AccelStepper to the desired speed

Using Arduino Programming Questions
1

Hi gurus,
I'm using accelstepper library to control the motor. The requirement is to make the motor to rotate 180 degree back and forth (1 cycle), complete 30 cycles in one minute.
I have written the program as below, however it takes around 1minute 24 secs to complete 30 cycles. Thank you in advance for your input.

#include <AccelStepper.h>

#define stepPin 9
#define dirPin 8
#define En 4

AccelStepper stepper(AccelStepper::DRIVER, stepPin, dirPin);

int stepsPerRevolution = 1600; // steps per revolution
int stepsPerHalfRevolution = stepsPerRevolution / 2; // steps for 180 degrees
const int totalCycles = 30; // total cycles
const int totalTimeSeconds = 60; // total time in seconds
const int timePerCycle = totalTimeSeconds / totalCycles; // time per cycle in seconds
const int timePerHalfMove = timePerCycle / 2; // time for 180-degree move (1 second)
float stepsPerSecond = float(stepsPerHalfRevolution) / timePerHalfMove; // steps per second 
float stepsPerSecond_S = stepsPerSecond * 2;

void setup() {
  pinMode(En, OUTPUT);
  Serial.begin(9600);
  stepper.setMaxSpeed(stepsPerSecond); // Set speed to achieve 180 degrees in 1 second
  stepper.setAcceleration(stepsPerSecond_S); // Set acceleration
}

void loop() {

  if (Serial.available()) {
    String data_from_display = "";
    delay(10);
    while (Serial.available()) {
      data_from_display += char(Serial.read());
    }
    sendData(data_from_display);
  }
}

void Start() {
  Serial.println("START invert");
  for (int x = 0; x < totalCycles; x++) {

    // Move 180 degrees clockwise
    stepper.moveTo(stepper.currentPosition() + stepsPerHalfRevolution);
    while (stepper.distanceToGo() != 0) {
      stepper.run();
    }

    // Move 180 degrees counterclockwise
    stepper.moveTo(stepper.currentPosition() - stepsPerHalfRevolution);
    while (stepper.distanceToGo() != 0) {
      stepper.run();
    }

    if (Serial.available()) {
      String data_from_display = "";
      //delay(30);
      while (Serial.available()) {
        data_from_display += char(Serial.read());
      }
      if (data_from_display == "S")
        stepper.stop();
      break;
    }
  }
  delay(2000);
  digitalWrite(En, LOW);  //disable motor drive to make it free rotate
  Serial.println("DISABLE");
}


void sendData(String data_from_display) {
  if (data_from_display == "START") {
    Start();
  }
  
  if (data_from_display == "disEn") {
    digitalWrite(En, LOW);
    Serial.println("DISABLE");
  }
  if (data_from_display == "En") {
    digitalWrite(En, HIGH);
    Serial.println("EN");
  }
  if (data_from_display == "200") {
    stepsPerRevolution =200;
    Serial.println("200");
  }
  if (data_from_display == "400") {
    stepsPerRevolution =400;
    Serial.println("400");
  }
  if (data_from_display == "800") {
    stepsPerRevolution =800;
    Serial.println("800");
  }
}
3

so you set the max speed at 800 steps / seconds and the acceleration at 1600.00 steps / seconds / seconds

if your max speed is 800 steps / seconds and you want to perform 800 steps in one second, you would need to instantly accelerate to 800 steps / seconds at the first step ➜ you need an infinite acceleration... You would have to calculate a max speed that is > 800 steps/s and an acceleration/deceleration that is suitable to deliver those 800 steps at the end of the first second. Not easy ➜ accelStepper might not be the best library for your need as it's driven in position rather than pure speed or acceleration.

may be consider constant speed ? or MobaTools or other libraries ?

1 Like
4

Interpolate ten revolutions.

  If (10_rev_time > 10) increase_speed((10_rev_time - 10) / 2);
  If (10_rev_time < 10) decrease_speed((10 - 10_rev_time) / 2);
5

Yes and I think this will work.
You can drive stepper-motors with a constant speed as long as the speed is not too high.
This is called start-stop-speed.
Within the limits of start-stop-speed you can rotate as many or as less steps CW or CCW as you like. The stepper-motor is able start and stop at this speed without acceleration.

So 180 degrees clockwise and back counter-clockwise is 1600 steps.

I assume it is a standard stepper-motor which has 200 fullsteps per rotation.
Which means stepper-motor-driver is configured to 1/8 microstepping.
With microstepping the speed will be more or less the same as in fullsteps.

In fullsteps it is 200 steps per cycle.
Each cycle takes 2 seconds 60 second per minute / 30 cycles per minute = 2 seconds per rotation.

So the stepper-motor is rotating at 0.5 rotations per minute.
Should be very doable with constant speed.

Should be doable with acceleration too
but you will have to set the maximum-speed higher than 800 steps/second as a part of the way is done at less than 800 steps per second.