A gripper is a mechanical device that enables us to hold an object to be manipulated. The gripper can be described in a much easier way by thinking it’s a human hand. Just like fingers of the hand, gripper enables us to hold, tighten, release and handle an object.
A gripper can be a part of a fixed automation system or it may be attached to the robot for performing specific operations.
There are a variety of grippers available in the industry.
Operating Principle of Gripper
The opening and closing of fingers of the gripper can be actuated either by pivoting or linear/translational movement.
Pivoting Movement: In this movement, the rotation of fingers is concerned with the pivoted points that are fixed for providing opening and closing action. To achieve this movement, it uses a linkage mechanism.
Linear/Translational Movement: In this movement, the gripper’s jaw moves parallel to the gripper’s body. These grippers are used in most applications. These types of grippers are more accurate than other types of grippers.
The design of linkage actuation helps to find out the conversion of the mechanical gripper’s force into the gripping force and the time taken by them to actuate the gripper and maximum capability to open the finger.
There are a number of designs available for linkage actuation, some of them are shown in the above figure.
Now moving towards the video, we will see how the gripper works. Here we will see, few mechanisms of robotic gripper and their models.
Type 1 gripper
A cylinder (it can be either hydraulic or pneumatic) attached to the slider (shown in pink color) causes the opening and closing of the gripper and hence permitting it to grasp and release the object.
The slider is connected to the links (shown in yellow color) which forms a slider-crank mechanism and thus, is responsible for actuation.
Type 2 gripper
In this mechanism, one end of the piston of the cylinder is attached to the rack or say any tooth-like mechanical element. This element engages in the respective meshing element (here pinion) which is pivoted at one point. As the cylinder actuated, the gripper opens and closes as per the motion of the piston. Thus, it creates a parallelogram mechanism.
Type 3 gripper
In this type of mechanism, a bar is directly connected to the piston of the cylinder responsible for the opening and closing of the gripper.
It is also an example of a slider-crank mechanism.
Type 4 gripper
It is quite similar to the type 3 gripper. Only the change is in the design of the mechanism.