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Last updated 22 April 2023

What is an exoskeleton? The answer in the exoskeleton guide

The No.1 Media Portal for Industrial & Medical Exoskeletons
Table of contents

The exoskeleton definition of the exoskeleton suit:

Exoskeleton "What is it?": The word exoskeleton comes from the Greek and includes the words "exo" (outside) and "skeletos" (desiccated body). An exoskeleton (also called a robotic suit) is the term used to describe a framework, usually mechanical and motor-assisted, that is attached to the outer body of a human and serves as a support corset for the wearer. Exoskeletons will also become more popular in the future under the heading of augmented mobility. 



Short and sweet:


Exoskeletons can enhance the performance of unimpaired users and restore movement to individuals with walking disabilities.


Who invented the exoskeleton?

The animal kingdom served as the engineering template for biomechanics, as primarily limbed animals use exoskeletons, including crustaceans and arachnids, since limbed animals do not have an internal skeleton, but use this type of exoskeleton (external skeleton) for stabilization. Probably the first recorded attempt to build a modern mechanical exoskeleton was the Hardiman, an unsuccessful experimental prototype built by General Electric in 1965. The Hardiman was intended to allow the user to carry loads weighing up to 680 kg. However, the user was unable to control the exoskeleton, so the project was abandoned. The Fraunhofer Institute for Production Systems and Design Technology was the first research institute in the world to succeed in developing a walking simulator called "HapticWalker," which is intended to enable stroke patients to relearn how to walk. The first exoskeleton without drive was patented by the Russian inventor Nicholas Yagn back in 1890. It consists of two leaf springs arranged parallel to the legs to improve the walking speed of infantry. 


Development until today:


Among other advances in the late twentieth and early twenty-first centuries, funding from the U.S. Defense Advanced Research Projects Agency's (DARPA) Exoskeleton for Human Performance Augmentation Program 6 enabled the development of wearable robots for the lower extremities ( notably the Berkeley lower extremity exoskeleton and the Sarcos Guardian XO to increase strength and reduce effort during load transport). The technology was then adapted to other fields, including rehabilitation and industry. 

How does an exoskeleton work?

The exoskeleton functionality easily explained: Today's exoskeletons are easy to assemble and are used in Industry 4.0 as a form of occupational health care as well as in medicine. Specifically in medical rehab (rehabilitation), these motor-assisted exoskeletons are used for the lower extremities. For example, patients with paraplegic symptoms, multiple sclerosis or paralysis after a stroke can benefit from training the system.

There are exoskeletons upper body systems and exoskeleton robots for legs as well as exoskeleton gloves.

In medical rehabilitation, e.g. in rehabilitation clinics, exoskeletons are limited to temporary local treatments. Here, for example, they serve as a training device for the duration of the inpatient or outpatient rehab measure.


Thanks to technical developments in the form of improved drive technology and long-lasting batteries, exoskeletons are now also used for personal use. Wearers can thus stand and walk independently again and become more independent of third parties. These modified exoskeletons are suitable for permanent use and personal use in the private everyday environment and are now also used there.


In medical applications, e.g. after paraplegia, an exoskeleton can be an additional option for the provision of aids if the structural and functional properties of the neuromuscular and skeletal system are too severely restricted to be able to achieve mobilization by means of an orthosis.


In patients with complete paraplegia, exoskeletons are used as an alternative for an orthosis under this criterion for lesion heights above the thoracic vertebra.

In patients with incomplete paraplegia, orthoses are suitable even for lesion heights above T12 in order to promote the patient's own activity to the extent that mobilization measures can be successful.


The design of the exoskeleton depends on the application and the body region to be supported. Exoskeletons can be divided into two types with regard to their power support: Passive and active exoskeletons.

How to distinguish exoskeletons?


While active exoskeletons provide their power assistance electrically or pneumatically, this happens mechanically with springs in the passive variants. Passive exoskeletons do not require an external energy supply. For active exoskeletons, a distinction is made between batteries or gas cylinders to be carried along and stationary supplies such as the power grid or compressed air systems.

