORAV. Those are so cool looking.
The 8 servos making up the ankles & feet are AX-12+ and the rest are original AX-12's.

Thanks everyone for the kind words and interest in my project.

Cheers!

:D

rebel
05-07-2011, 01:46 PM
That thing is scary lol :P

kamondelious
05-11-2011, 08:49 PM
I came to a couple interesting realizations today.

First off, the bracket that the linkages on the legs connect to are of no benefit.
Secondly, I'm not using a PLM design. I have 2 servos doing the job of one. PLM actually provides a mechanical advantage, mine does not. :(

I might change the leg configuration in time to actually be PLM, but I'll wait and see how the current setup performs.

From testing over the weekend, doing a proper (lift a foot off the ground) walking gait would be very difficult. The hips have way too much gear backlash.
To fix this, I have connected the tops of the hip servos (spanning the turret) with a metal plate so that the turret pitch servos don't effect the legs.
I have added 2 additional servos to the hips to assist the hip roll servos, but still need to link them to the existing servos.
The ankle pitch was also a weak point under load, so I've double those up as well.

Up to a whopping 26 servos, yikes!

All in all, I'm still feeling good about this design, but that doesn't stop me from feeling like a tool for my mistakes. Doh!

More pics soon. Video too, if I make it do anything worth looking at. :p

Cheers,

:D

jes1510
05-11-2011, 10:02 PM
Good observations about the leg design. I'm looking forward to seeing it walk. It really reminds me of Mr. Snuffleupagus for some reason.

http://muppet.wikia.com/wiki/Mr._Snuffleupagus

Edit: I also love the way that it looks like it's carrying it's own brain (Arbotix).

Noog
05-13-2011, 01:33 PM
RCMP looks awesome! Cool name too.

I am very curious to see how it looks now that you have added more servos to it.

How do you plan on controlling the legs? Inverse kinematics, static poses or something in between?

kamondelious
05-13-2011, 03:22 PM
Good observations about the leg design. I'm looking forward to seeing it walk. It really reminds me of Mr. Snuffleupagus for some reason.

http://muppet.wikia.com/wiki/Mr._Snuffleupagus

Edit: I also love the way that it looks like it's carrying it's own brain (Arbotix).

LOL! Never thought of it, but now I can see what you mean.



RCMP looks awesome! Cool name too.

I am very curious to see how it looks now that you have added more servos to it.

How do you plan on controlling the legs? Inverse kinematics, static poses or something in between?

Thanks Noog.

To start, i will do poses to make sure everything works. If that goes well, I will most definitely play with some IK. I'd like to see how smooth and fast I can make it move.

Cheers,

:D

Noog
05-17-2011, 06:54 PM
Thanks Noog.

To start, i will do poses to make sure everything works. If that goes well, I will most definitely play with some IK. I'd like to see how smooth and fast I can make it move.



I wish you luck when you start on the IK. You have some redundant servos so you won't have to calculate as much, but you still have a lot of DOFs.

I am interested in seeing how your ankles work when you get RCMP walking. I have been considering alternative ankle designs for my biped, but I am afraid of putting that much weight on the feet of my biped. I have a tendency to keep my CoG as high as I can which is a design characteristic that we seem to differ on.

RCMP reminds me of Jon Hyland's Microraptor (http://www.bioloid.info/tiki/tiki-index.php?page=MicroRaptor) mostly because they are both larger robots made from AX-12s. Esthetically, it kind of reminds me of the Puma mech (http://mecha-master.deviantart.com/art/MechWarrior-4-Puma-front-view-120104972).

I look forward to your updates!

kamondelious
09-09-2011, 11:32 PM
It's been a slow few months for robot progress, but here's where I'm at.

This is what RCMP currently looks like.

http://forums.trossenrobotics.com/attachment.php?attachmentid=3466&d=1315624080



3567



Looks ready for action, now I just need to program that.



http://forums.trossenrobotics.com/attachment.php?attachmentid=3468&d=13156240803573
3569
http://forums.trossenrobotics.com/attachment.php?attachmentid=3469&d=13156240803570








Turns out I was wrong, the linkages on the legs help a tonne. I tested with them off and without the brackets and both performed terribly. So I put them back on, but adjusted their orientation a bit.


http://forums.trossenrobotics.com/attachment.php?attachmentid=3467&d=1315624080


3568




After doubling up the ankle pitch servos, I discovered that the plastic brackets had too much flex. This made the second servo seem pretty useless and I had to go with something stronger. Picked up a sheet of aluminum from a local hobby store and cut/drilled out some replacement brackets which are holding up great.


http://forums.trossenrobotics.com/attachment.php?attachmentid=3464&d=1315624080


3572




I kept the gun servo linkage idea I used on Woodstock, but I think this remake will hold up better. The servo as pictured is rotated completely clockwise, which aims the guns mostly straight (but slightly inward). As it rotates counter clockwise, the guns aim inward more, to a convergence point roughly 20cm from the tip of the barrels.


http://forums.trossenrobotics.com/attachment.php?attachmentid=3465&d=1315624080


3571




From the back you can get a good view of the battery mounting. There's velcro holding them on at the top and a zap-strap tight enough to keep them from bouncing around, yet loose enough to slide in & out.

I did some playing with pose based walking and was pleased with how this leg configuration has performed. I have had a lot of issues getting my walk sequences to play consistently in pypose, which has made it difficult to tune and complete. If I keep trying, it'll usually start to work after a half hour or so and as soon as I power off, I have to start over. I don't have enough free time to justify continuing with it. So now it's on to inverse kinematics! Upgrayd was gracious enough to share his modified Dawin-OP code with me. :D Thanks again Upgrayd! It's by no means a drop in software solution since my leg design is completely different, but it's still a huge/helpful starting point on the IK.

Cheers!

:D

kamondelious
03-13-2012, 11:29 PM
Not much to update, been a bit busy (and lazy) getting things done, but here's a short video of the police lights I made.


http://www.youtube.com/watch?v=2_0MWw2ZwKE

I have it mounted right above the camera.For those interested, here's a closer look at the boards.

3796

(http://forums.trossenrobotics.com/gallery/files/2/2/9/4/img_9801.jpgHave)I have been getting into coding lately as I ramp up to finish in time for robogames, so hopefully I'll have more soon.

Cheers,

:D