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85 lines
3.1 KiB
85 lines
3.1 KiB
6 years ago
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import math
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from common.numpy_fast import clip
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MAX_ANGLE_OFFSET = math.radians(10.)
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MAX_ANGLE_OFFSET_TH = math.radians(9.)
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MIN_STIFFNESS = 0.5
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MAX_STIFFNESS = 2.0
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MIN_SR = 0.5
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MAX_SR = 2.0
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MIN_SR_TH = 0.55
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MAX_SR_TH = 1.9
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DEBUG = False
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class ParamsLearner():
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def __init__(self, VM, angle_offset=0., stiffness_factor=1.0, steer_ratio=None, learning_rate=1.0):
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self.VM = VM
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self.ao = math.radians(angle_offset)
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self.slow_ao = math.radians(angle_offset)
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self.x = stiffness_factor
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self.sR = VM.sR if steer_ratio is None else steer_ratio
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self.MIN_SR = MIN_SR * self.VM.sR
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self.MAX_SR = MAX_SR * self.VM.sR
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self.MIN_SR_TH = MIN_SR_TH * self.VM.sR
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self.MAX_SR_TH = MAX_SR_TH * self.VM.sR
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self.alpha1 = 0.01 * learning_rate
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self.alpha2 = 0.0005 * learning_rate
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self.alpha3 = 0.1 * learning_rate
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self.alpha4 = 1.0 * learning_rate
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def get_values(self):
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return {
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'angleOffsetAverage': math.degrees(self.slow_ao),
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'stiffnessFactor': self.x,
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'steerRatio': self.sR,
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}
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def update(self, psi, u, sa):
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cF0 = self.VM.cF
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cR0 = self.VM.cR
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aR = self.VM.aR
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aF = self.VM.aF
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l = self.VM.l
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m = self.VM.m
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x = self.x
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ao = self.ao
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sR = self.sR
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# Gradient descent: learn angle offset, tire stiffness and steer ratio.
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if u > 10.0 and abs(math.degrees(sa)) < 15.:
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self.ao -= self.alpha1 * 2.0*cF0*cR0*l*u*x*(1.0*cF0*cR0*l*u*x*(ao - sa) + psi*sR*(cF0*cR0*l**2*x - m*u**2*(aF*cF0 - aR*cR0)))/(sR**2*(cF0*cR0*l**2*x - m*u**2*(aF*cF0 - aR*cR0))**2)
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ao = self.slow_ao
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self.slow_ao -= self.alpha2 * 2.0*cF0*cR0*l*u*x*(1.0*cF0*cR0*l*u*x*(ao - sa) + psi*sR*(cF0*cR0*l**2*x - m*u**2*(aF*cF0 - aR*cR0)))/(sR**2*(cF0*cR0*l**2*x - m*u**2*(aF*cF0 - aR*cR0))**2)
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self.x -= self.alpha3 * -2.0*cF0*cR0*l*m*u**3*(ao - sa)*(aF*cF0 - aR*cR0)*(1.0*cF0*cR0*l*u*x*(ao - sa) + psi*sR*(cF0*cR0*l**2*x - m*u**2*(aF*cF0 - aR*cR0)))/(sR**2*(cF0*cR0*l**2*x - m*u**2*(aF*cF0 - aR*cR0))**3)
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self.sR -= self.alpha4 * -2.0*cF0*cR0*l*u*x*(ao - sa)*(1.0*cF0*cR0*l*u*x*(ao - sa) + psi*sR*(cF0*cR0*l**2*x - m*u**2*(aF*cF0 - aR*cR0)))/(sR**3*(cF0*cR0*l**2*x - m*u**2*(aF*cF0 - aR*cR0))**2)
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if DEBUG:
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# s1 = "Measured yaw rate % .6f" % psi
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# ao = 0.
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# s2 = "Uncompensated yaw % .6f" % (1.0*u*(-ao + sa)/(l*sR*(1 - m*u**2*(aF*cF0*x - aR*cR0*x)/(cF0*cR0*l**2*x**2))))
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# instant_ao = aF*m*psi*sR*u/(cR0*l*x) - aR*m*psi*sR*u/(cF0*l*x) - l*psi*sR/u + sa
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s4 = "Instant AO: % .6f Avg. AO % .6f" % (math.degrees(self.ao), math.degrees(self.slow_ao))
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s5 = "Stiffnes: % .6f x" % self.x
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s6 = "sR: %.4f" % self.sR
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print("{0} {1} {2}".format(s4, s5, s6))
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self.ao = clip(self.ao, -MAX_ANGLE_OFFSET, MAX_ANGLE_OFFSET)
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self.slow_ao = clip(self.slow_ao, -MAX_ANGLE_OFFSET, MAX_ANGLE_OFFSET)
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self.x = clip(self.x, MIN_STIFFNESS, MAX_STIFFNESS)
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self.sR = clip(self.sR, self.MIN_SR, self.MAX_SR)
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# don't check stiffness for validity, as it can change quickly if sR is off
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valid = abs(self.slow_ao) < MAX_ANGLE_OFFSET_TH and \
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self.sR > self.MIN_SR_TH and self.sR < self.MAX_SR_TH
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return valid
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