Gesture-Controlled Robot

Hi, my name is Ben, and I am a rising sophomore at Regis High School. For my intensive project, I constructed the gesture-controlled robot. Bend the flex sensors in unique combinations to elicit one of many preset movements from the servos or motors.

Engineer

Ben L

Area of Interest

Electrical Engineering

Computer Science

School

Regis High School

Grade

Incoming Sophomore

Reflection

Coming into BlueStamp, I had very minimal hands on experience with engineering. I feel that in the past six weeks, I developed many fundamental skills in mechanical, electrical, and computer engineering. I learned to problem solve on my own and extensively research problems before seeking help from a staff member. This method also helped me more fully understand the nature of each problem and, ultimately, learn more about engineering. The weeks I have spent at BlueStamp helped me understand that engineering is something I would like to pursue in the future, ideally at college. I discovered a new interest in the fields of electrical and computer engineering, as those were the two aspects of my intensive project that I most enjoyed. I really enjoyed my experience here at BlueStamp and plan to continue with STEM Summer camps in the years to come.

Method

  • Controlled by flex sensors

    Control the servos and motors with flex sensors on the same circuit.

  • Wireless connection

    Communication with radio transmission via the NRF modules.

  • Car chassis and glove

    Fit each device with all of the proper components.

Bill of Materials (BOM)

Final Milestone

My third and final milestone was to fully construct the car chassis and glove. I also programmed the receiving Arduino to interpret each character to perform different movements.
The car chassis itself was 3D designed using the online program, TinkerCAD. The entire car chassis measures approximately 5” x 8.5”, and is 1.25” high. See figure 1 for diagrams of the chassis. On the front, I have one caster wheel screwed on to balance the car. There is also a servo controlling the contraction of the claw which I attached using epoxy.
Motors
Mounted on the back end of the car, there are two 6V high torque motors. To get to this point, I went through two other motor types, each unable to move the entire mass of the car. In other words, they both did not have a high enough torque ratio. Once I switched to the motors seen here, the car was able to move.
Motor input is supposed to be digital, written as either a HIGH or LOW. However, I connected the input of the right motor to analog pins on the Arduino. Despite this, I was still able to use the analog input to mimic the function of digital input by setting each pin to either 1023 or 0.
Servo
Here is an example of a function I wrote to control servo movement:

void E() {
//clawopen
while (data.text == 69 && pos <= 90) {
pos=pos+30;
myservo1.write(pos);
myRadio.read( &data, sizeof(data));
}
}

The way I controlled the servo was by incrementing its position by 30° each time the loop was run. I set a minimum position for the function that decreased the position and a maximum for the function that increased the position since that is the range the servo can move in to control the servo in the claw mechanism. Anything more extreme might break it.
Car Schematic

Figure 1: Diagram of car chassis. For reference, each square on the grid measures 1″.

screen-shot-2018-08-03-at-10.42.46-am
Final Code
Final transmitter code

#include <SPI.h>
#include “RF24.h”

boolean OnOff = false;
RF24 myRadio (7, 8);
byte addresses[][6] = {“0”};

struct package
{
int id = 1;
float temperature = 18.3;
char text;
};

typedef struct package Package;
Package data;

const int flexPin1 = A0;
const int flexPin2 = A1;
const int flexPin3 = A2;
const int flexPin4 = A3;
const int flexPin5 = A4;

int val1;
int val2;
int val3;
int val4;
int val5;

int n = 10;

float average1;
float average2;
float average3;
float average4;
float average5;

const byte ledPin = 10;
const byte interruptPin = 2;
boolean state = false;

void setup() {
Serial.begin(115200);
delay(1000);
myRadio.begin();
myRadio.setChannel(115);
myRadio.setPALevel(RF24_PA_MAX);
myRadio.setDataRate( RF24_250KBPS ) ;
myRadio.openWritingPipe( addresses[0]);
delay(1000);
pinMode(ledPin, OUTPUT);
pinMode(interruptPin, INPUT);
attachInterrupt(digitalPinToInterrupt(interruptPin), blink, RISING);
pinMode(flexPin1, INPUT);
pinMode(flexPin2, INPUT);
pinMode(flexPin3, INPUT);
pinMode(flexPin4, INPUT);
pinMode(flexPin5, INPUT);
Serial.println(“setup finished”);
}

