Industrial Robots

Prerequisite – Robotics

Industrial robots are those robots which were created by programming the mechanical devices which in future can be used in the place of Human Being in order to perform dangerous tasks which may require repetition multiple times with much higher accuracy and without any failure. An industrial robot is typically a form of jointed structure which have different configurations. The structures are achieved by the linking of a number of rotary and/or linear motions or joints. 

Each of the joints provides a motion that collectively can position the robot structure, or robot arm, in a specific position. To provide the ability to position a tool, mounted on the end of the robot, at any place at any angle requires six joints, or six degrees of freedom, commonly known as six axes. An industrial robot is driven through a sequence of movements by a program of some kind. The program is executed by a controller. The controller turns on the joint actuators at the appropriate times, while signals from the joint sensors are returned to the controller and used for feedback. 

Classification Of Industrial Robots :
Industrial robots can be classified by the method of control and by the method of teaching or programming.

The main classes of the Method of Control are as follows –  

• Pick And Place –
  Pick and place robots use mechanical stops to set two stopping positions on each axis. The joint must travel backwards and forwards between these two end stops, whose positions can be adjusted when the machine is set up. 
  
• Point To Point –
  Point to point robots have servo position control of each axis and can go through a sequence of specified points. The program for such a robot consists of a series of points, for each point all the joint angles must be specified. 
  
• Continuous Path –
  Continuous path robots do not go through a finite list of target points but can ideally execute a smooth path of any shape with continuous variation of speed as the arm moves along the path. 
  

The main classes of Method of Teaching or Programming are as follows –  

• Programming Pick And Place Robots –
  The crudest form of programming is the setting up of a pick and place machine. This has two parts: the mechanical end stops which are set inplace for each axis and the sequence in which the joints operate is programmed. 
  
• Walk-through Teaching With Path Control –
  This method can be used only with a continuous path robot, although to the user who is teaching the robot may resemble it like teaching a point to point robot. 
  
• Lead-through Teaching –
  In this form of teaching the user carries out the required motions with his own hand, while holding some device for recording the path taken by the robot. 
  
• Off-line Programming –
  The alternative to teaching a robot by operations is to type in a program at a computer terminal. In the simplest case, the program consists of a series of commands of the form ‘move axis A through distance D’. These commands are expressed in some languages designed for robot programming. 
  

Categories of Industrial Robots :

• Cartesian Robots –
  Cartesian robots are also known as rectilinear or gantry robots. These robots have three linear joints that use the Cartesian coordinate system (x, y, z). 
  
• Scara Robots –
  Scara Robots are commonly used in assembly applications. Its arm is in cylindrical in design. It has two parallel joints which are used to provide compliance in one selected plane. 
  
• Articulated arm Robots –
  Articulated arm robots have a design which majorly features rotary joints and these can contain two joint structures to 10 or more joint structures. The arm is connected to the rotary joint and each joint is known as the axis which provides a range of movements. 
  
• Polar Robots –
  Polar robots are also known as spherical robots. The arm is connected to base with a twisting joint and have a combination of 2 rotatory joint and one linear joint. 
  

Applications of Industrial Robots :
There are many fields where industrial robots are in wide use – 

• Die Casting
• Spot Welding
• Arc Welding
• Injection Moulding
• Foundry Work
• Machine Tool Loading
• Heat Treatment
• Brick manufacturing
• Glass manufacturing
• Forging