Transcript Bump Switch System for WunderBot II

Bump Switch System
for WunderBot II
By:
Matt Barley
Detailed Subsystem
Specifications: Physical Design
• 2”x4”x21” Bracket
attached to bottom of
WunderBot II Platform
with additional 2”x4”x4”
block supports to stabalize
bumpers
• Bumpers constructed from
PVC piping attached to
brackets via 5/8” allthread, washers, nuts, and
springs between front
stabalizing blocks and
PVC
Detailed Subsystem
Specifications: Original Design
• The front bump switch
system contains two
tactile switches (right,
left)
• The rear bump switch
system has one tactile
switch
• All three are input into
a Combinational Logic
Circuit
Detailed Subsystem
Specifications
• The onboard PC is
notified of a collision
and also of what
bumper is in impact
via a 3-bit BCD
number from the
interfaced microcontroller.
Detailed Subsystem
Specifications: Circuit Design
• Input Variables:
•
X
 Rear Bump Switch Input
•
Y
 Front Right Bump Switch
Input
•
Z
 Front Left Bump Switch
Input
Detailed Subsystem
Specifications: Circuit Design
• Output Variables:
•
A
 Collision Indicator
•
B
 Third digit of Binary Coded
Decimal
•
C
 Second digit of Binary
Coded Decimal
•
D
 First digit of Binary Coded
Decimal
Detailed Subsystem
Specifications: Circuit Design
• BCD

•
•
•
1
2
3



4

Bumper
Binary
Representation
Front Left
001
Front Right
010
Both Front Left &
011
Right
Rear
100
• * Assume impact will not occur from front and
rear bumpers simultaneously
Detailed Subsystem
Specifications: Circuit Design
• Truth Table:
•
X Y Z | A B C D | Minterms
•
0 0 0 | 0 0 0 0 |
m0
•
0 0 1 | 1 0 0 1 |
m1
•
0 1 0 | 1 0 1 0 |
m2
•
0 1 1 | 1 0 1 1 |
m3
•
1 0 0 | 1 1 0 0 |
m4
•
1 0 1 | X X X X |
m5
•
1 1 0 | X X X X |
m6
•
1 1 1 | X X X X |
m7
* Notice inputs X, Y, Z are the same as outputs B, C, D
Detailed Subsystem
Specifications: Circuit Design
1
1
1
1
X
X
X
X
Z
Y
• Simplified Map for
Variable A:
• A=X+Y+Z
Detailed Subsystem
Specifications: Circuit Design
1
X
X
X
• Simplified Map for
Variable B:
• B=X
Detailed Subsystem
Specifications: Circuit Design
X
1
1
X
X
• Simplified Map for
Variable C:
• C=Y
Detailed Subsystem
Specifications: Circuit Design
1
1
X
X
X
• Simplified Map for
Variable D:
• D=Z
Detailed Subsystem
Specifications: Circuit Design
5.0 V
A
B
C
D
X
Y
(X + Y)
Z
Detailed Subsystem
Specifications: Revised Design
• Very difficult to
position tactile
switches with physical
bumper design;
working sufficiently
without damaging the
switches
• Replaced tactile
switches with IR
sensors
Detailed Subsystem
Specifications: Revised Design
• Revised physical
bump switch system
with IR Sensors in
position
• Sensors activated by
movement in wood
blocks attached to
bumpers’ bolts
underneath the
WunderBot II
Platform