Major benefits for stroke patients! Use the brain idea to control the exoskeleton

Most people may not know that one out of every six people may have a stroke; in Sweden, there are 16,000 strokes per year, and two-thirds of them will be paralyzed. Extended training allows patients to regain control of their arms and hands. Of course, the degree of damage to the brain directly affects the degree of recovery. This is the result of the traditional physiotherapy capabilities, and now we have a new alternative - robots.

Roger Gassert, a professor at the Federal Institute of Technology in Zurich, has developed a series of robotic technology devices that can train arm functions that can be part of the rehabilitation of stroke patients. However, whether it is physiotherapy or robot-assisted treatment, the treatment consists of one or two training sessions per day, which is very stressful for the patients, because they spend a lot of time on the way to and from the treatment center.

The exoskeleton is transformed into a training robot

"My point is, don't let the patients go to the clinic for rehabilitation training. On the contrary, we have to make this exercise into every bit of their home life," Gassert said. This is his and Japan. The idea that Professor Jumpei Arata of Kyushu University got after the exchange (Arata worked in Gassert's lab during the 2010 academic holidays).

“First, the existing exoskeleton is too heavy, which makes it difficult for patients to lift their hands. Second, they also have difficulty perceiving the presence of objects. Third, when they want to grab objects, They don't know how much effort they should make. So, we want to invent a model that gives them more freedom so that they can perform everyday tasks and achieve motor and physical functions," Gassert said. In response to this problem, Arate invented a finger triple leaf spring. The engine moves in the middle of the spring, which transmits power through the other two springs to various parts of the finger. In this way, the finger can automatically adapt to the shape of the object, so that the patient can grasp the object.

However, this integrated power setting increases the weight of the exoskeleton to 250 grams, which is already very heavy for patients in clinical trials. The solution to this problem is to retrofit the engine to the patient's back so that power can be transferred to the exoskeleton through the bicycle brake line. The hand device model weighs less than 120 grams, but it is strong enough to lift a bottle of one liter of mineral water.

Exploring brain processing mechanisms

What is the mystery in the brain? After the stroke, how does the brain pass instructions to the hands and feet? Gassert explained: "The connection between the brain and the hand of a severely ill person has been severely disrupted, so we need to help them pass the instructions naturally to the robotic device." That is, they are aware of the movement of the hand in the patient's brain. The intention, and the transfer of this information to the exoskeleton, is a process that is beneficial to treatment. According to Gassert, many studies have shown that regular exercise has the potential to strengthen the existing neural connections between the hands and brains. One of the main points is that when the brain sends a movement command, it can receive the sensory feedback from the hand.

To better understand the brain's processing mechanisms, Gassert has conducted an important study with clinicians, neuroscientists, and physiotherapists. In this study, researchers used a variety of visual imaging techniques, such as functional magnetic resonance imaging (fMRI), which helped scientists map brain activity. This technology gives them some new insights, fMRI is expensive and complicated, and is not suitable for physical therapy at all. “In addition, they are not portable,” adds Gassert. So, he began to want to use some simpler technologies, such as electroencephalography and functional near-infrared spectroscopy (fNIRS), which are the cheapest in their class. Currently, Gassert is working on the practical application of fNIRS, which is even more challenging.

Other basic insights

There is another problem here: we have not fully understood how the brain controls the limbs and allows them to interact with the surrounding environment. “Robot technology has made a significant contribution to fundamental research,” explains Gassert. For example, robotics experts have invented an exoskeleton that limits knee activity within 200 milliseconds as people walk and increases their degrees of freedom by five degrees. With the help of sensors, scientists can measure the various forces involved in the process and use relevant data to figure out how the brain adjusts the stiffness of the knee joint. This invention can be applied to the control of new active prostheses.

If scientists have successfully established an interactive connection between the brain and the exoskeleton, they can develop equipment for treatment. But if the trauma is permanent, robotic equipment can be used as an alternative to wound therapy to provide long-term support for patients. However, if stroke patients are looking forward to achieving considerable recovery, robotic assistive therapy is definitely the best choice.