14.6 Command: Fixed Waypoint
at Waypoint 3 (WP_3). To avoid collisions with the object and other obstacles (O),
the robot must approach WP_3 in the direction coming from Waypoint 2 (WP_2). So
three waypoints are introduced to create a path that fulfils the requirements.
Figure 14.2: WP_1: initial position, WP_2: via point, WP_3: pick up position, O: obstacle.
Without configuring other settings, the robot will make a stop at each waypoint,
before continuing the movement. For this task a stop at WP_2 is not optimal since
a smooth turn would require less time and energy while still fulfilling the require-
ments. It is even acceptable that the robot does not reach WP_2 exactly, as long as
the transition from the first trajectory to the second happens near this position.
The stop at WP_2 can be avoided by configuring a blend for the waypoint, allow-
ing the robot to calculate a smooth transition into the next trajectory. The primary
parameter for the blend is a radius. When the robot is within the blend radius of
the waypoint it can start blending and deviate from the original path. This allows
for faster and smoother movements, as the robot does not need to decelerate and
re-accelerate.
Blend parameters Apart from the waypoints, multiple parameters will influence
the blend trajectory (see figure 14.3):
• the blend radius (r)
• the initial and final speed of the robot (at positions p1 and p2, respectively)
• the movement time (e.g. if setting a specific time for a trajectory this will
influence the initial/final speed of the robot)
• the trajectory types to blend from and to (MoveL, MoveJ)
If a blend radius is set, the robot arm trajectory blends around the waypoint, allow-
ing the robot arm not to stop at the point.
Blends cannot overlap, so it is not possible to set a blend radius that overlaps with
the blend radius of a previous or following waypoint as shown in figure 14.4.
Conditional blend trajectories The blend trajectory is affected both by the way-
point where the blend radius is set and the following one in the program tree.
CB3 II-74 Version 3.4.5
Copyright © 2009–2017 by Universal Robots A/S. All rights reserved.
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