RPI Step Motor controller - Viktor Mihalovic

Project Overview:

The primary goal of the RPI Step Motor Controller project is to automate the process of controlling the height of the Oree R-t model laser arm for laser marking in production. This automation involves automatically scanning a product's serial number, retrieving information from a database, and adjusting the height of the laser arm accordingly. This project was focused on part to manage height of laser arm

Hardware Setup:

• Raspberry Pi Model 4 4GB
• Oree R-t model laser
• Step Motor: 57CM22X
• Microstep Drive: DM542
• Controller with display: MC-24MR-4MT-500-FX-A
• Bottom and top sensors: TL-Q5MC1-Z

Software Setup:

Programming Language: Python Libraries/Frameworks: RPi.GPIO, time

User Interface:

The project currently does not include a user interface. Control signals are sent automatically based on the scanned product serial number and database information.

Testing and Validation:

Testing of the functionality involves:

Challenges and Solutions:

Challenges encountered during development:

Integrating the Raspberry Pi with the Microstep Drive DM542. Ensuring accurate height adjustments based on database information. Solutions:

Using Python for GPIO control on the Raspberry Pi. Implementing specific wiring configurations for proper communication with the Microstep Drive DM542.

Code Explanation:

1. Import necessary libraries

import RPi.GPIO as GPIO import time

1. Set GPIO mode

GPIO.setmode(GPIO.BCM)

class Arm:

   def __init__(self):
       # Initialize GPIO pins and variables
       self.settings()
       self.sensor_down = False
       self.sensor_up = False
       self.buttonUp = False
       self.buttonDown = False
       self.actHeight = -1
       self.check_read_sensors()
       self.numberOfSteps = 0
   
   # Function to initialize GPIO settings
   def settings(self):
       # Define GPIO pins for motor control, sensors, and buttons
       self.motor_direction_pin = 27
       self.motor_step_pin = 22
       self.sensor_down_pin = 23
       self.buttonUpPin = 25
       self.buttonDownPin = 6
       self.sensor_up_pin = 24
       self.delay = 0.000003  # Adjust this delay for motor speed
       self.pulses_per_rev = 5000   # Set pulses per revolution
       # Setup GPIO pins
       GPIO.setup(self.motor_direction_pin, GPIO.OUT)
       GPIO.setup(self.motor_step_pin, GPIO.OUT)
       GPIO.setup(self.sensor_down_pin, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)
       GPIO.setup(self.sensor_up_pin, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)
       GPIO.setup(self.buttonUpPin, GPIO.IN, pull_up_down=GPIO.PUD_UP)
       GPIO.setup(self.buttonDownPin, GPIO.IN, pull_up_down=GPIO.PUD_UP)

   # Function to perform a single step
   def step_once(self):
       self.numberOfSteps += 1
       GPIO.output(self.motor_step_pin, True)
       time.sleep(self.delay)
       GPIO.output(self.motor_step_pin, False)
       time.sleep(self.delay)
   
   # Function to step the motor forward
   def step_forward(self):
       GPIO.output(self.motor_direction_pin, True)
       self.step_once()
       self.actHeight += 0.0008
       
   # Function to step the motor in reverse
   def step_reverse(self):
       GPIO.output(self.motor_direction_pin, False)
       self.step_once()
       self.actHeight -= 0.0008

   # Function to stop the motor
   def stopMotor(self):
       GPIO.output(self.motor_step_pin, False)
       
   # Function to read sensor states
   def check_read_sensors(self):
       self.sensor_down = not GPIO.input(self.sensor_down_pin)
       self.sensor_up = not GPIO.input(self.sensor_up_pin)
       self.buttonUp = not GPIO.input(self.buttonUpPin)
       self.buttonDown = not GPIO.input(self.buttonDownPin)

   # Main function to start height adjustment
   def start(self):
       while True:
           self.check_read_sensors()
           if self.sensor_down and self.buttonDown:
               self.stopMotor()
               print('Hit bottom')
               continue
           if self.sensor_up and self.buttonUp:
               self.stopMotor()
               print('Hit top')
               continue
           if self.buttonUp and self.buttonDown:
               self.stopMotor()
               print('Both Sensors')
               break
           if self.buttonUp:
               self.step_forward()
               print('Forward')
               continue
           if self.buttonDown:
               self.step_reverse()
               print('Backward')
               continue
           self.stopMotor()
       GPIO.cleanup()

   # Function to find the bottom position
   def findBottom(self):
       while not self.sensor_down:
           self.check_read_sensors()
           self.step_reverse()
       self.actHeight = 143
       self.numberOfSteps = 0
   
   # Function to move to a specified height
   def goto(self, height):
       self.check_read_sensors()
       if self.actHeight <= height:
           while round(self.actHeight,2) != round(height,2) and not self.sensor_up:
               self.step_forward()
               self.check_read_sensors()
       else:
           while round(self.actHeight,2) != round(height,2) and not self.sensor_down:
               self.step_reverse()  
               self.check_read_sensors()

1. Main function

if __name__ == "__main__":

   print("Program has started")
   a = Arm()
   a.findBottom()
   print('I am at 0 cm')
   time.sleep(4)
   print('Going up to 480 mm')
   a.goto(480)
   print('I am at 480 mm')
   time.sleep(4)
   print('Going up to 200 mm')
   a.goto(200)
   print('I am at 200 mm')
   time.sleep(4)
   print('Going up to 0 mm')
   a.goto(0)
   print('Stopped at 143 mm due to height limit')
   GPIO.cleanup()

Conclusion:

The RPI Step Motor Controller project successfully achieves the goal of automating the process of controlling the height of the Oree R-t model laser arm. With further improvements and enhancements, it can effectively contribute to the automation of the laser marking process in production.