The idea of using robots as the go-to for handling disaster situations isn't new, but part of the problem has been how to build robots light enough to move about easily, yet are strong enough and tough enough to handle things like a smashed up nuclear reactor. As part of the answer, the Tokyo Institute of Technology and Bridgestone Tires have partnered to develop a new hydraulic robotic muscle that is lightweight, yet is five to ten times as strong as conventional electric motors and much more durable.

The locations in disaster areas where the responders are needed most urgently are often the ones that are the hardest to get to, precisely because they've been hit so hard. The 2011 Fukushima nuclear disaster is a prime example. Despite the damage done to the nuclear power plant by the sea wave that struck it, the subsequent explosion and meltdown could have been avoided had emergency workers been able to reach it with the right equipment in time to make repairs and re-power the cooling systems.

This is one reason why robots are so attractive. Autonomous robots have the potential to be able to move in and handle such emergencies, even to the point of using found tools and vehicles to accomplish tasks. Unfortunately, even though robots have a reputation for being steel giants possessing superhuman strength, mobile robots tend to be more on the weak and fragile side.

Developed since 2014 as part of the Impulsing PAradigm Change through disruptive Technologies Program (ImPACT) Tough Robotics Challenge, an initiative of Japan's Cabinet Office Council for Science, Technology and Innovation, the new hydraulic muscles may be one way of making stronger, more robust robots that are still lightweight and capable of precision movements. According to the creators, the expectation is that the mature technology could one day produce that smallest, lightest, and most powerful consumer robots ever created.

The team says that the key to improving disaster response robots is to produce tough hydraulic actuators, which are the components that move and power robotic limbs. Most actuators are electric but lack precision and have a poor strength to weight ratio – not to mention being very susceptible to shocks and vibrations.

The Tokyo Tech/Bridgestone artificial muscle is a very simple device based on the human muscle, only instead of using contracting muscle tissue it uses a rubber tube bound by woven high-tensile fibers, which contracts in length as its pressurized with hydraulic fluid. The combination of rubber and fabric gives it a structure like that of the human artery, so it responds dynamically as pressure is applied and released, allowing it to move smoothly and precisely. In addition, it has a very high strength-to-weight ratio.

Another aspect of the simple design is that the muscle is very tough and resistant to shocks and vibration. This makes it suitable for hostile environments and for high-intensity jobs, like pushing down walls or clearing debris.

According to the team, producing the muscle required the development of a new oil-resistant rubber that also has excellent deformation characteristics. The sheath needed a new technique for weaving high-tension chemical fibers, and the tube ends required special tightening to resist high pressure without leaking. The result was an actuator five to ten times the strength-to-weight of electric motors or solid hydraulic cylinders.

The researchers say they will continue development of robots based on the new muscles, as well as a consumer-use robot actuator.

The video below shows the new robotic muscle in action.

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