Robocurve has run OpenAI's GPT-6 Astra and Anthropic's Claude Fable 5.1 against physical robot arms, and the results split sharply by task. Astra completed the easy task 19 times out of 20. On the harder task it managed 2 out of 20, exactly matching Fable 5.1. Robocurve published the Astra results on September 4, 2026, and the Fable 5.1 results the day before.
Robocurve is an independent evaluator, not either lab. It describes itself as a Public Benefit Corporation and says it is backed by Y Combinator.
The two tasks and the numbers
Both models drove the same rig: bimanual I2RT YAM arms, six degrees of freedom each, parallel-jaw grippers, three camera views. Each model ran 20 trials per task, scored by human graders on a five-point stage scale.
The first task was picking a red block into a bowl. The second was placing a blue puzzle piece into a matching groove.
