1. Control a motors angular position with a flex sensor
2.2 Flex Control
Control a motors angular position with a flex sensor

2. 2.1 Learning Objectives Different types of Motors
Pulse Width Modulation (PWM)
Flex and Bend Sensors
Mapping and Converting a range of numbers

3. 2.2 DC Motors
DC (Directional Current) Motors are basically electromagnets that converts electrical power into mechanical power by electromagnetism
Therefore depending on the direction of current flow you can change the direction the motor spins
Speed is a result of how much voltage is applied

4. 2.2 Servo Motors
Servos are an electromagnetic motor with a built in potentiometer
Servos move from 0 to 180 degrees
Potentiometer is used to measure the angular position
They are able to hold their position and exert a force.
The amount of force a servo can exert is known as torque

5. 2.2 Pulse Width Modulation
Servos receive a pulse every 20ms
The length of that pulse determines how far the motor will turn
For Example:
1.0ms pulse moves 0 degrees
1.5ms pulse moves 90 degrees
2.0ms pulse moves 180 degrees
To maintain the position of the servo the pulse is continuously
being sent

6. 2.2 Flex Sensors Acts as a variable resistor when flexed
A voltage divider is used to detect the change in resistance
Generally the more bend the more resistance is provided
We then obtain a range of analog values depending on flexion

7. 2.2 Breadboard Diagram
Hardware: Servo Motor Flex Sensor 10k Resistor

8. 2.2 Variable Initialization
Initialize the variables at the top of the program similarly to other C languages.
#include <Servo.h>
// Servo Object
Servo myServo;
// Flex Sensor Pin initialization
const int FLEX_PIN = A0;
// Servo Motor Pin initialization
const int SERVO_PIN = 9;
// Initialize variables for position
int flexPos;
int flexPosPrev;
int servoPos;
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9. 2.2 Setup
We now initialize our servo motor and start its position at location 0.
void setup() {
// Start the Serial Monitor to display data
Serial.begin(9600);
flexPos = 0;
flexPosPrev = 0;
servoPos = 0;
// Initialize what we are doing with each pin variables with "pinMode".
myServo.attach(SERVO_PIN); }
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10. 2.2 Loop
In our loop now we want to map out the servos position according to the flex sensors bend resistance
void loop() {
flexPos = analogRead(FLEX_PIN); // Read the analog input of the flex sensor.
// This if statement only changes the servos position of a difference greater than 30 is occurred.
if (abs(flexPos - flexPosPrev) >= 30) {
servoPos = map(flexPos, 600, 900, 0, 180); // use the flexPos to map out the new servoPos variable
servoPos = constrain(servoPos, 0, 180); // Constrain the max and min values to 0 and 180.
myServo.write(servoPos); // Write the servoPos variable to the Servo. This will start turning the Servo
Serial.print(" ");    
 Serial.print(flexPos);    
  Serial.print(" ");     
Serial.println(servoPos);
delay(50);
flexPosPrev = flexPos; // Reset the flexPosPrev variable to be used again to keep the if statement going. }
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