How to ensure the safety and reliability of underwater robots when performing dangerous tasks?

Hello, that's an excellent question. Sending a hunk of metal weighing millions, or even tens of millions, of tons to work in the pitch-black, thousands of meters deep, high-pressure environment of the seabed – where the pressure can flatten steel plates – and ensuring its safe return, is indeed quite complex. You can imagine it as sending a "deaf, mute, and blind" astronaut to explore an alien planet; it requires the best equipment and the most comprehensive plan.

Essentially, everyone ensures its foolproof operation from these aspects:

1. The robot itself must be "hardcore"

Indestructible Body: The robot's shell must withstand the immense deep-sea pressure and seawater corrosion. Typically, lightweight and strong materials like titanium alloy are used. All electrical interfaces and cover seams must be sealed with special multi-layered gaskets to ensure not a single molecule of water can penetrate. This is like outfitting it with top-tier custom diving armor.
Powerful "Heart" and "Stamina": The power system is crucial. Usually, multiple battery packs or power supply systems are designed to act as backups. If one fails, another can immediately take over, ensuring it has enough power to complete the mission and return. This is like carrying two fully charged power banks when you go out, giving you peace of mind.
Sensitive "Senses" and Smart "Brain": In the dark seabed, it has to "see" its own way. So, it's equipped with sonar (like dolphins using sound for navigation), high-definition cameras, and laser scanners. At the same time, its control system is highly intelligent, capable of autonomously avoiding obstacles and even performing "self-health checks." For instance, if a component's temperature is abnormal or a tiny bit of water enters a sealed compartment, it can immediately detect it, alert the surface, and even take some emergency measures itself.

2. Thorough "Drills" and "Contingency Plans" Before Departure

Never Unprepared: Before the robot is deployed, technicians conduct extensive simulations on computers. They create a 3D virtual environment identical to the real seabed and have the robot run through the entire mission process. This allows them to identify design or procedural issues in advance, avoiding "pitfalls" during the actual mission. This is similar to pilots training for thousands of hours in a flight simulator.
Anticipating "If... Then..." Scenarios: It's essential to anticipate all possible accidents and develop corresponding response plans. For example: What if contact with the control center is lost? (Pre-programmed: wait for a signal, if none after 10 minutes, automatically ascend). What if it gets entangled in a fishing net? (Pre-programmed: activate the cutting tool on its robotic arm). These emergency protocols are written into its program and can be life-saving in critical moments.

3. Reliable "Lifeline" and "Support Team" During the Mission

The Connecting "Tether": Underwater wireless communication is very difficult, as electromagnetic waves don't travel far. Therefore, for the most critical missions, the robot usually trails a long fiber optic cable, which we call an "umbilical cable." This cable not only supplies power but also transmits high-definition video and data back to the mother ship without delay, making operators feel as if they are on-site. This "tether" is the most reliable guarantee.
Ever-Present "Guardian Angels": In the control room of the mother ship, a team of experienced operators (whom we call "pilots") constantly monitors screens 24/7, analyzing various data transmitted by the robot and ready to intervene manually at any time. Complex situations that the robot's autonomous system cannot handle are taken over by human operators.
Last Resort for Survival: In the absolute worst-case scenario, such as a complete power failure and total loss of contact with the mother ship, the robot still has a final "trump card." It will automatically jettison its ballast (e.g., heavy iron blocks), allowing it to float to the surface by buoyancy, awaiting rescue. This is like a submarine's emergency ballast blow, a last hope for survival.

In summary, ensuring the safety and reliability of underwater robots relies not on a single technology, but on a comprehensive system encompassing hardware design, software programming, personnel operation, and emergency preparedness. Through such multi-layered defenses, these "deep-sea warriors" can safely "return home" after completing dangerous missions.