diff options
| -rw-r--r-- | System_Python/system.py | 41 |
1 files changed, 37 insertions, 4 deletions
diff --git a/System_Python/system.py b/System_Python/system.py index 064700c..d3a7ba4 100644 --- a/System_Python/system.py +++ b/System_Python/system.py @@ -26,7 +26,7 @@ class System: self.encoder_angular = Encoder(encoder_clock_pin, encoder_angular_cs_pin, encoder_data_pin)
self.encoder_angular.set_zero()
# Initialize the linear encoder.
- self.encoder_linear = Encoder(encoder_clock_pin, encoder_linear_cs_pin, encoder_data_pin)
+ self.encoder_linear = Linear_Encoder(encoder_clock_pin, encoder_linear_cs_pin, encoder_data_pin)
self.encoder_linear.set_zero()
# END __init__()
@@ -43,9 +43,7 @@ class System: angular_position = self.encoder_angular.read_position('Degrees')
if angular_position > 180:
angular_position = angular_position - 360
- # TODO: Implement linear position
- # Need to determine how to keep track of position based on gearing and rotations.
- #linear_position = self.encoder_linear.read_position('Raw')
+ #linear_position = self.encoder_linear.read_position()
linear_position = 0
return (angular_position, linear_position)
# END measure()
@@ -65,4 +63,39 @@ class System: self.motor.move(speed)
# END adjust()
# END System
+
+# Linear Encoder class
+# This class is to help with using an absolute encoder for linear position sensing as assembled in the physical system.
+# The function definitions here are the same as with the regular encoder (pseudo-interface).
+class Linear_Encoder:
+ DIAMETER = 4 # MEASURE THIS
+
+ def __init__(self, clk_pin, cs_pin, data_pin):
+ self.encoder = Encoder(clk_pin, cs_pin, data_pin)
+ set_zero()
+ def set_zero(self):
+ # Set the zero position for the encoder
+ self.encoder.set_zero()
+ # Reset the internal position counter
+ self.rotations = 0
+ self.last_position = 0
+ def read_position(self):
+ # Read the position of the encoder
+ position = self.encoder.read_position('Raw')
+ # Compare to last known position
+ # NOTE: For now, assume that we are moving the smallest possible distance (i.e. 5 -> 1 is -4, not 1020)
+ if position - self.last_position > 0:
+ if position < 512 and self.last_position > 512:
+ # We are moving to the right (positive) and have completed a new rotation
+ self.rotations++
+ else:
+ if position > 512 and self.last_position < 512:
+ # We are moving to the left (negative) and have completed a new rotation
+ self.rotations--
+ # Save the last position for the next calculation
+ self.last_position = position
+
+ # compute the position based on the system parameters
+ # linear position = (2pi*r)(n) + (2pi*r)(position/1024) = (2pi*r)(n + position/1024) = (pi*d)(n + position/1024)
+ return (pi*DIAMETER)*(self.rotations + position/1024)
\ No newline at end of file |