Supported body regions

Exoskeletons are available for hands, arms, shoulders, trunk and legs.

Support type

 Exoskeletons are divided according to their support function: those for strength support, those for increasing the wearer's endurance, and those for higher movement speed.


Active exoskeletons weigh significantly more than the passive ones. They start at 15 kg to 25 kg.

Application reason

Lightweight, passive exoskeletons are often used to correct posture (when lifting or sitting) or to support the weight of tools during overhead work. Active exoskeletons offer the possibility of relieving the wearer during lifting work.

A distinction is made here between passive exoskeletons and active exoskeletons:

  • Passive exoskeletons save effort by providing targeted support when moving loads. Primary use for monotonous work with equal weights.
  • Active exoskeletons are powered by an external energy source. They are also often more dynamic and variable in use.
  • Passive and active exoskeletons differ mainly in the way energy is supplied. 
  1. Passive exoskeletons: Industry
  2. Active exoskeletons: Medicine
  3. Overview
  4. Passive exoskeletons: practical operation
  5. Active exoskeletons: practical operation
  6. Summary and overview

Basically, exoskeletons can be divided into two types with regard to their type of power assistance: Passive and active exoskeletons.


Passive exoskeletons support the wearer by means of mechanical aids such as spring or cable systems. Energy is stored mechanically by means of springs, and the potential energy with which the springs are preloaded when a body part moves in a certain way subsequently assists the employee in moving in the opposite direction. They therefore do not require the use of motors and sensors, are usually lighter or quieter, and are significantly easier to set up.

Active exoskeletons create active mechatronic force support for single or combined physical loads. Since they are operated pneumatically or by motors, are powered by electricity and are usually modular and expandable, they have a much higher complexity, weight and instruction. The energy supply for active exoskeletons is usually electrical. Either there is an integrated battery in the support structure or the exoskeleton is directly connected to the power grid. In addition, the drive can also be pneumatic.



1. passive exoskeletons: What is a passive exoskeleton?


A passive exoskeleton receives its energy via the pre-tension of a spring mechanism or a rubber band, which must be returned to the exoskeleton via its own muscle power after each force support in the opposite direction. Consequence: The force is redistributed and is available again for the next load movement. As a result, the load is better adapted to natural movement sequences of the human body. The exoskeleton adds force during the overhead lifting process and supports the musculoskeletal system around the shoulders and arms. In the downward movement, the actuator is energized again by the user for the next lifting operation. The available support force of the passive exoskeleton is thus limited by the force to be applied by the user to preload the system. Higher preloads would also have to be generated for higher support performance, e.g. when moving heavy loads. The constant tensioning and relaxing of the exoskeleton can be very tiring in very monotonous and repetitive movement sequences. 

Recommendation: For an activity to be used at height, up to 45 minutes at a time, so that the exoskeleton counteracts the weight force of the tool to be lifted as an equivalent.



2. active exoskeletons: What is an active exoskeleton?

 Active exoskeletons, on the other hand, rely on their own energy source in the form of electric batteries or compressed air. The exoskeleton is controlled via an external controller and sensors. Due to the use of rechargeable batteries, active exoskeletons usually weigh more. 

3. comparison and classification in the practical context

 The decision to use a passive or active exoskeleton depends on factors such as the person, activity, severity, frequency, and height. 

4. passive exoskeletons: practice

 Passive exoskeleton systems are designed for a fixed force curve, since the spring characteristic of the exoskeleton determines the angle and force effect. The support characteristic is then determined by the combination of the kinematic structure of the linkage and lever arms.

Often, the preload is variable and can be individually adjusted in terms of force level and maximum spring force using knurled nuts or tools. This allows the support characteristics to be adjusted, but not during the work process. Depending on the structure and system design, the passive exoskeleton must be removed and partially converted for this purpose, which is time-consuming and often impractical. 



