Grasp Stability with a Robotic Exoskelton Glove
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Grasp stability was studied and researched upon by various research groups, but mainly focused on robotic grippers by devising conditions for a stable grasp. Maintaining grasp stability is important so as to reduce the chances of the object slipping and dropping. But there was little focus on the grasp stability of robotic exoskeleton gloves and most of the research was focused on mechanical design. A robotic exoskeleton glove was developed as well as novel methods to improve the grasp stability. The exoskeleton glove developed is intended for patients who have suffered paralysis of the hand due to stroke or other factors. The robotic glove aids them in grasping objects as part of daily life activities. The glove is constructed with rigidly coupled 4-bar linkages attached to the finger tips. Each linkage mechanism has 1- Degree of Freedom (DOF) and is actuated by a linear Series Elastic Actuator (SEA). Two methods were developed to satisfy two of the conditions required for a stable grasp. These include deformation prevention of soft objects, and maintaining force and moment equilibrium of the objects being grasped. Simulations were performed to validate the performance of the algorithms. A battery of experiments was performed on the integrated prototype in order to validate the performance of the algorithms developed.
General Audience Abstract
An exoskeleton glove is robotic device that can aid people who suffer from paralysis of their hands caused by a stroke or other factors with the primary goal of allowing them to regain the basic ability of grasping objects and thereby improving their quality of life. The exoskeleton glove developed in this research is focused on objects grasping assistance rather than for rehabilitation purposes. Since the exoskeleton glove lacks conscious senses like a human hand typically possesses, it may not be able to apply sufficient grasping force or may apply excessive force than required irrespective of the object being grasped. In order to ensure that the exoskeleton glove applies the proper amount of force, two novel methods were developed which help improve the overall grasping performance of the robotic glove. These methods use sensors that enable the glove to react to the force interaction changes that exists between the hand and the object being grasped through the exoskeleton glove. The first method detects any deformation that may occur while grasping a soft object and applies lesser force accordingly to prevent further damage to the object. The second method uses motion sensor to detect any movement by the user while grasping the object and applies corrective forces so that the object doesn’t slip from the hand. A prototype was designed and integrated and the two methods were tested on the prototype to validate them.
- Masters Theses