Making the robot detect pets

The preceding code is good, and I'm sure it would be dispensing the food at set times. However, there can be a problem, as the robot would not be effective if the pet does not know whether the food had been fetched. Hence, we need to have an alarm that should inform the pets that the food is ready to be eaten. 

Even in the previous program, we have used a buzzer that will inform the pet when the food is being dispensed, but, that was only for a very short period of time. However, what we are talking about here is an alarm system that will keep on ringing till the time the pet does not come and eat the food. To do this, connect the system as follows and mount the ultrasonic sensor in such a way that it notes the distance of the pet while he is eating the food.

Now, to do that, you will need to upload the following code:

import time
import Adafruit_ADS1x15
import RPi.GPIO as GPIO

Motor1a =  21
Motor1b = 20
Buzzer = 14
FSR = 16

GPIO.setmode(GPIO.BCM)
GPIO.setup(Motor1a...