diff options
Diffstat (limited to '')
| -rw-r--r-- | System_Python/system.py | 129 |
1 files changed, 127 insertions, 2 deletions
diff --git a/System_Python/system.py b/System_Python/system.py index ff38628..de9a8d1 100644 --- a/System_Python/system.py +++ b/System_Python/system.py @@ -2,6 +2,9 @@ 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
### Motor pins
@@ -15,12 +18,14 @@ encoder_data_pin = 3 encoder_angular_cs_pin = 4
### Linear encoder pins
encoder_linear_cs_pin = 5
-
+### Limit switch pins (configured to PULLUP)
+limit_negative_pin = 19
+limit_positive_pin = 26
# System Class
# This is the primary interface a student will use to control the pendulum.
class System:
- def __init__(self):
+ def __init__(self, negative_limit=float('nan'), positive_limit=float('nan')):
# Initialize the motor.
self.motor = Motor(motor_speed_pin, motor_forward_pin, motor_reverse_pin)
# Initialize the angular encoder.
@@ -28,9 +33,65 @@ 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
+ GPIO.setup(limit_negative_pin, GPIO.IN, pull_up_down=GPIO.PUD_UP)
+ GPIO.add_event_detect(limit_negative_pin, GPIO.FALLING, callback=negative_limit_callback, bouncetime=300)
+ GPIO.setup(limit_positive_pin, GPIO.IN, pull_up_down=GPIO.PUD_UP)
+ GPIO.add_event_detect(limit_positive_pin, GPIO.FALLING, callback=positive_limit_callback, bouncetime=300)
+
+ # Setup soft limits if defined by the user (this is "challenge mode" for the user, making the constraints more difficult).
+ # By default, the soft limits will not be used (when set NaN), and the whole extent of the system is available (to the HW limits).
+ self.negative_soft_limit = negative_limit
+ self.positive_soft_limit = positive_limit
+ # If both limits have been defined, verify that they are valid (i.e. positive limit must be greater than the negative limit)
+ if not math.isnan(negative_limit) and not math.isnan(positive_limit) and not negative_limit < positive_limit
+ print("ERROR: Invalid software limits provided. Must be valid floating-point numbers and positive limit must be greater than negative limit. Software limits will be disabled.")
+ self.negative_soft_limit = float('nan')
+ self.positive_soft_limit = float('nan')
+ # NOTE: If only one limit has been defined, this should always work (hardware limits will be the absolute edge on the undefined side, although this would be difficult for users to utilize unless we provide the position of the hardware limits on each side
+ # NOTE: If neither limit is defined, the hardware limits will be the only limits in effect.
+
+ # Create and setup results file (to be sent back to the server and displayed/downloaded to the user)
+ # Results file is a CSV with the following entries: angle, position, speed
+ self.result_filename = "~/test_results/" + datetime.now().strftime("%d-%m-%Y_%H:%M:%S") + ".csv"
+ result_file = open(self.result_filename, "w+")
+ 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).
### angle: 0 indicates the pendulum is exactly straight up.
@@ -45,6 +106,21 @@ class System: if angular_position > 180:
angular_position = angular_position - 360
linear_position = self.encoder_linear.read_position()
+ # Check soft limits
+ if not math.isnan(self.negative_soft_limit) and linear_position < self.negative_soft_limit:
+ # Print negative soft limit violation to the results file.
+ result_file = open(self.result_filename, "a")
+ result_file.write("Negative software limit %f has been reached!" % self.negative_soft_limit)
+ result_file.close()
+ # Fire the limit trigger method (stops motor, kills program immediately).
+ self.limit_triggered()
+ if not math.isnan(self.positive_soft_limit) and linear_position > self.positive_soft_limit:
+ # Print positive soft limit violation to the results file.
+ result_file = open(self.result_filename, "a")
+ result_file.write("Positive software limit %f has been reached!" % self.positive_soft_limit)
+ result_file.close()
+ # Fire the limit trigger method (stops motor, kills program immediately).
+ self.limit_triggered()
return (angular_position, linear_position)
# END measure()
@@ -63,6 +139,55 @@ class System: self.motor.coast()
self.motor.move(speed)
# END adjust()
+
+ # Append data to the results file
+ def add_results(self, angle, position, speed):
+ # open the results file
+ result_file = open(self.result_filename, "a")
+ # Write the results
+ result_file.write("%d," % angle) # Write angle
+ result_file.write("%d," % position) # Write position
+ result_file.write("%d\n" % speed) # Write speed (end of line)
+ # Close the results file
+ 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.
+ result_file = open(self.result_filename, "a")
+ result_file.write("Negative hardware limit has been reached!")
+ result_file.close()
+ # Fire the limit trigger method (stops motor, kills program immediately).
+ self.limit_triggered()
+ # END negative_limit_callback
+ # Callback for when positive limit switch is triggered.
+ def positive_limit_callback(self, channel):
+ # Print positive limit trigger to the results file.
+ result_file = open(self.result_filename, "a")
+ result_file.write("Positive hardware limit has been reached!")
+ result_file.close()
+ # Fire the limit trigger method (stops motor, kills program immediately).
+ self.limit_triggered()
+ # END positive_limit_callback
+ def limit_triggered(self):
+ self.motor.brake()
+ sleep(2)
+ self.return_home()
+ sys.exit(1)
# END System
# Linear Encoder class
|