HJCD-IK#

Hybrid Jacobian Coordinate Descent Inverse Kinematics — a GPU-accelerated, batched inverse kinematics solver that generates many candidate solutions in parallel for a 6-DOF end-effector target, with optional collision avoidance. One CUDA block per IK problem, one candidate per warp.

Built on GRiD (robot kinematics codegen) and GLASS (single-block / warp-scoped CUDA linear algebra).

Paper: arXiv:2510.07514 (IROS 2026). Project page: a2r-lab.org/HJCD-IK.

Get started

Install the extension and run your first batched IK solve.

Installation & Quickstart
How it works

The three-phase algorithm: coordinate-descent init, Jacobian polish, collision filter.

The HJCD-IK algorithm
Examples & results

Runnable examples, benchmark results vs. cuRobo / PyRoki / IKFlow, and how to reproduce.

Examples & Results
Custom robots

Generate kinematics for a new URDF / end-effector frame.

Custom robot (GRiD codegen workflow)
API reference

The Python API and the Doxygen-generated C++/CUDA reference.

API Reference
Developer guide

Contributing, the codegen/build discipline, and how to edit these docs.

Contributing & editing the docs

Quick start#

from hjcdik import generate_solutions, sample_targets, num_joints

target = sample_targets(num_targets=1, seed=0)[0]   # [x, y, z, qw, qx, qy, qz]
out = generate_solutions(target, batch_size=2000, num_solutions=4)
print(out["count"], "solutions; best position error:", out["pos_errors"].min())