Despite the fact that they are still at an eraly stage of their development, they already represent one of the most ground-breaking achievements of engineering and mechanical science and fascinate people the world over thanks to the role that they are beginning to play in society in general. We are talking about exoskeletons, artificially created support structures designed for use by organisms, and particularly humans. Also referred to as an external skeleton, the exoskeleton is not a direct part of the supporting body but itself supports and strengthens the latter’s movements by supplying mechanical forces. In terms of its core characteristic, the exoskeleton is based on the orthosis, which has been in use for a considerable time in the medical world for stabilising and relieving certain regions of the body. As a result of the progress achieved in the fields of robotic and sensory engineering, new models are being constantly developed, with the result that the application spectrum of exoskeletons already extends well beyond the field of medicine.
In terms of their construction and component configuration, exoskeletons can be divided into passive and active support structures. Passive exoskeletons support the wearer’s body only by means of mechanical components such as springs, rails and weights, but they do not contain any actively controlled drive component. Any stresses acting on them are absorbed by the support structure and converted to energy or diverted to the ground. Active exoskeletons on the other hand are equipped with additional active drive components, alongside the mechanical elements, which play a role in force reduction and load alleviation. In this context, the short strain wave gears of the CSD and SHD series made by Harmonic Drive AG are primarily employed in combination with very compact electric motors. In certain models, sensors may be included for the purpose of informing the exoskeleton’s actuators in advance of impending human motions. The movement steps can be controlled by muscle tensions, which are in turn detected by the sensors. Alternatively, they can be controlled via an operating console.
There are advantages and disadvantages associated with both active and passive exoskeletons. While models without an electrical drive are not bound to an energy supply, active support structures must be fitted with batteries to supply the necessary components with electricity. In the latter case, it follows that fully continuous use cannot be guaranteed; moreover, active exoskeletons are frequently significantly heavier than their passive counterparts. Active models, on the other hand, generally offer a higher degree of support and are able to relieve the wearer of a higher load than passive support structures. The relevance of individual advantages and disadvantages can ultimately only be determined in relation to the corresponding application.
Exoskeletons are accorded a promising and forward-looking role in the field of medicine. It is here that the full potential of the physically protective characteristics and support functions of the structure can be exploited – they help people with physical impediments to perform everyday movements, to regain their freedom of movement and to fulfil their existential needs. The use of specially made exoskeletons that fulfil medical requirements for patients suffering from a variety of paralyses is being investigated in a number of clinical studies. It has become clear that the task of the exoskeleton is not so much to improve a patient’s existing abilities as far as possible but to restore capabilities to patients who have lost them through illness or medical conditions.
The significance of the exoskeleton becomes particularly clear when one considers the developments taking place in society in general. Increasing life expectancies and demographic transformation are already beginning to present medicine, science and the economy with multiple challenges. In this context, medicine is set to play a particularly important role, to ensure that nobody will need to do without basic freedoms of movement and mobility upon reaching a high age. The innovative advancements in exoskeleton technology should accordingly not be viewed exclusively from a medical perspective but also against an overall social background.
Exoskeletons are above all known for their use as support structures for paraplegics. They enable them to walk upright and to enjoy all the advantages associated with it, such as regaining independence, being able to communicate eye to eye with other people, and above all, benefiting from improved blood circulation, particularly in the legs.
Another area that the application spectrum of exoskeletons extends to is the industrial sector, where external supporting structures can be found performing ancillary functions. Workers are frequently called upon to carry, lift and work with heavy loads, which subjects them to considerable physical stress for extended periods. By imitating and in turn reinforcing these movements by means of electronic, sensory and mechanical processes, exoskeletons ease the workloads of users wearing them in an industrial environment. As a consequence, potential complaints, primarily those in the wearers’ torso and back muscles are prevented and their working efficiency is enhanced. Today, several companies in the logistics sector and the automobile industry are already making use of both active and passive exoskeletons.
Taking the so-called Industry 4.0 - the technical evolution of industrial production - into consideration, exoskeletons represent a necessary merger of man and machine. The aim is to use technology to make human work not only more efficient and productive but also healthier and more sustainable.
Military applications are similar to industrial ones, as developments in this field are also primarily focused on transporting heavy loads. In addition, exoskeletons can provide protection to soldiers and other military personnel employed in dangerous situations or marching on rough terrain. It is true that current realistic prototypes cannot be compared with models seen in the realm of science fiction, but the drive of innovation continues unchecked and it can be expected that exoskeletons and protective armour will merge together more and more as time goes on.
The future is sure to hold many more opportunities for the use of exoskeletons. For instance, in 2014, research was already being conducted into the use of external skeletons for fire fighters. Other imaginable areas of application for exoskeletons of all types are in the care sector, the building and construction industry, and many other physically demanding professions.