# JAX-IK: Real-Time Inverse Kinematics for Generating Multi-Constrained Movements of Virtual Human Characters

arXiv: https://arxiv.org/abs/2507.00792 · HTML: https://mlsanity.com/paper/2507.00792/

## Key facts

- Cited by 1 papers in the map (data through 14 Oct 2026).
- Builds on 13 of its 53 references that are in the map.
- First posted on arXiv 1 Jul 2025.

## Builds on (most cited first, 13 of 13)

- [Adam: A Method for Stochastic Optimization](https://mlsanity.com/paper/1412.6980/) (2014)
- [Expressive Body Capture: 3D Hands, Face, and Body from a Single Image](https://mlsanity.com/paper/1904.05866/) (2019)
- [End-to-End Training of Deep Visuomotor Policies](https://mlsanity.com/paper/1504.00702/) (2015)
- [EMAGE: Towards Unified Holistic Co-Speech Gesture Generation via Expressive Masked Audio Gesture Modeling](https://mlsanity.com/paper/2401.00374/) (2023)
- [Cautious Optimizers: Improving Training with One Line of Code](https://mlsanity.com/paper/2411.16085/) (2024)
- [WANDR: Intention-guided Human Motion Generation](https://mlsanity.com/paper/2404.15383/) (2024)
- [Retrieving Semantics from the Deep: an RAG Solution for Gesture Synthesis](https://mlsanity.com/paper/2412.06786/) (2024)
- [GAN-based Reactive Motion Synthesis with Class-aware Discriminators for Human-human Interaction](https://mlsanity.com/paper/2110.00380/) (2021)
- [An ADMM-Based Interior-Point Method for Large-Scale Linear Programming](https://mlsanity.com/paper/1805.12344/) (2018)
- [A Combined Inverse Kinematics Algorithm Using FABRIK with Optimization](https://mlsanity.com/paper/2209.02532/) (2022)
- [Real-Time Character Inverse Kinematics using the Gauss-Seidel Iterative Approximation Method](https://mlsanity.com/paper/2211.00330/) (2022)
- [An Avatar Robot Overlaid with the 3D Human Model of a Remote Operator](https://mlsanity.com/paper/2303.02546/) (2023)
- [Fitted avatars: automatic skeleton adjustment for self-avatars in virtual reality](https://mlsanity.com/paper/2307.09558/) (2023)

## Built on by (most cited first, 1 of 1)

- [ImaGGen: Zero-Shot Generation of Co-Speech Semantic Gestures Grounded in Language and Image Input](https://mlsanity.com/paper/2510.17617/) (2025)

## Abstract (arXiv)

Generating accurate and realistic virtual human movements in real-time is of high importance for a variety of applications in computer graphics, interactive virtual environments, robotics, and biomechanics. This paper introduces a novel real-time inverse kinematics (IK) solver specifically designed for realistic human-like movement generation. Leveraging the automatic differentiation and just-in-time compilation of TensorFlow, the proposed solver efficiently handles complex articulated human skeletons with high degrees of freedom. By treating forward and inverse kinematics as differentiable operations, our method effectively addresses common challenges such as error accumulation and complicated joint limits in multi-constrained problems, which are critical for realistic human motion modeling. We demonstrate the solver's effectiveness on the SMPLX human skeleton model, evaluating its performance against widely used iterative-based IK algorithms, like Cyclic Coordinate Descent (CCD), FABRIK, and the nonlinear optimization algorithm IPOPT. Our experiments cover both simple end-effector tasks and sophisticated, multi-constrained problems with realistic joint limits. Results indicate that our IK solver achieves real-time performance, exhibiting rapid convergence, minimal computational overhead per iteration, and improved success rates compared to existing methods. The project code is available at https://github.com/hvoss-techfak/JAX-IK