Design and Functional Assessment of a Versatile Gripper for a Care-Robot
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Abstract
The Netherlands has a severe shortage of care workers. The shortage is expected to increase in the coming years. Care-robots could provide a solution, by taking work out of the hands of the care workers. The potential utility of the care-robot is dependent on the functionality of the gripper. The goal of this study was to design and develop a new gripper for a care-robot, applicable in a care environment. Furthermore, the functional performance of the gripper was to be assessed and evaluated. The new gripper needed to outperform the previous gripper of the robot, named the RPG, in terms of functionality. A new gripper was designed in this study, named the 4FH. The 4FH has four fingers, resembling a human thumb, index, middle and ring finger. Sideways rotation of the thumb allows for two grasping modes, namely a pinch mode and a power grip mode. The 4FH has three DOFs in total. A glove is fitted around the gripper for hygiene. An improvement was made to the 4FH by modifying the shape of the thumb. The improved version is named the 4FH-i. A set of three assessments was drawn up for measuring functional performance of a gripper for a care-robot. The set consists of the the EIT, modified SHAP and modified AHAP. The SHAP and AHAP were modified in this study to make them representative for applications of a care-robot. Both the 4FH and 4FH-i outperformed the RPG on the modified SHAP and on the modified AHAP. All grippers passed the EIT. The results showed a significant increase in grasp stability, comparing the 4FH and 4FH-i to the RPG. The higher scores on the assessments indicated that the 4FH and 4FH-i have improved functional performance compared to the RPG.