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@LemonPi LemonPi released this 11 Mar 22:05
· 8 commits to master since this release
v0.9.0
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Learn about vigilant mode.

Highlights

  • torch.compile support: New forward_kinematics_tensor and jacobian_tensor APIs are fully compatible with torch.compile(fullgraph=True)
  • Improved IK convergence: Adaptive Levenberg-Marquardt damping boosts single-retry convergence by ~20 percentage points
  • IK refactoring: Bug fixes, dead code removal, eliminated redundant FK calls

New APIs

  • Chain.forward_kinematics_tensor(th) — returns (num_frames, B, 4, 4) tensor, compile-compatible
  • SerialChain.jacobian_tensor(th) — returns (B, 6, DOF) Jacobian, compile-compatible
  • PseudoInverseIK new parameters: lm_damping, position_weight, orientation_weight, clamp_to_limits

torch.compile support

Forward kinematics, Jacobian, and rotation conversions (matrix_to_quaternion, quaternion_to_axis_angle, axis_angle_to_quaternion) are now compatible with torch.compile(fullgraph=True). Boolean indexing patterns were replaced with torch.where, torch.gather, and torch.clamp.

chain = pk.build_serial_chain_from_urdf(urdf, "end_effector")
fk_compiled = torch.compile(chain.forward_kinematics_tensor, fullgraph=True)
jac_compiled = torch.compile(chain.jacobian_tensor, fullgraph=True)

The IK solver also supports use_compile=True to compile the FK, Jacobian, and IK step kernels.

IK improvements

  • Adaptive LM damping (lm_damping=0.1 default): Scales regularization by error magnitude — large errors get more damping (stable), small errors get less (fast convergence)
  • Default learning rate changed from 0.2 to 1.0
  • Bug fixes: hardcoded Adam optimizer, line search crash on non-converged problems, dtype mismatch with non-default dtypes
  • Per-coordinate weighting: position_weight and orientation_weight parameters for task-specific tuning
  • Fused IK kernel: delta_pose + DLS solve in a single function, compilable with torch.compile

Performance

All benchmarks: Kuka IIWA 7-DOF, 500 goals, 30 iterations. GPU is NVIDIA RTX 4070.

FK & Jacobian (B=500)

v0.8.0 v0.9.0 eager v0.9.0 compiled
CPU FK 2.07ms 1.09ms (1.9x) 0.52ms (4.0x)
CPU Jacobian 5.51ms 1.36ms (4.1x) 0.59ms (9.3x)
GPU FK 1.45ms 0.64ms (2.3x) 0.32ms (4.5x)
GPU Jacobian 2.76ms 0.75ms (3.7x) 0.36ms (7.7x)

IK — 500 goals, 10 retries

v0.8.0 v0.9.0 eager v0.9.0 compiled
CPU 614ms, 99.6% 140ms, 99.8% (4.4x) 92ms, 99.8% (6.7x)
GPU 387ms, 98.8% 76ms, 99.4% (5.1x) 51ms, 99.4% (7.6x)

IK — 500 goals, 1 retry (hardest case)

v0.8.0 v0.9.0 eager v0.9.0 compiled
CPU 239ms, 67.4% 70ms, 89.4% (3.4x) 32ms, 89.4% (7.5x)
GPU 263ms, 71.0% 51ms, 75.2% (5.2x) 24ms, 75.2% (11.0x)

Bug fixes

  • Fixed SerialChain crash when all joints are fixed (0 DOF)
  • Fixed IKSolution dtype mismatch when chain uses non-default dtype
  • Fixed line search crash on non-converged problems
  • Eliminated redundant FK calls in IK loop and Jacobian wrapper
Assets 2
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