Grasping, holding, opening and closing – the functions of a human hand are a complex interplay of muscles, bones and nerve fibers. Diseases such as muscle weakness, spasticity or motor deficits may interfere with the functionality of the hand. At the University of Stuttgart, a hand exoskeleton has now been developed with which the gripping ability of a paralyzed hand can be restored.
Following brain or spinal cord injuries, impairments such as loss of muscle strength, apraxia or ataxia, spasticity or paralysis of the hand can occur. Due to the restrictions in the professional and private sector, this is a major loss of quality of life for those affected.
Researchers at the Institute for Industrial Production and Factory Operation (IPFO) have developed a hand exoskeleton that consists of a central assembly module and individual, movable finger modules. Compared to existing hand exoskeletons, the model developed in Stuttgart has decisive advantages. On the one hand, the modules can be designed individually for each patient and, above all, the finger modules can be designed very flexibly. This also gives the patient the opportunity to spread his hand and move it laterally and move individual fingers. On the other hand, the exoskeleton is easier to handle by this type of embodiment and the patient can create it independently. Thanks to the open shell system, the patients can individually attach the modules to their hands, as inventor Jonathan Eckstein explains, who works as a research assistant in the field of propulsion systems and exoskeletons at the IPFO. The individual modules are plugged in and can then be stretched or bent by motor.
The newly developed hand exoskeleton is made of a special plastic. This makes it possible to produce the individual modules with a small wall thickness, which is important especially in the finger modules. The exoskeleton weighs about 400 grams with motors and electronics – the hand module weighs about 80 grams. This makes it very light, stable and wearable at the same time.
A next step in the project will be the control of the hand exoskeleton, as Eckstein explains. Currently, the module is connected to EMG and proximity sensors as a stand-alone forearm-borne device to initially evaluate the electro-mechanical functionality of the exoskeleton. Eckstein: “In the coming development phase, the exoskeleton will also be controlled by brain waves that are combined, for example, with eye movements.” Researchers at the University of Tübingen are investigating this, while the scientists at Reutlingen University are working on 3D object recognition To recognize everyday objects and to preset the hand exoskeleton according to the required grip mode.