The wearer of the exoskeleton can use a smartwatch to adjust the level of support during an operation.

© German Bionic Systems

In contrast, the software-controlled active exoskeletons that are now coming onto the market are technically more sophisticated and are also equipped with sensors and actuators. They are driven electrically, pneumatically or hydraulically. The electrically powered 'Cray X', for example, the exoskeleton from German Bionic Systems, uses Makita rechargeable batteries with energy recovery to cover the energy requirements for an eight-hour working day. Gyroscopes, torque sensors in the drives and position sensors controlled by software are used to control the motors. The level of support can be entered manually via a graphical user interface (GUI) - specifically a smartwatch. The Cray X also has an additional interface for an EMG wristband, which is used to measure the degree of muscle tension.

Detailed view of the drive unit of the Cray X from the inside.

© German Bionic Systems

Another important differentiation criterion for exoskeletons is the type of physical support, i.e. whether legs or arms and back are supported. Exoskeletons for leg support are used more frequently in the medical field. The US company Ekso Bionics recently became the first manufacturer to receive approval from the US Food and Drug Administration (FDA) for the use of its 'EksoGT' exoskeleton for the rehabilitation of people with spinal injuries and stroke patients. The H-MEX model from Hyundai, which was presented at CES in Las Vegas last year, is designed to enable people with spinal cord injuries to sit, stand, walk and climb stairs again.

Two electric motors sit above the hip joints and pull the wearer's upper body up again from a bent position. This reduces muscle tension in the lower back by 30 to 40 %.

© German Bionic Systems

Exoskeletons with arm and back support are particularly relevant for use in production. The aforementioned series models from Laevo and German Bionic Systems, which are already being used in factories, support their wearers in the manual handling of goods and tools and specifically reduce the compression pressure in the lower back area when lifting heavy loads. The aim is to reduce the risk of musculoskeletal disorders and prevent injuries. Exoskeletons with arm support can also already be found in production. At its plant in Spartanburg (South Carolina), for example, car manufacturer BMW has been using passive exoskeletons from American manufacturer Levitate for some time now for assembly steps that have to be carried out overhead and are therefore considered tiring and unergonomic. A mechanical spring support is integrated into the joints of the Levitate Airframe, which increases the strength of the arms.

Finally, the Swiss company Noonee has developed a special form of exoskeleton for work on the production line: the 'chairless chair' - a kind of seat that can be strapped to the body. The purely mechanical system is designed to relieve strain on the knees, back and neck. Wearers can adjust the exo-seat individually and continuously - the lowest possible position is a 90-degree angle between the lower leg and thigh.

Back to the Cray X: the foundations for the wearable, back-supporting robotic system from German Bionic Systems were developed together with research and industry partners as part of the multi-year EU research project Robo-Mate. The project partners included universities and research institutes, such as the Fraunhofer IAO, as well as the Italian car manufacturer Fiat.

The details behind Cray X

Since 2016, the concept has finally been developed further into an industrial series model and, with the inclusion of work ergonomics, designed specifically for the manual handling of goods and tools weighing up to 15 kg. Compared to lifting cranes, which are usually used in production for this type of work, the exoskeleton is mobile and can therefore be used more flexibly and ultimately more effectively.

The exoskeleton is driven by two highly integrated BLDC motors for microcontroller-controlled real-time regulation using torque sensors, gyroscopes and EMG signals, which support the lifting activities of its wearer with around 20 Nm each. In order to advance research into intelligent human-machine and AI systems, work is currently underway to develop a software platform based on open source technology and open standards. This will be used to anonymize and make freely available sensor data obtained for the purpose of further developing the Cray X and other active systems for analysis and research purposes. Another novelty: in future, the software will be able to be updated 'over-the-air' via a cloud platform, which will make it easier to maintain the systems and ensure that software updates can be transferred to the systems in real time. The cost of such an exoskeleton is just under 40,000 euros.

Authors:
Eric Eitel is Head of Corporate Communications at German Bionic Systems;
Peter Heiligensetzer is Managing Director of German Bionic Systems.

Why are exoskeletons necessary?

According to the Federal Institute for Occupational Safety and Health (BAuA), musculoskeletal disorders - MSDs for short - are responsible for 23% of all days of incapacity for work in Germany and lead to an estimated 10 billion euros in lost production and 17 billion euros in lost gross value added every year.

The main causes of MSDs are incorrect physical strain when lifting and carrying at work, which results in damage to muscles and ligaments as well as bones and cartilage.

The figures from the European Working Conditions Survey (EWCS) from 2015 are similarly alarming: according to the survey, 32% of European workers move heavy objects for more than 25% of their working time. Furthermore, 42% of them are exposed to painful or tiring positions for more than 25% of their working time. In total, 43% of those surveyed in the EWCS complained of back pain - this corresponds to 110 million of the 259 million European workers.

The figure appears even more dramatic against the backdrop of an ageing population and the already noticeable shortage of skilled workers in production. In many cases, aids such as forklifts or cranes could improve the situation for workers. However, these static aids often prove to be too inflexible in practice or the acquisition costs are relatively high.

Our working society is also a long way from having all the work done by armies of robots. An important recent finding is that not every type of human work can be replaced economically by full automation or robotic systems. Exoskeletons could help here - be it lifting heavy loads in the logistics sector, in care or on the production line.