PDRAUTOMATIC PET FEEDER

USF college of engineering

EEL 4906.001 - Engineering Design1

Term & Meeting Info: Spring 2015. M 6:30pm – 9:15pm.

Angelina Colannino, John Hook, Kjersti Raabe, Brian Wagner

Automatic Pet Feeder

Programmable, RFID controlled automatic feeder

User defined scheduled feeding time

Minimal product management required

Current Model

Project Driving Requirements

1. RFID Tags must be in range Must operate with material between tag and

receiver

2. RFID receiver must operate without tag collisions

3. Timer Interface must be defined by user Must store 3 set times Must take input from interface

4. Motor Circuits triggered by logic circuit/timer

5. Power Supply

1. RFID tags in range

Material must be thin enough to avoid interfering with RF signal.

Receiver must be mounted on front of module so that tags can be within 4” range.

Receiver must be mounted parallel to front of module in order to receive signal

Tags operating on frequency of 125 kHz

2. RFID tag collisions

Receiver must sense presence of RFID tags without error

The presence of more than one tag may cause tag collisions, which result in receiver error.

Test plans include tag collision experiment.

3. User-defined timing

Timer must be set by interface screen/buttons on front of module.

Screen must display current time, as well as interface for setting feeding times.

Timer must store up to 3 feeding times.

4. Motor circuits trigger

Motor circuit must respond to trigger from logic circuit.

Logic circuit must take input from RFID receiver as well as timer.

Trigger must be produced when both timer signal is present and RFID tag signal is received.

Typical servos operate from PCM signals

5. Power supply

Primary: 120 VAC-4.5VDC (regulate between 4-6 V)

step down transformer power supply Secondary:

Battery Back-up (Alkaline) 4.5 V DC 42 hrs when in active use 10-year shelf life

http://www.energizer.com/batteries/energizer-max-alkaline-batteries#dhttp://data.energizer.com/PDFs/e95.pdf

5. Power Supply (cont.)Voltage Regulator LM7805 would make most sense for designing/regulating the power supply if using a chip to do so

5. Power Consumption

RFID Reader 4.5-5.5 VDC

Arduino Uno Operating Voltage 5V Input Voltage Limits 6-20V

Servomotors 4-6V DC Maximum current draw is 140 +/- 50 mA at 6 VDC

when operating in no load conditions, 15 mA when in static state

file:///C:/Users/John-Hook/Desktop/28140-28340-RFID-Reader-Documentation-v2.3.pdf

https://www.parallax.com/sites/default/files/downloads/900-00005-Standard-Servo-Product-Documentation-v2.2.pdf

Top-Level System Diagram

Internal Interface

Self contained

Subsystems interface with each other RFID serial connection with Arduino Timing Logic Circuit

Verification

RFID sensor Range Interference Tag collisions

Timing Circuit Interface operation Produce trigger Storage

Servo Motors Respond to trigger Weight/strength

State Transition Diagram

Data Flow Diagram

Data Flow Diagram

Sequence Diagram

Technical Trades

Arduino Code vs. User Interface Corkscrew vs. “Water Wheel” Dispenser Drawer vs. Door Scale vs. Clear Reservoir Wi-Fi vs. Manual Setting Alarm tone vs. Voice

Project Test Plans: Initial Verification

RFID sensor Range Interference Tag collisions

Timing Circuit Interface operation Produce trigger Storage

Servo Motors Weight/strength

Project Test Plans: General Construction

Temperature Place system in extreme temperatures and

verify operation. Accessibility

Test operation of lid on top of module. Test operation of buttons/screen

Capacity Test amount of food reservoir can hold

Project Test Plans: RFID

Range Read data from RFID receiver, holding tags at

several different distances. Interference

Read data from RFID receiver when different materials are used for module.

Project Test Plans: Timing Circuit

User-defined Settings Use interface to set 3 separate feeding times. Demonstrate that the feeding times produce a

trigger. Storage

Demonstrate that feeder will store three feeding times at once.

Project Test Plans: Motor Circuit

Trigger Produce trigger from timing and RFID receiver

to demonstrate that motor will respond. Drawers

Demonstrate that motor can move the drawer. Refilling mechanism

Produce trigger and demonstrate that refilling mechanism operates properly.

Project Risk

Inherent Overheating Motors Battery Failure

Implementation Probability of microcontroller failing

(prototyping) Timing Circuit RFID Interference

Risk 1: Timing Circuit

Probability (Likelihood)

1

0Consequence

Performance

Cost

Schedule

Potential Degradation

Sys Reqt not Achieved

Element Increase > 50%

System Increase > 40%Element Increase

Increase >10%

x

x

x

x

High Risk – Severe disruption expected to performance, cost, and / or schedule even with risk mitigation plans in place.

Moderate Risk –Expected disruption to performance, cost, and / or schedule can be overcome by implementing risk mitigation plans.

Low Risk – Little disruption expected to performance, cost, and / or schedule.

Mitigation of the Timing Circuit

Double checking the code Testing the code before finalizing the

feeder

Risk 2: RFID

Probability (Likelihood)

1

0Consequence

Performance

Cost

Schedule

Potential Degradation

Sys Reqt not Achieved

Element Increase > 50%

System Increase > 40%Element Increase

Increase >10%

x

x

x

x

High Risk – Severe disruption expected to performance, cost, and / or schedule even with risk mitigation plans in place.

Moderate Risk –Expected disruption to performance, cost, and / or schedule can be overcome by implementing risk mitigation plans.

Low Risk – Little disruption expected to performance, cost, and / or schedule.

Mitigation of RFID Interference

Testing of Multiple RFID tags Range of the tags Interference

Project Schedule

Bill of Materials

Review Action Items