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” all- thread, 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 micro- controller.
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 Bumper Binary Representation 1 Front Left001 2 Front Right010 3 Both Front Left &011 Right 4 Rear100 * 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 | | m | | m | | m | | m | | m | X X X X | m | X X X X | m | X X X X | m 7 * Notice inputs X, Y, Z are the same as outputs B, C, D
Detailed Subsystem Specifications: Circuit Design Simplified Map for Variable A: A = X + Y + Z 111 1XXX X Z Y
Detailed Subsystem Specifications: Circuit Design Simplified Map for Variable B: B = X 1XXX
Detailed Subsystem Specifications: Circuit Design Simplified Map for Variable C: C = Y 11 XXX
Detailed Subsystem Specifications: Circuit Design Simplified Map for Variable D: D = Z 11 XXX
Detailed Subsystem Specifications: Circuit Design 5.0 V A B C D XY (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