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It was found the most optimal way to achieve perfect Ackerman is to align the steering arm at the same angle as the line that connects the intersection of the track and wheelbase to the middle of the back wheelbase line.
Model of Ackerman can be found: GrabCAD\MSXIV\Development\Dynamics\Steering
In the file “Ackerman 2D model” or “Overlay”.
Overlay contains the master sketch with the Ackerman model.
~85~88.6mm 67mm of travel in rack of model when at perfect Ackerman (~27 degrees).
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Overlay model with wheels turned at 26 degrees.
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Side view of mount, rack is tilted 15 degrees.
Interference Check
Found in the MAX UP and MAX DOWN configurations in ASSEM-Dynamics.
Centerlink is fixed to move only horizontally, there is a distance mate which sets the centerlink right plane 90mm (max travel) from the right plane of the assembly.
See Video below.
Steering Intro Spring 2020
Google drive slides | ||
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Finalized CAD (May 30, 2020)
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View file | ||
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View file | ||
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Bump Steering Characteristics
Upright | Centerlink | Result (wheel to neutral, deg) |
neutral | neutral | 0 |
right 90mm | 27.14 | |
left 90mm | 24.61 | |
up 35mm | neutral | 0.38 |
right 90mm | 27.64 | |
left 90mm | 24.22 | |
down 20mm | neutral | 0.13 |
right 90mm | 27.3 | |
left 90mm | 24.48 |
Note, a travel of 90mm was used for convenience.
Bump steer was characterized using mates of an assembly between the upright and steering system.
The upright was moved up or down to simulate moving past a bump
The centerlink was moved 90mm to simulate the largest angles the wheels would be allowed to turn at
The above chart is used to compare the difference in wheel angles when a bump is encountered vs the upright at a neutral position
The spindle face was measured against the right plane to obtain measurements
As can be seen, the difference in wheel angle is trivial
DRI
Name | Responsibility |
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Emily Guo | Steering lead (general inquires), ackerman geometry, Steering Arm FEA, Design, Interference Checks. |
Shijing Yang | Steering column drawings, stock spec. |
Leif Blake | FEA of centerlinke, rack extension, tie rod. |
Arshia Khanifar | Calculation of forces involved in steering column. |
Vansh Dhingra | VR3 Documents (tie rode, centerlink, rack extension). |
Ambreen Ahmed | Archived FEA of steering system. |
Anna Wei | Tilt mechanism. |