void vals() {
val1 = analogRead(flexPin1);
average1 = 0;
for (int k = 1; k <= n; k++) {
average1 = average1 + analogRead(flexPin1);
}
average1 = average1 / n;

val2 = analogRead(flexPin2);
average2 = 0;
for (int k = 1; k <= n; k++) {
average2 = average2 + analogRead(flexPin2);
}
average2 = average2 / n;

val3 = analogRead(flexPin3);
average3 = 0;
for (int k = 1; k <= n; k++) {
average3 = average3 + analogRead(flexPin3);
}
average3 = average3 / n;

val4 = analogRead(flexPin4);
average4 = 0;
for (int k = 1; k <= n; k++) {
average4 = average4 + analogRead(flexPin4);
}
average4 = average4 / n;

val5 = analogRead(flexPin5);
average5 = 0;
for (int k = 1; k <= n; k++) {
average5 = average5 + analogRead(flexPin5);
}
average5 = average5 / n;

val1 = map(average1, 500, 810, 0, 100);
val2 = map(average2, 500, 810, 0, 100);
val3 = map(average3, 500, 810, 0, 100);
val4 = map(average4, 500, 810, 0, 100);
val5 = map(average5, 500, 810, 0, 100);
}

void carforward() {
data.text = 65;
//Serial.println(“expecting A”);
OnOff = true;
delay(500);
vals();
OnOff = false;
}
void carbackward() {
data.text = 66;
//Serial.println(“expecting B”);
OnOff = true;
delay(500);
vals();
OnOff = false;
}
void carleft() {
data.text = 67;
//Serial.println(“expecting C”);
OnOff = true;
delay(500);
vals();
OnOff = false;
}
void carright() {
data.text = 68;
//Serial.println(“expecting D”);
OnOff = true;
delay(500);
vals();
OnOff = false;
}
void clawopen () {
data.text = 69;
//Serial.println(“expecting E”);
OnOff = true;
delay(500);
vals();
OnOff = false;
}
void clawclose() {
data.text = 71;
//Serial.println(“expecting G”);
OnOff = true;
delay(500);
vals();
OnOff = false;
}
void noChar() {
data.text = “”;
OnOff = true;
delay(500);
vals();
OnOff = false;
}
void blink() {
state = !state;
digitalWrite(ledPin, state);
}
void loop() {
//Serial.println(“top of loop”);
myRadio.write(&data, sizeof(data));
//Serial.println(“myRadio”);
digitalWrite(ledPin, state);
//Serial.println(“digitalWrite”);
vals();
//Serial.println(“vals”);
/*
Serial.println(val1);
Serial.println(val2);
Serial.println(val3);
Serial.println(val4);
Serial.println(val5);
Serial.println();
*/
if (state == false) {
//Serial.println(“CAR”);
if (val1 < 75 && val2 >= 60 && val3 >= 60 && val4 < 60 && val5 < 60 && OnOff == false) {
carforward();
}
else if (val1 < 75 && val2 < 60 && val3 < 60 && val4 < 60 && val5 < 60 && OnOff == false) {
carbackward();
}
else if (val1 < 75 && val2 >= 60 && val3 >= 60 && val4 >= 60 && val5 < 60 && OnOff == false) {
carleft();
}
else if (val1 < 75 && val2 < 60 && val3 >= 60 && val4 >= 60 && val5 >= 60 && OnOff == false) {
carright();
}
else {
noChar();
}
}
else {
//Serial.println(“CLAW”);
if (val1 < 75 && val2 >= 60 && val3 >= 60 && val4 >= 60 && val5 >= 60 && OnOff == false) {
clawopen();
}
else if (val1 < 75 && val2 < 60 && val3 < 60 && val4 < 60 && val5 < 60 && OnOff == false) {
clawclose();
}
else {
noChar();
}
}
Serial.print(“\nPackage:”);
Serial.print(data.id);
Serial.print(“\n”);
Serial.println(data.temperature);
Serial.println(data.text);
data.id = data.id + 1;
data.temperature = data.temperature + 0.1;
delay(100);
}

