Enhanced Barrier By Chickadees: Final Documentation

Overview

For our final project, we collaborated with CMU's Facilities Management Services to create a device that would help them with their work. We created a device for our client, Mark Jones, who works as a plumber in FMS. After working closely with Mark and learning about his day-to-day routines at work, we decided to create an enhanced barrier to support him and his team when they are working on maintenance and repairs. 

Our group built an enhanced barrier to prevent entry into bathrooms when the plumbing staff is working.  We designed a two-part system that collapses down to a small size for transport. Sensors on the outside of the door trigger when someone approaches the door, and it plays a sound saying "bathroom closed, do not enter". A flashing LED on the end of the barrier also flashes. When someone approaches the barrier from the inside, the physical barrier opens, and the alarm sensing is deactivated. If someone needs to enter the front of the barrier without the alarm going off, they can scan their ID on a reader, and the barrier will open, and the alarm will be deactivated.

Mark the plumber needs to replace a pipe in the women's bathroom. He is nervous about doing so because people often ignore the bathroom is closed sign he puts up outside. The team is short-staffed, so he cannot bring another person to stand at the door while he does his work. Instead, he brings his smart barrier system, which has a physical barrier and plays sound to get people's attention and make sure they do not enter the bathroom. Mark is able to get his work done without worrying that people will enter the bathroom.

Prototype

To begin, we created two prototypes to answer two questions we had about the product. First, we made a prototype to look at the form and collapsibility of the nodes. We focused on curating a 3D print that captured the ease of usage we wanted for the device, and we tested that out by printing the collapsible device on the left.  After the print came out and we played around with it, we decided to move forward with a structure that contained the L-shaped slots. The second prototype we made was to answer the question of the features that would be useful in the design. For instance, some of the considerations were the intensity of the light & radio modules, the implementation of the barriers, and an RFID tag for the plumbers to deactivate the system as the go in and out of the bathroom.

After creating our prototype, we were able to give Mark a better idea of the device we were making. He was very happy with both of our prototypes, and thought that the collapsible design was something he thought could be very useful for transporting the device. For the functionality, he was happy with everything we were doing and could not think of anything else that he wanted. He was happy that we had thought through all of the use cases, such as him leaving the bathroom and coming back in. At this point in the project, we had been following our original schedule to a pretty decent extent and have kept up with the building process.

Most of the feedback we received were clarifications about the size of the design now that Mark, our client, had more of an idea of what it was going to look like. He asked that we make it taller than we were planning because he wanted the physical barrier to be more at eye level. Although we did make it taller than we originally planned, we did not make it all the way to eye level because the barrier bar would not go straight horizontally, so it gave height to the system itself.

Process

In essence, we learned a lot about designing features and housing catered to a client's wants and needs. Our final crit gave us a lot of insight into the work we had done, especially with the feedback we had gotten. Though our device wasn't fully done, Mark seemed quite happy with the results and he looks forward to when we can hand off the device to him. Other reviewers commented a lot on how the housing's collapsible structure was "interesting and unique", and they enjoyed playing around with the collapsible stools. Moreover, one of the reviewers mentioned how our device "could be used anywhere when maintenance needs an area to be blocked off, not just the bathroom". We appreciated getting feedback that spoke on the versatility and consideration that went into our design. From our final crit, we learned that the construction and integration of the design is more complicated than it seems. Since we had issues with our 3D printer and parts were not done when expected a limited amount of time leads to things not working and no time to debug. We will move forward by reprinting a couple of the components and making sure that integration goes smoothly before the final hand off.

In addition, this project really emphasized the importance of iterative prototyping and testing for us. Through our two prototype stages, we were able to better understand the physical structure and functional features that would make the device effective for our client. Our final collapsible structures design was a direct result of multiple rounds of testing and interacting with the printed model. Along the way, we also learned about the integration of electronics with the housing and ensuring all components are accounted for in the design. Similarly, experimenting with sensors, alarms, and RFID integration allowed us to think more critically about real-world use cases, such as authorized entry and conditioned alarm triggers. 

Working with Mark also gave us a lot of insight as to how we approach thinking about the device versus how our client would think about it. His input on the functionality and appearance of the barriers helped us refine our design to better match his practical needs in a real work environment. In particular, he focused more on the ease of use and reliability of the system, pushing us to think about how intuitive the device would be for someone using it in a work environment that is usually fast-paced and urgent. Overall, we all enjoyed working with Mark; he was very clear with his wants and needs regarding the project and always supported our process.