5. active exoskeletons: practical operation

They are conditioned by the actuators used and the kinematic structure. The control system nevertheless allows adjustment during the work process. Both the support power and the force in relation to the joint angle can be adjusted at any time. In addition, no extra force is required for pretensioning the spring mechanism, elastic band or expander. Intelligent systems can also detect whether support is desired based on the movements and through sensors. 

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Copyrighted by Tom Illauer

Where are exoskeletons used? Which exoskeletons are available?

Scientifically, exoskeletons are studied in rehabilitation robotics and empirically researched at many universities. Especially in therapeutic purposes it is part of an interdisciplinary research field. Please visit our section Studies and Researching Universities with lists and contacts. You will find an exoskeleton use overview in our overview.

Primary use of exoskeletons:

Who can use an exoskeleton? What are the requirements for exoskeletons?

This depends specifically on the manufacturer and the solution, as well as the desired area of application and your diagnoses or general conditions. Also how you should wear the exoskeleton, respectively how an exoskeleton reduces back pain, you will find here following:

Regardless, there are some common denominators, but we strongly recommend seeking individual advice:

  1. The patient can support himself with his hands on crutches or by other walking aids. A distinction is made here between mono- and bilateral support of one leg, or both legs. Furthermore, there are exoskeletons for support when one can still walk by oneself, as well as models for persons who are extra incapable of walking.
  2. The patient's skeleton does not show any fractures
  3. The patient has a healthy and strong bone density
  4. The patient has a good physique
  5. The height of the patient is between 160 cm to 195 cm
  6. The weight of the patient is not more than 100 - 120 kg

The systems are designed for people with complete or incomplete paraplegia who can support themselves with their hands and shoulders on forearm crutches. Factors such as adequate bone density and range of motion of the individual joints (hip, knee, foot) must be clarified in advance. Regular standing training (e.g. standing table or standing wheelchair) in advance is advantageous with regard to stability of the cardiovascular system and trunk control. A declaration of no objection to testing signed by a physician (you will receive the template for this from us) and a current measurement of bone density (DXA measurement on the thigh) is required for testing.

Who cannot use an exoskeleton? What are the exclusion criteria for exoskeletons?

Use is not recommended when patients:


  • Have severe neurological injury other than spinal cord injury (multiple sclerosis, cerebral palsy, amyotrophic lateral sclerosis, traumatic brain injury, etc.). 
  • Heterotopic ossification exists
  • Have psychiatric or cognitive disorders that could interfere with proper operation of the device
  • Have significant contractures
  • Pregnant are
  • Severe comorbidities present: Infections, circulatory disorders, heart or lung disease, pressure ulcers.
  • Severe spasticity (Ashworth 4) persist
  • Unstable spine or unhealed fractures exist in the limb or pelvis

What can an exoskeleton do? What are the advantages of an exoskeleton?

Potentially, the aid can simplify the following activities: (Please read studies and seek advice from your doctor! According to manufacturer's information:)


  • Access to buildings without wheelchair ramp
  • Waiver stairlifts
  • Stand upright
  • Independent walking
  • More independence
  • Walk
  • Get to high objects
  • Effects on bone density
  • Reduction of body fat
  • Improve balance and posture
  •  Improvement of cardiorespiratory function
  • Improved bowel/bladder function
  • Improved sitting posture
  • Less pain and fatigue symptoms
  • Reduced spasticity
  • Reduced use of medications for certain conditions
  • Improved bladder and bowel function
  • Improvement of the mental condition
  • Better sleep and less fatigue
  • Reduction of the body fat percentage
  •  Less pain
  • Improve posture and balance

Personal use systems are lightweight, body-worn exoskeletons with motors at the hip and knee joints. The user controls the movements with slight shifts of his center of gravity. Using a sensor, forward flexion of the upper body is sensed by the system, which initiates the first step. A repeated shift of the body weight initiates a series of steps that mimics the normal movement of the legs.

Areas of application for exoskeletons

FAQ Exoskeleton

Motor mechanics specifically relieve and causally support the areas from the back to the knees. 

