1. Using An Ultrasonic Sensor to Find An Object on a Coordinate Grid
By William H. Kusewich
William Hamlet

2. Background
Global positioning systems use sensors to locate many different objects (cars, planes, people, etc.)
Position of objects is commonly taught in algebra using x-y coordinate grid
The trigonometric functions sine and cosine can also be used to determine an object position if the angle is known and the distance from the origin is known

3. Background Ping Ultrasonic Sensor
Distance =elapse time * speed of sound
Emits high frequency (40kHz) sound wave to an objects and measures the time it takes for the wave to return

4. x-y Coordinate Grid
Object Testing

5. Using Sin and Cosine Distance y-point=(sine (Θ)*distance)
x-point=(cosine (Θ)*distance)
Ultrasonic sensor stand

6. Using Sin and Cosine
Angles in pBASIC are determine by using the unit brad
128 brads = 180 degrees
Sin (64 brads) = 1
Cos (64 brads) = 0

7. Ultrasonic Sensor Stand
As the servo motor rotates, the angle of rotation is determine
BOE
Servo Motor
Ping Sensor

8. Component Connection Pin Selection LCD Distance=40cm X=4 Y=3
Servo Motor
Ping
Ultrasonic
Sensor
BOE

9. Problems With Ping Sensor
False-positive reading
Fix -Fence
Ping not giving the correct distance
Fix-Change the types of objects
Totally missing the object
Fix – Reduce the number of brads rotated for each reading

10. Results Y=8 Y=7 Y=6 Y=5 Y=4 Y=3 Y=2 Y=1 Y=0
Dark Circle – completely accurate
Gray Circle – Accurate to within one unit
Clear Circle- Missed or no reading
X= X= X= X=3 X=4 X=5 X= X=7 X=8
Y=8
Y=7
Y=6
Y=5
Y=4
Y=3
Y=2
Y=1
Y=0

11. Future Works
Create another unit, and have both units move along their respective axes until the object is located.
Place sensors at end of x-y coordinates respectively. Solve two equations using the distance formula simultaneously for x and y.
Have locators find a moving object.