Servo motor does not respond to coding of Arduino

Projects Programming
1

Greetings,

i'm still a beginner with Arduino coding and i need to do a project involving robotic prosthesis hand. For my project, i need to move the prosthesis hand using flex sensors. I have bought flex sensors online via Amazon and calibrating it following these two Youtube videos.

Youtube video links:
Make a Flex Sensor for Robotic Hand and Arduino | DIY - YouTube (Calibrating flex sensors)
How to Make Arduino DIY Foam Robot Hand - YouTube (Assembling the flex sensors to the servo of the prosthesis hand)

This is an example of flex sensor number 1 that i have modified using my flex sensor specification based on the first youtube video:

#include <Servo.h>

Servo servo1 ;
const int flexpin = 0 ;

void setup()
{
Serial.begin(9600) ;
servo1.attach(9);

}

void loop()
{
int flexposition ;
int servoposition ;
flexposition = analogRead(flexpin) ;
servoposition = map(flexposition, 788, 1023, 0, 90) ;
servoposition = constrain(servoposition, 0, 90) ;
servo1.write (servoposition) ;
Serial.print("sensor: ") ;
Serial.print(flexposition);
Serial.print(" servo: ") ;
Serial.println(servoposition);
delay(1000);

}

Then i continue with the second video with this (i only put the coding for the flex sensor no 1 here):

#include <Servo.h>

Servo servo_1 ;
Servo servo_2 ;
Servo servo_3 ;
Servo servo_4 ;
Servo servo_5 ;

int flex_1 = 0 ;
int flex_2 = 1 ;
int flex_3 = 2 ;
int flex_4 = 3 ;
int flex_5 = 4 ;

void setup()
{
servo_1.attach(5) ;
servo_2.attach(3) ;
servo_3.attach(9) ;
servo_4.attach(10) ;
servo_5.attach(6) ;

}

void loop()
{
int flex_1_pos ;
int servo_1_pos ;
flex_1_pos = analogRead (flex_1) ;
servo_1_pos = map (flex_1_pos, 1020, 1023, 180, 0) ;
servo_1_pos = constrain (servo_1_pos, 0, 180) ;
servo_1.write (servo_1_pos);
}

My problem is after i completed the assembly, it seems that the servo motor does not respond when i bend the flex sensor. I try to connect only 1 flex sensor but the problem still arise. Is there something i did wrong with my assembly, coding or etc?

Your help would be much appreciated. Thanks :slight_smile:

2

map(value, fromLow, fromHigh, toLow, toHigh)

3

DKWatson, what do you mean by map(value, fromLow, fromHigh, toLow, toHigh)? can you clarify about it further? which coding do you mean by this?

4

Example 1

servo_1_pos = map (flex_1_pos, 1020, 1023, 180, 0) ;

Will map values between 1020 and 1023 to values between 180 and 0. Really? That says 1020->180, 1021->120, 1022->60, 1023->0.

5

DKWatson i think i'm understand what you are trying to say. Hence i will try to modify the coding

From these:

void loop()
{
int flex_1_pos ;
int servo_1_pos ;
flex_1_pos = analogRead (flex_1) ;
servo_1_pos = map (flex_1_pos, 1020, 1023, 180, 0) ;
servo_1_pos = constrain (servo_1_pos, 0, 180) ;
servo_1.write (servo_1_pos);
}

To these:

void loop()
{
int flex_1_pos ;
int servo_1_pos ;
flex_1_pos = analogRead (flex_1) ;
servo_1_pos = map (flex_1_pos, 788, 1023, 0, 90) ;
servo_1_pos = constrain (servo_1_pos, 0, 90) ;
servo_1.write (servo_1_pos);
}

I will get back to you with an update whether it is successful or not. Thank you for helping me.