Animating a Car on a Path in 3ds Max - Part 03 - Turning the Wheels

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  • Design Visualization
  • Animation
  • 2015
  • 3ds Max
Skill Level
  • Intermediate
9 min

Animating a Car on a Path in 3ds Max - Part 03 - Turning the Wheels

In this tutorial, you establish the relationship between the car’s front wheels and the steering wheel, so that the front wheel’s turn when the steering wheel rotates.

  • Recorded in: 3ds Max 2015
  • This tutorial is intended for use with 3ds Max version 2015 or higher.


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Now that you have the car wheels spinning properly based on car travel, the next step is to control the turning of the front wheels.

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What I call Turning in this case is a rotation you apply to the front wheels as the car steers left or right.

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Here you will establish a link between the turning of the front wheels and the rotation of the steering wheel.

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This way, you'll be able to keyframe the rotation of the steering wheel and the front wheels will react to that change.

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Continue working on your file. You can also use the file named Car-Rig_wheel-turn.max if you need to catch up.

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Select the steering wheel and set your rotation mode to Local.

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As the steering wheel rotates on its local Z-axis, you want the front wheel helpers to also pivot on their local Z-axis.

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Make sure the steering wheel is selected and right-click to access the Quad menu.

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Choose Wire Parameters > Transform > Rotation > Zero Euler XYZ > Z Rotation.

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With the rubber band appearing, the next step is to select the Front Left wheel helper.

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As mentioned in the last movie, it's easy to make a mistake and pick the wrong object instead.

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Rather than risk that, use the H key or the Scene Explorer to select the Car_hlp_FL helper object.

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Wire the steering wheel to the helper's Transform > Rotation > Zero Euler XYZ > Z Rotation

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In the Wiring dialog, set the direction so that the steering wheel controls the helper,

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and click Connect.

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Do not dismiss the dialog just yet. Make sure the steering wheel is selected and test out the results by rotating it locally on its Z-axis.

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Not bad but the rotation is inverted.

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Place a - (minus) sign in front of the formula and update it.

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Try it again…

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Much better but you still need to fine-tune it.

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Usually, a steering wheel lock-to-lock range as it is called is far superior to that of a turning wheel.

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The front wheels on an average car may turn to about 45 degrees left or right giving them a range of about 90 degrees.

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A steering wheel however typically has about 3.5 revolutions, from left lock to right lock.

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In fact, the ratio between steering wheel and front wheel rotations is often about 14:1 on a regular car.

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Sports car may have a smaller ratio, maybe 9:1 or 10:1.

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It's even smaller on race cars. A Formula 1 car for example is probably closer to a 3:1 ratio.

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On your average every-day car, especially one built in the sixties, the ratio is around 14:1

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Therefore, divide the formula by 14 and update it again.

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Test the results; they should be quite a bit more natural this time around.

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Copy the formula using Ctrl+C,

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and repeat the procedure for the right wheel helper.

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Dismiss all wiring dialogs when done.

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With the car animated to travel along the path, you will now animate the steering wheel based on the path curves.

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Select the steering wheel and make sure you are in Local Rotate mode.

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Also, switch back your Time Display to Frames only, to ensure keyframes do not fall into the subdivisions.

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Enable Auto Key and take a global look at the animation.

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For the first 10 frames or so, the car is practically moving in a straight line.

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Go to Frame 10,

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and right-click the Time Slider bar.

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In the Create Key dialog, make sure only Rotation is enabled and click OK.

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This creates a rotation key at frame 10 ensuring no rotational changes happen before that frame.

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Now scrub the animation until the car is in the middle of the first turn.

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Frame 52 looks about right.

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Zoom in for a better view and rotate the steering wheel on its local Z-Axis until the front wheels are aligned with the turn.

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Zoom back again and scrub the animation until the car is in the middle of the second turn.

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Frame 112 looks good.

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Zoom in again and rotate the steering wheel the other way,

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until the front wheels look properly aligned.

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Finally go to the frame where you feel the wheel should be straight again,

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frame 140 seems like a good fit.

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Here you need to bring back the steering wheel to its original position.

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Although we didn't take note of the rotation values we established a second ago, there is an easy way to reverse them.

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One way is to copy the keyframe at frame 10 which represents the steering wheel at the original 0 angle.

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This can be done by holding the Shift key and moving the keyframe from 10 to 140.

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Another easier way comes courtesy of freezing the transforms earlier in the tutorial.

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Because of that, you can use Alt with a right-click and then choose Rotation to Zero.

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This realigns the steering wheel to its original state and creates a keyframe since Auto Key is enabled.

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Exit Auto Key when done.

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Adjust your view,

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and scrub the animation to test the results.

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At this point, you may want to reset the Time Display to Frames and Ticks to smooth the viewport playback.

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The animation is getting better but you can improve on it still.

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A heavy car from the sixties tends to have a lot of body roll when taking a turn.

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You need to establish a link between the body rotation and the steering wheel.

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This way, every time the car makes a turn, the body will lean a bit towards the outside of the turn.

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This is what you do in the next movie.
Posted By
  • 3ds Max
  • Animation
  • 2015
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