It is very difficult to measure height because a child cannot sit still for a long time.
So we found a high-precision sensor at a low price, so we created a height measuring instrument that does not take up space and time.

Parts

Distance sensor VL53L0X

VL53L0X Time-of-Flight 距離センサモジュール

It is a sensor of the resolution 1mm in a great wide range!The library for Arduino is below.
　https://github.com/pololu/vl53l0x-arduino
6 axis motion sensor MPU6050

WeiKedz MPU-6050 使用３軸ジャイロスコープ・３軸加速度センサーモジュール

3-axis gyroscope and 3-axis accelerometer can sensing posture information.This time, we use horizontal x-axis and y-axis acceleration to measure the level of the measuring instrument.But it’s a mess!The library for Arduino is located below (using mpu6050 and I2cdev).
　https://github.com/jrowberg/i2cdevlib/tree/master/Arduino

LED (neopixel)

NeoPixel RGB TAPE LED
akibaLED ピカリ館

when the measuring instrument is non-horizontal, it is red, and when it is horizontal, it glows green.

LCD display
　https://www.arduino.cc/en/Tutorial/HelloWorld
Microcontroller Arduino Nano compatible

HiLetgo Nano V3.0 ATmega328P 5V 16M CH340 Arduinoと互換 Nano V3 ケーブルなし並行輸入品

I use a cheap compatible product:-)

Measuring instrument

The distance sensor VL53L0X is placed in the bottom of a box. The sensor can measure distances of up to 2m with 1 mm resolution.

Place the microcomputer Arduino Nano and 6-axis motion sensor MPU6050 in the box, the power supply was used a 9V battery.

MPU6050 is used to measure x-axis and y-axis of acceleration for detect the horizontal direction. The LED (Neopixel) is green , when measure is horizontal. When non-horizontal is light red.

Distances are displayed on the LCD display .

How to use

LCD Display

Normal mode

Turn on the power switch, the measure operates in the normal mode. In Normal Mode, The measurement distance is always displayed on LCD. The LED is green, when measure is horizontal. When non-horizontal is light red.

動画プレーヤー

Media error: Format(s) not supported or source(s) not found

ファイルをダウンロード: https://homemadegarbage.com/wp/wp-content/uploads/2016/09/VID_20160916_201545.mp4?_=1

00:00

ボリューム調節には上下矢印キーを使ってください。

Measurement mode

While you hold down the Meas. Button (tact switch) it will be the Measurement Mode. Put measure on head. Turn the Measurement Mode. When the distance in a horizontal state is detected, LED is blue light and measurement value is held.

距離センサVL53L0Xで長女ちゃん身長測定 pic.twitter.com/1tMOndvOgy

— HomeMadeGarbage (@H0meMadeGarbage) 2016年9月16日

Press the measurement button again to return to normal mode.

Arduino IDE Code

The distance sensor vl53l0x is used in Long_range mode and high_accuracy mode.
The distance is adjusted to the unit in CM and the sensor position is corrected (1mm).

#include "I2Cdev.h"
#include "MPU6050.h"
#include <Adafruit_NeoPixel.h>
#include <VL53L0X.h>
#include <LiquidCrystal.h>

// Arduino Wire library is required if I2Cdev I2CDEV_ARDUINO_WIRE implementation
// is used in I2Cdev.h
#if I2CDEV_IMPLEMENTATION == I2CDEV_ARDUINO_WIRE
    #include "Wire.h"
#endif

int mode = 0;

MPU6050 accelgyro; // class default I2C address is 0x68
int16_t ax, ay, az;
int diffAccel = 100;

#define PIN            8
Adafruit_NeoPixel pixels = Adafruit_NeoPixel(1, PIN, NEO_GRB + NEO_KHZ800);

//LiquidCrystal lcd(RS[4], E[6], DB4[11], DB5[12], DB6[13], DB7[14]);
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
char s[16];

VL53L0X sensor;
float height;

// Uncomment this line to use long range mode. This
// increases the sensitivity of the sensor and extends its
// potential range, but increases the likelihood of getting
// an inaccurate reading because of reflections from objects
// other than the intended target. It works best in dark
// conditions.
#define LONG_RANGE


// Uncomment ONE of these two lines to get
// - higher speed at the cost of lower accuracy OR
// - higher accuracy at the cost of lower speed
//#define HIGH_SPEED
#define HIGH_ACCURACY

void setup() {
  // join I2C bus (I2Cdev library doesn't do this automatically)
  #if I2CDEV_IMPLEMENTATION == I2CDEV_ARDUINO_WIRE
    Wire.begin();
  #elif I2CDEV_IMPLEMENTATION == I2CDEV_BUILTIN_FASTWIRE
    Fastwire::setup(400, true);
  #endif

