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fix: handle zero-blend trapezoidal velocity boundary #934

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fix: handle zero-blend trapezoidal velocity boundary #934

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6 changes: 5 additions & 1 deletion src/roboticstoolbox/tools/trajectory.py
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Original file line number Diff line number Diff line change
Expand Up @@ -724,7 +724,7 @@ def __init__(self, q0: float, qf: float, T: float, V: float | None = None) -> No
self._a = 0.0
else:
self.tb = (q0 - qf + vel * T) / vel
self._a = vel / self.tb
self._a = 0.0 if self.tb == 0 else vel / self.tb

self.V = vel
self._q0 = q0
Expand Down Expand Up @@ -753,6 +753,10 @@ def __call__(self, t: Any) -> Any:
for k, tk in enumerate(times.flat):
if tk < 0:
pk, pdk, pddk = q0, 0.0, 0.0
elif tb == 0 and tk <= T:
pk = q0 + V * tk
pdk = V
pddk = 0.0
elif tk <= tb:
# initial blend
pk = q0 + a / 2 * tk**2
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10 changes: 10 additions & 0 deletions tests/test_trajectory.py
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Original file line number Diff line number Diff line change
Expand Up @@ -87,6 +87,16 @@ def test_trapezoidal_time_origin(self) -> None:
getattr(actual, field), getattr(expected, field), atol=1e-12
)

def test_trapezoidal_zero_blend_velocity_boundary(self) -> None:
for q0, qf in ((0.0, 1.0), (1.0, 0.0)):
with self.subTest(q0=q0, qf=qf):
trajectory = tr.trapezoidal(q0, qf, np.array([0.0, 0.5, 1.0]), V=1.0)

self.assertEqual(trajectory.tblend, 0.0)
nt.assert_allclose(trajectory.q, [q0, 0.5, qf])
nt.assert_allclose(trajectory.qd, np.full(3, qf - q0))
nt.assert_allclose(trajectory.qdd, np.zeros(3))

def test_mtraj_time_origin(self) -> None:
elapsed = np.linspace(0, 2, 9)
for generator in (tr.quintic, tr.trapezoidal):
Expand Down
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