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96 lines
3.2 KiB
96 lines
3.2 KiB
6 years ago
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import numpy as np
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from selfdrive.controls.lib.drive_helpers import get_steer_max
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from common.numpy_fast import clip
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from common.realtime import DT_CTRL
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from cereal import log
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class LatControlLQR():
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def __init__(self, CP):
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self.scale = CP.lateralTuning.lqr.scale
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self.ki = CP.lateralTuning.lqr.ki
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self.A = np.array(CP.lateralTuning.lqr.a).reshape((2,2))
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self.B = np.array(CP.lateralTuning.lqr.b).reshape((2,1))
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self.C = np.array(CP.lateralTuning.lqr.c).reshape((1,2))
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self.K = np.array(CP.lateralTuning.lqr.k).reshape((1,2))
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self.L = np.array(CP.lateralTuning.lqr.l).reshape((2,1))
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self.dc_gain = CP.lateralTuning.lqr.dcGain
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self.x_hat = np.array([[0], [0]])
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self.i_unwind_rate = 0.3 * DT_CTRL
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self.i_rate = 1.0 * DT_CTRL
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self.sat_count_rate = 1.0 * DT_CTRL
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self.sat_limit = CP.steerLimitTimer
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self.reset()
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def reset(self):
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self.i_lqr = 0.0
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self.output_steer = 0.0
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self.sat_count = 0.0
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def _check_saturation(self, control, check_saturation, limit):
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saturated = abs(control) == limit
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if saturated and check_saturation:
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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 update(self, active, v_ego, angle_steers, angle_steers_rate, eps_torque, steer_override, rate_limited, CP, path_plan):
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lqr_log = log.ControlsState.LateralLQRState.new_message()
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steers_max = get_steer_max(CP, v_ego)
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torque_scale = (0.45 + v_ego / 60.0)**2 # Scale actuator model with speed
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# Subtract offset. Zero angle should correspond to zero torque
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self.angle_steers_des = path_plan.angleSteers - path_plan.angleOffset
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angle_steers -= path_plan.angleOffset
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# Update Kalman filter
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angle_steers_k = float(self.C.dot(self.x_hat))
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e = angle_steers - angle_steers_k
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self.x_hat = self.A.dot(self.x_hat) + self.B.dot(eps_torque / torque_scale) + self.L.dot(e)
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if v_ego < 0.3 or not active:
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lqr_log.active = False
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lqr_output = 0.
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self.reset()
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else:
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lqr_log.active = True
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# LQR
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u_lqr = float(self.angle_steers_des / self.dc_gain - self.K.dot(self.x_hat))
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lqr_output = torque_scale * u_lqr / self.scale
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# Integrator
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if steer_override:
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self.i_lqr -= self.i_unwind_rate * float(np.sign(self.i_lqr))
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else:
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error = self.angle_steers_des - angle_steers_k
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i = self.i_lqr + self.ki * self.i_rate * error
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control = lqr_output + i
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if ((error >= 0 and (control <= steers_max or i < 0.0)) or \
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(error <= 0 and (control >= -steers_max or i > 0.0))):
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self.i_lqr = i
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self.output_steer = lqr_output + self.i_lqr
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self.output_steer = clip(self.output_steer, -steers_max, steers_max)
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check_saturation = (v_ego > 10) and not rate_limited and not steer_override
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saturated = self._check_saturation(self.output_steer, check_saturation, steers_max)
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lqr_log.steerAngle = angle_steers_k + path_plan.angleOffset
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lqr_log.i = self.i_lqr
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lqr_log.output = self.output_steer
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lqr_log.lqrOutput = lqr_output
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lqr_log.saturated = saturated
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return self.output_steer, float(self.angle_steers_des), lqr_log
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