  Serial.begin(38400);

  pinMode(9, INPUT_PULLUP);

  pixels.begin();
  pixels.setBrightness(50);
  pixels.setPixelColor(0, pixels.Color(0,0,0));
  pixels.show();

  lcd.begin(16, 2);
  lcd.setCursor(0, 0);
  lcd.print("x");
  lcd.setCursor(9, 0);
  lcd.print("y");
  lcd.setCursor(0, 1);
  lcd.print("Height:");
  
  sensor.init();
  sensor.setTimeout(500);

  #if defined LONG_RANGE
  // lower the return signal rate limit (default is 0.25 MCPS)
    sensor.setSignalRateLimit(0.1);
    // increase laser pulse periods (defaults are 14 and 10 PCLKs)
    sensor.setVcselPulsePeriod(VL53L0X::VcselPeriodPreRange, 18);
    sensor.setVcselPulsePeriod(VL53L0X::VcselPeriodFinalRange, 14);
  #endif
    
  #if defined HIGH_SPEED
  // reduce timing budget to 20 ms (default is about 33 ms)
    sensor.setMeasurementTimingBudget(20000);
  #elif defined HIGH_ACCURACY
    // increase timing budget to 200 ms
    sensor.setMeasurementTimingBudget(200000);
  #endif

  // initialize device
  Serial.println("Initializing I2C devices...");
  accelgyro.initialize();

  // verify connection
  Serial.println("Testing device connections...");
  Serial.println(accelgyro.testConnection() ? "MPU6050 connection successful" : "MPU6050 connection failed");

  if(accelgyro.testConnection()){
    pixels.setPixelColor(0, pixels.Color(255,0,0));
    pixels.show();
  }

  // use the code below to change accel/gyro offset values
  accelgyro.setXAccelOffset(40); //0
  accelgyro.setYAccelOffset(-985);  //0
  accelgyro.setZAccelOffset(968); //16384    
}

void loop() {  
  //Measurement Mode
  while(digitalRead(9) == 0 && mode == 0){
    // read raw accel
    accelgyro.getAcceleration(&ax, &ay, &az);
    lcd.setCursor(1, 0);
    lcd.print(dtostrf(ax,6,0,s));
    lcd.setCursor(10, 0);
    lcd.print(dtostrf(ay,6,0,s));

    if(abs(ax) < diffAccel && abs(ay) < diffAccel){
      pixels.setPixelColor(0, pixels.Color(0,255,0));
      pixels.show();
      if (sensor.timeoutOccurred() == 0) {
        //Distance measurement
        height = sensor.readRangeSingleMillimeters()/10.0 + 0.1; 
        lcd.setCursor(8, 1);
        if(height <= 220.0){
          lcd.print(dtostrf(height,5,1,s));
          pixels.setPixelColor(0, pixels.Color(0,0,255));
          pixels.show();
          mode = 1;
        }
      }
    }else{
      pixels.setPixelColor(0, pixels.Color(255,0,0));
      pixels.show();
    }
  } 

  //Mode Reset
  if(digitalRead(9) == 1 && mode == 1){
    mode = 2;
    delay(100);
  }
  if(digitalRead(9) == 0 && mode == 2){
    mode = 0;
    delay(100);
  }

  //Normal Mode
  if(digitalRead(9) == 1 && mode == 0){
    // read raw accel
    accelgyro.getAcceleration(&ax, &ay, &az);
    lcd.setCursor(1, 0);
    lcd.print(dtostrf(ax,6,0,s));
    lcd.setCursor(10, 0);
    lcd.print(dtostrf(ay,6,0,s));
    
    if(abs(ax) < diffAccel && abs(ay) < diffAccel){
      pixels.setPixelColor(0, pixels.Color(0,255,0));
      pixels.show();
    }else{
      pixels.setPixelColor(0, pixels.Color(255,0,0));
      pixels.show();
    }
  
    if (sensor.timeoutOccurred() == 0) {
      //Distance measurement
      height = sensor.readRangeSingleMillimeters()/10.0 + 0.1;
      Serial.print(height); Serial.print("\t"); 
      lcd.setCursor(8, 1);
      if(height <= 220.0){
        lcd.print(dtostrf(height,5,1,s));
      }
    }
  }
}

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#include "I2Cdev.h"

#include "MPU6050.h"

#include <Adafruit_NeoPixel.h>

#include <VL53L0X.h>

#include <LiquidCrystal.h>

// Arduino Wire library is required if I2Cdev I2CDEV_ARDUINO_WIRE implementation

// is used in I2Cdev.h

#if I2CDEV_IMPLEMENTATION == I2CDEV_ARDUINO_WIRE

#include "Wire.h"

#endif

int mode = 0;

MPU6050 accelgyro; // class default I2C address is 0x68

int16_t ax, ay, az;

int diffAccel = 100;

#define PIN 8

Adafruit_NeoPixel pixels = Adafruit_NeoPixel(1, PIN, NEO_GRB + NEO_KHZ800);

//LiquidCrystal lcd(RS[4], E[6], DB4[11], DB5[12], DB6[13], DB7[14]);

LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

char s[16];

VL53L0X sensor;

float height;

// Uncomment this line to use long range mode. This

// increases the sensitivity of the sensor and extends its

// potential range, but increases the likelihood of getting

// an inaccurate reading because of reflections from objects

// other than the intended target. It works best in dark

// conditions.

