Hi all! this is my first project and it's for school. Our project is to create an automatic swing door opener using an ultrasonic distance sensor and a servo motor. It's a life-sized prototype so the door we built is really lightweight.
how we want it to work is that once the UDS detects an object within 50cm or so, it will trigger the servo to rotate. It will wait 5 seconds then check if the object is still there. If it is, it will stay open. If it isn't it will return the servo to initial position then repeat the whole thing again.
The challenge with this project is to be able to make the device portable, meaning it can be transferred from one swing door to another while still being fully functional.
Our problem right now is coding... no matter what we do, the servo will not stop rotating continuously. We think we may have bought a continuous servo without knowing, but it may just be from the code.
We're on a tight budget and schedule so any sort of input to this would be very much appreciated thank you!
#include <Servo.h>
// define pins for ultrasonic sensor
const int trigPin = 10;
const int echoPin = 11;
// define pin for servo
const int servoPin = 9;
// define variables for distance measurement
long duration;
int distance;
// create a servo object
Servo myServo;
void setup() {
// initialize serial communication
Serial.begin(9600);
// define the pin modes
pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);
pinMode(servoPin, OUTPUT);
// attach the servo to the corresponding pin
myServo.attach(servoPin);
}
void loop() {
// generate a pulse to trigger the ultrasonic sensor
digitalWrite(trigPin, LOW);
delayMicroseconds(2);
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);
// measure the duration of the pulse from the ultrasonic sensor
duration = pulseIn(echoPin, HIGH);
// calculate the distance in centimeters
distance = duration * 0.034 / 2;
// print the distance to the serial monitor
Serial.print("Distance: ");
Serial.print(distance);
Serial.println(" cm");
// check if an object is detected within 50 centimeters
if (distance < 50) {
// rotate the servo to 90 degrees
myServo.write(180);
Serial.println("OPEN");
// wait for 5 seconds
delay(5000);
// measure the distance again
duration = pulseIn(echoPin, HIGH);
distance = duration * 0.034 / 2;
// check if the object is still there
if (distance < 50) {
// keep the servo at 180 degrees
myServo.write(180);
Serial.println("OPEN");
} else {
// return the servo to the initial position
myServo.write(0);
Serial.println("CLOSED");
}
} else {
// return the servo to the initial position
myServo.write(0);
Serial.println("CLOSED");
}
// wait for some time before measuring the distance again
delay(500);
}
Well, now it's a matter of mechanics rather that electronics or program code.
How much torque do you need to open a life-sized door with the lever system shown in the video?
Once you figure that out then look for a servo that can deliver at least that much torque.
That's all the advice I can give.
I modified the code and ran it through WOKWI simulator (thank you!) and it works how we want it to! Our only problem now is the servo we bought The door that we have is pretty lightweight that it can be opened by wind. Is there any normal servo that could do the trick?
First, please don't go back and modify code that eveyone's been talking about. It makes trash of the conversation and takes our remarks out a context where they make sense.
New code, new contribution to this thread in the next post you make here on this thread.
So like do not start a new thread, just post the new code.
I said but should have been clear: in the wokwi, look around a bit, there is a giant "share" button, which would allow you to copy the URL and paste it here.
Which, BTW, you might have just done by grabbing the URL your browser no doubt shows when you are on the wokwi page simulating your heart away.
HTH and I am looking forward to playing with your door device.
Apologies, I am new to this forum. I figured it would be alright to edit the original post since the code wasn't discussed anyway. Here is the new code!
#include <Servo.h>
// define pins for ultrasonic sensor
const int trigPin = 10;
const int echoPin = 11;
// define pin for servo
const int servoPin = 9;
// define variables for distance measurement
long duration;
int distance;
// create a servo object
Servo myServo;
void setup() {
// initialize serial communication
Serial.begin(9600);
// define the pin modes
pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);
pinMode(servoPin, OUTPUT);
// attach the servo to the corresponding pin
myServo.attach(servoPin);
}
void loop() {
// generate a pulse to trigger the ultrasonic sensor
digitalWrite(trigPin, LOW);
delayMicroseconds(2);
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);
// measure the duration of the pulse from the ultrasonic sensor
duration = pulseIn(echoPin, HIGH);
// calculate the distance in centimeters
distance = duration * 0.034 / 2;
// print the distance to the serial monitor
Serial.print("Distance: ");
Serial.print(distance);
Serial.println(" cm");
// check if an object is detected within 50 centimeters
if (distance < 50) {
// rotate the servo to 90 degrees
myServo.write(180);
Serial.println("OPEN");
// wait for 5 seconds
delay(5000);
// measure the distance again
duration = pulseIn(echoPin, HIGH);
distance = duration * 0.034 / 2;
// check if the object is still there
if (distance < 50) {
// keep the servo at 180 degrees
myServo.write(180);
Serial.println("OPEN");
} else {
// return the servo to the initial position
myServo.write(0);
Serial.println("CLOSED");
}
} else {
// return the servo to the initial position
myServo.write(0);
Serial.println("CLOSED");
}
// wait for some time before measuring the distance again
delay(500);
}
Thank you for this, Paul! It's much appreciated, and yes this is how the device should function. We opted to only include the 5 second interval when the door is open so that it stays in that position to allow people to enter with enough time. We didn't include it when the door is closed because then people would have to wait 5 seconds before it would open.
We aren't at all proficient at coding at the moment, so apologies if the code ever seems messy haha
Yes, it's more than enough actually. The servo that we have at the moment is a DF15RSMG 360 Degree Motor 20kg Servo. I read something just earlier that "360 degree" is often a codename for continuous servos. We should have read more on servos before purchasing...
My group mate stated that the door that we have is for sure not heavier than 8kg
You can buy a normal 180 degree 20kg servo OR use the continuous servo with limit switches.
You would need to put the limit switches somewhere that would operate when the door is open and closed. The code will read the limit switches and stop the servo when the door is fully open or closed.
It's going to make you mechanical set-up more complicated but if you don't want to buy another servo it your only option. The code will also be different.
Yes. It would also allow doing the opening and closing at a specified speed… in the current code, when the servo is told to go to a new angle, it will do that as fast as it can.
for how a "180 degree" servo must be handled to slow it down.
Which you may want to consider doing in your sketch.
If you do use the "360 degree" servo (file that under you learn something every day!), the speed becomes very simple to adjust, as the speed is set by the servo signal and corresponds to how far off from 90 (stopped) you tell it, 100 (slow CCW), 10 (fast CW).
But you have to add physical switches and arrange them mechanically and code for limit switch logic.
We plan to keep the device as simple as possible, so I think buying a standard servo is our best option right now with the time that we have remaining for this project, especially with our lack of coding and wiring knowledge about limit switches.
I had just checked the shops in our area that sell servos, and I found something called Servo DF Metal Geared 15Kg Standard 270° (DSS-M15S). Any chance this is a standard servo and not a continuous one?
The door that we have is pretty lightweight that it can be opened by wind. Is there any normal servo that could do the trick?
as for the link for wokwi, i'm not quite sure how as it was my first time using it 