Agility, speed, strength, and balance are all qualities needed to fight fires, especially when those fires are shipboard. Such feats are difficult for humans, let alone humanoid robots. But that's just what the RoMeLa labs at Virginia Tech are working on.
"The SAFFiR [Shipboard Autonomous Firefighting Robot] will be able to carry and operate fire extinguishers, fire hoses, throw PEAT [propelled extinguishing agent technology] canisters, as well as interact with humans and find fires. We've already built the legs of the robot and are working on the rest of it," said Derek Lahr, a PhD candidate and project manager.
The SAFFiR's legs are a highly compact amalgamation of motors, pulleys, wire harnesses, and controllers that allow the robot not only to walk, but also to walk while on a ship as it pitches and rolls through waves. Key concerns while designing the SAFFiR included the need to control the robot's locomotion from both a purely mechanical stance and a balance standpoint. For example, if the ship pitches forward, the robot might need to speed its leg movement and produce a longer stride length to keep itself from getting off balance.
Tethered to a power system, the SAFFiR walks while packing more than 12 maxon motors and 10 EPOS controllers. (Source: maxon)
Lahr said that by using maxon precision motors' EPOS controls, the project engineers were able to interconnect all operations easily. "For six degrees of freedom in each leg, we use six motors. That's 12 motors being used in just the legs section of the SAFFiR." Both speed and torque were necessary, since at different parts of a stride, the leg will alternately move fast and free and then slow and more controlled.
Lahr and his team used multiple 30mm maxon motors for the legs. Wherever possible, they designed in 100W motors to help reduce the weight of the unit. The motors provide the largest amount of mass in the robot, so any reduction in weight was a plus. "Maxon motors actually provide the highest power to weight ratio we could find in a brushless motor anywhere," Lahr said. "And humanoid robots can be more sensitive to weight than an airplane."
For certain critical joints like those in the knees, 200W motors were used. The knees of the robot, just like human knees, take the brunt of the load, especially when squatting or kneeling. They also have to move the fastest while walking. Those joints needed the additional torque and speed combination available with the larger wattage units.
That all makes sense, GlennA. I was just thinking the tether could get hung up in tricky environments. Yet, it would have the benefit of unlimited power. I would guess they can make tethers that wouldn't be adversely affected by fire and heat.
Rob Spiegel; I agree that a tether could be a serious restriction. But if the battery pack is only good for 1/2 hour or so, and it only carried 25 to 50 lbs or so of fire extinguisher, it is really worth the cost to develop ? If this robot can drag a fire hose behind it, it should be able to drag a tether also. Someone is doing the cost justification between an autonomous unit vs. a tethered tele-operated unit. And they may decide to build both types for further evaluation, or for different applications. Or they may continue with a tethered unit (as it is now) until the battery pack version is viable.
I would think that remote operation would be a necessity with these robots. As for having a tether for a power supply, I would think that would add vulnerability as well as restricting movement to some degree.
Yes it is impressive, Chuck. We're seeing more and more of these automated robots doing both dangerous work as well as repetitive work. The benefits of robots doing dangerous work is obvious -- saving human lives. The repetive work is also beneficial as it eliminates some of the soul-killing jobs such as tightening the same bolt 25 times per hour, eight hours per day, year in and year out.
@roddalitz. I would tend to agree with your argument but in this case it was necessary to give the robot humanoid feet. Ships engine compartments have hatch doors that are raised from the ground. To step through would require bipedal action. In this case the design may not have been based on human hubris. Though...if the robot is tethered how far can it go crossing that threshold. Hmm.
With respect I must ask whether humanoid is the most effective design? Certainly Hughey from Silent Running was far more convincing than the Star Wars robots R2D2 and C3PIO. Two legs seems like a biological accident, whereas ants and spiders work fine in most environments without issues of balance.
Rob Spiegel; Saving lives is probably the driving justification for this. There would be little concern about sending a robot into a situation that would be deadly for a human because the robot could be repaired, or replaced. There are certainly more efficient mobile platforms, but a companionway or hatch could be too difficult for a non-humanoid design to navigate. The tether may be necessary for power, and to send back video to an operator.
I don't recall the article stating if these were supposed to be autonomous or tele-robotic (remotely operated).
@ G Cabrera: I have to admit, I feel the same way, but I held back from saying so. Seeing that robot come lumbering (or tearing) across the ship, depending on how the sensors program it to respond based on environmental conditions, might be enough to send ship mates overboard, retreating in fright--and not just from an onboard fire!
I agree, Rob. Here, we have a great application for robots -- doing tasks that are just plain dangerous or that humans don't want to do. It's amazing to see how much "muscle" the new breed of robots is providing.
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