Cartesian trajectories for the KUKA robots (KRC/KRL).

1. Kuka Robot Maintenance Manual
2. Kuka Krc2 Manual

KUKA System Software KUKA System Software 8.3 Operating and Programming Instructions for End Users KUKA Roboter GmbH Issued: Version: KSS 8.3 END V1 en (PDF). Now check out the Advanced Tutorials for more details regarding each of the above steps and in-depth information about the used commands if you like, or move on to the various How-to Guides. 2.2Advanced Tutorials The advanced tutorial slides give a more in-depth introduction to grl and its use including in-depth information.

Further reading

Trajectory composition¶

Cartesian trajectories can be composed in three ways (see manual_slides p. 23-32).:

• Linear Cartesian motions

  LIN

• Circular motions

  CIRC

• Joint space interpolation

  PTP

  • joint space movement to a given goal, which can be specified in joint space or in Cartesian space.

  • controller calculates the necessary angle differences for each axis

  • Preferred motion if a high TCP speed is wanted and the interpolation between both waypoints doesn’t have to follow a predefined path.

• Additional

  SLIN

  • The Spline Linear motion uses splines between linear motions

  SCIRC

  • The Spline Circular motion uses splines between circular motions

  SPTP

  • The Spline Point to Point motion is similar to PTP but it allows continuous spline motions.

Waypoint representation¶

(see kuka_system_software and manual_slides)

Kuka Robot Maintenance Manual

• Angles of rotation of the robot coordinate systems
• S and T specify a robot’s position unambiguously if more than one axis position is possible forthe same point in space (because of kinematic singularities). This is often written in integerform, thus the values above.
  • S (status): 3-bit binary value describing the robot’s configuration with predefined criteria
  • T (turn): direction of a turn.6-bit binary value, containing flip bits for each axis (0 when axis >= 0 deg, 1 when axis < 0deg)

Trajectory parameterization and execution¶

(see manual_advanced)

Specification of velocity¶

• Speed of TCP can be set within a move instructions in % by the ‘vel’ argument.

• For Continuous path motions ([LIN], [CIRC]) the velocity is constant from start to end.

• Realtive Joint Velocity can be set by: setJointVelocityRel(0.3)

• KUKA operation mode influence velocity

  Mode	description	velocity
  T1	Manual Reduced Velocity	max of 250mm/s
  T2	Manual High Velocity	as programmed
  AUT	Automatic	as programmed
  EXT	Automatic external	as programmed
  CPR	Safe Operation	max of 250mm/s

specification of acceleration¶

Relative Joint Acceleration can be set by: setJointAccelerationRel(0.5)

Blending¶

(source Angerer and Vistein)

Kuka Krc2 Manual

• Blending is enabled by the advance run mechanism enabling planning the next motion while executing a motion.

• To activate blending a motion needs to be marked as blendable by adding a keyword to the motion instruction. C PTP`for PTP motions and `C_DIS, C_VEL or C_ORI for motions in operation space.

• Blending between all motion types is supported. It is even possible to blend a PTP (joint space) into a LIN (Cartesian space) and vice versa.

• Blending can be done by defining a blend radius

  • as a relative value: IMotion.setBlendingRel(0.2)
  • in millimeters: IMotion.setBlendingCart(20)

Parallel IO operations¶

No information found so far

Online (real-time) trajectory modifications¶

Robot Sensor Interface (RSI) (see RobotSensorInterface)

• supported since KRC-4 controller
• influence the position of the robot by external sensors.
• robot position can be influenced by external sensors through overlaying a programmed motion with external control, like position correction from a sensor-based system
• default 4 ms cycle time for accepting set point, hence external controller requires hard real-time
• usually correction data is provided in relative values and applied directly to the running program. However, as absolute values are possible, the robot can be controlled externally while a KRL program only providing a fixed start position runs in the background.
• communication between KUKA and external controller via UDP/IP on a dedicated network segment
• RSI context is a library with RSI objects for configuration of the signal flow
• RSI monitor offers online a visualization of the RSI signals.