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"I, Robot" Added on: Fri Nov 17 2000 |
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IK-ing
If you want to use inverse kinematics properly in Maya make sure that joints like the knee and the elbow are already bent (just a few degrees) in the direction you want them to go once the Ik handles are in place.
Start by selecting the IK handle tool and click on the left hip joint and then the left ankle joint, end at the left toe joint. Press enter to confirm the IK handles. Now the IK handles will move the leg and the foot bones.
To give more control over the knee we will use a pole vector, this will let us determine the horizontal swing of the upper leg. First open the "create" menu and create a Locator. Place it in front of the left knee. Select the left leg IK handle and open it's attributes, go to the IKsolver attributes and make sure the IKsolver is set to IKRPsolver.
Now first select the locator and then the left leg IK handle, this order is important otherwise it doesn't work!
Once these are selected open the "constrain" menu and select "pole vector". The rotation plane of the Ik handle is now constrained to the locator, the knee will always point in the direction of the locator. Do the same for the left foot.
Repeat this for the other leg. repeat this also for the arms but you can skip the second IK handle, we will use forward kinematics (rotating joints at joint level) to control the wrist.
Spine and neck joints will also use forward kinematics so no IK's there.
Set Driven Key
To control the hand joints we will also resort to forward kinematics, except in this case we use "set driven keys" to control the movement of the fingers with the channel box. This way you can connect the rotation values of multiple joins to the value of an attribute in the channel box.
First start by creating new attributes for the wrist joint, we will control all the hand and finger movement through this joint. I will start by making a controller for the left hand index finger. Select the left wrist, go to the "modify" menu and select "add attribute..."
Now give this attribute a name like "index finger bend" or something. Assign a minimum value of 0 and a maximum value of 10, now close this menu. Next open the "animate" menu and the "set driven key" menu and select the "set" options. Make sure the wrist joint is still selected and click on the "load driver" button, then select the "index finger bend" attribute from the list.
Select the index finger knuckle joint from the viewport and click on the "load driven" button in the "set driven key" menu. The value of the "index finger bend" attribute in the channel box should still be 0. Now click on the "key" button. Your first key is set.
Repeat this for the remaining left hand index finger joints. The left hand index finger has it's current joint rotation values assigned to a value of 0 in the "index finger bend" attribute. Set the value of this attribute to 10, and rotate the index finger joints to their maximum bend position. Load the left hand wrist joint again as the "Driver" in the "set driven key" menu.
Select the index finger knuckle again from the viewport and load it as "Driven". Click on the "key" button and the current rotation values of the joints of the index finger are linked to the value 10 of the "index finger bend" attribute in the channel box.
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