Node 1 Code:

 /*

 Final Project: Enhanced Barrier

 60-223 Intro to Physical Computing

 PROJECT SUMMARY: This device is an enhanced barrier that would prevent entry into bathrooms while the maintenance

 staff is working. There are servos triggering two physical barriers, LEDs, and a speaker. There is also an RFID tag reader to allow staff to enter without triggering the alarm.

  Pin mapping:

 Arduino pin | role  |  description

 -------------------------------------

 A0           in/out   alarm sensor

 A1           in/out   disable sensor

 5            output   servo pin

 6            output   TX DFPlayer

 7            output   RX DFPlayer

 8            output   LED pin

 9            output   CE radio module

 10           output   CSN radio module

 11           in/out   MOSI radio module

 12           in/out   MISO rado module

 13           output   SCK radio module

*/

#include <SPI.h>

#include <nRF24L01.h>

#include <RF24.h>

#include <SoftwareSerial.h>

#include <DFRobotDFPlayerMini.h>

#include <Servo.h>

// ---------------- RF ----------------

RF24 radio(9, 10);

const byte txAddress[6] = "00001";

const byte rxAddress[6] = "00002";

// ---------------- DFPLAYER ----------------

SoftwareSerial mp3(6, 7);

DFRobotDFPlayerMini player;

// ---------------- PINS ----------------

const int alarmSensor   = A0;

const int disableSensor = A1;

const int ledPin        = 8;

const int servoPin      = 5;

Servo myServo;

// ---------------- SETTINGS ----------------

const int           threshold  = 120;

const unsigned long lockTime   = 5000;

const unsigned long windowTime = 100;

// ---------------- STATE ----------------

enum Mode { NONE, ALARM, DISABLE };

Mode activeMode = NONE;

unsigned long modeStart = 0;

// ---------------- TRIGGER TRACKING ----------------

int           alarmHits       = 0;

int           disableHits     = 0;

unsigned long firstAlarmHit   = 0;

unsigned long firstDisableHit = 0;

// ---------------- SEND STATE ----------------

void sendState(char s) {

 radio.stopListening();

 radio.writeFast(&s, sizeof(s));

 radio.txStandBy();

 radio.startListening();

}

// =====================================================

// SETUP

// =====================================================

void setup() {

 Serial.begin(9600);

 pinMode(ledPin, OUTPUT);

 myServo.attach(servoPin);

 myServo.write(45);

 mp3.begin(9600);

 delay(1500);

 if (!player.begin(mp3)) {

   Serial.println("DFPlayer FAIL");

   while (true);

 }

 player.volume(25);

 radio.begin();

 radio.setChannel(108);

 radio.setPALevel(RF24_PA_LOW);

 radio.setDataRate(RF24_250KBPS);

 radio.setAutoAck(false);

 radio.setRetries(0, 0);

 radio.openWritingPipe(txAddress);

 radio.openReadingPipe(1, rxAddress);

 radio.startListening();

 Serial.println(radio.isChipConnected() ? "Radio connected" : "Radio NOT connected");

 Serial.println("NODE 1 READY");

}

// =====================================================

// LOOP

// =====================================================

void loop() {

 int alarmValue   = analogRead(alarmSensor);

 int disableValue = analogRead(disableSensor);

 Serial.print("Alarm: ");

 Serial.print(alarmValue);

 Serial.print(" | Disable: ");

 Serial.println(disableValue);

 bool alarmState   = alarmValue   > threshold;

 bool disableState = disableValue > threshold;

 unsigned long now = millis();

 // =====================================================

 // IDLE — WATCH FOR TRIGGERS

 // =====================================================

 if (activeMode == NONE) {

   // ---------- ALARM ----------

   if (alarmState) {

     if (alarmHits == 0) {

       alarmHits     = 1;

       firstAlarmHit = now;

       Serial.println("Alarm hit 1");

     } else if (alarmHits == 1 && now - firstAlarmHit <= windowTime) {

       alarmHits   = 0;

       activeMode  = ALARM;

       modeStart   = now;

       disableHits = 0;

       Serial.println("LOCAL ALARM");

       player.play(1);

       sendState('A');

     } else if (alarmHits == 1 && now - firstAlarmHit > windowTime) {

       alarmHits     = 1;

       firstAlarmHit = now;

       Serial.println("Alarm hit reset");

