Extending the Reach of Exoskeletons

DN Staff

January 23, 2009

2 Min Read
Extending the Reach of Exoskeletons

The rest of us may think mechatronics is the ultimate inmultidisciplinary work, but to Jacob Rosen, associate professor ofcomputer engineering at the University of California of Santa Cruz, "the human body is the most multidisciplinary thing I know of."

That's why Rosen has been working since 1993 on building a robotthat someone can wear, a concept best known as an exoskeleton. (Seesome of Rosen's previous researchfrom the University of Washington's BioRobotics Laboratory.) Hereceived a National Science Foundation grant to develop a fullyarticulated arm, and worked with the design of a University ofWashington mechanical engineering PhD student named Joel Perry.

The result is now ready for commercialization, Rosen believes.People with muscular dystrophy and other neuromuscular disabilitiescould use the exoskeleton to amplify their muscle strength, and itcould also be used for rehabilitation and physical therapy, accordingto Rosen.

He adds that one of the major challenges in this field is toestablish an effective human-machine interface, such that the robotbecomes a natural extension of the human body. Rosen has dubbed thisthe "bio-port," and he cites it as one of the differentiations of hisdesign. "I decided to use a different level of the neural system. Myapproach is to use surface electronics on the skin on top of themuscles."

Rosen, who has degrees in mechanical engineering, biomedicalengineering, and computer engineering, says that his exoskeletonprovides seven degrees of freedom, covering 95% of the traditionalrange of motion. Other systems only offer five degrees of freedom, henotes.

To support seven degrees of freedom requires seven actuators, but inhis design, four of the actuators are on the 40-pound base of hisdevice. "Because you only move three of the seven actuators, it'slightweight, and the inertia is less."

While the primary applications of this kind of medical roboticsfocus on augmenting human capabilities, especially among the disabled,it also brings capabilities to the field of haptics,the science of applying touch to interaction with software. His designuses cables and pulleys because gears generate friction. "The principalidea in haptics is to minimize the effect of the device. You don't wantto feel anything. All the gearing system is done with cables so you getalmost no friction at all."

As a result, the weight of the exoskeleton to users is about thesame weight as their own arm. "We developed a gravity compensationalgorithm so that when you wear it, you don't feel the weight as well.To the user, it's weightless."

Rosen is excited by the challenge and the potential of medicalmechatronics. "Medical robotics is by definition a multidisciplinaryfield, and that's one reason I was so attracted to it," Rosen says."One of the most challenging issues in research and development ofmedical technology is to create a multidisciplinary group of cliniciansand engineers that can effectively communicate and collaborate. Wespeak different languages, and we have to overcome these barriers inorder to work together. But the opportunities to benefit people's livesare tremendous."

Extending the Reach of Exoskeletons_imageA

Extending the Reach of Exoskeletons_imageA

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