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Reliable therapy thanks to precise drive technology

14 January 2020

When it comes to drive technology for use in the medical sector, precision, compactness and power density are key - challenges that have all met by Harmonic Drive.

With these market requirements in focus, products developed based on the wave gear principle have found their place in a wide variety of medical applications. Harmonic Drive installation kits, gearboxes with an output bearing or servo drives are installed in surgical robots, exoskeletons or X-ray devices, to name a few.

The importance of exoskeletons becomes particularly clear when considering the development of society. Medicine will play a very special role here, because even in old age, no one should have to do without their basic freedom of movement and mobility. The innovative progress of exoskeleton technology is therefore not only against a medical background, but also against an overall social background.

The Spanish company GOGOA Mobility Robots specialises in the development of exoskeletons for the lower extremities. The Hank exoskeleton was developed to help adults who have suffered a neurological injury such as a stroke. However, the system can also be used to compensate for walking in patients who have paralysis of the lower limbs after a spinal cord injury.

"The CE marking is an important achievement for us. Exoskeletons are subject to strict regulatory requirements - especially with regard to security standards," said Carlos Fernandez, CEO of GOGOA Mobility Robots. "The certification confirms the quality of our system and we are very pleased to be able to introduce Hank in various countries in close cooperation with our sales partners to give even more people the opportunity to improve their quality of life."

Hank is an exoskeleton for the rehabilitation of adults between 1.50 and 1.95 m tall and with a maximum weight of 100 kg. The exoskeleton is designed for gait training in the clinical setting as a bilateral portable device with six degrees of freedom, which drives the hip, knee and ankle. The mechanical design was characterized by various criteria: an exoskeleton should be ergonomic, comfortable and light and adaptable to different users. Based on this, Hank mainly used high-strength 7075 aluminum. Including the battery, the exoskeleton weighs only about 12 kg. The swivel angle of the driven joints is mechanically limited for safety reasons.

“Thanks to the additional motorised ankles, an even more natural movement is possible. In order to reduce the engine speed to the correct running speed, we opted for gear installation kits from Harmonic Drive as the transmission mechanism. We tested various drive systems and finally the Harmonic Drive gear installation kit of the CSD series turned out to be as the best option for our ergonomic and ultralight design. The integration of the gearbox into our joint structure enables a compact design and thanks to the gear ratio, the high torques required for the loads can be achieved with the help of compact motors. The backlash-free Harmonic Drive gear installation kit also makes it much easier to control the system, ”said Carlos Fernandez, CEO, GOGOA Mobility Robots.

Harmonic Drive gear installation kits work according to the wave gear principle and are characterized by high single-stage gear ratios, backlash-free and precise motion transmission as well as the highest torques with low weight and compact dimensions. Consisting of the three components Circular Spline, Flexspline and Wave Generator, they allow maximum flexibility in the structural integration. Harmonic Drive gear installation kits are ideal for applications with existing output bearings. The housing structure can be used to achieve both a low overall weight and a compact design within the application.