Pacific Rim and exoskeletons

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Science Robotics  28 Mar 2018:
Vol. 3, Issue 16, eaat3911
DOI: 10.1126/scirobotics.aat3911


The giant robots in the Pacific Rim movies could take lessons from advances in legged robots and from real-world exoskeletons being designed to prevent worker injuries, accelerate physical therapy, and help paralyzed children walk.

The Pacific Rim and Pacific Rim Uprising movies pose an intriguing question: Would a giant robot piloted by human operators inside the head or chest actually work? It is a question that has been around since 1943, when comic boy heroes Jackie Law and his Boy Rangers climbed into Loco the robot to fight the Nazis (1). By 1972, any questions as to the feasibility of giant robots were overwhelmed by the general coolness of Mazinger Z, the manga that bootstrapped the piloted mecha genre. As time went on, movies like Aliens, Iron Man, and Avatar kept the coolness but scaled the mecha down to person-sized augmentations known as exoskeletons. In parallel, a similar smaller-is-better trend occurred in research. Although some giant piloted robots have been built for disaster response and construction, notably the Japanese T-52 Enyru and the Korean METHOD series, the focus shifted to exoskeletons. In 2013, Pacific Rim rebooted the giant piloted mecha genre, telling a story of 250-foot-tall Jaeger robots locked in mortal combat with equally giant kaiju aliens. However, the science of the movie remained in the 1970s. This article will explore one of those advances that would simplify Jaeger control plus some of the inspiring applications of real exoskeletons.

In Pacific Rim and The Themis Files, a best-selling book series about an alien-built piloted mecha, the underlying assumption is the bigger the robot, the harder it is to control. Thus, a giant robot would require more operators. However, science shows that the more complex the machine, the less likely a human can directly manage it. Consider Hardiman, which is considered the first exoskeleton (2). It was developed for the U.S. military in the 1960s and is the progenitor of Tony Stark’s Iron Man and the more utilitarian fighting units worn by Tom Cruise in Edge of Tomorrow. In theory, Hardiman enabled a soldier to feel like they were lifting 4.5 kg while actually lifting 110 kg. However, in practice, the system could not be safely controlled, and so no one ever wore it. Controlling a piloted mecha would be like trying to manually control a fly-by-wire stealth bomber; it cannot be done. Since Hardiman, a major thrust in exoskeleton research has been on how the physical interface can actively interpret the wearer’s intent and to translate that into the commands coordinating joints and actuators.

In Pacific Rim and The Themis Files, two of the major functions that seem to take an inordinate amount of time and effort are walking and running. The operators inside the robot wear a master suit to explicitly direct the robot, which mirrors their movements. In reality, locomotion is becoming one of the easiest functions to totally delegate to a robot. After all, a rider does not consciously tell a horse what hooves to lift and where to place them. Instead, the rider strategically plans what to do and then uses reins and heels to communicate to the horse the desired speed and direction. The horse tactically determines the best gait and precise footfall for the strategic goals. Horses—indeed, all legged animals—manage the complex movements of trotting, cantering, and galloping with multiple legs by exploiting neurophysiological loops called central pattern generators (CPGs). CPGs essentially encapsulate a gait as a macro or schema, similar to a reflex. Another part of the horse’s brain dynamically adjusts the automation to the terrain. The result is “left front leg, right rear leg down” from the CPG combined with an additional command of “left front leg, extend further out.” Ever since Marc Raibert’s breakthrough Ph.D. work in 1986 on control of legged robots, bots such as Boston Dynamics’ BigDog and the humanoids in the Defense Advanced Research Projects Agency Robotics Challenge have exploited elegant biological principles such as CPGs. (As a fun aside, the video of Raibert’s thesis experiments is called “Robots that run. And topple and fall.”)

A sci-fi role model for exoskeletons is the power lifter used by Sigourney Weaver in Aliens. In the first Environmental Lab Day on the Hill at the U.S. Senate, Carol Landry, the international vice-president of United Steelworkers, encouraged the Department of Energy to accelerate development of upper body power lifters. A surprising case of a labor union asking for more robots, not less! Why? One reason is that a power lifter could prevent the back and hand sprains that plague highly trained steelworkers as they decommission Cold War nuclear sites. Another reason is that power lifters equalize sexual dimorphisms (and age differences), enabling women like Ripley and an aging population to do the same jobs as easily as Matt Damon in Elysium.

However, Hollywood has overlooked what might be the most inspiring uses of exoskeletons: as an orthosis for the injured or a tool for physical therapy. Exoskeletons such as Yoshiyuki Sankai’s Hybrid Assisted Limb enable people with spinal cord injuries to walk (3). Other robots are being introduced into physical therapy, where the technology that enables an assistive exoskeleton to help lift heavy loads is flipped. Aside from helping to minimize effort, rehabilitation exoskeletons subtly guide and maximize the effort of the person performing a task, either actively or passively, producing substantial improvements in recovery.

After all is said and done, the question of how a giant robot might work is dwarfed by how the underlying technology would be used. Pacific Rim imagines a world where giant piloted robots help soldiers fight hostile aliens, whereas robotics researchers in Spain imagine a world where the same technologies help children with neuromuscular diseases walk—as well as adapt and grow with them (4). In this case, science appears to be more imaginative than science fiction.

As we wait for lightweight active exoskeletons or passive exoskeletons built into our clothes to help us as we grow older, a good place to learn more is “Human-Robot Augmentation,” in the Springer Handbook of Robotics (5).


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