What is an exoskeleton and what is its purpose?
The Remotion exoskeleton is a medical robotic device designed to provide powered motion to the patient’s lower limbs. With many programmable motion modes available such as squatting, standing up, walking, marching on the spot etc., the doctor can select a setting and initiate the movement. The exoskeleton is adjustable to the anthropometric variability and offers a fixation system, due to which the device is comfortable to wear for prolonged functional training sessions.
Remotion has two versions: Remotion Base and Remotion Kids, for adult and children rehabilitation. The Remotion Base version is designed for adult patients with height from 160 to 190 cm and weight up to 100 kg, the children’s version of Remotion Kids is designed for children with height from 130 to 160 cm and weight up to 60 kg.
Modularity of the Remotion exoskeleton
Virtually all exoskeletons currently existing in Russia and abroad have a common serious drawback, which is their one-piece design. Remotion is free from this shortcoming thus offering the attending physician and the patient a number of advantages. Modularity is an innovative feature of the design that allows, in a couple of minutes, to connect or disconnect the foot, lower leg, or thigh modules in varying combinations, depending on the disease and the patient’s physical condition. For any single session, the doctor determines which modules to use based on the medical reasons and feedback from the patient. Table 1 shows module configurations available. Why is modularity so important? The answer is because wearing the exoskeleton on a healthy limb is completely pointless and even hampers the rehabilitation session! If a patient can employ his/her healthy leg in walking, then let him/her do it while concentrating on the training of the impaired lower limb.
Setting up a module configuration does not present any difficulty for a doctor or assistant: all they need is to loosen one bolt and disconnect one connector.
Functional Electrical Stimulation
Medical science has been studying and applying muscle stimulation since the 19th century while proving its effectiveness and safety. The idea of using electrical stimulation in combination with exoskeleton solutions became fairly self-evident long ago, though its practical application requires the development of reliable safety measures against sprains, cramps, ruptures, and other injuries. To ensure compliance with these requirements, as well as the ease of installing and programming various rehabilitation techniques is a major technical challenge that has not yet been overcome in any stock-produced exoskeleton.
This means that the Remotion exoskeleton will be number one! Equipped with 5 four-channel stimulation units, Remotion represents a single hardware and software system distinguished by the synchronized, coherent performance. The doctor himself/herself sets up the functional electrical stimulation (FES) parameters for each channel to ensure synchronization of the stimulating waves with the gait cycle. The intensity of the stimulation is agreed upon with the patient and can be adjusted with high precision at any time. This is the only approach that makes it possible to maximize the functional recovery effect of exoskeleton-assisted training sessions.
The design of the electrical stimulation units allows the implementation of electromyography (EMG) through the same 20 channels; this functionality is highly relevant for any rehabilitation physician. EMG does not belong to the class of high-precision studies; however, it enables reliable determination of the patient’s progress as a stable increase in muscle biopotentials, for example, at the end of the rehabilitation program compared to its beginning. The user guide contains a detailed illustrated atlas for the installation of electrodes for both FES and EMG procedures.
The interfaces of nearly all modern exoskeletons are executed as primitive control panels sending simple commands such as “sit down / stand up / walk / stop”, etc., which makes customized high-quality rehabilitation employing such devices extremely difficult.
Remotion has an up-to-date control panel with a color capacitive display enabling operational work with “out of the box” software configurations. However, the full potential of Remotion can only be reached by using a special RemotionTool utility to be run on the doctor’s personal computer connected to the exoskeleton via Wi-Fi.
RemotionTool contains a ready-made toolset for developing rehabilitation techniques with various modularity, FES and EMG channel configurations, patients’ anthropometric parameters, and other features. Creating a new technique in itself is a process of high responsibility; therefore, to eliminate errors and save the doctor’s time, a full-scale software simulation of the session is provided. In the process of modeling, the doctor can see the selected modularity option, the gait cycles and the goniograms adjusted accordingly, as well as the FES channel activation, and the overall dynamics of the patient wearing the exoskeleton. Next, the technique is uploaded to the exoskeleton via Wi-Fi and is tested without a patient’s participation. Only in the case of successful testing, real sessions with patients are permitted.
To ensure responsibility sharing, the use of RemotionTool requires the creation of separate accounts for doctors and patients. The software keeps a detailed log of all events, so it is easy to find out which specialist conducted sessions with which patient, and which techniques were applied.
Thus, Remotion is a powerful and convenient hardware and software system capable of meeting the needs of a contemporary practicing rehabilitation professional or researcher in this subject area. None of the exoskeletons which have been developed to date (as of 2019) is equipped with such functional software and operation options.
Team of Mechatronic Systems Lab and Development Process
Remotion consists of approx. 1,800 parts of varying complexity, not including fasteners and standard components. The hardware consists of a control unit, its own explosion-proof fire-resistant battery, four electric drives, and five FES and EMG units. The units are connected by an industrial noise-resistant interface. This colossal amount of work was accomplished by a small group of 16 enthusiastic engineers in just two years!
In the Remotion design, imported components were used in electronics and electric drives. The unique development of the project is its cycloid speed reducer ensuring the accuracy, reliability and excellent weight-size dimensions. Plastic and metal structural elements were designed by the engineers of the Mechatronic Systems Lab and then manufactured at domestic enterprises. Due to its complete compliance with the Unified System for Design Documentation standards, Remotion can be adapted to the production base of any morern enterprise.
Indications for exoskeleton use
Finally, let us list the main (but not all) diseases for treating which Remotion is intended:
- Diseases of the central nervous system:
- central and peripheral plegia and paresis;
- consequences of cerebral palsy in the form of hemiparesis;
- hemiplegia, hemiparesis, paraplegia, and paraparesis including those caused by a cerebral stroke;
- diseases of the central and peripheral nervous system accompanied by impaired walking function.
- Consequences of injuries and diseases of the musculoskeletal system, accompanied by the dysfunction of the lower limbs:
- consequences of long-term immobilization of the lower limbs;
- consequences of injuries and diseases of the joints, bones and muscles of the lower limbs and pelvic girdle;
- postoperative rehabilitation after endoprosthesis replacement of large joints in the lower limbs;
- postoperative treatment of disorders affecting the joints, muscles, bones and tendons of the lower limbs and pelvic girdle;
- recovery after osteosynthesis of the bones of the lower limbs and pelvic girdle;
- conservative treatment of osteoarthritis affecting lower-limb large joints;
- dorsopathies accompanied by significant walking impairment.