Exoskeletons, also known as outer skeletons or support robots, are support structures worn on the body, which reduce the load on the body and reduce the risk of injury by means of (electro-)mechanical support. Exoskeletons are still at an early stage of development and the first industrial companies are now starting to use them in regular operations.

Active and passive exoskeletons

A basic distinction is made between passive and active exoskeletons.

Passive exoskeletons support the wearer exclusively by means of mechanical aids, such as spring or cable systems, which absorb occurring loads like a kind of counterweight and thus convert them into energy. Especially when lifting heavy loads, the strain on the worker can be reduced by up to 40 percent.

Active exoskeletons provide additional external force support through electric motors or pneumatic systems acting on the joints or other neuralgic points of the wearer. These systems allow a much higher level of support. However, the additional power takes its toll through a significantly higher dead weight of the suit due to motors and the necessary energy supply via batteries. This power supply is necessary to maintain full freedom of movement, but due to the use of batteries, its use is limited in time.

What are exoskeletons used for?

In logistics and production, the physical strain on personnel is often very high, which in the long run puts great strain on the health and performance of the employees. Older members of staff, in particular, are often stressed to or above their capacity limit when moving heavy objects, which is a major problem in an ageing society. By using exoskeletons, physical handicaps can be compensated and postural deformities and physical deterioration can be avoided from the outset as physical peak loads are eliminated.

If workplaces cannot be ergonomically optimized due to the physical conditions, the exoskeleton can help to restore balance by stabilizing certain parts of the body and thus reducing the effort required.

Applications in the industry

In a very simple version, a support structure that is limited exclusively to the legs makes it possible to adopt a variable sitting position. The operator can stiffen the mechanism fixed to the hips and legs in any position and is provided with a seat that is precisely adjusted to the situation. This variant, known as the chairless chair, is used by Audi at its Neckarsulm site, for example.

The logistics service provider Geodis in Venlo in the Netherlands relies on passive exoskeletons that support the back and thus assist the warehouse worker with lifting and carrying activities during order picking. The suits are currently used for employees who have to move more than 4,000 kilograms per day.

The workers of the BMW plant in Spartanburg in the United States are also provided with mechanical support. They wear vests that support the upper body via a mechanism especially for tasks which require overhead assembly.

The aircraft manufacturer Airbus is currently testing both passive and active systems to make work more ergonomic. “In aircraft production, there are often not very ergonomic body positions in aircraft production due to difficult accessibility, which we try to make healthier for the employee by means of support systems if the workplace cannot be fundamentally modified”, explains development engineer Dr. Robert Goehlich in an interview with the magazine ‘Produktion’.

The economic factor

The still quite high acquisition costs for this specialized equipment still deter many companies from equipping entire departments with exoskeletons. According to a study conducted by the DAK in 2014, however, 21.5 percent of days of absence from work, and thus the largest proportion of all causes of absence, are attributable to diseases of the musculoskeletal system. According to David Minzenmay, a scientist at the Fraunhofer Institute for Manufacturing Engineering and Automation (IPA), this would result in around 125 million lost working days per year and thus a shortfall in value-added of around 22.7 billion euros.

If these figures are taken into account, the investment for the employer is put into a new perspective. A study by ABI Research at the end of 2015 predicts a potential market volume of 1.8 billion dollars for exoskeletons in 2025.

Where is the development of exoskeleton systems going?

In the near future, active exoskeletons will become more compact and will be able to use sensors to detect when the wearer needs support and then take appropriate action. Using special gloves, for example, the system will record the strain and use weight estimation to determine how much external energy is required. Such a solution is currently being developed in the SensHand research project (German Source) of the Federal Ministry of Education and Research (BMBF) in cooperation with the Fraunhofer IPA.

The Fraunhofer IPA is also conducting research on a modular kit that enables the custom configuration of individual exoskeleton components for different applications. If this system reaches market maturity, investment costs could fall considerably and the spread of supporting systems could increase significantly.

Further information on ergonomic aspects can be found in the article Ergonomics in the warehouse.

Source Teaser image: Ekso Bionics, licencse (CC BY-ND 2.0)

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