Episode 4: From Simulation to Reality – Embodiment and Real-World Deployment

Shaoqing Tan
Wed, 23 Jul 2025 06:04:00 GMT

Welcome back! So far we’ve tackled the concept of OpenVLA and the training of OpenVLA. Now it’s time for the real fun: robots! In this episode, we’ll discuss how OpenVLA connects to actual robot hardware and different embodiments. How does one model control many types of robot arms? What happens when you take it off the computer and put it on a real robot in a real environment? We’ll cover the generalization across embodiments, the process of deploying in the real world, and some impressive experiments they performed to prove OpenVLA’s prowess.

One of the flagship features of OpenVLA is its ability to handle multiple robot embodiments out-of-the-box. In the world of robotics, “embodiment” just means the physical form of the robot – its shape, joints, degrees of freedom, etc. Traditional robot policies are usually tied to one embodiment (e.g., a policy for a 6-DoF arm with a two-finger gripper won’t work on a drone or even on a different arm without retraining). OpenVLA was trained on demonstrations from many robots, and as a result it learned a sort of cross-embodiment skill representation. In their evaluations, the OpenVLA team showed that the model could control at least two very different robot platforms without any additional training for each. Specifically, they tested: (1) a WidowX arm (a small 6-DoF robotic arm often used in lab experiments, which was featured in the Bridge datasets) and (2) a “Google Robot” from the RT series (this refers to an industrial robot arm used in Google’s Robotics Transformer research, likely something like a UR5 or similar). These robots have different kinematics, different camera perspectives, and were from entirely separate data sources. Yet, OpenVLA could take an instruction and image for either robot and output correct actions for each, all using the same neural network weights. It didn’t freak out or get confused; it implicitly “knows” which robot it’s controlling based on the visual input (it can see the robot’s own arm in the camera, typically) and perhaps subtle cues in the prompt or environment.

How is this possible? A big part of the answer is normalization and calibration. During training, each robot’s action data was normalized to a common range (like joint motions or end-effector deltas scaled to roughly –1 to 1 range). The model outputs actions in this normalized space. To execute on a real robot, you then un-normalize those tokens back to actual angles or distances using that robot’s calibration data. OpenVLA’s code uses an “unnorm key” to specify which robot’s stats to use for this step. For example, if the model outputs a move “0.5” in X (normalized), the un-normalization for a WidowX might turn that into, say, +3 cm, whereas for a larger robot, +3 cm might be a smaller normalized value. The model itself doesn’t have to explicitly know numbers like the arm’s length – it just outputs abstract actions that the execution layer maps to the specific hardware. This separation of concerns is clever: it means one policy can drive different robots as long as you have those calibration mappings and the robot was represented in training.

Another factor is that the model was exposed to multiple embodiments during training. So it learned to handle the different dynamics and constraints in a statistical sense. In fact, one of the striking results reported was that training on multi-embodiment data yielded positive transfer: experience from one robot helped it perform better on another. For instance, having seen a task done by a smaller arm might help it do the task with a larger arm, because the core concept (grasp object, move it) is similar, just scaled. This is a new paradigm: instead of building a separate brain for each robot, we train one big brain that’s slightly specialized to each when needed.

Let’s talk about real-world deployment. In simulations or labs, it’s one thing to get good results; but they actually took OpenVLA and ran it on physical robots to see how it performs in reality (with all its noise and unpredictability). The project’s website showcases videos of OpenVLA doing zero-shot control on two real robots: the WidowX arm and a robot from Google’s lab. “Zero-shot” here means they took the pretrained OpenVLA model (no further fine-tuning on those specific robots beyond what was in the pretraining data) and directly used it to control the real robot on new tasks it hadn’t specifically seen. And it worked remarkably well. In one example, the WidowX was instructed to place a toy block onto a plate in a cluttered scene – the model successfully navigated to the block, picked it, and placed it as asked. In another, the Google robot arm was told to upright a knocked-over Coke bottle – and it did so smoothly. These demonstrations illustrate the model’s robustness: even without tailored training for those exact conditions, it could interpret the command and visual scene and execute competent actions.

Of course, some embodiments required fine-tuning for optimal results. The Franka Panda robot experiments are a good example. The Panda is a high-precision 7-DoF arm, and they introduced tasks like “wipe the table with a sponge” or “flip the pot” with it. Those tasks have long horizons and possibly tricky contact dynamics. OpenVLA was fine-tuned on small demonstration sets for those tasks and achieved over 50% success on all of them, outperforming baselines like an earlier generalist model (Octo) or a diffusion policy. Notably, the diffusion policy (trained from scratch for that robot) did well on very precise single-step tasks but struggled on the multi-step, language-oriented ones, whereas OpenVLA shined there. This suggests that OpenVLA’s strength is understanding the intent behind the instruction and maintaining context across a sequence of actions – something a from-scratch policy might lack if it wasn’t trained on diverse language instructions.

