Exoskeleton controlled by myogram
The experimental device, built by Jacob Rosen and his colleagues from the University of California at Santa Cruz (UCSC), is distinguished from the exoskeletons of the past by at least two fundamental innovations.
Firstly, it is the ability to move limbs in all planes – in the new exoskeleton, it is such that it provides a person with 95% of the natural range of actions, whereas other machines of this kind limited mobility more.
Secondly, and this is the main thing, the drives of the new device are controlled by the neural signals of the owner! While in previous exoskeletons, engineers used a tracking servo that detects the effort of a person's hands (or legs) (or their weak movement) and then multiplies it by an infinite number of times.
Rosen, on the other hand, believes that a real sense of unity between man and machine can be achieved only if the power drives displace the iron limbs almost before the living muscles begin to strain. A new experimental development – Exoskeleton Prototype 3 (EXO-UL3) – is designed to work out such a control system in practice.
The control principle of the new exoskeleton (Professor Rosen "inside" it) is similar to that of the bionic arm (photographs by Jim MacKenzie).
This exoskeleton for hands is fixed on the wall for now. For greater safety, the drives are still quite powerful, and the weight of the car is not small. But in the future, American experts want to build a fully wearable version.
The system works like this. The "desire" of a person to move his hand somewhere (shoulder, hand...) the machine detects thanks to non–invasive surface electromyography - a set of sensors that remove the bio-currents that command the muscles.
The computer uses the natural, elusive delay between the appearance of the first myoelectric signals and the actual beginning of the movement of a particular muscle to have time to calculate the expected displacement of the arm using its digital model of a human limb (feedback from sensors of the actual position and speed of machine parts is additionally involved).
As a result, the drives of the robot suit work absolutely synchronously with the muscle contractions and "press" in the direction in which the wearer of the device wants to bend his arm. Therefore, it seems to a person that EXO-UL3 is an extension of his body.
However, while this control system (the authors of the robot call it "bioport") – raw. Professor Rosen's group is just working on its development and configuration. But the first results are quite encouraging.
It is curious that EXO-UL3 (or rather, those machines into which it supposedly evolves) Jacob dreams of seeing not on the battlefield, but in hospitals or even patients' homes. He says that a suit sensitive to biological currents is able to strengthen the weak muscles of people suffering from neurodegenerative diseases, stroke survivors, and so on.
An exoskeleton could not only make life easier for such patients, but would also contribute to their rehabilitation, serving as a good simulator. At the same time, the machine can be made in a one-sided version.
With a stroke, half of the motor cortex of the brain usually suffers, the researchers explain, and the restoration of the functions of the paralyzed half of the body depends on both the flexibility of the cortex and on grueling training.
It should be noted that Jacob is one of the few engineers "pushing" exoskeletons into the field of helping fully or partially paralyzed patients, the elderly (look at the latest Honda cybernogs and the "serial" HAL) and talking about the potential of such systems in the field of rehabilitation of the disabled (here you can only recall the "self–propelled" Lokomat).
Some details of this work can be found in the press release of the university.
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