17. Machine design¶

Assignments for the week¶

Group assignments¶

Actuate and automate your machine.
Document the group project.

Individual assignment¶

Document your individual contribution.

Requirements¶

Shown how your team planned and executed the project.
Described problems and how the team solved them.
Listed future development opportunities for this project.
Included your design files.
Optionally included an aprox. 1 min video (1920x1080 HTML5 MP4) + slide (1920x1080 PNG).
Explained your individual contribution to this project on your own website.

Group assignments¶

The mechanical part¶

See Week 15 for the mechanical part making progess

Electronics¶

Parts	Spec.	Quantity
A4988 stepper Driver	-	4
Arduino Nano	-	1
Power adaptor	12v	1
Connect Wire	male-male	46

It is control by 4 A4988 module and a Arduino Nano.

Datasheet of A4988

A4988 driver

Eagle library for A4988 and Arduino Nano v3

Datasheet of 28BYJ-48 – 5V Stepper Motor

Wiring¶

Install motors.

Wiring A4988 and 28byj-48 pins by following table:

Please check this with your datasheet before Connecting.

A4988	28byj-48	OTHER
VMOT	–	12V of adaptor
GNDMOT	–	GND of adaptor
2B	Pink	–
2A	Orange	–
1A	Yellow	–
1B	blue	–
RST	–	SLP of A4988 it self
SLP	–	RST of A4988 it self
VDD	–	5V of Arduino
GND	–	GND of Arduino

Wiring Arduino Nano and A4988s pins by following table:

Arduino Nano	A4988	Channel
3	Dir	A
4	Step	A
5	Dir	B
6	Step	B
7	Dir	C
8	Step	C
9	Dir	D
10	Step	D

Check setting and calculate¶

High voltage of Dir pins means the stepper runs clockwise and make syringes pump backward.

1 resolution = 2048 step = 0.8 mm of M5 screw.

1mpr= 1/rpm = (60*1000)/2048 = 29.3 ms/step
1 steps/ms = 29 rpm

Build a testing LED to watch status of pin step of A4988.
The minimum delay tested is 1150 microseconds.
Althought A4988 motor driver can handle much faster frequency,
but 28byj-48 just stop and make a sound.

Check the current of stepper.

Code¶

A simple code for Arduino to run motors.

/*     Test code for 4-channel syringe pump made for Fab Academy 2019.
 *      
 *  by Wei-Sung
 *  
 */

const int dirPin_a = 3;  // Set pin numbers.
const int stepPin_a = 4; 
const int dirPin_b = 5; 
const int stepPin_b = 6; 
const int dirPin_c = 7; 
const int stepPin_c = 8; 
const int dirPin_d = 9;
const int stepPin_d = 10;

void setup() {
  pinMode(dirPin_a,OUTPUT);  // set up pins output.
  pinMode(stepPin_a,OUTPUT);
  pinMode(dirPin_b,OUTPUT);
  pinMode(stepPin_b,OUTPUT);
  pinMode(dirPin_c,OUTPUT);
  pinMode(stepPin_c,OUTPUT);
  pinMode(dirPin_d,OUTPUT);
  pinMode(stepPin_d,OUTPUT);
}

void loop() {
  digitalWrite(dirPin_a,LOW); // Turn the motor to move forward A
  for(int x = 0; x < 20480; x++) { // for 10 resolutions
    digitalWrite(stepPin_a,HIGH); //at 19.53 rpm
    delay(1); 
    digitalWrite(stepPin_a,LOW); 
    delay(1);
  }

  digitalWrite(dirPin_a,HIGH); // Then backward.
  for(int x = 0; x < 20480; x++) { // 10 resolutions.
    digitalWrite(stepPin_a,HIGH); //at 19.53 rpm
    delay(1); 
    digitalWrite(stepPin_a,LOW); 
    delay(1);
  }

  digitalWrite(dirPin_b,LOW); // Turn the motor to move forward B
  for(int x = 0; x < 20480; x++) { // for 10 resolutions
    digitalWrite(stepPin_b,HIGH); //at 19.53 rpm
    delay(1); 
    digitalWrite(stepPin_b,LOW); 
    delay(1);
  }

  digitalWrite(dirPin_b,HIGH); // Then backward.
  for(int x = 0; x < 20480; x++) { // 10 resolutions.
    digitalWrite(stepPin_b,HIGH); //at 19.53 rpm
    delay(1); 
    digitalWrite(stepPin_b,LOW); 
    delay(1);
  }

  digitalWrite(dirPin_c,LOW); // Turn the motor to move forward C
  for(int x = 0; x < 20480; x++) { // for 10 resolutions
    digitalWrite(stepPin_c,HIGH); //at 19.53 rpm
    delay(1); 
    digitalWrite(stepPin_c,LOW); 
    delay(1);
  }

  digitalWrite(dirPin_c,HIGH); // Then backward.
  for(int x = 0; x < 20480; x++) { // 10 resolutions.
    digitalWrite(stepPin_c,HIGH); //at 19.53 rpm
    delay(1); 
    digitalWrite(stepPin_c,LOW); 
    delay(1);
  }

  digitalWrite(dirPin_d,LOW); // Turn the motor to move forward D
  for(int x = 0; x < 20480; x++) { // for 10 resolutions
    digitalWrite(stepPin_d,HIGH); //at 19.53 rpm
    delay(1); 
    digitalWrite(stepPin_d,LOW); 
    delay(1);
  }

  digitalWrite(dirPin_d,HIGH); // Then backward.
  for(int x = 0; x < 20480; x++) { // 10 resolutions.
    digitalWrite(stepPin_d,HIGH); //at 19.53 rpm
    delay(1); 
    digitalWrite(stepPin_d,LOW); 
    delay(1);
  }

}

Video¶

machine video (Speed up 15X)