Tiger ScrambleTiger ScrambleRobot Design

Hannah HoppenstedtJosh Nelson

Presentation Outline

• Major Component Connections• Operations• Subsystems and Components

– Requirements

– Component Specifications

• Budget

Major Component Connections

RF Receiver

BS2 BS2p 40BumperSwitch

Servo

MMC

Motor Motor

Communication Ball Control

Brains

Locomotion

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 Memory Required (Bytes)

Pick Ball 29

Go To Ball 16

Go To Goal 3

Avoid Opponent 5

TOTAL 53

Control RequirementsComponent 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% (stall) 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 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

BS2BS2pMMC

ServoReceiver

Bumper Switch

Top Chassis Layer

Budget

Revision 2

Item Quantity Price per Unit ($)

Motors & Mounts 2 30.98

Wheels & Hubs 2 7.35

Motor Mind C 1 55.00

BS2 - IC 1 49.00

BS2p 40 1 89.00

PCB 1 100.00

Chassis 1 9.38

Battery 1 29.00

Gripper 1 12.69

TOTAL 382.40

Conclusion

• Simple design

• Meets requirements– Speed– Microcontroller capabilities– Ball control

• Within budget

Questions or comments?