Relative Waypoint

Description

A relative waypoint is created by defining two waypoints. These two waypoints determine the distance and direction the relative waypoint should move

The relative waypoint can be defined to the robot arm’s previous position, such as “two centimeters to the left”.

The second waypoint is dependent on the first.

This waypoint can be created when adding the relative waypoint. It can also be a previously defined waypoint, such as a fixed waypoint.

 

When to use: 

  • When using a BeforeStart to move the robot straight up from any position. For example, if the robots is stopped in a position near parts.

  • If the first waypoint is relative and you press play. You don't need to move the robot into position to start the program.

  • When using SubPrograms to make repeatable movements at different locations around the robot. For example, screwdriving at multiple locations: move down 50mm, turn screwdriver on/off, move up 50mm.

When not to use: 

  • When a specific location must be reached repeatably.

  • When a constant path is desired.

 
Example: Add relative waypoint

To move the robot 20 mm along the z-axis of the tool:

var_1=p[0,0,0.02,0,0,0]
Movel
Waypoint_1 (relative position): 
Use variable=var_1, Feature=Tool
Add a relative waypoint to a robot program

  1. In the Program tab, select the Basic menu

  2. Tap Waypoint

    1. Notice the selector is automatically set to Fixed position

    2. Change the waypoint to Relative position.

  3. Set the first waypoint (from point...)

  4. Set the second waypoint (...to point)

 
Detail

The movement between two relative waypoints is always the shortest path for the robot depending on the move type.

The distance for relative waypoints refers to the Cartesian distance between the TCP in the two positions. The angle states how much the TCP orientation changes between the two positions, or more precisely, the length of the rotation vector describing the change in orientation.

It does not matter where the relative waypoint position was located around the robot, before the program moved into the relative waypoint.

As soon as PolyScope moves to the relative waypoint in the program tree, the robot moves from its current position, to the distance and in the direction the relative waypoint has saved.

Repeated relative positions can move the robot arm out of its workspace.

 
Use Case: Welding and changing welding items

 

If you have a welding procedure, and you need to weld a seam around a rectangle, you can define the first corner with a fixed waypoint, and then make the robot and welding tool hit the remaining three corners using relative waypoints.

The first waypoint will start the welding seam around the rectangle, and the relative waypoints will finish the remaining corners.

Then if you need to weld something that is still a rectangle, but larger or smaller, then you can change the distance of the relative waypoints, and quickly modify the robot program.