Animating an IK system

The animation sequence occurs over a 180 frame period. Before you begin to set keyframes you set the playback range in the Time Slider.

To set the playback range in the Time Slider

1. In the Animation Time and Range Slider, set the following start and end times for the animation:
   • Playback Start Time: 1
   • Playback End Time: 180
     

To simplify the keyframe workflow, you first set keyframes for the mechanical arm, and then set keyframes for the weight attributes of each parent constraint for the cargo box.

To set keyframes for the mechanical arm

1. In the Time Slider, go to frame 1.
2. Select only ArmControl.
3. In the Channel Box, set the following values:
   • Translate Y: 0
   • Translate Z: -13
4. From the main menu, select Animate > Set Key.

To set the remaining keyframes for the arm and the swivel base, use the table below as a guide, and set the attributes in the following order:

• Set the frame using the Time Slider.
• Set the attributes for the object in the Channel Box.
• Set the keyframe (Animate > Set Key).
  Note

  Don’t be concerned if the list of keyframes indicates to set a key twice for the same position over two frames. This is necessary to animate the parent constraint weights over a period of one frame.

  Frame	Select	Set attribute	Select
  1	ArmControl	TransY: 0 TransZ: -13	Set Key
  30	ArmControl	TransY: 7 TransZ: -13	Set Key
  59	ArmControl	TransY: -9 TransZ: 0	Set Key
  60	ArmControl	TransY: -9 TransZ: 0	Set Key
  80	ArmControl	TransY: 6 TransZ: -13	Set Key
  80	SwivelBase	RotateY: 0	Set Key
  100	SwivelBase	RotateY: -100	Set Key
  100	ArmControl	TransY: 6 TransZ: -13	Set Key
  120	ArmControl	TransY: -9 TransZ: 0	Set Key
  121	ArmControl	TransY: -9 TransZ: 0	Set Key
  140	ArmControl	TransY: 6 TransZ: -13	Set Key
  140	SwivelBase	RotateY: -100	Set Key
  160	SwivelBase	RotateY: 0	Set Key
  160	ArmControl	TransY: 6 TransZ: -13	Set Key
  180	ArmControl	TransY: 0 TransZ: -13	Set Key

Once the keyframes for the mechanical arm are set you can use the playback controls to playback the motion for the mechanical arm.

To playback the animation using the playback controls

1. Click play on the Time Slider playback controls to play the animation.

   The mechanical arm animates over 180 frames. The cargo box does not move because the weight attributes for the parent constraints are set to zero and have not yet been set for the animation.

2. Click stop on the Time Slider playback controls to stop the playback.

In the next steps, you set keyframes for the parent constraint weight attributes so the cargo box is lifted, moved, and placed in the second location. You set keys for the weight attributes on the parent constraint node.

To set keyframes for the parent constraint weights

1. In the Time Slider, go to frame 1.
2. In the Hypergraph, select the node for the parent constraint directly below CargoBox.
   
3. In the Channel Box, set the following values (if they are not set already):
   • ArmControl W0: 0
   • Platform W1: 0
4. In the Channel Box, select the ArmControl and Platform channels by shift-clicking on the names.
5. Right-click on either one of the selected names.

   A drop-down list appears.

6. From the drop-down list, choose Key Selected.

   Key Selected sets a keyframe for the selected attributes only.

To set the remaining keyframes for the parent constraint weights, use the table below as a guide, keeping in mind that you set the attributes in the following order:

• Set the frame using the Time Slider.
• Set the parent constraint attributes in the Channel Box.
• Right-click on the selected names and select Key Selected.

  Frame	Select	Set attribute	Select
  1	CargoBox parentConstraint	ArmControl W0: 0 Platform W1: 0	Key Selected
  59	CargoBox parentConstraint	ArmControl W0: 0 Platform W1: 0	Key Selected
  60	CargoBox parentConstraint	ArmControl W0: 1 Platform W1: 0	Key Selected
  120	CargoBox parentConstraint	ArmControl W0: 1 Platform W1: 0	Key Selected
  121	CargoBox parentConstraint	ArmControl W0: 0 Platform W1: 1	Key Selected

To playback the animation using the playback controls

1. Click play on the Time Slider playback controls to play back the animation.

   The mechanical arm moves through the motion of the animation and picks up and moves the cargo box to the new location.

2. Click stop on the Time Slider playback controls to stop the playback.

   You have completed this lesson.