The robot vacuum starts and your dog either runs under the bed or follows it barking. Both responses tell you the current setup is too much. Stop the machine and move your dog to a quiet, safe room before cleaning. Do not let them chase a device that can catch fur or bump into them, and do not allow a worried dog to be cornered by it.
Set the vacuum schedule for times when you can supervise or when the dog is safely away from it. A gate or closed door is more reliable than telling a dog to ignore a moving machine. If their fear spreads to other ordinary sounds or they remain panicked even when separated, talk to your veterinarian and a qualified, reward-based behavior professional.
Separate sight, sound, and movement
Show the switched-off robot at a comfortable distance, reward your dog for looking calmly, and put it away. Later, run it behind a closed door so the sound is quieter. If that is easy over several short sessions, allow a distant view while it is moving, with a clear path for your dog to leave. Stop before barking or hiding begins. If they retreat, freeze, or refuse food, the next session should be easier.
Keep charging cables and the device itself out of reach when not in use. The goal does not have to be sharing a room with the robot. A dog who relaxes elsewhere while floors are cleaned has a perfectly workable plan. For a broader approach to sound fears, see the noise-fear guide, the moving machine should remain off or separated during early practice
Sources: Dogs Trust: How to introduce a vacuum cleaner to your dog. VCA Animal Hospitals: Reducing Fear and Stress with Desensitization and Counterconditioning.