The cost exoskeleton models vary greatly. This depends on the case of the individual. The health insurance company for, for example, training in a rehabilitation center, the health insurance company for, among others, paraplegics, company health insurance companies and company cooperatives for occupational integration, pension insurance companies, etc. come into question. The probability of a positive decision increases with the probability of disability compensation. Furthermore, it plays a role whether the exoskeleton is to provide cosmetic or functional support. Most exoskeletons (except ReWalk) do not have an assistive device number, which in turn makes the application process more difficult, though not impossible. However, there are a few providers of exoskeletons with certified permission to bill the exoskeleton as an aid with the aid number ( and to health insurance companies or long-term care insurance companies.

Alternatively, there is also a stair-climbing wheelchair with aid number in the premium range called Scewo.

You want to buy an exoskeleton? The cost of an exoskeleton averages five to six figures. The common exoskeleton prices for personal use are settled on average with at least 100,000 EUR. If your insurance company approves your application, you will only have to pay your statutory co-payment up to a maximum of €10. You would like to borrow an exoskeleton? This is also possible. You can rent the exoskeleton, whether exoskeleton with motor or exoskeleton without motor. 

This depends specifically on the manufacturer, the model, the wearer and the training course. In principle, you can achieve a walking speed of up to 4 km/h with exoskeletons.

The positive effect of exoskeletons has been analyzed and proven in numerous studies. Here you can find more information about the studies. They are also listed for you below. 

This depends specifically on the model and the area of use. Military exoskeletons usually have a significantly higher load capacity. However, exoskeletons should always be protected from extreme sunlight (- 15 to 45 degrees Celsius). Furthermore, direct contact with fire, embers and heat should be avoided.

An exoskeleton can be a very effective tool for relieving heavy physical activities, for example the back.

In the field of medicine, a clear no. In the field of industrial use, "yes", because they relieve rather than increase the own performance, nevertheless, exoskeletons in Industry 4.0 improve the ergonomics of the employee and thus increase employee satisfaction, which most employers find performance-enhancing. 

This depends on the model. Industrial exoskeletons can be put on and taken off in under 30 seconds. Medical exoskeletons can be used within a few minutes (approx. five minutes). 


The wearing time of exoskeletons is not limited. Due to the simple donning and doffing, exoskeletons can be easily taken off in the meantime, for example when rotating workstations or during breaks. 


The wearing time of exoskeletons is limited. It is recommended to always take longer breaks and not to exceed the wearing time for several hours at a time.

The textiles of an exoskeleton are removable, washable and thus reusable. The technology can be wiped with a damp cloth. 

We recommend personal use of the exoskeleton individually. Only in this way can the optimal effectiveness of the exoskeleton be ensured through correct adjustment on the device. 

Furthermore, for hygienic reasons, it should not be passed on to another user. 

In total, we have more than 75 Manufacturer of exoskeletons listed. Feel free to read our overview by application, diagnosis, industry, etc. Here are a few examples, leading in Germany in our opinion are OttoBock, Keeogo, ReWalk and Myomo. Exoskeletons with propulsion are currently being developed in the USA, South Korea, Japan and Germany, among others. Usable models have been developed first by military-related institutions since the beginning of the millennium, but there are no reports of deployments yet. We have listed the following exoskeleton suppliers and exoskeleton companies, among others:

  • ATOUN Inc.
  • B-Teamia
  • Bionics Laboratories Corporation
  • Cyberdyne Inc.
  • Daiya Industry Co., Ltd.
  •  Holdings, Inc.
  • Focal Meditech BV
  • Hocoma AG
  • Honda Motor Co., Ltd.
  • Lockheed Martin Corporation
  • Mitsubishi Heavy Industries, Ltd.
  • Myomo Inc.
  • P&S Mechanics Co. Ltd.
  • Parker Hannifin Corporation
  • ReWalk Robotics Ltd.
  • Rex Bionics PLC
  • Otto Bock
  • uvm.

