Using Applied IK

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If you work with the Inverse Kinematics toggle on, it is termed Interactive IK. Another mode of Inverse Kinematics is Applied IK. With Applied IK, you can independently animate the follow object or any object in its kinematic chain, and get Autodesk VIZ to solve the IK solution for all frames in the animation.

In the next section, the LOWER ARM is animated, and Applied IK is used to animate the remainder of the assembly.

Set up:

To start from this point, do one of the following:

Continue from the previous lesson, or open your saved file, myassy01.max.
If you want to begin the tutorial at this point, open tut_mech_04.max from the \tutorials\mech_design directory.

Set the animation range:

In the time controls, click Time Configuration.
In the Time Configuration dialog > Animation area, set the End Time to 300 frames and click OK to close the dialog.
Right-click in the Perspective viewport to make it active, and click Min/Max toggle to make the viewport full screen.
Click Arc Rotate. Rotate the Perspective viewport to see the LOWER ARM.
Press H and select the LOWER ARM from the list.
Turn on Auto Key.
Scrub the time slider to frame 100.
On the toolbar, click and then right-click Select And Rotate.

The Rotate Transform Type-In dialog appears.
In the Rotate Transform Type-In, enter −8 degrees in the Offset: World Y-axis field and press Enter.

Don’t be concerned that the remainder of the assembly doesn’t follow. It will do so later when you use Applied IK.
Scrub the time slider to frame 200.
In the Rotate Transform Type-In dialog, enter 16 degrees in the Offset:World Y-axis field. Press Enter.
Scrub the time slider to frame 300.
In the Rotate Transform Type-In dialog, enter −8 degrees in the Offset: World Y-axis field.

This will bring the LOWER ARM back to its original orientation.
Turn off Auto Key.
Close the Rotate Transform Type-In dialog.
On the toolbar, click Select Object to cancel Rotate.
In the time controls, click Play. The LOWER ARM moves up, down, and then back to its original position.

Use Applied IK:

Press H and select CARRIER from the list.
In the Hierarchy panel > IK > Inverse Kinematics rollout, set the End frame field to 300.

This will make Autodesk VIZ calculate the IK solution for every frame in the animation.
In the Hierarchy panel > Inverse Kinematics rollout, click Apply IK.

The solution is determined for all frames in the specified range. The time slider moves across the screen as each frame is solved.
In the time controls, click Play.

The suspension moves as required.
In the time controls, click Stop.

Animate WHEEL rotation:

In this step you will add WHEEL rotation to the animation.

In the time controls, click Go to Start.
Press H and select WHEEL from the list.
Right-click the WHEEL and choose Curve Editor from the quad menu.
Select the Rotation track.
Right-click the Rotation track and select Assign Controller from the quad menu.
In the Assign Rotation Controller dialog, select Euler XYZ, then click OK to close the dialog.

The Euler XYZ rotation controller lets you animate each axis individually.
Select the X Rotation track.
On the Track View toolbar, click Add keys.
Click the curve at approximately frames 0 and 300.
On the Track View toolbar, click Move Keys.
Click the Keyframe at frame 0 and enter a value of 0 degrees. There are two small fields at the bottom of the Track View dialog. The second field is the value field.
Click the Keyframe at frame 300 and enter a value of 720 degrees (two revolutions).
Click Zoom Value Extents, at the bottom-right of the Track View.

This will compress Track View graph so that you can view the values.
Close the Track View dialog.

Play the animation:

In the time controls, click Time Configuration.
In the Time Configuration dialog > Playback area, click Speed ¼x then click OK.
In the time controls, click Play.

The WHEEL rotates as the suspension moves up and down. If the animation is not playing back smoothly, right-click the Perspective viewport label and select Wireframe.
Stop the animation and return the time slider to frame 0.

Notice that the dummy objects are visible. Although dummy objects will not appear in the rendering you may wish to turn them off in the viewport. To accomplish this, you use the Display panel.
In the Display panel > Hide By Category rollout, click the Helpers check box.

The Dummy objects disappear from view.

The final step in the animation is the WHEEL turning angle.

Animate WHEEL turning angle:

The WHEEL turning angle can be animated by rotating the CARRIER. Since the WHEEL is a child of the CARRIER, it will inherit its rotation.

On the toolbar, click Select And Rotate.
Press H and select CARRIER from the list.
Scrub the time slider to frame 100.
Turn on Auto Key.
In the toolbar, right-click Select And Rotate.

The Rotate Transform Type-In dialog appears.
In this dialog, enter 20 in the Z Offset:World field and Press Enter.
Scrub the time slider to frame 300.
In the Rotate Transform Type-in dialog, enter −20 in the Offset:World Z axis field and press Enter.
Turn off Auto Key.
Close the Rotate Transform Type-In dialog.
In the time controls, click Play. The WHEEL rotates, turns, and moves up and down.
Stop the animation and return the time slider to frame 0.

Save your work:

On the menu bar, choose File > Save As. Name your scene myassy02.max. You can see a finished version of this animation in the file suspen3.avi.

Summary

In this tutorial, you have learned several key concepts and tools for animating mechanical assemblies with Autodesk VIZ:

How to keyframe individual object movements, and how to fade objects in and out by editing the Visibility track in Track View.
The difference between forward kinematics and inverse kinematics (IK), and their role in animating object assemblies.
Manipulating pivot points.
The fundamentals of Interactive IK and Applied IK.