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

Raspberry Pi Contact Board:

To interface the Raspberry Pi with the Microstep Drive DM542 and incorporate buttons and LEDs for control and feedback, a custom contact board was created. The contact board consists of the following components:

• Transistors
• Resistors
• Buttons
• LEDs
• Wires

This contact board facilitates the control and monitoring of the stepper motor and provides visual feedback through LEDs. It is responsible for translating signals between the Raspberry Pi GPIO pins and the connected components, enabling seamless integration into the overall system. Chalange was to change input signals to 3.3V and output signals to 5V. For this purpose I need to use transistors and other components.

Software Setup:

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

Testing and Validation:

Extensive testing was conducted to ensure the accuracy and reliability of the height adjustment process. Commands were implemented to adjust the height for different locations, and the system demonstrated precise control, achieving adjustments accurate to within a tenth of a millimeter.

Code Explanation:

---

import RPi.GPIO as GPIO #Import necessary libraries import time GPIO.setmode(GPIO.BCM) #Set GPIO mode 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.

Sources:

• DM542
• Raspberry forums
• Oree laser machine
• Step motor rotation speed