     }

   } else {

     alarmHits = 0;

   }

   // ---------- DISABLE ----------

   if (disableState) {

     if (disableHits == 0) {

       disableHits     = 1;

       firstDisableHit = now;

       Serial.println("Disable hit 1");

     } else if (disableHits == 1 && now - firstDisableHit <= windowTime) {

       disableHits = 0;

       activeMode  = DISABLE;

       modeStart   = now;

       alarmHits   = 0;

       Serial.println("LOCAL DISABLE");

       myServo.write(90);

       sendState('D');

     } else if (disableHits == 1 && now - firstDisableHit > windowTime) {

       disableHits     = 1;

       firstDisableHit = now;

       Serial.println("Disable hit reset");

     }

   } else {

     disableHits = 0;

   }

   // ---------- RF receive ----------

   if (radio.available()) {

     char s;

     radio.read(&s, sizeof(s));

     if (s == 'A' || s == 'D' || s == 'N') {

       Serial.print("Received: "); Serial.println(s);

       if (s == 'A') { activeMode = ALARM;   modeStart = now; player.play(1); }

       if (s == 'D') { activeMode = DISABLE; modeStart = now; myServo.write(90); }

     }

   }

 }

 // =====================================================

 // ALARM MODE

 // =====================================================

 if (activeMode == ALARM) {

   digitalWrite(ledPin, (millis() / 250) % 2);

   if (millis() - modeStart >= lockTime) {

     activeMode = NONE;

     digitalWrite(ledPin, LOW);

     player.stop();

     myServo.write(45);

     sendState('N');

     Serial.println("ALARM END");

   }

 }

 // =====================================================

 // DISABLE MODE

 // =====================================================

 else if (activeMode == DISABLE) {

   if (millis() - modeStart >= lockTime) {

     activeMode = NONE;

     myServo.write(45);

     sendState('N');

     Serial.println("DISABLE END");

   }

 }

 delay(50);

}

Node 2 Code:

/*

 Final Project: Enhanced Barrier

 60-223 Intro to Physical Computing

 PROJECT SUMMARY: This device is an enhanced barrier that would prevent entry into bathrooms while the maintenance

 staff is working. There are servos triggering two physical barriers, LEDs, and a speaker. There is also an RFID tag

 reader to allow staff to enter without triggering the alarm.

  Pin mapping:

 Arduino pin | role  |  description

 -------------------------------------

 A0           in/out   alarm sensor

 A1           in/out   disable sensor

 5            output   servo pin

 6            output   CE radio module

 7            output   CSN radio module

 8            output   LED pin

 9            output   RST RFID

 10           in/out   SDA RFID

 11           in/out   MOSI radio module and RFID

 12           in/out   MISO rado module and RFID

 13           output   SCK radio module and RFID

*/

#include <SPI.h>

#include <nRF24L01.h>

#include <RF24.h>

#include <MFRC522.h>

#include <Servo.h>

// ---------------- RF ----------------

RF24 radio(6, 7);

const byte txAddress[6] = "00002";

const byte rxAddress[6] = "00001";

// ---------------- RFID ----------------

#define SS_PIN 10

#define RST_PIN 9

MFRC522 rfid(SS_PIN, RST_PIN);

// ---------------- PINS ----------------

const int alarmSensor   = A0;

const int disableSensor = A1;

const int ledPin        = 8;

const int servoPin      = 5;

Servo myServo;

// ---------------- SERVO POSITIONS ----------------

const int SERVO_OPEN   = 45;  // barrier open

const int SERVO_CLOSED = 90;  // barrier closed

// ---------------- SETTINGS ----------------

const int           threshold  = 120;

const unsigned long lockTime   = 5000;

const unsigned long windowTime = 500;

// ---------------- STATE ----------------

enum Mode { NONE, ALARM, DISABLE };

Mode activeMode = NONE;

unsigned long modeStart = 0;

// ---------------- TRIGGER TRACKING ----------------

int           alarmHits       = 0;

int           disableHits     = 0;

unsigned long firstAlarmHit   = 0;

unsigned long firstDisableHit = 0;

// ---------------- SEND STATE ----------------

void sendState(char s) {

 radio.stopListening();

 radio.writeFast(&s, sizeof(s));

 radio.txStandBy();

 radio.startListening();