Final receiver code

#include <SPI.h>
#include “RF24.h”
#include <Servo.h>

Servo myservo1;

RF24 myRadio (7, 8);
struct package
{
int id = 0;
float temperature = 0.0;
char text = ‘e’;
};

byte addresses[][6] = {“0”};

typedef struct package Package;
Package data;

int pos = 180;

const int motor1_1Pin = 10;
const int motor1_2Pin = 2;
const int motor2_1Pin = A0;
const int motor2_2Pin = A1;
const int enablePin = 3;

void setup() {
myservo1.attach(9);
Serial.begin(115200);
pinMode(motor1_1Pin, OUTPUT);
pinMode(motor1_2Pin, OUTPUT);
pinMode(motor2_1Pin, OUTPUT);
pinMode(motor2_2Pin, OUTPUT);
pinMode(enablePin, OUTPUT);
digitalWrite(enablePin, HIGH);
delay(1000);
myRadio.begin();
myRadio.setChannel(115);
myRadio.setPALevel(RF24_PA_MAX);
myRadio.setDataRate(RF24_250KBPS);
myRadio.openReadingPipe(1, addresses[0]);
myRadio.startListening();
}

void A() {
//carforward
digitalWrite(motor1_1Pin, HIGH);
digitalWrite(motor1_2Pin, LOW);
analogWrite(motor2_1Pin, 0);
analogWrite(motor2_2Pin, 1023);
}
void B() {
//carbackward
digitalWrite(motor1_1Pin, LOW);
digitalWrite(motor1_2Pin, HIGH);
analogWrite(motor2_1Pin, 1023);
analogWrite(motor2_2Pin, 0);
}
void C() {
//carleft
digitalWrite(motor1_1Pin, LOW);
digitalWrite(motor1_2Pin, HIGH);
analogWrite(motor2_1Pin, 0);
analogWrite(motor2_2Pin, 1023);
}
void D() {
//carright
digitalWrite(motor1_1Pin, HIGH);
analogWrite(motor1_2Pin, LOW);
analogWrite(motor2_1Pin, 1023);
digitalWrite(motor2_2Pin, 0);
}
void E() {
//clawopen
while (data.text == 69 && pos <= 90) {
pos=pos+30;
myservo1.write(pos);
myRadio.read( &data, sizeof(data));
}
}
void G() {
//clawclose
while (data.text == 71 && pos > 0) {
pos=pos-30;
myservo1.write(pos);
myRadio.read(&data, sizeof(data));
}
}

void loop() {
if (myRadio.available()) {
while (myRadio.available()){
myRadio.read( &data, sizeof(data));
}
Serial.print(“\nPackage:”);
Serial.print(data.id);
Serial.print(“\n”);
Serial.println(data.temperature);
Serial.println(data.text);
if (data.text == 65) {
A();
}
else if (data.text == 66) {
B();
}
else if (data.text == 67) {
C();
}
else if (data.text == 68) {
D();
}
else if (data.text == 69) {
E();
}
else if (data.text == 70) {
G();
}
else {
digitalWrite(motor1_1Pin, 0);
digitalWrite(motor1_2Pin, 0);
digitalWrite(motor2_1Pin, 0);
digitalWrite(motor2_2Pin, 0);
}
}
}

