Students at Johns Hopkins University have designed a portable muscle enhancement device to help a disabled man grasp a number of household items.
Jonathan Hofeller, Christina Peace and Nathaniel Young developed the device in the Department of Mechanical Engineering’s Senior Design Project course.
The project originated when the man with inclusion body myositis, a rare degenerative muscle disorder, sought help from Volunteers for Medical Engineering, a non-profit Baltimore group that uses technology to assist people with disabilities. The client, who wishes to remain anonymous, explained that his nerves were intact, meaning that he could control the placement of his fingers around an object. But progressive muscle deterioration left him unable to grasp objects.
To help move his fingers and elbow, the students tested and rejected systems using electromagnets and air pressure systems. They settled on two small stepper motors that could move the fingers and elbow in small, slow increments, allowing the client to clasp a cup firmly without crushing it.
These motors didn’t require continuous electrical current to stay in position, preserving battery power. The students linked the motors to cables and springs to enable the device to move the man’s arm and help his fingers grasp and release.The students opted for voice recognition software as an easy way for the man to control the grasping device.
After the software is trained to the client’s voice, the man will first say ‘arm’ or ‘hand’ to take command of one of the two motors. The elbow motor will then respond to ‘raise,’ ‘down’ or ‘stop.’ The hand motor will respond to ‘open,’ close’ and ‘stop.’ The device is hard-wired to a control box that contains a miniature computer and two programs that turn the voice commands into signals that tell the motors how to operate the bending and grasping motions.
The unit is powered by a rechargeable 12volt lead-acid battery whilst the control box fits inside a small pack the man can carry on his waist.