Showing posts with label actuators. Show all posts
Showing posts with label actuators. Show all posts

Mini Project on Robotic Gripper Mechanism

Gripper is a mechanical device which enables us to hold an object to be manipulated. Gripper can be described in much more easier way by thinking its a human hand. Just like fingers of hand, gripper enables us to hold, tighten, release and handle an object. A gripper can be a part of fixed automation system or it may be attached to the robot for performing specific operations.
There are a variety of grippers available in industry.

Operating Principle of Gripper

The opening and closing of fingers of 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 linkage mechanism.
Linear/Translational Movement : In this movement, the gripper jaw moves parallel to the gripper body. These grippers are used in most of the applications. These type of grippers are more accurate than other types of grippers.
Mini Project on Robotic Gripper Mechanism |
Linkage Actuation

Linkage Actuation

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 number of designs available for linkage actuation, some of them are shown in 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 piston of cylinder is attached to rack or say any tooth like mechanical element. This element engages in respective meshing element (here pinion) which is pivoted at one point. As the cylinder actuated, the gripper open 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 slider crank mechanism.

Type 4 gripper :

   It is quiet similar to the type 3 gripper. Only the change is in design of mechanism.

Basic Components of Pneumatic System

Pneumatic system plays an important role in Industrial area. It has lots of advantages and hence can be efficiently used in Industry.
General layout of Pneumatic System

Pneumatic system basically consist following main components :

Air : As we are using pneumatic system air is medium of transfer of energy.

Compressor : Compressor is said to be the heart of  pneumatic system. Without compressor, it is impossible to run the system. Compressor compresses the air coming from the surroundings and pressurizes it for its use.


Air Reservoir Tank: Reservoir tank is used to store the air that is compressed by air. As per the requirements, size of reservoir tank is used. Mostly in Industries large storage tanks/ reservoir tanks are used, because of large need of air in pneumatic system.

FRL Unit : FRL unit stands for Filter, Regulator and Lubricator. Figure below shows a FRL unit. Starting from left, first component is Filter followed by Regulator and Lubricator.

FRL Unit

  • Filter filters the impure air coming inside the compressor for its proper working. Generally, filter contains a porous gauge which acts as obstacle for the particles coming inside with the air. The size of gauge is mainly in microns to obtain almost pure air.
  • Regulator regulated the flow of air, that is it controls the rate of air flow through the pipes. A pressure gauge mounted on the Regulator indicates the pressure flowing through it.
  • Lubricator unit is used for lubrication purpose. Unlike hydraulic system, pneumatic system doesn't make use for its fluid as lubricator. So in order to keep moving parts live, some amount of lubrication is necessary and it is done by Lubricator. Small amount of drops are released with the flowing air. As air moves ahead, Lubricating oil sticks to the moving parts and lubrication is done.

DCV: DCV stands for Direction Control Valve. As the name suggests, DCV is used for controlling the direction of flowing air through the system. As per requirement, the valve is opened and closed.

Actuators: Actuators are nothing but the piston cylinder arrangement. Now-a-days, thousands of actuators are present in market with their respective specifications. Single acting spring return cylinders are more economical as compared to others. Actuators are used for linear motion, that is for pulling or pushing purposes. Cylinders are fitted with pistons of different diameters and strokes of various lengths.

Spring return cylinder