}

// =====================================================

// SETUP

// =====================================================

void setup() {

 Serial.begin(9600);

 pinMode(ledPin, OUTPUT);

 myServo.attach(servoPin);

 myServo.write(SERVO_CLOSED);  // start closed

 SPI.begin();

 rfid.PCD_Init();

 radio.begin();

 radio.setChannel(108);

 radio.setPALevel(RF24_PA_LOW);

 radio.setDataRate(RF24_250KBPS);

 radio.setAutoAck(false);

 radio.setRetries(0, 0);

 radio.openWritingPipe(txAddress);

 radio.openReadingPipe(1, rxAddress);

 radio.startListening();

 Serial.println("NODE 2 READY");

}

// =====================================================

// LOOP

// =====================================================

void loop() {

 int alarmValue   = analogRead(alarmSensor);

 int disableValue = analogRead(disableSensor);

 Serial.print("Alarm: ");

 Serial.print(alarmValue);

 Serial.print(" | Disable: ");

 Serial.println(disableValue);

 bool alarmState   = alarmValue   > threshold;

 bool disableState = disableValue > threshold;

 unsigned long now = millis();

 // =====================================================

 // IDLE — WATCH FOR TRIGGERS

 // =====================================================

 if (activeMode == NONE) {

   // ---------- ALARM ----------

   if (alarmState) {

     if (alarmHits == 0) {

       alarmHits     = 1;

       firstAlarmHit = now;

       Serial.println("Alarm hit 1");

     } else if (alarmHits == 1 && now - firstAlarmHit <= windowTime) {

       alarmHits   = 0;

       activeMode  = ALARM;

       modeStart   = now;

       disableHits = 0;

       Serial.println("LOCAL ALARM");

       myServo.write(SERVO_CLOSED);

       sendState('A');

     }

   } else {

     if (alarmHits == 1 && now - firstAlarmHit > windowTime) {

       alarmHits = 0;

       Serial.println("Alarm hit expired");

     }

   }

   // ---------- DISABLE ----------

   if (disableState) {

     if (disableHits == 0) {

       disableHits     = 1;

       firstDisableHit = now;

       Serial.println("Disable hit 1");

     } else if (disableHits == 1 && now - firstDisableHit <= windowTime) {

       disableHits = 0;

       activeMode  = DISABLE;

       modeStart   = now;

       alarmHits   = 0;

       Serial.println("LOCAL DISABLE");

       myServo.write(SERVO_OPEN);

       sendState('D');

     }

   } else {

     if (disableHits == 1 && now - firstDisableHit > windowTime) {

       disableHits = 0;

       Serial.println("Disable hit expired");

     }

   }

   // ---------- RFID ----------

   if (rfid.PICC_IsNewCardPresent() && rfid.PICC_ReadCardSerial()) {

     Serial.println("RFID DISABLE");

     activeMode  = DISABLE;

     modeStart   = now;

     alarmHits   = 0;

     disableHits = 0;

     myServo.write(SERVO_OPEN);

     sendState('D');

     rfid.PICC_HaltA();

     rfid.PCD_StopCrypto1();

   }

   // ---------- RF receive ----------

   if (radio.available()) {

     char s;

     radio.read(&s, sizeof(s));

     Serial.print("Received: "); Serial.println(s);

     if (s == 'A') {

       activeMode = ALARM;

       modeStart  = now;

       myServo.write(SERVO_CLOSED);

     }

     if (s == 'D') {

       activeMode = DISABLE;

       modeStart  = now;

       myServo.write(SERVO_OPEN);

     }

     if (s == 'N') {

       activeMode = NONE;

       myServo.write(SERVO_CLOSED);

     }

   }

 }

 // =====================================================

 // ALARM MODE

 // =====================================================

 if (activeMode == ALARM) {

   digitalWrite(ledPin, (millis() / 250) % 2);

   myServo.write(SERVO_CLOSED);  // enforce closed

   if (millis() - modeStart >= lockTime) {

     activeMode = NONE;

     digitalWrite(ledPin, LOW);

     myServo.write(SERVO_CLOSED);

     sendState('N');

     Serial.println("ALARM END");

   }

 }

 // =====================================================

 // DISABLE MODE

 // =====================================================

 else if (activeMode == DISABLE) {

   myServo.write(SERVO_OPEN);  // enforce open

   if (millis() - modeStart >= lockTime) {

     activeMode = NONE;

     myServo.write(SERVO_CLOSED);  // FIXED

     sendState('N');

     Serial.println("DISABLE END");

   }

 }

 delay(50);

}