What is the history behind robotic exoskeletons?

Author: Sharon Jang | Reviewer: Riley Louie | Published: 7 April 2021 | Updated: ~

A conceptual diagram of the Hardiman.

The term “exoskeleton” was originally borrowed from animal biology. An exoskeleton (such as a shell) is an outer cover that protects and supports the animal. In a similar way, robotic exoskeletons have been designed to help externally support and enhance human movement.

The earliest exoskeletons were developed with a military focus, aimed to help soldiers carry heavier loads, run faster, and jump higher. In 1968, the first exoskeleton, dubbed “the Hardiman” was developed in partnership with the US military. This exoskeleton was originally designed to help amplify soldiers’ strength by 25 times (i.e., lifting a 1500 item would feel like you are lifting a 60 lb item). Although the Hardiman was created and worked, it was not without limitations. First of all, the exoskeleton itself weighed 1500 lb. It was hydraulically-powered and required pumps and bladders that could fill a room. Despite its abilities, it was not very functional.

In 1972, a team from Yugoslavia developed the first functional exoskeleton: the kinematic walker. This device was the first of its kind; a powered robot consisting of a single hydraulic actuator (motor), which reduced its size. The kinematic walker was designed as a walking orthotic, and allowed for smooth movements to be made. Some movements the exoskeleton was able to perform included flexion and extension of the hip, knee, and ankle, in addition to abduction and adduction of the legs. Although this exoskeleton only weighed 12 kg, it required a separate power source and a computer, which were externally located from the exoskeleton.

For more information on treadmill-based robotics, refer to our articles on Body Weight Supported Treadmill Training and Functional Electrical Stimulation for more information on treadmill based robotics.

In 2001, the first exoskeleton products started being sold. The Lokomat, a robotic exoskeleton that was suspended over a treadmill, was one of the first exoskeletons used for rehabilitation. Meanwhile, the US Defense Advanced Research Projects Agency (DARPA) had announced their Human Performance Augmentation program which offered funding to develop exoskeletons for military use. From this funding, two separate groups developed exoskeletons – the Berkeley Lower Extremity Exoskeleton (BLEEX) and the Raytheon XOS suit. Both suits were created to help soldiers carry extra weight (up to 200 lb!) without feeling it.

Starting in 2010, more rehabilitation-based exoskeletons started entering the market. These include gait-assistive devices commonly seen in the media today, such as the Ekso, the ReWalk, and the Indego exoskeletons. These models are described in the section below