Selection and design considerations in robot gripper
The industrial robots use grippers as an end effector for picking up the raw and finished work parts. A robot can perform good grasping of objects only when it obtains a proper gripper selection and design. Therefore, Joseph F. Engelberger, who is referred as Father of Roboticshas described several factors that are required to be considered in gripper selection and design.
· The gripper must have the ability to reach the surface of a work part.
· The change in work part size must be accounted for providing accurate positioning.
· During machining operations, there will be a change in the work part size. As a result, the gripper must be designed to hold a work part even when the size is varied.
· The gripper must not create any sort of distort and scratch in the fragile work parts.
· The gripper must hold the larger area of a work part if it has various dimensions, which will certainly increase stability and control in positioning.
· The gripper can be designed with resilient pads to provide more grasping contacts in the work part. The replaceable fingers can also be employed for holding different work part sizes by its interchangeability facility.
Moreover, it is difficult to find out the magnitude of gripping force that a gripper must apply to pick up a work part. The following significant factors must be considered to determine the necessary gripping force.
· Consideration must be taken to the weight of a work part.
· It must be capable of grasping the work parts constantly at its centre of mass.
· The speed of robot arm movement and the connection between the direction of movement and gripper position on the work part should be considered.
· It must determine either friction or physical constriction helps to grip the work part.
· It must consider the co-efficient of friction between the gripper and work part.