In some animals of the arthropod group, such as spiders, scorpions and crabs, the structure responsible for providing support and protection to vital organs is not located inside the body – as is the case with our skeleton – but outside of it. They are exoskeletons. The concept of an exoskeleton is today an idea explored by researchers working in the field of technology for the rehabilitation of patients with motor difficulties. On the Unesp campus in São João da Boa Vista, a research project is developing a robotic exoskeleton aimed at the recovery of movements of the lower limbs, with particular emphasis on patients who present with motor incapacity due to having suffered a vascular accident cerebral (stroke) ).
The ExoTAO project, as it is called, has been developed by Professor Wilian Miranda dos Santos since 2011, when he was still a student at Master funded by Fapesp Nope Robotic rehabilitation lab from the São Carlos School of Engineering, USP, of which he is now a collaborating professor. The main objective of the project, which in addition to USP also has the Federal University of São Carlos (UFSCar) as a collaborator, is on patients who have stroke sequelae and who have suffered an incomplete lesion of the spinal cord, the condition of which requires a process of rehabilitation of the lower limbs. . A prototype of the exoskeleton is already in operation and has been tested, for the moment, in people without motor disabilities. But the goal is to start using it in patients later this year, on an experimental basis.
Stroke is the leading cause of death in Brazil
Stroke is the leading cause of death in Brazil, and estimates from the Ministry of Health indicate that more than two million people are living with the consequences today. Among them, more than 500,000 suffer from a severe disability. Often these patients have their mobility and autonomy compromised, and it is necessary to go through a long, disciplined and complex rehabilitation process that involves, for example, dozens of physiotherapy and occupational therapy sessions, in addition to frequent travel. in rehabilitation centers. .
Santos explains that the first robotic devices developed for rehabilitation purposes worked to impose an ideal gait. That is, the device guided the execution of the correct movement, but did not force the patient to make efforts: he performed the exercises in an absolutely passive way. Over time, this approach has proven ineffective. “For the patient to relearn to perform the movement after a stroke, cortical reorganization is necessary. This reorganization is only possible if there is an effort on his part,” explains the engineer.
From the very first steps of the ExoTAO project, the researchers established as one of their challenges to develop a mechanism capable of reading the intensity necessary for the patient to perform the movement, but not to the point of replacing his effort. “It’s like the relationship between teacher and student. The robot must assist the patient, but cannot do the movement for the patient. That should help to some extent. The student must be able to complete the task on their own,” Santos compares.
In order to obtain a compatible response from the device to the effort exerted by the patient while providing safety, the researchers equipped the device with a series of elastic actuators, which are motors equipped with springs located in each of the joints of the exoskeleton. . By reading the force of the patient carried out by algorithms, the actuators are able to calculate the intensity of the force that the exoskeleton must impart on the movement carried out by the patient. How the structures work has been detailed in published articles in the scientific journal Control engineering practice in 2019 and in 2017. “ExoTAO allows you to perform various decisive passes during the different moments that constitute a walk. What characterizes it as a robotic device is precisely the fact that it can obtain information and adapt to it, displaying a certain decision-making autonomy,” explains Santos.
Another goal was to give the project a modular structure. This facilitates the removal of actuators located in the joints to meet individual treatment demands, thereby allowing for individualized device use and treatment.
Another feature is the ability to capture a series of patient data through the device. The exoskeleton can provide, for example, information on the measure of the force applied by both the individual and the robot during a gait, as well as the length of the stride and the speed of movement of the patient, between other indicators.
The integration of this data in the evaluation of patients or the design of rehabilitation protocols is not, however, the specialty of the engineers developing the exoskeleton. To support this clinical sphere, the group has the collaboration of researchers in the field of physiotherapy at UFSCar. Marcela de Abreu Silva Couto is currently doing a postdoctoral fellowship at the Robotic Rehabilitation Laboratory, but since 2013 she has been part of the group, contributing to the clinical perspective of the projects. in your doctorate, evaluated the effects of a single session of robotic therapy combined with video game activity in patients with chronic stroke. The study found positive results.
Potential for accelerating recovery
A relevant question raised in the work is its collaboration for the design of future protocols and reflections on the use of this type of technological resource. Couto explains that one of the differentiators of robotic rehabilitation is its ability to generate and make available datasets, which allows its use as an assessment tool. However, explains the researcher, there is still a long way to go to synchronize this data with what is already interpretable.
Part of the research carried out by the physiotherapist is to combine these results provided by the equipment with the gold standard techniques currently used – for example, gait analysis carried out using cameras. “The idea is to develop not only the equipment itself, but all this very rich input of information that the equipment brings with it, and thus establish a conversation between the typical functional tests that we already apply in physiotherapy and this developing technology,” he explains.
The researcher points out that the rehabilitation process for a person suffering from motor restrictions following a stroke is generally long, tiring and demotivating, both for the patient and for the healthcare professionals. What the researchers noticed, however, was that the application of robotics showed the potential to speed up the recovery process.
“Rehabilitation robotics has the particularity of offering intensive therapy. Depending on the equipment and how it is used, the patient benefits from a greater number of hours compared to what is done through conventional therapy. Sometimes, in half an hour of using robotic equipment, you can obtain the equivalent result of more than three hours of conventional rehabilitation”, explains the researcher, who recently studied the application of robotics to patients with Parkinson disease.
Couto makes the reservation that the application of robotics must be seen as another resource to be associated with rehabilitation and not as a magic solution. “There is no point in idealizing a future where people are sitting in front of machines recovering. We will always need an individualized look and the combination of several approaches in therapy,” he says. It uses the concept of a therapeutic environment, in which technological resources such as robots, video games and virtual reality are used, but which does not renounce conventional techniques.
Possibility of cheaper access to technology
The development of a robotic rehabilitation device with national technology also offers the prospect of making this treatment modality cheaper. The value of imported equipment is, in Santos’ opinion, one of the biggest obstacles to robotic rehabilitation becoming more accessible to the general population. Commercial devices similar to the device developed by the Unesp, USP and UFSCar team currently cost at least 300,000 euros, which makes it practically impossible to acquire them, except for certain large rehabilitation centers.
In 2018, a patent was filed highlighting the structure and the modular concept of the exoskeleton, and more recently the group is working to transform the prototype into a product. For this new stage, Santos indicates as main challenges the optimization of certain parts, in order to reduce their weight, and the elaboration of an optimized design which contributes to make it commercially viable.
But, despite the still prohibitive prices, he asserts that the application of robotic devices in rehabilitation has good reasons to become widespread in the future, supported by advantageous aspects such as the proven effectiveness in improving patient rehabilitation, the development of new protocols and treatment strategies with this resource and the trend towards the incorporation of artificial intelligence in decision-making devices.
Exoskeleton photos: personal collection.