F12: Evil Watchdog

Abstract

The Evil Watchdog takes the responsibilities of a pet guarding a house. It will roam around a predefined environment, avoid obstacles, and sound an alarm whenever foreign motion is detected.

Introduction

The objective of this project is to design a vehicle to imitate a guard dog. The following items will be incorporated to accomplish this goal :

• Motor driven chassis
• Vehicle will move in a random path detecting motion
• Vehicle will sound an alarm when motion is detected

Technology used

• Motion sensor
• Distance sensor

Team Members and Roles & Responsibilities

• Waymond Chen: Front motor control and distance sensor programming
• Hung Vuong: Distance and motion sensor programming
• Erik Montoya: Backside motor control and programming

Schedule

Starting	Ending	Planned Activities	Actual
Oct 26, 2012	Nov 1, 2012	Acquire parts Identify interfaces to be used Identify pin selections Review datasheets	Received distance sensors Received motion sensors
Nov 2, 2012	Nov 8, 2012	Build chassis Build motors and wheels Test motors and wheels	Prepared chassis and wheels Tested motors and steering
Nov 9, 2012	Nov 15, 2012	Write PWM driver Control rear wheels Program and test distance sensors	Created PWM driver Began controlling rear wheels Successfully tested distance sensors
Nov 16, 2012	Nov 22, 2012	Integrate motion sensors Test motion sensors Control/steer front wheels
Nov 23, 2012	Nov 29, 2012	Integrate alarm system Unite all parts
Nov 30, 2012	Dec 6, 2012	Testing and design final product Complete and revise project report
Dec 7, 2012	Dec 13, 2012	Finalize and deliver project

Parts List and Costs

The following table will be updated as parts arrive.

Item	Source	Cost Ea.	Qty.	Total
Alarm	RadioShack	$3.69	x1	$3.69
ARM7 NXP LPC2148 Microcontroller	SJValley Engineering	$60.00	x1	$60.00
Batteries - AA	Costco	$1.33	x5	$6.65
Chassis, Motors, and Wheels	Fry's Electronics	$15.34	x1	$15.34
Distance Sensors (3)*	SJValley Engineering	$25.00	x3	$75.00
LEDs	HSC Electronics	$0.35	x2	$0.70
Motion Sensor*	Preet Kang
Motor Controllers (2)*	SJValley Engineering	$35.00	x2	$70.00
Voltage Regulator - LM7805CV	HSC Electronics	$1.99	x1	$1.99

*generously provided by Dr. Ozemek and Preet Kang

Design and Implementation

Hardware Design

Original toy car prior to disassembly.

For convenience, a New Bright toy RC car was purchased and disassembled. The motors and wheels were already pre-mounted onto the chassis, allowing electronic parts to control the car. On the chassis, slots above the wheel wells were large enough to house motor controllers while the center of the chassis provided enough room to include a small breadboard and the microcontroller. All wires were shortened to the shortest length possible to reduce clutter.

The sensors, which guided car control, were strategically mounted in front and above the car. This increased visibility of the sensors. Three distance sensors were used to detect obstacles: a left-, a center-, and a right-side sensor was used to determine steering of the vehicle. A front-mounted sensor would seek motion as the car was stopped. Should motion be seen, the piezo buzzer sitting at the front of the car would promptly be sounded.