Posture Sensor

Introduction: Posture Sensor

This is an Instructables to help you create your very own posture sensor. The idea here is that  by clipping an accelerometer to the back of your collar you can get a somewhat accurate reading of whether or not you have bad posture, and use a vibration motor and buzzer to alert you of that. The momentary switch allows you to set a "base" posture which the program will then read a difference from. The idea behind adding the bluetooth module in is to be able to visualize the data in processing or another visual programming language. 

Step 1: Components

Components Required:

Arduino Nano x1
Accelerometer x1
Bluetooth Module x1
Vibrating Motor x1
Piezo Buzzer x1
Momentary Switch x1

Step 2: Schematic

Step 3: Arduino Code Part 1

#include "pitches.h"
//momentarty switch pin
const int buttonPin = 12;
int buttonState = 0;
//Mapped sensor value
int backPos;
//Value for the "normal position"
int basePos = 40;
//vibration motor digital pin
int vibePin = 9;
//buzzer digital pin
int buzzerPin = 13;
//length of delay between alarms
long intervalAlarm = 400;
// will store last time buzzer was updated
long previousMillisAlarm = 0;
int value, value2 ;
long time=0;
int periode = 100;
int displace = 500;

void setup() {
//Initialize the appropriate pins to outputs or inputs
pinMode(vibePin, OUTPUT);
pinMode(buzzerPin, OUTPUT);
pinMode(buttonPin, INPUT);

void loop() {
//Start reading the y axis values coming from the accelerometer.
int yAxis = analogRead(A0);

// map the values to a range that is easier to work with (1-100).
backPos = map(yAxis, 240,400,0,100);

//start reading the button state
buttonState = digitalRead(buttonPin);

//if the button is pressed set the value of base position to the current back position
// this sets a "normal" state that the code will then measure a difference from.
if (buttonState == HIGH) {
basePos = backPos; }

//if backPos is in a bad postion
if(backPos > basePos + 5){
//turn on the vibration motor
//turn on the piezo buzzer
//otherwise turn off the motor and buzzer
else {
digitalWrite(vibePin, LOW);
digitalWrite(buzzerPin, LOW);

//fuction that controls the piezo buzzer
void alarm(){
//use blink with out delay logic and tone library to pulse the alarm.
unsigned long currentMillisAlarm = millis();
if(currentMillisAlarm - previousMillisAlarm > intervalAlarm) {
//reset the "timer" previousMillisAlarm = currentMillisAlarm;
//turn on buzzer tone(buzzerPin, 65,200);

//fuction that controls the vibration motor
void vibeMotor(){
//fade without delay logic pulses the vibration motor.
time = millis(); value = 128+127*cos(2*PI/periode*time);
value2 = 128+127*cos(2*PI/periode*(displace-time));
analogWrite(vibePin, value);

Step 4: Arduino Code Part 2

//Create a new tab in your Arduino sketch and call it called it: pitches.h
//Put this code in the new tab

* Public Constants
#define NOTE_B0 31
#define NOTE_C1 33
#define NOTE_CS1 35
#define NOTE_D1 37
#define NOTE_DS1 39
#define NOTE_E1 41
#define NOTE_F1 44
#define NOTE_FS1 46
#define NOTE_G1 49
#define NOTE_GS1 52
#define NOTE_A1 55
#define NOTE_AS1 58
#define NOTE_B1 62
#define NOTE_C2 65
#define NOTE_CS2 69
#define NOTE_D2 73
#define NOTE_DS2 78
#define NOTE_E2 82
#define NOTE_F2 87
#define NOTE_FS2 93
#define NOTE_G2 98
#define NOTE_GS2 104
#define NOTE_A2 110
#define NOTE_AS2 117
#define NOTE_B2 123
#define NOTE_C3 131
#define NOTE_CS3 139
#define NOTE_D3 147
#define NOTE_DS3 156
#define NOTE_E3 165
#define NOTE_F3 175
#define NOTE_FS3 185
#define NOTE_G3 196
#define NOTE_GS3 208
#define NOTE_A3 220
#define NOTE_AS3 233
#define NOTE_B3 247
#define NOTE_C4 262
#define NOTE_CS4 277
#define NOTE_D4 294
#define NOTE_DS4 311
#define NOTE_E4 330
#define NOTE_F4 349
#define NOTE_FS4 370
#define NOTE_G4 392
#define NOTE_GS4 415
#define NOTE_A4 440
#define NOTE_AS4 466
#define NOTE_B4 494
#define NOTE_C5 523
#define NOTE_CS5 554
#define NOTE_D5 587
#define NOTE_DS5 622
#define NOTE_E5 659
#define NOTE_F5 698
#define NOTE_FS5 740
#define NOTE_G5 784
#define NOTE_GS5 831
#define NOTE_A5 880
#define NOTE_AS5 932
#define NOTE_B5 988
#define NOTE_C6 1047
#define NOTE_CS6 1109
#define NOTE_D6 1175
#define NOTE_DS6 1245
#define NOTE_E6 1319
#define NOTE_F6 1397
#define NOTE_FS6 1480
#define NOTE_G6 1568
#define NOTE_GS6 1661
#define NOTE_A6 1760
#define NOTE_AS6 1865
#define NOTE_B6 1976
#define NOTE_C7 2093
#define NOTE_CS7 2217
#define NOTE_D7 2349
#define NOTE_DS7 2489
#define NOTE_E7 2637
#define NOTE_F7 2794
#define NOTE_FS7 2960
#define NOTE_G7 3136
#define NOTE_GS7 3322
#define NOTE_A7 3520
#define NOTE_AS7 3729
#define NOTE_B7 3951
#define NOTE_C8 4186
#define NOTE_CS8 4435
#define NOTE_D8 4699
#define NOTE_DS8 4978

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    7 years ago on Introduction

    Wouldn't using a bend sensor along the spine be a better way to measure one's posture?

    A little more information would be nice regarding what it does. I was expecting something like ThinkGeek's Technomancer Hoodie which uses body movement (arms, mainly) to display several "magic" effects, something I have wanted to incorporate into some projects of mine that never left the ground. Anyway, I wonder what it is you are trying to do with only one sensor. In this, I think Veda got a point ;).


    Reply 8 years ago on Introduction

    Updated the description to give a bit more context as to my intentions with the project. This project was somewhat of an experiment but I definitely got OK results considering I was only using one sensor. Hope this helps clarify things for both you and Veda88. Let me know if your have any more questions.


    8 years ago on Step 4

    So it is used to keep your back straight?