FANUC America Corporation


Smooth Robot Motion using Constant Path

Robots complete their programmed task moving from point to point along a path. That path is then played back in various testing and automatic modes in order to complete an application. Often factors, such as robot speed, can cause the path to change during playback. When FANUC Robotics' Constant Path feature is used, the robot maintains the same path regardless of static or dynamic speed override changes. A path that has been taught and tested at a low speed override, in teach mode for example, will be maintained when the program is executed at maximum speed override in automatic mode. This drastically reduces path teaching and verification time.

Constant Path also maintains the same path if the program includes instructions, such as wait instructions for I/O for example, in order to modify playback. This allows the robot to remain on the same path regardless of the wait time. The same path is also maintained when the program is resumed after the motion is interrupted by a HOLD or other event. This is extremely useful in a real production environment where motion interruption events can occur randomly. The Constant Path option, available for all applications, maintains an uninterrupted path.

In addition, FANUC Robotics also provides the Advanced Constant Path option to give the user more direct control of the motion path and cycle time. The Advanced Constant Path option consists of the following features.

  • Linear Distance

  • Corner Region

  • Process Speed

  • Max Speed

The Linear Distance feature is useful for path control in many applications such as palletizing – where typically the user wants to ensure a certain distance along a straight line when picking up a part and when dropping off a part. This prevents the part from hitting the bins. This feature is a time saving tool during path teaching and verification.

Corner Region allows the user to have direct control/adjustment of the amount of corner rounding between two Cartesian motion lines, by specifying a distance from the taught position. The robot path will be maintained within a sphere with the center at the taught position and the radius equal to the value specified in the corner region instruction.

Process Speed is useful in situations where there is a need to improve (or slow down) the cycle time while maintaining the same taught path. It is most suitable for applications with continuous path motion that do not normally use maximum program speed such as in sealing and waterjet cutting applications.

The Max Speed feature is most suited for situations where the main objective is to reduce the cycle time for long linear motions where it is not important to maintain a constant speed along the path, and that some path deviations are acceptable. An example is in a Load/Unload application. By relaxing the requirement for constant linear speed, this feature can minimize the move time on-the-fly along the linear path while staying within the maximum capability of the robot.

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