Exoskeletons and manufacturing
21 marzo 2019

A powered exoskeleton is the ultimate marriage of man and machine. A sort of wearable robot, or roboticised bodysuit, it is designed to enhance the strength and endurance of the human frame far beyond its natural limitations. Perhaps the most high-profile versions of the idea have, to date, been the assisted-walking devices that have revolutionised the lives of some paraplegics, or therapeutic models that through regimes of stimulation restore functionality to limbs damaged by accidents or strokes.

The idea would seem to have obvious applicability to the world of manufacturing too. Lifting and manoeuvring heavy tools and component parts can be arduous and not always easy to reconcile with accurate, consistent work. Take away the weight, stress and risk of injury, and – as with any investment in robotics – there are surely dividends to be had in terms of quality and productivity.

The powered exoskeleton experience

But how developed is exosuit technology for manufacturing purposes? What do the wearables that have been devised so far look like? How have its concepts and designs panned out on the factory floor – and what do any successes or failures say about the future of this technology in an industrial environment? 

The problems facing the exoskeleton engineer are amply illustrated by an early example. For six years in the late 1960s, General Electric and the United States Armed Forces together worked on a full, powered exoskeleton that would enable wearers to lift objects 25 times heavier than those they could otherwise manage. The device, called Hardiman, gave the inventors nothing but a hard time.

It was a gigantic double-shell that weighed over half a tonne, moved slowly and was liable to topple over. Much thought and work went into making Hardiman safe to operate – so that it would not use too much force, snapping and crumpling everything it touched – but it was in the end judged too unpredictable to take beyond prototype.

Needless to say, technology has come a long way since then. The development of small, powerful accelerometers and other sensors, together with advances in their coordinated deployment (sensor fusion), have helped bring precision to exoskeleton movement. This has been complemented by parallel progress in the design and sensitivity of the motors and drives that make up the actuators of mechanical joints.

Soft robotics and exoskeleton suits

In fact, all the hardware that constitutes a powered exosuit is now relatively lightweight and compact. Being significantly less power-hungry, too, means that wearable batteries can figure as part of the device, rather than the whole thing having to be moored inconveniently to a power source.

A lightweight exoskeleton is essential for the comfort of the wearer. Carbon fibre and aluminium alloys with high tensile strength have been found to be appropriate materials. Even the lightest suit, however, has the potential to feel uncongenial if worn for long periods of time. These things are, after all, not tailored to fit, embedded with electronics and are another layer to wear in an already warm environment.

Hence the attraction of soft robotics. This engineering subfield specialises in the construction of robotic elements from flexible materials, though in the case of exoskeletons the technology is still in the research and development phase. The biologically appropriate force transmissions it envisages, however, together with its exploration of pneumatics, for example, as an alternative to electromechanics, promise new levels of compatibility with the requirements of the human form.

Robotic suits transforming the manufacturing industry

Exosuit technology continues to make rapid progress. And a recent estimate puts the projected annual growth rate for the robotic exoskeleton market during the coming decade at a little over 40%.

This is partly based on the anticipated level of uptake by the manufacturing sector. A glance at the kind of devices most recently developed for use in factories and similar environments, however, shows a predominating concern – at this stage – not with full body suits but with smaller attachments geared towards specific types of labour; and not so much with robotic power as with passive weight redistribution.

Lightweight frames worn on the upper body and arms have been particularly successful in assisting workers who need to wield heavy tools, such as drills or wrenches, in an elevated position – such as when working on the underbodies of cars. The spring-loaded arm section diverts most of the held weight down through the frame to the ground, making the tool itself feel a mere fraction of its unsupported weight.

Variations on this basic model lie behind both Levitate Technologies’ Airframe, which BMW began trialling last year, and the EksoVest, now used in a number of Ford factories around the world. Early reports indicate strong enthusiasm among users and a fall in the number of work-related injuries.

Passive exoskeleton

Other types of passive exoskeleton proving useful in this environment are forms of central body support that reduce the stress on back muscles when bending forward, and the so-called chairless chair – a flexible body frame that locks into a sitting or crouching position, taking the strain off the user who may have to maintain the posture over an extended period.

One example of recently well-received workwear that features powered robotics is Bioservo’s Ironhand, a soft, sensor-equipped glove connected to servo motors in a backpack which automatically augments the strength of the user’s grip. The patented SEM (soft extra muscle) technology behind the device credits its development as much to neuroscience as to mechanics.

The manufacturing arena, then, is responding most favourably to those interpretations of exoskeleton technology that are either basically non-robotic or that hail from the emerging world of soft robotics. Long-term wearability, ease of use, and supportive force only when smoothly, fully continuous with instinctive human motion have established themselves as the key criteria of what works best.

As other trends, such as voice-based, graphical or other intuitive user interfaces, suggest, natural-feeling connectivity between man and machine seems a clear theme, and precondition for efficiency, in the increasingly automated workplace.

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