Graduation Year

2004

Document Type

Thesis

Degree

M.S.M.E.

Degree Granting Department

Mechanical Engineering

Major Professor

Dubey, Rajiv.

Keywords

force sensors, rehabilitation, grasp, contact forces, Labview

Abstract

The application of technology makes a lot of things easier, but for individuals with disability, it makes things possible. Rehabilitation robotics aims at providing robotic devices, which can act as functional extensions of the user, while performing basic activities. Providing a well-designed gripper as its end-effector can greatly enhance the performance of a rehabilitation robot. The gripper performs simple tasks like picking up objects and manipulating objects, which help in performing activities of daily living. This thesis describes the development of a prototype gripper for a wheelchair mounted robot. The pre-development surveys conducted before the development of commercialized robotic assistive devices were analyzed and user task priorities were understood. The role of the gripper as an object-grasping device was focused upon. The size and weight parameters, which the gripper should effectively grasp, were decided.

Based on these parameters, a prototype was developed. Force sensors were used to monitor the gripping forces. The data was acquired using a Data Acquisition System. The gripping forces were measured using a Labview program that utilized the force-voltage relationship for the sensor. This relationship was obtained by performing calibration experiments. The performance of the prototype was tested using objects that are used in everyday environment and was analyzed by conducting a set of experiments. A relay circuit was designed that would stop the motors once the gripping forces exceeded a threshold value for a given object. This avoided any damage to the object during the gripping process. The gripping forces measured were found to be in close agreement to the theoretically calculated force values.

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