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| Problems with IK HI setup :: Robotic arm |
 mr_pablo |
I am currently trying to set up a robotic arm, who's manipulator/hand/tool on the end, will follow an animated object.
I figured an IK setup, with the end goal linked to the animated object, would mean i dont have to hand animate the arm, making life much easier.
However, after setting up an IK HI bone rig, I am having trouble with the rotational axis constraints. I want the first bone (the one furthest from the goal) to only move in 1 direction, side to side. However, this completely fudges the IK HI setup. Without the rotation being limited to one axis, the rig works fine, apart from the last object acting as the base for the arm, tilts in all directions, which is what im trying to stop.
I would also like to limit the main arm parts to be one directional.
Can anyone help me fix these problems, or explain how to make a good rig for what im after. please note, ive seen the tutorial on the net about the robotic arm, and using a spline IK rig, i tried, but the spline setup is not very effective for my needs. I have also tried just using the arm objects, linked and an IK solver applied, but i has similiar issues.
Apologies for length.
Paul
2D & 3D Graphic Design/Web Development/Games Design & Development/Womaniser
read 1332 times
11/16/2007 9:36:10 AM (last edit: 11/16/2007 9:36:10 AM)
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| mrgrotey |
This is quite a vague question mate, can you give us any images of what you are talking about with some sort of arrow diagram of which ways you want the arms to move and what way you want them locked and so on.
Heres a robot arm helper i did for someone a while back, although it may not be compeltley what you are after it may give you some thoughts.
http://www.maxforums.org/thread.aspx?tid=437245
But again, images please! :)
read 1327 times
11/16/2007 9:42:08 AM (last edit: 11/16/2007 9:43:35 AM)
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| mr_pablo |
ok, heres a screen shot.
The blue bar with the omni lights moves back and forth, and end the end of each pass, moves upwards a bit.
I want the end of my robot arm to be attached to the end of the bar, and follow its movements, to make it look like the arm is moving the bar. As you can see, the robot is made from 3 main arm pieces, a base(a cube with half a cylinder on top), and a hemisphere stand. I want the base block to be restrained to one axis (side to side).
You can see i has bones setup (IK HI) and the pieces are linked to them. One wierd thing that happens when i restrain the bone inside the base, is that if i move the goal helper left, the arm swings right.
If you need any more info, just ask. as for screenshots, im about to leave work, and im off for a week so :P
2D & 3D Graphic Design/Web Development/Games Design & Development/Womaniser
read 1320 times
11/16/2007 9:56:23 AM (last edit: 11/16/2007 9:56:46 AM)
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| mrgrotey |
so the problem you are having is that the arm tilits over to the side rather than swivling round? just so im clear.
read 1315 times
11/16/2007 10:01:32 AM (last edit: 11/16/2007 10:01:32 AM)
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| mr_pablo |
with basic IK HI settings, yes, the base block tilts in all directions, and i want it limited to one axis, like a real robotic arm.
I read your previous posts, would this rig be easier to setup like you did with that other chaps robotic arm? I have another file, the same, except no IK, and have linked the parts in the correct order, but im at a loss on how to make them work like an arm without using bones or IK.
2D & 3D Graphic Design/Web Development/Games Design & Development/Womaniser
read 1312 times
11/16/2007 10:04:08 AM (last edit: 11/16/2007 10:04:08 AM)
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| mrgrotey |
Ive not tried it yet so i would probably run into other problems but you may be able to do it that way (which is still IK orientated) but have a position constraint for the omni light bar to the lower dummy and link the end of the arm to the lower dummy too (which it pretty much is already). as i said i havent tried it yet, but hopefully ill come up with something, i like these challenges :)
oh by the way as these are all solid objects there si absolutely no point in adding bones, just link the parts of the arm together themselves and move their pivot points to the corrects places, adding bones to nondeforming objects is pointless
read 1307 times
11/16/2007 10:09:17 AM (last edit: 11/16/2007 10:12:40 AM)
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| mr_pablo |
quick Q, with look at constraints, how do i limit them to one axis? ive got the base following the movement of the bar now, but it tilts up as the bar moves up, and i want to restrain that =)
2D & 3D Graphic Design/Web Development/Games Design & Development/Womaniser
read 1298 times
11/16/2007 10:16:24 AM (last edit: 11/16/2007 10:16:24 AM)
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| mrgrotey |
i dont think you can constrain them to one axis no, you have to do a work around.
aside from that, is this what you were after?
