ECE415 SDP DesignECE415 SDP Design

MAPPER: A Perfectly Portable Exploration Robot

Rohan Balakrishnan (CSE)

Conan Jen (EE)

Andrew Lok (EE)

Jonathan Tang (EE)

ECE415 SDP Design

Project Inspiration

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ECE415 SDP Design

Project Vision• Reconnaissance is always important for the

military• Desired solution is autonomous, small and

cheap implementation• With importance of human lives, robots are

perfect replacement

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ECE415 SDP Design

Decided Implementation• Autonomous robotic platform capturing

information about its surroundings • Wireless communication link will transfer data

back to PDA or Laptop• Transferred data used to construct a 2-D bird's

eye view of the environment

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ECE415 SDP Design

Project Considerations • Multiple platform considerations

– Non-mobile• Leaves very little time for scanning• Must be impact hardened• Scan rotation depends entirely on trajectory of throw

• Multiple sensor considerations– Laser

• Expensive, loses accuracy at range, bulky– Radar

• Power hungry, large, expensive, complicated– Optical

• Needs large bandwidth on wireless link, software based distancing detection

– Ultrasound• Inexpensive, accuracy issues

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ECE415 SDP Design

Project Specs / Scenario • Initial Phase– Room Limitations: 20'x20‘, flat floor– Method: rotating ultrasonic sensors– Scan time: 5-15 mins– Stationary walls and large objects (minimum 1'x1')

only– No manual intervention, straight movement into

room– Wireless communications: 100+ ft

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ECE415 SDP Design

Room Scenario

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ECE415 SDP Design

GUI Mockup

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ECE415 SDP Design

Budget PARTS / BUDGET:

Ultrasound Sensor $28Roomba Create $130Roomba Standard Rechargable Battery $50PCB $150Wireless communication device $27-60Arduino Clone (ATmega168) Free (M5) Total $385-418

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ECE415 SDP Design

Block Diagram

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ECE415 SDP Design

Roomba Create • Robotics platform from iRobot• Provides serial input to the base• Has a multitude of sensors built in• Allows for addition of parts through expansion

port

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ECE415 SDP Design

Standard Roomba Create

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ECE415 SDP Design

Wireless Link Considerations: Bluetooth, RF, WLanSecurity:• Important because of military applications• Do not want enemy knowing what you know• Do not want false data injectionRange:• Need to be able to go through objects• Link must be robust, cannot fail easily• Must be able to deal with interference• Jamming / interference is an issue, especially with

military applications

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ECE415 SDP Design

Stepper Motor • LA23GCK-213 Stepper

Motor• Provides basic platform for

sensor to turn and sweep• Used to mount the

ultrasound sensor onto• 1.8° per step• Ultrasound sensor beam

width @ 20 ft. ≈ 6°• Oversampling max room by

a factor of 3

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ECE415 SDP Design

Microcontroller • Arduino clone - ATmega168• Based on the larger Wiring development

board• Rapid development with Processing.• Flexibility of AVR C on ATmega

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ECE415 SDP Design

Ultrasound Sensor

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Sensitivity to Ambient Conditions:• Average room temperature

changes will cause sensor to report readings of accuracy ± 5%

ECE415 SDP Design

Power Sources • The Roomba has its own internal battery– 12 AA alkalines or rechargeable equivalent– Expected battery life (1.5 hrs)

• 5V supply from Roomba, 16V supply from Roomba battery– Pin 8 (5V regulated)– Pin 9 (Battery power unregulated)

• Power for all our components can be drawn from Roomba

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ECE415 SDP Design

Project Responsibilities • Rohan: Map application on computer/Arduino

interfacing• Conan: Wireless/Ultrasound• Andrew: ATMega168/Arduino interfacing• Jon: Stepper Motor + Wireless

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ECE415 SDP Design

Rough Timeline

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ECE415 SDP Design

Challenges• Ultrasonic sensor may have accuracy issues• Roomba movement integration

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ECE415 SDP Design

Questions? • Questions? Comments?

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