35 lines
1.0 KiB
Python
35 lines
1.0 KiB
Python
class PID:
|
|
def __init__(self, proportional_k, integral_k, differential_k, set_point):
|
|
self.proportional_k = proportional_k
|
|
self.integral_k = integral_k
|
|
self.differential_k = differential_k
|
|
self.set_point = set_point
|
|
|
|
self.error_sum = 0
|
|
self.last_value = 0
|
|
self.min_output = -1
|
|
self.max_output = 1
|
|
|
|
|
|
def update(self, measurement, time_delta):
|
|
error_value = measurement - self.set_point
|
|
proportional = error_value * self.proportional_k
|
|
|
|
# calculate integral
|
|
self.error_sum += error_value * time_delta
|
|
# clamp it
|
|
self.error_sum = min(self.max_output, self.error_sum)
|
|
self.error_sum = max(self.min_output, self.error_sum)
|
|
|
|
integral = self.error_sum * self.integral_k
|
|
|
|
differentiated_error = (error_value - self.last_value) / time_delta
|
|
differential = differentiated_error * self.differential_k
|
|
|
|
output = proportional + integral + differential
|
|
# clamp output
|
|
output = min(self.max_output, output)
|
|
output = max(self.min_output, output)
|
|
|
|
return output
|