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fix: honour flipped standard-DH joints in DHLink.A #618

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fix: honour flipped standard-DH joints in DHLink.A #618

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2105ecb
fix: use joint ET for DHLink flip handling
tahazarif10 Aug 18, 2026
d9b98d4
test: add regression coverage for flipped standard-DH joints
tahazarif10 Aug 18, 2026
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2 changes: 1 addition & 1 deletion src/roboticstoolbox/robot/DHLink.py
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Original file line number Diff line number Diff line change
Expand Up @@ -616,7 +616,7 @@ def A(self, q: float) -> SE3:
sa = _sin(self.alpha)
ca = _cos(self.alpha)

if self.ets[-1].isflip:
if self.v is not None and self.v.isflip:
q = -q + self.offset
else:
q = q + self.offset
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27 changes: 27 additions & 0 deletions tests/test_DHRobot.py
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Original file line number Diff line number Diff line change
Expand Up @@ -168,6 +168,33 @@ def test_qlim(self):
nt.assert_array_almost_equal(r0.qlim, ans)
nt.assert_array_almost_equal(r1.qlim, np.c_[qlim])

def test_A_flip_standard_dh(self):
q = 0.3

flipped = rp.RevoluteDH(
d=0.2, a=0.3, alpha=0.4, offset=0.1, flip=True
)
normal = rp.RevoluteDH(
d=0.2, a=0.3, alpha=0.4, offset=0.1
)

nt.assert_array_almost_equal(
flipped.A(q).A,
normal.A(-q).A,
)

flipped = rp.PrismaticDH(
theta=0.2, a=0.3, alpha=0.4, offset=0.1, flip=True
)
normal = rp.PrismaticDH(
theta=0.2, a=0.3, alpha=0.4, offset=0.1
)

nt.assert_array_almost_equal(
flipped.A(q).A,
normal.A(-q).A,
)

def test_fkine(self):
l0 = rp.PrismaticDH()
l1 = rp.RevoluteDH()
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