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COVER STORY ADVERTISEMENT FEATURE


gs give PhysiCal oT a helPing hand


REHAbILITATION:


and medical equipment. They can handle radial, thrust and moment loads at the same time, with high rotational accuracy. CRBH crossed roller bearings are available with basic dynamic load ratings ranging from 2,910 to 102,000 newtons, basic static load ratings from 2,430 to 207,000 newtons and shaft diameters from 20 to 250 millimetres. The series also boasts:


• An inseparable design that integrates the inner and outer rings into one structure for high rigidity.


• Separators between cylindrical rollers which ensure smooth rotation even at high rotational speeds. For the main arm Harmonic Bionics chose


a model with a dynamic load rating of 8,610 newtons and static load rating of 10,600 newtons – more than enough load-carrying ability to meet their moment load requirement of 100 newton-meters. And with a 40- millimeter shaft diameter, 65-millimeter outer diameter, 10-millimeter width and light weight of 0.15 kilograms, the designers had no problem incorporating the crossed roller bearing within the exoskeleton’s limited space. IKO proved once again that its level of


support does not stop at simply offering part numbers and pricing. The Technical Sales team continually questioned the design along the way, offering their opinions on product selection and the pros and cons of each choice. The company found that the CRBH crossed


roller bearing is the most straightforward and compact way to carry the moment loads imposed on the exoskeleton, providing ‘just enough assistance’ to the patient. This is in


large part due to the CRBH’s low CoF. More than 50 sensors monitor the positions of the patients, and the forces their joints exert. The low CoF allows the system to run the algorithms that customize the levels of resistance and support that the patient receives, relative to gravitational forces. High friction can otherwise compromise the sensor measurements. During the prototype build it became apparent


very quickly that IKO’s CRBF variant would offer the most efficient assembly process. With mounting holes on both the inner and outer rings this allowed the engineers to install the bearing without machining, special housings or fixing plates to micron tolerances. The mounting holes saved space and simplified assembly before the company shifted to the CRBH Series for the final production units. Harmonic Bionics’ upper-limb exoskeleton


improves the clinical efficacy and productivity of physical therapy for stroke rehabilitation. With the help of IKO crossed roller bearings, the exoskeleton can power the movements of both sides of a stroke survivor’s body, enabling novel physical therapy techniques.


TRANSFORMING POST-STROKE PHYSICAL THERAPY AND SURVIVORS’ LIVES


Hospitals have long sought a clinical intervention that will lead to better clinical results than conventional treatments for shoulder rehabilitation for stroke survivors. Harmonic Bionics’ successful upper limb rehabilitation exoskeleton robot design shows that when a machine must handle large moment loads within


IKO’s crossed roller bearings are both compact and rigid


a limited space, not all roller bearings are created equal. Thanks to IKO’s CRBH and CRBF crossed roller bearings’ combination of high moment load handling capabilities, excellent rigidity, small size and low coefficient of friction, Harmonic Bionics is poised to revolutionise physical therapy and improve the lives of many stroke survivors.


IKO UK & Ireland T: 01908 566144 enquiries@iko.co.uk www.ikont.eu/en/


“Thanks to IKO’s CRBH and CRBF crossed roller bearings’


combination of high


moment load handling capabilities, excellent


rigidity, small size and low coefficient of friction, Harmonic Bionics is poised to


The designers needed a roller bearing that


could carry large moment loads so the


exoskeleton can move coaxially with the patients’ skeletal structure as they move their arms


MARCH 2023 DESIGN SOLUTIONS 9


revolutionise physical therapy and improve the lives of many stroke survivors”


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