Second Milestone

Figure 1: Flow chart of logic used by Arduinos
Figure 1: Flow chart of logic used by Arduinos
screen-shot-2018-07-29-at-9.16.29-am
For my second milestone, I established wireless connection between the Arduinos using NRF. This allows the two to send and receive data from the flex sensors.
The NRF24L01 transceiver module uses a 2.4 GHz band to send radio signals, which I operated at a baud rate of 115.2 mbps.
To toggle between control of the car and of the claw, I integrated a button into my existing circuit because some of the same gestures had different meanings for each. For example, a closed fist would make the claw contract on one setting and the wheels rotate backward on the other setting. See Figure 1 for the logic used by the Arduino to determine which function to perform. To indicate which mode the glove was set to, I used an LED to shine when controlling the claw.
In the transmitter code, I attached an interrupt to stop its current function and execute code designed to react to the change of input.

const byte interruptPin = 2;
void setup() {
pinMode(interruptPin, INPUT);
attachInterrupt(digitalPinToInterrupt(interruptPin), blink, RISING);
}

This change in input is the press of a button and change in state for the LED. I also wrote functions that interpreted different gestures, considering the mode, to send a unique character to the receiving NRF. This would allow the other Arduino to interpret the characters and cause certain movements from either the car or the claw.
One of my main issues for this milestone was inconsistency with the button. For my purposes, bouncing is the tendency of a button to generate multiple signals as it opens or closes a circuit. It is a mechanical part that bounces up and down. This leads to confusion when the Arduino has to determine if the button has been pushed. Debouncing is a method of ensuring that only a single signal will be sent at a time, with no fluctuation. To debounce my circuit, I used a .001 µF 50V capacitor, which functioned to store charge until it releases it all at once, effectively sending one signal at a time. See Figure 2 for the general debouncing circuit used here.
Figure 2: Schematic for debouncing circuit
Glove Schematic
screen-shot-2018-08-02-at-9.22.01-am
Code
Transmitter code

#include <SPI.h>
#include “RF24.h”

boolean OnOff = false;
RF24 myRadio (7, 8);
byte addresses[][6] = {“0”};

struct package
{
int id = 1;
float temperature = 18.3;
char text;
};

typedef struct package Package;
Package data;

const int flexPin1 = A0;
const int flexPin2 = A1;
const int flexPin3 = A2;
const int flexPin4 = A3;
const int flexPin5 = A4;

int val1;
int val2;
int val3;
int val4;
int val5;

int n = 10;

float average1;
float average2;
float average3;
float average4;
float average5;

const byte ledPin = 10;
const byte interruptPin = 2;
boolean state = false;

void setup()
{
Serial.begin(115200);
delay(1000);
myRadio.begin();
myRadio.setChannel(115);
myRadio.setPALevel(RF24_PA_MAX);
myRadio.setDataRate( RF24_250KBPS ) ;
myRadio.openWritingPipe( addresses[0]);
delay(1000);
pinMode(ledPin, OUTPUT);
pinMode(interruptPin, INPUT);
attachInterrupt(digitalPinToInterrupt(interruptPin), blink, RISING);
pinMode(flexPin1, INPUT);
pinMode(flexPin2, INPUT);
pinMode(flexPin3, INPUT);
pinMode(flexPin4, INPUT);
pinMode(flexPin5, INPUT);
Serial.println(“setup finished”);
}

void vals() {
val1 = analogRead(flexPin1);
average1 = 0;
for (int k = 1; k <= n; k++) {
average1 = average1 + analogRead(flexPin1);
}
average1 = average1 / n;

val2 = analogRead(flexPin2);
average2 = 0;
for (int k = 1; k <= n; k++) {
average2 = average2 + analogRead(flexPin2);
}
average2 = average2 / n;

val3 = analogRead(flexPin3);
average3 = 0;
for (int k = 1; k <= n; k++) {
average3 = average3 + analogRead(flexPin3);
}
average3 = average3 / n;

val4 = analogRead(flexPin4);
average4 = 0;
for (int k = 1; k <= n; k++) {
average4 = average4 + analogRead(flexPin4);
}
average4 = average4 / n;

