Professor designs exoskeletal device for handicapped
Assistant professor Brett BuSha of The College of New Jersey created an exoskeletal device with his team to assist people whose hands have been weakened from disease or injury.
BuSha gave a presentation last Tuesday at the Electrical Engineering Building on Busch campus.
The focus of his work is on creating an exoskeletal frame that can help its user perform everyday tasks, such as opening a door or grasping an object, said BuSha, who graduated from Rutgers in 1998 with a Ph.D. in biomedical engineering.
“I’m not here to talk about replacing the hand,” he said. “I’m here to talk about augmenting what’s left. There [are] a lot of people out there who have all their appendages. They just can’t use them effectively.”
BuSha has worked in the biotech and biomedical fields and was invited to speak by the Rutgers Solid-State Circuits Society because of the uniqueness of his project, said Nagi Naganathan, an adjunct professor in the School of Engineering.
BuSha said the motivation for his research stems from a desire to help people at a manageable scale.
“About 500,000 people in America currently have some sort of muscular or skeletal disorder that causes a lack of, a decrease or a loss of strength and/or dexterity. Things like muscular dystrophy, multiple sclerosis, carpal tunnel and all types of trauma and injuries [to the hands],” he said.
Older models of augmented hands have had significant limits in bulk, weight and application, he said. Some devices lock the thumbs and wrists, which decrease their effectiveness. In addition, a large amount of the power supplied through batteries would go toward overcoming the weight of the device itself.
Previous designs utilized flexors and extensors — the tendons that allow fingers to bend and straighten — coupled with motors to allow users to open and close their hands, he said.
Sometimes, springs are used instead of flexors or extensors. This results in a motor performing one function and a spring performing the other, decreasing the overall weight.
People do not need much force to open their hands up, he said. More often they use force to close their fingers, similar to how alligator jaws are designed to bite down but are much less powerful when trying to open.
The goal for BuSha and his team is to create a glove-like object that somebody could simply pull on their hands and use in everyday life, he said. This exoskeleton would use the wearer’s residual hand strength to control the motion of the device.
BuSha’s team consists of senior level biomedical, mechanical and industrial engineering students. He said TCNJ does not have engineering graduate students.
The design for the fingers in an early prototype consisted of concentric metal bands hinged at locations corresponding to the knuckles of a finger, he said. The bands themselves sat between the joints.
“These bands keep the force next to the finger,” he said. “We’re really trying to mimic the tendon system. We’re just a couple millimeters away from it at this stage.”
The first prototype was made out of aluminum with braided steel cables, he said. The design itself is simple — getting the parts to work together is a bit more complex.
According to a TCNJ web page, the first prototype was successfully tested in the summer of 2009.
One of the downsides to using aluminum is the expense, BuSha said. The material itself is expensive, and each part has to be machined, which requires a specialist to spend many man-hours working on it.
To counteract the cost, the team is currently in the process of recreating the device using printed materials to replace the machined parts.
“I can’t see any reason not to go 3-D printing,” he said. “For cost and time, 3-D printing is much cheaper and happens much faster.”
Reproducibility also goes up, he said. They only made one prototype of the initial design due to its cost.
To see how the device would be controlled, the team first placed sensors on top of and underneath the “fingers” to gather data about how the hand would move, he said. The sensors would determine where pressure is placed and how much is applied.
The final control system is still in development, BuSha said.