The following points highlight the top two methods of robot programming. The methods are: 1. Sequencing Operations 2. Teach by Showing.
Method # 1. Sequencing Operations:
Limited sequence robots are programmed by setting limit switches and mechanical stops to control the end points of their motions. A sequencing device determines the sequence in which the motions occur, the order in which each joint is actuated to complete the motion cycle.
It would be realised that the setting of limit switches and wiring the sequencer is more of a manual set up than programming. However modern robots use microprocessor chips as controller and also employ memory units to store programs.
Method # 2. Teach by Showing:
Also known as lead through programming, it involves teaching of the task by moving the manipulator through the required motion cycle, thereby entering the program into the controller memory. Usually powered lead through mode is used for playback robots with point-to-point control. A hand-held control box (teach pendant) is used for this purpose.
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It houses push buttons and toggle switches for controlling the movement of the manipulator joints. With these controls on pendant, the programmer drives the robot arm to the desired positions, in sequence, and the respective positions are recorded in memory. During subsequent playback, the robot moves, through the sequence of positions under its own power.
The lead through method provides a very natural way of programming motion commands using a teach pendant to drive the manipulator. The speed of the robot is controlled by means of a dial on teach pendant. Speed control also permits try out of a program at safe slow speed and then operating at high speed during actual use. Interlocks with limit switches are incorporated to regulate the sequence of the operation of playback robots programmed by means of lead through techniques.
Lead through methods can be readily learnt by shop personnel since these involve only moving the arm through the desired motion path and no knowledge of computer programming. However lead through programming method is not readily compatible with modern computer-based technologies.
Thus robot languages are more popular in a computer- integrated manufacturing environment. Robot languages permit program logic control far beyond the capabilities of lead through methods and also communications with other computer systems.
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The textual programming languages for robots offer improved capabilities of program logic control, and of course, the advantages of computation and data processing and easy communications. A variety of commercial robot languages are available. Many-times combination of textural statements and lead through techniques are used for motion programming.
Textual statements describe the motion, and lead through methods define the position and orientation of the course of robot. Commands are available to move robot from one position to other, interpolation motions, incremental moves, speed of robot, input interlock, output interlock, opening/closing of gripper, performing computations, etc.
Off-Line programming permits the robot program to be prepared at a remote computer terminal and downloaded to the robot controller for execution.