val5 = analogRead(flexPin5);
average5 = 0;
for (int k = 1; k <= n; k++) {
average5 = average5 + analogRead(flexPin5);
}
average5 = average5 / n;

val1 = map(average1, 500, 810, 0, 100);
val2 = map(average2, 500, 810, 0, 100);
val3 = map(average3, 500, 810, 0, 100);
val4 = map(average4, 500, 810, 0, 100);
val5 = map(average5, 500, 810, 0, 100);
}

void carforward() {
data.text = 65;
//Serial.println(“expecting A”);
OnOff = true;
delay(500);
vals();
OnOff = false;
}
void carbackward() {
data.text = 66;
//Serial.println(“expecting B”);
OnOff = true;
delay(500);
vals();
OnOff = false;
}
void carleft() {
data.text = 67;
//Serial.println(“expecting C”);
OnOff = true;
delay(500);
vals();
OnOff = false;
}
void carright() {
data.text = 68;
//Serial.println(“expecting D”);
OnOff = true;
delay(500);
vals();
OnOff = false;
}
void clawopen () {
data.text = 69;
//Serial.println(“expecting E”);
OnOff = true;
delay(500);
vals();
OnOff = false;
}
void clawclose() {
data.text = 70;
//Serial.println(“expecting F”);
OnOff = true;
delay(500);
vals();
OnOff = false;
}
void clawleft() {
data.text = 71;
//Serial.println(“expecting G”);
OnOff = true;
delay(500);
vals();
OnOff = false;
}
void clawright() {
data.text = 72;
//Serial.println(“expecting H”);
OnOff = true;
delay(500);
vals();
OnOff = false;
}
void clawup() {
data.text = 73;
//Serial.println(“expecting I”);
OnOff = true;
delay(500);
vals();
OnOff = false;
}
void clawdown() {
data.text = 74;
//Serial.println(“expecting J”);
OnOff = true;
delay(500);
vals();
OnOff = false;
}
void noChar() {
data.text = “”;
OnOff = true;
delay(500);
vals();
OnOff = false;
}
void blink() {
state = !state;
digitalWrite(ledPin, state);
}
void loop() {
//Serial.println(“top of loop”);
myRadio.write(&data, sizeof(data));
//Serial.println(“myRadio”);
digitalWrite(ledPin, state);
//Serial.println(“digitalWrite”);
vals();
//Serial.println(“vals”);
/*
Serial.println(val1);
Serial.println(val2);
Serial.println(val3);
Serial.println(val4);
Serial.println(val5);
Serial.println();
*/
if (state == false) {
//Serial.println(“CAR”);
if (val1 < 75 && val2 >= 60 && val3 >= 60 && val4 < 60 && val5 < 60 && OnOff == false) {
carforward();
}
else if (val1 < 75 && val2 < 60 && val3 < 60 && val4 < 60 && val5 < 60 && OnOff == false) {
carbackward();
}
else if (val1 < 75 && val2 >= 60 && val3 >= 60 && val4 >= 60 && val5 < 60 && OnOff == false) {
carleft();
}
else if (val1 < 75 && val2 < 60 && val3 >= 60 && val4 >= 60 && val5 >= 60 && OnOff == false) {
carright();
}
else {
noChar();
}
}
else {
//Serial.println(“CLAW”);
if (val1 < 75 && val2 >= 60 && val3 >= 60 && val4 >= 60 && val5 >= 60 && OnOff == false) {
clawopen();
}
else if (val1 < 75 && val2 < 60 && val3 < 60 && val4 < 60 && val5 < 60 && OnOff == false) {
clawclose();
}
else if (val1 < 75 && val2 >= 60 && val3 >= 60 && val4 >= 60 && val5 < 60 && OnOff == false) {
clawleft();
}
else if (val1 < 75 && val2 < 60 && val3 >= 60 && val4 >= 60 && val5 >= 60 && OnOff == false) {
clawright();
}
else if (val1 >= 75 && val2 < 60 && val3 < 60 && val4 < 60 && val5 < 60 && OnOff == false) {
clawup();
}
else if (val1 >= 75 && val2 >= 60 && val3 < 60 && val4 < 60 && val5 < 60 && OnOff == false) {
clawdown();
}
else {
noChar();
}
}

