Programming Methods

Programming Methods

1. Teach Programming

   • Point to Point
     • most common method
     • robot moved to each point in turn and the point recorded
     • recored position of joints in controllers memory
     • teach pendant used
       • hand held device connected to robot controller
     • easier to manoeuvre using cartesian co-ordinates (not joint coordinates)
       • joint coordinates need to be transformed to cartesian co-ordinates
         • Kinematic model of robot used
     • cylindrical coordinate can be used
       • useful when FMC is arranges in circle
     • Disadvantages
       • any path can be taken by robot to reach the coordinates
         • dangerous
         • could bang into objects
     • velocity each joint moves proportional to distance
       • so all joints take same time to move to their new positions
       • joint interpolated control
       • allows robot to move with maximum velocity
     • desirable joints move in straight line to avoid collision
       • computer creates series closely spaced target points
         • joins successive taught points
         • closer the points the straighter the line
       • useful if robot needs to follow outline of complex shape
     • robot controller sends signals to other equipment
     • robot receives signals from sensors
     • simple programming language
   • Continuous
     • programmer holds end of robot arm and moves it along path
     • spray painting
     • joint positions recorded automatically at series of closely spaced points
     • teaching arm available which is lighter and more representative of movement of spray gun
     • can not be used for precision
       • NOT for arc welding (point to point)
   • disadvantages
     • risk to programmer in such close proximity to the robot
     • positioning relies on human judgement (error prone)
     • teaching and debugging very time consuming
     • robot out of work whilst being programmed
       • mas production not too bad because used for long time
       • Batch new programme has to be taught regularly
   • accepted form of programming
     • high degree of accuracy
     • arm moves where its been taught

2. Off Line Programming

   • programme CNC machine tools
     • doesn't involve any other equipment so no collisions
     • part remains in one position so no transformations required
   • generate robot programme away from robot
   • programme created on computer using know data about geometry
   • precise data used
   • robot does not need to be taken out of production
   • Disadvantages
     • accurate data is required
     • programmer may have problems visualising movement of robot
       • need to prevent it from colliding with things
     • kinematic models required to transform cartesian co-ordinates to joint coordinates
       • kinematic models not perfect representations
       • simplified models reduce time but reduce degree of accuracy
     • costly for all the programming
   • Computer simulations with 3D models of robot cells can be used
   • expected to replace teach programming