All i was doing was moving the light bar
if so ill give you an expalination of what i did, if not can you explain what i did wrong?
the only problem i can see is that the last section of bar doesnt bend as much as the first two, it does bend but not much
read 1282 times
11/16/2007 10:32:36 AM (last edit: 11/16/2007 10:34:28 AM)
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| mr_pablo |
thats exactly what im after! would i be able to set this up and just attach it to my already animated bar?
i was close just, using a dummy, a look at constraint and a simple IK HI solver, but the base block stil tilted a bit =(
2D & 3D Graphic Design/Web Development/Games Design & Development/Womaniser
read 1275 times
11/16/2007 10:34:34 AM (last edit: 11/16/2007 10:34:34 AM)
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| mrgrotey |
Good stuff,yeah shouldnt be a problem attaching to the pre animated bar.
Im off hime right now but ill do a diagram of how i did it when i get home (in about 1/2 hr)
read 1268 times
11/16/2007 10:37:25 AM (last edit: 11/16/2007 10:37:25 AM)
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| mr_pablo |
super quick - is there a way for me to link my dummy to the bar, but only have it move on one axis? its currently linked, so goes up and down as well as side to side. if i can do this, then im sorted!
2D & 3D Graphic Design/Web Development/Games Design & Development/Womaniser
read 1266 times
11/16/2007 10:39:23 AM (last edit: 11/16/2007 10:39:23 AM)
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| mattymoose |
I <3 Grotorials
We need a featured thread with all the grotorials that have been posted to date, and then linked to from the FAQ
read 1257 times
11/16/2007 10:49:18 AM (last edit: 11/16/2007 10:49:30 AM)
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| mrgrotey |
if you go to the heirachy tab then click 'link info' you can untick the axis that you dont want the dummy to inherit from its linkage to the bar. (under the 'inherit' heading of course)
if this works i wont bother doing the diagram for mine
read 1249 times
11/16/2007 11:10:27 AM (last edit: 11/16/2007 11:14:04 AM)
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| mrgrotey |
As i went to the trouble of making the arm i thought I may as well do the diagram in case your way didnt work and im not around when you say so, also, for anyone interested.
Here we go, very simple
Pivot Point:
These must be sorted out first.
Also the pivot points of B and C MUST be in the exact same position for this rig to work other wise things go squiffy. hopefully you can understand the diagram here.
If you have scaled any of the objects at this point its very important to reset their xforms BEFORE continuing (in fact so it any to eliminate that from and future problems)
Linking:
Link all the objects in the expected order apart from when it comes to the base area, you link C to A and link B to C
Ik Chain:
add an IK Chain between C and F
IK Target:
not sure if you've used this before but its in the motion tab when the IK chain is selected, click the 'none' button and choose the dummy, the dummy must be place directly above the pivot points of the objects below as shown by the yellow centre-line.
If the base of the arm isnt going anywhere then just leave the dummy unlinked, if the base of the arm needs to move then you will need to link the dummy to A
Look at constraint:
If F will always be locked onto the bar then theres no real point in it being a separate onject, just physically attach it, if it needs to be a separate part add a look-at constraint between it and G.
Any problems just shout
read 1239 times
11/16/2007 12:05:40 PM (last edit: 11/16/2007 12:07:01 PM)
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| mr_pablo |
sorry for the late reply, first chance i got on a computer since work. i can't test out the things youve suggested, as im off work for the week, but i have 3dsm at home also, so will give it a whirl for personal pleasure :P
im pretty sure if i just limited the dummy movements to the one axis, it would of worked fine =)
2D & 3D Graphic Design/Web Development/Games Design & Development/Womaniser
read 1219 times
11/17/2007 8:49:50 AM (last edit: 11/17/2007 8:49:50 AM)
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