Blend Trajectories

14.1:  Joint space (MoveJ) vs. cartesian space (MoveL) movement and blend.

Depending on the movement type (i.e., MoveL, MoveJ, or MoveP), different blend trajectories are generated.

• Blends in MoveP When blending in MoveP, the position of the blend follows a circle arc at constant speed. The orientation blends with a smooth interpolation between the two trajectories. You can blend a MoveJ or a MoveL into a MoveP. In such a case, the robot uses the circular arc blend of MoveP, and interpolate the speed of the two motions. You cannot blend a MoveP to a MoveJ or a MoveL. Instead, the last waypoint of the MoveP is regarded as a stop point with no blend. You cannot perform a blend if the two trajectories are at an angle close to 180 degrees (reverse direction) because it creates a circular arc with a very small radius which the robot cannot follow at constant speed. This causes a runtime exception in the program which can be corrected by adjusting the waypoints to cause a less sharp angle.

• Blends involving MoveJ MoveJ blends cause a smooth curve in joint space. This goes for blends from MoveJ to MoveJ, MoveJ to MoveL and MoveL to MoveJ. Blending is not performed if time is specified instead of velocity and acceleration for both motions.

• Blends in MoveL MoveL blends cause a smooth curve in Cartesian space. The orientation blends with a smooth interpolation between the two trajectories. The robot may decelerate on the trajectory before the blend to avoid very high accelerations (e.g., if the angle between the two trajectories are close to 180 degrees).