Benjamin Genre Advisor Dr Ho Hoon Lee Dr Cris Koutsougeras ET 493 Senior Design Project I Spring 2017 Goal of Project Create a CProgram capable of calculating steering error for any Mini Baja design ID: 804356
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Slide1
DESIGN OF STEERING SYSTEM OF SELU MINI BAJA CAR
Benjamin Genre
Advisor: Dr. Ho-
Hoon
Lee
Dr.
Cris
Koutsougeras
ET 493 Senior Design Project I
Spring 2017
Slide2Goal of Project
Create a C-Program capable of calculating steering error for any Mini Baja design.
Determine the best setup to be used on the two different frame designs.
Slide3Background
In 2013 a research paper about the steering design of an SELU Mini Baja car was written by Alfred Showers, Dr. Ho-
Hoon
Lee, and Dr.
Cris
Koutsougeras. It was determined that a commercially available Rack-and-pinion system would be best used for a Mini Baja car.A rack-and-pinion system uses rotational motion of a pinion gear and converts it into linear motion with the rack, moving the wheels of a vehicle left and right.
Slide4With this design, steering error would become a factor and the placement of the rack-and-pinion would be a design parameter.
The distance from the front axle to the placement of the rack-and-pinion is the main value the program helps to determine.
Rack and Pinion System
Slide5Ackerman Steering Principle
States that the axial lines of all the wheels should meet at the same point.
Slide6When the projections of the two front wheels do not meet at the same point on the rear axle’s axis.
By changing the distance from the front axle to the rack, the steering error also changes.
Ackermann Steering Error
Steering Error
Slide7Flow Chart
Program made with Microsoft Visual Studio.
At the start of the program, the user is asked to input the constants of the design. These include:
Length from front axle to rear axle.
Width of car.
Length of the rack and pinion.
Length of steering arm.
Angle between steering arm and wheel.
Maximum displacement of rack.
Initial value of S (the distance between the front axle and rack.)
Maximum value of S.
Slide8Flow Chart
Everything is calculated as a function of S using the equations derived in the paper.
Prints values of S,
lt
,
θ
l,
θ
r, and
es
.
S is increased and then compared to
Smax
.
If S <
Smax
, the calculations start over with new value for S
If S >
Smax
, then the program ends.
Slide9Output Frame 1
Steering Error Calculator
Enter length from front axle to rear axle:
64
Enter width of car:
38
Enter length of rack and pinion:
11
Enter length of steering arm:
4
Enter angle between wheel and steering arm in degrees:
16.5
Enter maximum displacement of the rack:
2.25
Set initial value of S, the distance between the front axle and rack and pinion:
2.5
Set Max value of S, the distance between the front axle and rack and pinion:
4.5
Slide10Table Frame 1
Steering Error Output for Frame 1
s (in)
lt
(in)
Ol
(rad)
Or (rad)
es
(in)
2.500000
12.435833
-2.698303
1.561025
32.791946
2.600000
12.425493
-2.681408
1.542593
27.116013
2.700000
12.415951
-2.664580
1.523945
21.834167
2.800000
12.407207
-2.647819
1.505060
16.904785
2.900000
12.399262
-2.631127
1.485913
12.291878
3.000000
12.392121
-2.614508
1.466477
7.964203
3.099999
12.385782
-2.597961
1.446716
3.894279
3.199999
12.380248
-2.581490
1.426593
0.058311
3.299999
12.375521
-2.565096
1.406059
3.564545
3.399999
12.371598
-2.548780
1.385054
-6.993240
3.499999
12.368484
-2.532545
1.363509
-10.244102
3.599999
12.366177
-2.516391
1.341329
-13.331718
3.699999
12.364678
-2.500320
1.318400
-16.269325
Slide11Output Frame 2
Steering Error Calculator
Enter length from front axle to rear axle:
64
Enter width of car:
40
Enter length of rack and pinion:14Enter length of steering arm:4
Enter angle between wheel and steering arm in degrees:
17.35
Enter maximum displacement of the rack:
2.25
Set initial value of S, the distance between the front axle and rack and pinion:
2.05
Set Max value of S, the distance between the front axle and rack and pinion:
3.05
Slide12Table Frame 2
Steering Error Output for Frame 2
s (in)
lt
(in)
Ol
(rad)
Or (rad)
e
s
(in)
2.050000
11.938805
-2.727748
1.595668
41.716309
2.150000
11.924406
-2.709923
1.576939
34.935944
2.250000
11.910830
-2.692160
1.558010
28.682266
2.350000
11.898078
-2.674464
1.538864
22.893677
2.450000
11.886154
-2.656836
1.519481
17.517822
2.550000
11.875060
-2.639279
1.499837
12.509750
2.650000
11.864799
-2.621795
1.479902
7.830841
2.750000
11.855372
-2.604387
1.459646
3.447845
2.849999
11.846783
-2.587056
1.439030
-0.668266
2.949999
11.839031
-2.569805
1.418006
-4.542877
3.049999
11.832120
-2.552636
1.396518
-8.198227
Slide13Design Comparison
Rack Length: 11”
S: 3.2”
Es
: 0.058”
Xr
: 102.0”Xl: 102.06”Turn Radius: 8.5 ft
Frame 1
Rack Length: 14”
S: 2.85”
Es
: -0.67”
Xr
: 104.2”
Xl: 103.0”
Turn Radius: 8.583
ft
Frame 2
Slide14Cost Analysis
Parts List
Part
Description
Cost
Steering Rack-Frame 1
(Figure 5)
11” Rack and Pinion Unit
Weights 2.25
lbs
desertkarts.com
$100.00
Steering Rack-Frame 2
(Figure 5)
14” Rack and Pinion Unit
Weights 2.25
lbs
desertkarts.com
$100.00
Steering U-Joint
(Figure 6)
Universal Joint with
5/8” Splines
desertkarts.com
$28.00
Steering Quickener
(Figure 7)
Howe 5224 2:1
Quickener
summitracing.com
$86.97
(Optional)
Steering Shaft Coupler
Steering Coupler, Steel, 5/8 in.
36-Spline, 3/4 in.
summitracing.com
$19.49
11” Rack-and-Pinion
Steering
Quickener
Steering U-Joint
Slide15Accomplishments
Studied Research Paper
Constructed Flowchart
Created Steering Error Calculating Program
Determined Steering Error for Frame Designs
Estimated Cost for Steering Parts
Future Work
Determine Steering Column Length for Final Design
Finalized Design Dimensions
Collect All Parts
Assemble Steering System