An overview of all manufacturers with filter options can be found in our Exoskeleton Manufacturer Overview.

According to the German Statutory Accident Insurance: "Employers are also obliged to carry out a risk assessment. As a result, protective measures including instructions must be derived and implemented. In particular, the protection goals and requirements of the Ordinance on Industrial Safety and Health and, if applicable, the Ordinance on Safety and Health in the Use of Personal Protective Equipment at Work must be taken into account."

The commercial trade association Berufsgenossenschaft Handel und Warenlogistik in Germany rates the use of exoskeletons by employees in their industry as "an exciting innovation, but one that still needs development work."

It is essential to get intensive advice before ordering, because the following problems could occur: 


  • in case of incorrect or missing aid approval
  •  in case of insufficient or missing documentation / instruction
  • in the event of occupational accidents resulting from the use of the assistive device
  • in the absence of insurance coverage
  •  Health impairment
  • in the event of non-compliance with occupational health and safety regulations
  • in the event of consequential damage caused by the use of the aid
  • In Call of Duty: Advanced Warfar
  • In Aliens: The Return 
  • In Elysium
  • In Iron Man 
  • In matrix
  • In Avatar
  • In Starship Troopers 
  • In Death Stranding

The endoskeleton is the hard part inside the body, while the exoskeleton is the hard part outside the body. Generally, the endoskeleton is derived from the endoderm, while the exoskeleton is derived from the ectoderm. Endoderm is the innermost layer and ectoderm is the outermost layer of the three primary germ layers found in the very early embryo. Endoskeleton is found in vertebrates and exoskeleton in arthropods. The endoskeleton is living and consists of bone and cartilage, while the exoskeleton, a non-living component, consists of an outer covering of chitin or calcium compounds. The hydrostatic skeleton is a water-based skeleton found in worms.

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Advantages of exoskeleton human: exoskeleton disadvantages


  • Falling prices due to innovative battery technology 
  • More acceptance of health insurance and aid numbers
  • Employee satisfaction
  • Lower workplace injury rates

Exoskeleton Disadvantages:


  • The cost
  • Potential battery charge
  • Restricted range of motion with reduced speed

Yes! After a non-binding consultation, you have the opportunity to try out the exoskeleton on site in your area with a certified partner. We will gladly obtain offers, depending on the exoskeleton use, and create an exoskeleton Germany partner list in your area. So before you order the exoskeleton, check the exoskeleton cost coverage and get intensive advice from us, your therapist, doctor or BG. 

Visit our opposition service with certified specialist lawyers, here you will also find an overview of all current BGH and court decisions on the subject of exoskeletons. 

Exoskeletons are only one solution of many, because automation could also make exoskeletons superfluous. In work areas with stationary workstations, these can be ergonomically designed in most cases so that exoskeletons can be dispensed with. Furthermore, there is the risk assessment whether exoskeletons can be used at all. Exoskeletons are expensive and not maintenance-free. Also, exoskeletons cannot be ISO free. It would be conceivable to classify them as technical aids in accordance with Directive 2006/42/EC (Machinery Directive). In this way, binding protection targets are described. These can already provide indications for the avoidance of hazards to safety and health when using exoskeletons. In Germany, this EC Directive is implemented into national law by the Ninth Ordinance to the Product Safety Act (Machinery Ordinance - 9th ProdSV). Malfunctions cannot be completely ruled out, especially with active exoskeletons with electronics or with pneumatic drives. When using an exoskeleton, hazards can arise in connection with tripping or falling accidents. In addition, it must be questioned in what way it is possible to escape quickly and safely from a suddenly occurring dangerous situation with an applied exoskeleton. The considerable dead weight of some models, for example, could be critical.

Exoskeletons support and reinforce movements so that people can walk and stand again. Joints are driven by servo motors. The exoskeleton design depends on the passive or active use. 

The word exoskeleton means external structure. The external structure, which replicates the musculoskeletal system, can redirect forces and protect sensitive areas of the body, such as the lumbar region, which is particularly susceptible to disc problems.