View Full Version : Arm rigging max 5 problem

03 March 2003, 04:06 PM

I'm stuck there and can't find right solution.
For now I've connected dummy to "bone2" and lock one of its axis. Then used look-at constraint on "Bone1" and Dummy and it's worked.
Problem came when I wanted to animate entire rig. Dummy with one axis locked couldn't move in one direction. (logical...)
Maybe someone know beter solution.:shrug:

Turrok :hmm:

03 March 2003, 08:41 PM
I'm not sure exactly the kind of motion your trying to get. Could you explain a little more about, ultimately, the movement you want from the robot arm?


03 March 2003, 09:28 AM
I've made some simple animations to show you what I want to achieve.
I've come with some results with Look-at constraint, but couldn't limit unneeded rotations. :shrug:
Desired effect (
Unwanted "default" effect (


04 April 2003, 06:26 AM
hi there Turrock; im pretty sure ive got an answer.

use your arm set up, lock bone 1 Y and Z rotation (the shoulder) and start the IK chain from bone 2 to the hand. make sure the IK goal and Bone 1 is on a Y position of 0.00 (or just make sure they're both on the same y axis)

Once this is done, select bone 1 and right click > wire perimeters > transform > rotation > x rotation. (mine was x rotation, not sure about yours)

Next, select the ik goal (or what ever your arm control object is) and transform > IK goal > position > Y position.

Now, this should open the Parimeter wire dialog. on the left there should be Bone 1, and on the right there should be your IK goal. Click the arrow pointing left, giving the IK goal's Y position control of the X rotation of Bone 1.

Then under "Expression for Bone01's X_Rotation", change :
Y_Position / 100
This will make it nice and smooth, as it might be too sensitive to IK goal's Y position. You may have to apply a different number other than 100, depending on the unit scale of your setup.

Well, all thats left is make sure the IK goal, and Bone 1 are connected to a dummy at the pivot point of Bone 1. Then connect this dummy to the shoulder connection area of the robot's spine, or where ever you choose. This is to ensure that as the character moves forward, his shoulder doesnt rotate away for no apparent reason.

Remember that if your character is moving along, the IK goal on his arm will technically not be moving if it is linked to a parent dummy. Even though it's changing world position, it's not changing it's own Y_position.

Thanks for your question! I didnt know how to adjust wire sensitivity before, it was just a guess. Hell i dont even know maxscript, but obviously im sure its alot more complex than mathematical division :rolleyes:

Hope it all goes well! MichaelComet from your previous post is very knowledgable, you should take a look at some of his IK leg setups on his website, they're awsome! Let me know if it doesn't work for some reason.

04 April 2003, 10:31 AM
Hi JeT,

Thanks for such detailed answer.
I almost gave up, but now... :)
I'l try it in evening and let you know about results tomorrow.


04 April 2003, 11:15 AM
never give up! in max with maxscript I've been told you can do just about anything! I don't know myself, of course.. because I haven't tried everything... if only there was more time and more patience :p

04 April 2003, 06:58 AM
I've wired Bone1 "x-rotation" to IK goal "y-position" and it's worked.
I've tried this method before, but didn't know about dividing value of IK goal "y-position".
Still, the problem comes when I want to move my IK goal up (z-axis in my case).
Bone2 rotates a lot, but bone1 doesn't.



04 April 2003, 03:05 PM
Well this is probably because of the way you want to structure your arm.. most arms have shoulders, its only natural.

Obviously bone 1 doesnt rotate.. u stated you didnt want it to rotate up. and the ik chain starts from bone 2.. so its obviously not going to affect bone 1 rotation.

I suggest you look at what you want your character to do. its much preferred to trying to make that rig for every situation.

04 April 2003, 03:31 PM
Hey JeT,

I think you misunderstood me. (my bad English):hmm:
When I move my IKGoal up, Bone2 and last bone in a chain rotate automatically.
Besides of Bone 1 rotation after moving my IK goal in y-axis, it should also rotate when I move IK goal on z-axis (up).

This animation doesn't show it to well but you should imagine how this red part in the anim should rotate when I move my IK goal up.

ex. (


04 April 2003, 01:34 PM
hmm well im suggesting you seek a more forward kinematics system for animating this guy. I mean, I wouldnt spend an awful lot of time on it if hes only going to be showing for a few minutes. I think Forward kinematics are the way to go; ditch the inverse, or use a combo of the two. sorry i couldnt be of much more assistance.

rock on :airguitar

CGTalk Moderation
01 January 2006, 06:00 PM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.