Serial.print(“\nPackage:”);
Serial.print(data.id);
Serial.print(“\n”);
Serial.println(data.temperature);
Serial.println(data.text);

data.id = data.id + 1;
data.temperature = data.temperature + 0.1;
delay(100);
}

Receiver code

#include <SPI.h>
#include “RF24.h”

RF24 myRadio (7, 8);
struct package
{
int id=0;
float temperature = 0.0;
char text =”empty”;
};

byte addresses[][6] = {“0”};

typedef struct package Package;
Package data;

void setup()
{
Serial.begin(115200);
delay(1000);
myRadio.begin();
myRadio.setChannel(115);
myRadio.setPALevel(RF24_PA_MAX);
myRadio.setDataRate( RF24_250KBPS ) ;
myRadio.openReadingPipe(1, addresses[0]);
myRadio.startListening();
}

void loop()
{
if ( myRadio.available()) {
while (myRadio.available()){
myRadio.read( &data, sizeof(data));
}
Serial.print(“\nPackage:”);
Serial.print(data.id);
Serial.print(“\n”);
Serial.println(data.temperature);
Serial.println(data.text);
}
}

First Milestone

My first milestone was to connect the servos and motors to the Arduino and get them working with the input from the flex sensors. Flex sensors are variable resistors, meaning that you can change the amount of resistance it introduces to the circuit based on the extent to which you bend it. Before I set up any circuits with servos or motors, I used sample code that I found online to set up a simple circuit to test the flex sensors alone. I found that when the flex sensors are straight, they produce approximately 10KΩ of resistance. When bent 90°, they produce around 20KΩ of resistance.
There is also a voltage divider between the resistors in series (51KΩ + 5.1KΩ) and the flex sensor to create an output voltage that is a fraction of the input, so that the Arduino can handle the current it receives. Figure 1 depicts the voltage produced by a voltage divider, which can be described by the equation, Vout = Vin(R1/(R1+R2)).
Figure 1: Diagram of a voltage divider.
Servos
The way the servos work is that when you bend the flex sensor, the servo will rotate proportionally, since its movement is restricted to 180°. The servo is actively responding, so the moment you release the flex sensor, the servo will return to its original position. Because the Arduino was not receiving a full range of values from the flex sensor, they range from 130-350.  Therefore, I adjusted the range of the input in the map function from 0-1023 to 130-350. When mapping the new values to a number between 0 and 180, I was able to get the full range of movement from the servo, whereas before its movement was restricted to a small range of only a few degrees.

val = map(average, 130, 350, 0, 180);

The readings for the flex sensor were very sporadic, so I wrote a for loop that averaged every 50 values to get a more constant data set.

int flexpin = A0;
int val;
float average;
void loop() {
val = analogRead(flexpin)-454;
average=0;
for(int k=1; k<=50; k++){
average=average+analogRead(flexpin);
}
average=average/50;

Motors
This is the circuit for the DC motor. It works with 2 flex sensors because here I began experimenting with very basic combinations with the flex sensors, since I will need to develop that as I continue my project. I could not find a schematic that had a flex sensor connected to a DC motor; however, I was able to find one with a switch controlling the motor. So, I had to adjust the schematic to account for the new flex sensors in place of the switch. Also, the switch was also connected by a jumper wire to the digital 2 pin on the Arduino. I had to move that connection to the A0 pin, since the flex sensor records analog values. This transition from digital to analog input very important. Digital input is represented as an ON or OFF by each pin, like in binary. Analog values are more dynamic and can be any number or decimal between 0-1023. Analog input allows the flex sensor to give variable resistance, not by (un)bent, but by the extent to which it is bent. On the circuit for the motors, there is also an H-bridge component which allows current to be applied across a load in both directions. In this case, the H-bridge allows the motor to rotate forwards or backwards.
Figure 2: SN75441ONE H-Bridge
Code for servos