#define LONG_RANGE

// Uncomment ONE of these two lines to get

// - higher speed at the cost of lower accuracy OR

// - higher accuracy at the cost of lower speed

//#define HIGH_SPEED

#define HIGH_ACCURACY

void setup() {

// join I2C bus (I2Cdev library doesn't do this automatically)

#if I2CDEV_IMPLEMENTATION == I2CDEV_ARDUINO_WIRE

Wire.begin();

#elif I2CDEV_IMPLEMENTATION == I2CDEV_BUILTIN_FASTWIRE

Fastwire::setup(400, true);

#endif

Serial.begin(38400);

pinMode(9, INPUT_PULLUP);

pixels.begin();

pixels.setBrightness(50);

pixels.setPixelColor(0, pixels.Color(0,0,0));

pixels.show();

lcd.begin(16, 2);

lcd.setCursor(0, 0);

lcd.print("x");

lcd.setCursor(9, 0);

lcd.print("y");

lcd.setCursor(0, 1);

lcd.print("Height:");

sensor.init();

sensor.setTimeout(500);

#if defined LONG_RANGE

// lower the return signal rate limit (default is 0.25 MCPS)

sensor.setSignalRateLimit(0.1);

// increase laser pulse periods (defaults are 14 and 10 PCLKs)

sensor.setVcselPulsePeriod(VL53L0X::VcselPeriodPreRange, 18);

sensor.setVcselPulsePeriod(VL53L0X::VcselPeriodFinalRange, 14);

#endif

#if defined HIGH_SPEED

// reduce timing budget to 20 ms (default is about 33 ms)

sensor.setMeasurementTimingBudget(20000);

#elif defined HIGH_ACCURACY

// increase timing budget to 200 ms

sensor.setMeasurementTimingBudget(200000);

#endif

// initialize device

Serial.println("Initializing I2C devices...");

accelgyro.initialize();

// verify connection

Serial.println("Testing device connections...");

Serial.println(accelgyro.testConnection() ? "MPU6050 connection successful" : "MPU6050 connection failed");

if(accelgyro.testConnection()){

pixels.setPixelColor(0, pixels.Color(255,0,0));

pixels.show();

}

// use the code below to change accel/gyro offset values

accelgyro.setXAccelOffset(40); //0

accelgyro.setYAccelOffset(-985); //0

accelgyro.setZAccelOffset(968); //16384

}

void loop() {

//Measurement Mode

while(digitalRead(9) == 0 && mode == 0){

// read raw accel

accelgyro.getAcceleration(&ax, &ay, &az);

lcd.setCursor(1, 0);

lcd.print(dtostrf(ax,6,0,s));

lcd.setCursor(10, 0);

lcd.print(dtostrf(ay,6,0,s));

if(abs(ax) < diffAccel && abs(ay) < diffAccel){

pixels.setPixelColor(0, pixels.Color(0,255,0));

pixels.show();

if (sensor.timeoutOccurred() == 0) {

//Distance measurement

height = sensor.readRangeSingleMillimeters()/10.0 + 0.1;

lcd.setCursor(8, 1);

if(height <= 220.0){

lcd.print(dtostrf(height,5,1,s));

pixels.setPixelColor(0, pixels.Color(0,0,255));

pixels.show();

mode = 1;

}

}else{

pixels.setPixelColor(0, pixels.Color(255,0,0));

pixels.show();

}

//Mode Reset

if(digitalRead(9) == 1 && mode == 1){

mode = 2;

delay(100);

}

if(digitalRead(9) == 0 && mode == 2){

mode = 0;

delay(100);

}

//Normal Mode

if(digitalRead(9) == 1 && mode == 0){

// read raw accel

accelgyro.getAcceleration(&ax, &ay, &az);

lcd.setCursor(1, 0);

lcd.print(dtostrf(ax,6,0,s));

lcd.setCursor(10, 0);

lcd.print(dtostrf(ay,6,0,s));

if(abs(ax) < diffAccel && abs(ay) < diffAccel){

pixels.setPixelColor(0, pixels.Color(0,255,0));

pixels.show();

}else{

pixels.setPixelColor(0, pixels.Color(255,0,0));

pixels.show();

}

if (sensor.timeoutOccurred() == 0) {

//Distance measurement

height = sensor.readRangeSingleMillimeters()/10.0 + 0.1;

Serial.print(height); Serial.print("\t");

lcd.setCursor(8, 1);

if(height <= 220.0){

lcd.print(dtostrf(height,5,1,s));

}

Operation

Because it can measure at relatively high speed and the accuracy is high, I can measure it easily even in the height of the eldest son who is restless in this ♪