Robotic walking aids for paraplegics
In the animal kingdom exoskeletons provide stability and protection for many creatures, such as crustaceans and insects. They are also an inspiration for scientists working at the interface of bionics and medical technology to develop fascinating orthopaedic aids, Anja Behringer reports
A ‘wearable’ robotic exoskeleton that helps paraplegics to walk recently went on show in Europe. Initially, exoskeletons were developed for military purposes, to help soldiers carry heavy weaponry, for example. Over the last few years the adaptation of such devices began for their medical use. In this field, leading research companies include Argo Medical Technologies (Israel), Rex Bionics (New Zealand), Ekso Bionics (USA) and Cyberdyne (Japan) – which offers a robotic system called HAL (Hybrid Assistive Limb). Ekso Bionics, a spin-off of the University of California at Berkeley, develops and manufactures exoskeletons that help paraplegics to stand and walk. Formerly called eLEGS, Ekso is currently undergoing in-depth tests at ten major rehabilitation medicine centres in the US for its potential integration into therapy plans. The firm has now also entered the European market. Ekso, a wearable, batterypowered robot, helps wheelchairbound
people to stand up and walk. Four engines move the legs. The user controls the steps via sensors in handheld crutches. The sensors understand the user’s intention, compute the movement and instruct the device to perform the movement. The battery lasts four hours and the paraplegic testing the system in Europe reported that the harness is not tiring.
However, the robot will suit only about 10% of paraplegics because it requires a body height of 1.50 to 1.90 metres, a body weight below 100 kg and a maximum hip width of 43 cm. Additionally, the torso has to be strong enough to use crutches or walking aids and the user needs to be able to change positions without help. Robotic exoskeletons offered by Ekso Bionics’ three competitors follow similar approaches, except for the device developed by Rex Bionics, which does not include crutches. Battery life is 2, 4, 5 resp. 8 hours and the weight of the devices varies between 18 and 35 kg. The exoskeletons were designed for different pathologies and have different objectives. All the firms entered European markets in 2011 and are currently conducting studies. HAL is being tested at Bergmannsheil hospital in Bochum, Germany. Ekso, which is planning a pan-European study, has recruited hospitals in Barcelona, Glasgow, Norway and Denmark and is now looking for a partner in Germany. Ekso Bionics CEO Eythor Bender has spoken with to rehabilitation centres in Hamburg, Heidelberg and Murnau, Bavaria.
Unlike the competitors who offer leasing programmes for their devices, Ekso Bionics will sell its product. The current price tag is €100,000, after completion of the test phase the target price for private users is €50,000. ‘Comparable to the price of a midsized car,’ Ekso Managing Director Andy Hayes points out. All four companies will launch their most recent products in 2013 – if the tests go according to plan. The studies must answer basic issues: Which patient can use which robotic device in what stage of the particular medical condition and which physiological conditions in terms of circulation, muscles, bone density and cerebral functions have to be met. However, one thing is clear: For a wheelchair-bound person the prospect of being able to stand and walk with the help of a robotic device is exceptionally motivating.
20.12.2011