To give you a sense of the breadth of tasks OpenVLA handled, consider some of the evaluated scenarios. The model was tested on generalization in various dimensions:

Visual generalization: e.g., different background scenes, distractor objects present. They found OpenVLA could still pick the right target object even if there were other similar objects around – it wouldn’t as easily be fooled or distracted. It could also handle variations in object color or appearance that it hadn’t seen during training.

Positional generalization: e.g., objects in new locations or orientations. The model could adjust its motion accordingly – for instance, if a block was in a new spot, it still moved the correct relative distances to reach it.

Physical generalization: e.g., objects of new sizes or shapes. Within reason, OpenVLA could adapt its grasp or movement even to slightly different objects than seen in training (thanks to its vision encoder recognizing them as, say, “some graspable cup”).

Semantic generalization: e.g., entirely new instructions or goals that combine concepts from training in novel ways. The model has some ability to compose skills. Anecdotally, the team noted it could follow instructions pulling in concepts from the internet or common sense (perhaps via the language model’s knowledge) – like “put the toy that looks like a horse into the bin,” which requires recognizing a “yellow pony” toy and understanding the goal.

One particularly impressive qualitative behavior: error recovery. They observed cases where OpenVLA would make a small mistake (like not gripping an object tightly enough so it slipped). Instead of just continuing blindly or giving up, the model detected something went wrong (presumably from vision feedback) and corrected – e.g., re-grasping the object properly on a second attempt. This kind of resiliency is hard-coded in no classical pipeline, but emerged naturally from end-to-end learning. It suggests the model learned a bit of “if drop, try again” from demonstrations.

Now, how do we physically run OpenVLA on a real robot? The typical setup is: you have a computer with a GPU running the model. The robot provides camera images in real time to the computer. The model processes each image+instruction and outputs an action. That action is then sent as a command to the robot’s controller (which could be position increments for joints, for example). This loop repeats every few tenths of a second. In the OpenVLA repository, they provide example code for, say, controlling a WidowX in the BridgeV2 simulated or real environment with a simple loop. The takeaway is that integrating the model isn’t too difficult: as long as you can feed in images and send out motion commands, the model handles the decision-making in between. One does need to ensure safety – large random motions could occur if the model were wildly off, but in practice with a well-trained model, actions are usually reasonable. Still, for real deployments, often you’d keep some safety checks (joint limits, collision sensors, etc.) just in case.

OpenVLA was also compared against other policies in real hardware tests. For example, in direct head-to-head on controlling a given robot, OpenVLA outperformed RT-1-X (which was previously the best open generalist policy using similar data) and matched or beat a much bigger model RT-2-X that was tested internally. And when fine-tuned, it leaped ahead of specialized models. What we’re seeing is the emergence of generalist robot controllers that are actually better than specialist ones in many cases, especially when tasks involve varying conditions or understanding instructions. It’s a bit like how a well-rounded human worker can adapt to many situations better than a rigidly trained machine that only knows one routine.

Before we close this episode, it’s worth noting the limits of OpenVLA’s embodiment generality. It’s not magic: if you present it with a completely unseen robot type or configuration that wasn’t in the training data at all, it likely won’t work zero-shot. For instance, if all training robots were stationary arms and you ask it to control a flying drone or a bipedal humanoid, the visual input and required actions are so different that the model wouldn’t know what to do. In such cases, the approach would be to collect some data on that new embodiment and fine-tune OpenVLA accordingly (leveraging what it can transfer, like understanding instructions and basic vision). The authors themselves emphasize: it doesn’t zero-shot generalize to arbitrary new robots not represented in the pretraining mix. So while it covers many arms, we’re not yet at a single model that can control, say, every possible robot. We are, however, moving in that direction as datasets expand.

In summary, OpenVLA in the real world has shown a remarkable ability to jump between different robot bodies and still perform a wide array of tasks reliably. It’s able to use its learned knowledge to succeed in unstructured environments, handle new variations, and even recover from mistakes. This kind of robustness is what you need if you ever want to see home assistant robots or adaptable factory robots that you can instruct on the fly. OpenVLA is a step toward that vision: a general “robot brain” that you can put into different bodies and still get competent behavior.

Next, we’ll broaden our view even more and look at the bigger ecosystem. OpenVLA isn’t the only player in town. How does it compare to other VLA models and what complementary approaches are out there? In the final episode, we’ll talk about related models like RT-Trajectory, Octo, and recent advances, as well as where the field is heading beyond OpenVLA. Stay tuned for the grand finale!

Robots of different shapes and sizes, zero-shot success, and even a bit of error recovery – we’ve seen OpenVLA prove its mettle in real-world conditions across embodiments. It’s exciting to imagine one AI brain controlling many kinds of robots, and OpenVLA gives us a taste of that future. Coming up in our final episode, we’ll place OpenVLA in the wider context. What other models are out there pushing the envelope? How are researchers making VLAs even better – faster, smaller, or more capable? And what might the next generation of these systems look like? Don’t miss it – we’re rounding out the series with a look at the cutting edge and beyond.