Self-Correcting VLA: Online Action Refinement via Sparse World Imagination
Organizations: Tongji University · University of Technology Sydney · University of Electronic Science and Technology of China · Advanced Institute of Big Data
Abstract
Standard vision-language-action (VLA) models rely on fitting statistical data priors, limiting their robust understanding of underlying physical dynamics. Reinforcement learning enhances physical grounding through exploration yet typically relies on external reward signals that remain isolated from the agent's internal states. World action models have emerged as a promising paradigm that integrates imagination and control to enable predictive planning. However, they rely on implicit context modeling, lacking explicit mechanisms for self-improvement. To solve these problems, we propose Self-Correcting VLA (SC-VLA), which achieve self-improvement by intrinsically guiding action refinement through sparse imagination. We first design sparse world imagination by integrating auxiliary predictive heads to forecast current task progress and future trajectory trends, thereby constraining the policy to encode short-term physical evolution. Then we introduce the online action refinement module to reshape progress-dependent dense rewards, adjusting trajectory orientation based on the predicted sparse future states. Evaluations on challenging robot manipulation tasks from simulation benchmarks and real-world settings demonstrate that SC-VLA achieve state-of-the-art performance, yielding the highest task throughput with 16% fewer steps and a 9% higher success rate than the best-performing baselines, alongside a 14% gain in real-world experiments. Code is available at https://github.com/Kisaragi0/SC-VLA.
Figures & tables
| Model | ManiSkill Tasks | Avg | |||
| Stack Cube | Place Sphere | LiftPeg Upright | Peg Insertion | ||
| DP ‡ | 0.46 | 0.90 | 0.10 | 0.00 | 0.36 |
| DP † | 0.88 | 1.00 | 0.80 | 0.40 | 0.77 |
| ACT ‡ | 0.50 | 0.88 | 0.60 | 0.12 | 0.52 |
| ACT † | 0.64 | 0.90 | 0.46 | 0.04 | 0.51 |
| 0.66 | 0.86 | 0.48 | 0.22 | 0.55 | |
| Model | ManiSkill Tasks | Avg | |||
| Stack Cube | Place Sphere | LiftPeg Upright | Peg Insertion | ||
| DP ‡ | 162 | 146 | 202 | 800 | 327 |
| DP † | 132 | 125 | 197 | 233 | 172 |
| ACT ‡ | 148 | 131 | 207 | 250 | 184 |
| ACT † | 198 | 126 | 203 | 230 | 189 |
| 265 | 179 | 331 | 331 | 276 | |
| Model | ManiSkill Tasks | Avg | |||
| Stack Cube | Place Sphere | LiftPeg Upright | Peg Insertion | ||
| SC-VLA w/o state | 0.88 | 1.00 | 0.84 | 0.42 | 0.78 |
| SC-VLA w/o prog | 0.92 | 1.00 | 0.80 | 0.50 | 0.80 |
| SC-VLA w/o state_prog | 0.78 | 1.00 | 0.72 | 0.40 | 0.72 |
| SC-VLA(SPI) | 0.96 | 1.00 | 0.82 | 0.50 | 0.82 |
| Model | Real World Tasks | Avg | |||
| Stack Cube | Place Sphere | Push Cube | Peg Insertion | ||
| DP ‡ | 0.30 | 0.40 | 0.45 | 0.00 | 0.28 |
| GR00T N1.5 | 0.75 | 0.45 | 0.80 | 0.30 | 0.57 |
| SC-VLA(SPI) | 0.85 | 0.60 | 1.00 | 0.40 | 0.71 |
Appendix figures & tables6 assets
Supplementary material from the paper’s appendix.
Appendix
| Tasks | Success Criteria | Max Steps |
| StackCube | The task is considered successful if the horizontal offset of the red cube relative to the green cube does not exceed the half-diagonal of the cube plus 5 mm, the vertical distance between the centers of the two cubes equals one cube edge length with a tolerance of 5 mm, and the red cube remains stationary and is not grasped by the robot end-effector. | 800 |
| PlaceSphere | The task is considered successful if the horizontal offset of the sphere relative to the center of the container does not exceed 5 mm, the vertical position satisfies that the contact point between the bottom of the sphere and the container floor has an error within 5 mm, and the sphere is not grasped by the robot end-effector. | 500 |
| LiftPegUpright | The task is considered successful if the peg’s orientation is close to the upright configuration, with a deviation around the vertical axis not exceeding 0.08 rad, and the vertical position of the peg’s center of mass deviates from its half-length by no more than 5 mm. | 800 |
| PegInsertionside | The task is considered successful if the tail end of the peg lies within the coordinate frame of the box hole, with an offset along the insertion direction no greater than 2 cm, and offsets along the other two orthogonal directions both smaller than 8 mm. | 800 |
| Hyperparameter | Value |
| Batch size | 32 |
| Training steps | 50,000 |
| Learning rate | |
| Model init seed | 42 |
| Optimizer | AdamW |
| Shared Parameters | Task-Specific Parameters | |||
| Tasks | Hyperparameter | Value | Hyperparameter | Value |
| StackCube | Random seed 0 Replay buffer size Total steps Discount factor 0.97 Target smoothing 0.01 Batch size 1024 Policy learning rate Critic learning rate Entropy coeff. 0.2 Gradient clipping 50 Update-to-Data (UTD) 0.5 Training frequency 64 Guide weight 0.6 | Total timesteps | 500,000 | |
| Learning start steps | 30,000 | |||
| Exploration steps | 100,000 | |||
| Residual scale (train) | 0.01 | |||
| Residual scale (eval) | 0.005 | |||