#include <Servo.h>

Servo myservo;

int flexpin = A0;
int val;
float average;

void setup() {
myservo.attach(9);
Serial.begin(9600);
}

void loop() {
val = analogRead(flexpin)-454;
average=0;
for(int k=1; k<=50; k++){
average=average+analogRead(flexpin);
}
average=average/50;
Serial.println(average);
val = map(average, 130, 350, 0, 180);
myservo.write(val);
delay(150);
}

Code for motors

const int flexPin1 = A0; // flex sensor 1 input
const int flexPin2 = A1; // flex sensor 2 input
const int motor1Pin = 3; // H-bridge leg 1 (pin 2, 1A)
const int motor2Pin = 4; // H-bridge leg 2 (pin 7, 2A)
const int enablePin = 9; // H-bridge enable pin
int val1;
int val2;

void setup() {
Serial.begin(9600);
// set the flex sensor as an input:
pinMode(flexPin1, INPUT);
pinMode(flexPin2, INPUT);

// set all the other pins used as outputs:
pinMode(motor1Pin, OUTPUT);
pinMode(motor2Pin, OUTPUT);
pinMode(enablePin, OUTPUT);

// set enablePin high so that motor can turn on:
digitalWrite(enablePin, HIGH);
}

void loop() {
val1 = map(analogRead(flexPin1), 250, 520, 0, 100);
val2 = map(analogRead(flexPin2), 250, 520, 0, 100);
Serial.println(analogRead(flexPin1));
if (val1 >= 50 && val2 >= 50) {
digitalWrite(motor1Pin, 0);
digitalWrite(motor2Pin, 0);
}
// if the switch is low, motor will turn in the other direction:
if (val1 >= 50 && val2 < 50) {
digitalWrite(motor1Pin, 0);
digitalWrite(motor2Pin, 0);
}
if (val1 < 50 && val2 >= 50) {
digitalWrite(motor1Pin, HIGH); // set leg 1 of the H-bridge high
digitalWrite(motor2Pin, LOW); // set leg 2 of the H-bridge low
}
if (val1 < 50 && val2 < 50) {
digitalWrite(motor1Pin, LOW); // set leg 1 of the H-bridge low
digitalWrite(motor2Pin, HIGH); // set leg 2 of the H-bridge high
}
}

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The Useless Machine

          Hi, my name is Ben and I’m a rising sophomore at Regis High School. For my starter project, I constructed the useless machine. It is essentially a box that, once turned on, will work to turn itself back off. When you flip the toggle switch on the top to start the motor, the arm will raise out of the flap. It will rotate until it flips the toggle switch back. This causes the motor to change direction and rotate the arm back down until the end of the arm contacts a snap switch located on the bottom of the circuit board, stopping the movement of the motor. This preserves the motor and prevents it from breaking. The toggle switch is what determines the direction the motor rotates, and the snap switch is able to turn the circuit itself on or off. The printed circuit board functions with many components soldered onto it. Along with the switches, there are also resistors, terminals, and a light-emitting diode. The resistors function to regulate the current throughout the circuit, because the motor can only handle so much. Terminals provide a point of connection to external circuits. Common among all diodes, the LED only allows current to pass in one direction. It also shines a light when electricity passes through it. One of the main problems I encountered throughout this process pertained to the resistors. On the circuit board, there are two resistors: a 100Ω resistor and a 220Ω resistor. When testing the machine, I noticed the motor wasn’t working consistently. To solve this issue, I ran a resistance check with the multimeter to test the resistance between the red and black ends. When testing the 220Ω resistor, it read 1 in the leftmost digit, meaning there was infinite resistance, or that the resistor was not connected. So, I desoldered the 220Ω resistor and then resoldered it to the PCB. This established a strong connection between the resistor and the circuit board.

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