diff options
| -rw-r--r-- | System_Python/initialize_system.py | 7 | ||||
| -rw-r--r-- | System_Python/system.py | 47 |
2 files changed, 54 insertions, 0 deletions
diff --git a/System_Python/initialize_system.py b/System_Python/initialize_system.py new file mode 100644 index 0000000..4eb287a --- /dev/null +++ b/System_Python/initialize_system.py @@ -0,0 +1,7 @@ +# This file should be run on system startup. It will initialize the linear position to the center so that all tests originate from a proper position.
+# The center is found by using the hardware limit switches
+from system import System
+
+# Main program
+sys = System()
+sys.initialize()
diff --git a/System_Python/system.py b/System_Python/system.py index 20e9844..faffb73 100644 --- a/System_Python/system.py +++ b/System_Python/system.py @@ -3,6 +3,7 @@ from motor import Motor from encoder import Encoder
import math
from datetime import datetime
+from time import sleep
import RPi.GPIO as GPIO
# IO pin definitions
@@ -32,6 +33,7 @@ class System: self.encoder_angular.set_zero()
# Initialize the linear encoder.
self.encoder_linear = Linear_Encoder(encoder_clock_pin, encoder_linear_cs_pin, encoder_data_pin)
+ # We assume that the system has been initialized on startup to a 0 position, or that the previous run ended by returning the system to 0
self.encoder_linear.set_zero()
# Enable hardware interrupts for hardware limit switches
@@ -59,6 +61,36 @@ class System: result_file.write("angle(degrees),position(inches),speed(percentage)\n")
result_file.close()
# END __init__()
+
+ def initialize(self):
+ # Temporarily disable the limit switch interrupts: we do not want the program to exit if the switch is triggered
+ GPIO.remove_event_detect(limit_negative_pin)
+ GPIO.remove_event_detect(limit_positive_pin)
+ # Begin moving slowly in the negative direction until the negative limit switch is triggered
+ if not GPIO.input(limit_negative_pin) == False:
+ self.motor.move(-1)
+ GPIO.wait_for_edge(limit_negative_pin, GPIO.FALLING)
+ self.motor.brake()
+ # Set zero at the negative end of the track for easy reference in determining the extent
+ self.encoder_linear.set_zero()
+ # Begin moving slowly in the positive direction until the positive limit switch is triggered
+ self.motor.move(1)
+ GPIO.wait_for_edge(limit_positive_pin, GPIO.FALLING)
+ self.motor.brake()
+ # Get the current position (the extent of the track)
+ extent = self.encoder_linear.read_position()
+ # Move back towards the center until we reach position extent/2
+ position = extent
+ self.motor.move(-1)
+ while not position == extent / 2:
+ position = self.encoder_linear.read_position()
+ self.motor.brake()
+ # Set zero again: this is the real zero
+ self.encoder_linear.set_zero()
+ # Re-enable the limit switch interrupts
+ GPIO.add_event_detect(limit_negative_pin, GPIO.FALLING, callback=negative_limit_callback, bouncetime=300)
+ GPIO.add_event_detect(limit_positive_pin, GPIO.FALLING, callback=positive_limit_callback, bouncetime=300)
+ # END initialize
# Get the values of the encoders to determine the angular and linear position of the pendulum.
# Values are returned as a tuple: (angle, linear).
@@ -121,6 +153,19 @@ class System: result_file.close()
# END add_results
+ # Go back to the zero position (linear) so that the next execution starts in the correct place.
+ def return_home(self):
+ position = self.encoder_linear.read_position()
+ # slowly move towards 0 until we get there
+ if position > 0:
+ self.motor.move(-1)
+ elif position < 0:
+ self.motor.move(1)
+ while not position == 0:
+ position = self.encoder_linear.read_position()
+ self.motor.brake()
+ # END return_home
+
# Callback for when negative limit switch is triggered.
def negative_limit_callback(self, channel):
# Print negative limit trigger to the results file.
@@ -141,6 +186,8 @@ class System: # END positive_limit_callback
def limit_triggered(self):
self.motor.brake()
+ sleep(2)
+ self.return_home()
sys.exit(1)
# END System
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