siliconindia | | December 20189The large inertia from a heavy exoskeleton would increase energy expenditure and impede body joint movement The application of robotic devices has several benefits that could lead to added value in stroke rehabilitation:1. Repetitive & Assistive: The re-peatable robotic output can increase training intensity and dosage without requiring more physical effort from the therapists.2. Programmable and Customiz-able: Therapists can adjust the level of assistance and powered assistance profile to customize it to the needs of individual patients.3. Multi-sensory: Integrated sen-sors and control algorithms can iden-tify movement patterns and classify user intention, which enables active voluntary assistance.4. Therapeutic Effect: Synchro-nized with residual joint movement with afferent sensory feedback that enhances experience-driven neuro-plasticity for motor relearning.5. Instrumentation: The com-puter can evaluate and report pa-tients' performance and therapeutic progression using quantitative and objective measurements.The R&D and Global Mar-ket for Exoskeleton RobotsThe research & development of reha-bilitation-oriented exoskeleton robots began proliferating about two decades ago, and has been growing exponen-tially from 2010 onwards. Over 300 studies related to wearable health-care technology have been published in 2016 alone. Literature review up to now counted a non-exhaustive list of at least 52 different versions of exoskeleton robots designed for upper-limb assistance ­ on shoul-der, elbow, wrist, hand ­ and more than 18 exoskeleton robots designed for lower-limb assistance ­ on hip, knee and ankle.Translation of robotic research into clinical application requires in-vestigators to follow evidence-based research practices. Large-scale ran-domized controlled trials (RCT) have been conducted to evaluate the safety and effectiveness of robotic devices in stroke rehabilitation. Some no-table examples of exoskeleton robots being tested in RCT are MIT-Manus ­ an end-effect or type of upper-limb trainer, and Lokomat ­ a treadmill-based body-weight-support gait trainer. The results of these clinical trials demonstrate the efficacy of exoskeleton robotics in stroke reha-bilitation, including the significant improvements in hand and wrist mo-tor recovery, and gait independency.The global market for wearable devices has been evolving rapidly in recent years. Many exoskeleton ro-bots have been commercialized into the market in the healthcare sector. The projected size of this global mar-ket is anticipated to increase signifi-cantly from $105.27 million in 2015 to $17.8 billion in 2021. With this trend, we can be confident that exo-skeleton robotics will play a big role in the market for rehabilitation.Current Trend of Exoskel-eton Robotic DesignAs a wearable device for assistive and rehabilitative purposes, device weight and portability are some of the important design considerations in exoskeleton robots. By today's stan-dards, stroke patients are unlikely to be willing to wear a heavy and bulky metal suit made up of a rigid metal frame for mobility and ADL ­ unless they are the Iron Man. The large in-ertia from a heavy exoskeleton would increase energy expenditure and im-pede body joint movement. Although rigid-bodied exoskel-etons are simple and robust, the ro-bots actually transfer force/torque by bypassing the body joint they are assisting. Long-term use of the rigid device may do more harm than good as the users may become dependent on the system. Therefore, the control system design tends to use an assist-as-needed approach, which provides power just sufficient to assist pa-tients' residual joint movement to en-courage active participation.Recently, researches on soft ro-botics have begun to gain popular-ity. The actuators of soft robots are often lightweight and flexible, which would be ideal for exoskeleton at dis-tal joints ­ such as ankle and hand ­ as they often require more rigor-ous movement and carry a larger moment of inertia. Many research groups use different kinds of power transmission systems, like Bowen cables and pneumatic and hydraulic actuators, to transfer power without the need of a rigid mounting frame. More research & development of soft exoskeleton robots is expected in the rehabilitation field as these designs could address many func-tional requirements of wearable de-vices, like the device weight and user compliance.
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