Tiger Scramble
Robot Design
Hannah Hoppenstedt
Josh Nelson
Presentation Outline
• Major Component Connections
• Operations
• Subsystems and Components
– Requirements
– Component Specifications
• Budget
Major Component Connections
RF Receiver
Servo
Brains
BS2
BS2p 40
Communication
Locomotion
Motor
Bumper
Switch
Ball Control
MMC
Motor
Operations
•
•
•
•
Find closest ball to goal
Travel to and capture ball
Put ball in goal
Avoid opponent robot
Subsystems and Components
• Microcontrollers
• Locomotion
– Motors
– Wheels
• Ball-Control Apparatus
• Battery
• Chassis
Communication Requirements
• Receive data from vision system
– Want to receive every packet
– Do not want BS2p40 tied up for 33 ms per
packet
Basic Stamp 2
• Receives info from the vision system
• Sends the data to the BS2p 40 for
calculations
– At the maximum flow control baud rate of
19.2k, it takes 3.75 ms to send 9 bytes
• BS2 to BS2p Connection (4 I/O pins)
– One pin for serial data transfer
– One pin for flow control
– Two pins for handshaking
AI Requirements
• Calculations on vision system information
– Distance
– Angle
– Integer Comparison
• Interpret commands from Vision System
• Execute all functions between packets
– 100 ms between first bits of two consecutive packets
• Memory
– 53 Bytes
Basic Stamp 2p 40
AI Requirements
Routine
Pick Ball
Memory Required
(Bytes)
29
Go To Ball
16
Go To Goal
3
Avoid Opponent
5
TOTAL
53
Control Requirements
Component Connection
• Sufficient number of I/O pins
– Control servo (1)
– Bumper switch (1)
– Motor Mind C (2)
• Fill registers on MMC to control speed and direction
– BS2 (4)
• Need 8 I/O pins
Basic Stamp 2p 40 AI
Routine
Execution Time (µs)
Pick Ball
8,220
Go To Ball
1,150
Return To Goal
1,150
Avoid Opponent
1,138
TOTAL
11,658
Basic Stamp 2p 40 AI
• Connection
– Need 8 I/O pins
– BS2p 40-pin module
has 32 general purpose
I/O pins
• Memory
– Need 53 bytes
– BS2p has 128 bytes of
scratch pad RAM and
26 bytes of variable
RAM
Locomotion Requirements
• Motor Control
• Motors
– Motor Mounts
• Wheels
– Wheel hubs
Motor Control Requirements
• Generate pulse width modulation
– Speed control
• Provide adequate current to motors
Motor Mind C
• Generate pulse width modulation
– Duty cycle of PWM varied according to
register value in serial mode
• Includes 2 H-Bridges
– Current control
• Connected to each motor with three output
lines
Motor Requirements
• Sufficiently low stall current
– 1.5 A
• Lightweight
• Speed
– 0.5 m/s
• Torque
– Minimum 18.08 oz-in
Copal Gearmotor 60:1
Stall Current
1.6 A
Rated Current 400 mA
Weight
0.88 oz
Rated Voltage 6-12 V
Torque
21 oz-in
Motor Mount
• Lexan
• Light weight
– 4 grams
• Simple assembly
Wheel Requirements
• Provide adequate ground clearance
– Minimum of 2 cm
• Shock absorbent for motors
Lite Flite Wheels
• Foam
– Light weight
• 11.3 g each
– Shock Absorbent
• Ground Clearance
– 6.35 cm diameter
wheels
• 3 cm
Ball-Control Apparatus
• Gripper
– Simple design
– Detect Ball Capture
• Bumper Switch
– Ball Capture
• Servo and armature
Ball-Control Apparatus
• Detect Ball Capture
– SPDT Switch
– SL-2NW1
• Ball Capture
– Servo and armature
– Futaba Continous
Rotation Servo
Battery Requirements
• 12 V
– Speed control flexibility
• Withstand 15 minute rounds
– 0.3 AH at 12 V
Battery Usage
Component
Voltage(V)
Current(A)
% Usage
Power (W)
2 Motors
6
3.2
4%
0.768
6
1.6
96% (normal) 9.216
BS2p40
5
0.075
100%
0.375
BS2-IC
5
0.04
100%
0.2
Motor Mind C
12
0.03
100%
0.36
Servo
5
0.2
100%
1.2
5 V regulator
7
0.322
100%
2.254
Receiver
5
0.007
100%
0.035
TOTAL
(stall)
14.4
Capacity = Total Power / 12V * (15 / 60) = 0.3 AH
12-V 500 mAH
NiMh Brick AntPack
• 0.5 AH exceeds
required 0.3 AH
• Meets 12 V
requirement
• Run Time = 25 mins.
Chassis Requirements
•
•
•
•
•
•
Space availability
Allow easy access to parts
Flat black top
Flat front for ball control apparatus
Lightweight
Durable
Expanded PVC
• Weight
– 450 g with standoffs
• Weight Limit
– 4 kg
– Need 750 g
• Easy to design and build a robot out of this
material
• Easy to implement multiple decks
Bottom Chassis layer
Battery
Middle Chassis layer
Bumper Switch
Receiver
Servo
BS2
BS2p
MMC
Top Chassis Layer
Budget
Revision 2
Item
Quantity
Price per Unit ($)
Motors & Mounts
Wheels & Hubs
Motor Mind C
BS2 - IC
BS2p 40
PCB
Chassis
Battery
Gripper
TOTAL
2
2
1
1
1
1
1
1
1
30.98
7.35
55.00
49.00
89.00
100.00
9.38
29.00
12.69
382.40
Conclusion
• Simple design
• Meets requirements
– Speed
– Microcontroller capabilities
– Ball control
• Within budget
Questions or comments?