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89 lines
2.6 KiB
89 lines
2.6 KiB
6 years ago
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import numpy as np
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from common.numpy_fast import clip, interp
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def apply_deadzone(error, deadzone):
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if error > deadzone:
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error -= deadzone
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elif error < - deadzone:
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error += deadzone
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else:
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error = 0.
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return error
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class PIController():
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def __init__(self, k_p, k_i, k_f=1., pos_limit=None, neg_limit=None, rate=100, sat_limit=0.8, convert=None):
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self._k_p = k_p # proportional gain
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self._k_i = k_i # integral gain
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self.k_f = k_f # feedforward gain
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self.pos_limit = pos_limit
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self.neg_limit = neg_limit
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self.sat_count_rate = 1.0 / rate
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self.i_unwind_rate = 0.3 / rate
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self.i_rate = 1.0 / rate
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self.sat_limit = sat_limit
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self.convert = convert
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self.reset()
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@property
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def k_p(self):
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return interp(self.speed, self._k_p[0], self._k_p[1])
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@property
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def k_i(self):
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return interp(self.speed, self._k_i[0], self._k_i[1])
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def _check_saturation(self, control, check_saturation, error):
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saturated = (control < self.neg_limit) or (control > self.pos_limit)
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if saturated and check_saturation and abs(error) > 0.1:
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self.sat_count += self.sat_count_rate
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else:
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self.sat_count -= self.sat_count_rate
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self.sat_count = clip(self.sat_count, 0.0, 1.0)
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return self.sat_count > self.sat_limit
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def reset(self):
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self.p = 0.0
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self.i = 0.0
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self.f = 0.0
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self.sat_count = 0.0
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self.saturated = False
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self.control = 0
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def update(self, setpoint, measurement, speed=0.0, check_saturation=True, override=False, feedforward=0., deadzone=0., freeze_integrator=False):
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self.speed = speed
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error = float(apply_deadzone(setpoint - measurement, deadzone))
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self.p = error * self.k_p
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self.f = feedforward * self.k_f
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if override:
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self.i -= self.i_unwind_rate * float(np.sign(self.i))
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else:
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i = self.i + error * self.k_i * self.i_rate
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control = self.p + self.f + i
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if self.convert is not None:
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control = self.convert(control, speed=self.speed)
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# Update when changing i will move the control away from the limits
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# or when i will move towards the sign of the error
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if ((error >= 0 and (control <= self.pos_limit or i < 0.0)) or \
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(error <= 0 and (control >= self.neg_limit or i > 0.0))) and \
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not freeze_integrator:
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self.i = i
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control = self.p + self.f + self.i
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if self.convert is not None:
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control = self.convert(control, speed=self.speed)
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self.saturated = self._check_saturation(control, check_saturation, error)
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self.control = clip(control, self.neg_limit, self.pos_limit)
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return self.control
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