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16.1 Soft Float

16.1.1 Overview

The Soft Float function changes the robot from a rigid state to a compliant state. After Soft Float is enabled, if an external force is applied during motion, the end-effector yields to the force and the actual trajectory may deviate from the planned trajectory. After the external force is removed, and if the planned start point has not been reset, the robot attempts to return to the planned trajectory.

The deviation between the actual trajectory and the planned trajectory depends on the magnitude and direction of the external force, as well as Soft Float ratio and maximum deviation range settings. In general, a larger external force or a “softer” setting in the corresponding direction results in a more noticeable offset.

16.1.1

Soft Float is suitable for scenarios such as pick positions that differ from locating positions, assembly fitting, and die-casting unloading. It helps reduce the risk of damage to the robot or workpiece caused by rigid contact, without relying on an external force sensor.

Soft Float parameters are managed by process number. Each process includes three settings: coordinate system, Soft Float ratio, and maximum deviation range. Up to 16 processes (process numbers 1–16) can be saved. After configuration, enable Soft Float on the UI first, then use the RL commands SoftFloatStart / SoftFloatStop / SoftFollow to start, stop, and follow Soft Float.

  • SoftFloatStart and SoftFloatStop must be used in pairs.

  • Avoid prolonged operation near singularities while Soft Float is enabled. It is recommended to remove the external force before stopping Soft Float to reduce rebound or vibration risk.

  • Soft Float conflicts with collision detection: Soft Float cannot be enabled while collision detection is on.

16.1.2 Soft Float commands

Soft Float provides the following three RL commands:

  • SoftFloatStart: Enable Soft Float with the specified process number

  • SoftFloatStop: Disable Soft Float

  • SoftFollow: Reset the planned start point (Soft Float follow)

16.1.2.1 SoftFloatStart

Explanation

Enable Soft Float. After the command is executed, the robot enters a compliant state according to the coordinate system, Soft Float ratio, and maximum deviation range of the specified process number. During motion, if an external force is applied, the actual trajectory may deviate from the planned trajectory.

Definition

SoftFloatStart(SoftNum);
SoftNum, process number, range 1–16, used to select the Soft Float process configuration.

Example

Example 1
MoveJ(p1, v100, z50, tool0);
SoftFloatStart(1);
MoveL(p2, v100, z50, tool0);
MoveL(p3, v100, z50, tool0);
SoftFloatStop();
MoveL(p4, v100, z50, tool0);
Enable Soft Float with process number 1. External-force offsets may occur on the motion segments to p2 and p3. After Soft Float is stopped, the robot moves to p4.

Attention

  • Before use, complete the parameter configuration for the corresponding process number on the Soft Float page, and turn on the Enable switch in the upper-right corner. If Soft Float is not enabled, executing this command triggers a warning.

  • Must be paired with SoftFloatStop.

  • Soft Float cannot be enabled while collision detection is on.
Process configuration

Each process number contains the following three settings. Up to 16 different configurations can be saved.

16.1.2

Coordinate system

The Soft Float reference coordinate system can be:

  • Base coordinate system (Base)

  • Work object coordinate system (Wobj)

  • Tool coordinate system (Tool)

Both Soft Float ratio and maximum deviation range are interpreted relative to the selected coordinate system.

Soft Float ratio

The Soft Float ratio ranges from 0 to 100 and can be set independently for the six Cartesian directions (X, Y, Z, A, B, C):

  • A larger value means the direction is “softer” and easier to push with an external force

  • A smaller value means the direction is “stiffer” and harder to push with an external force

  • A value of 0 means the direction is not affected by external force

Maximum deviation range

The maximum deviation range is the maximum allowed offset of the actual trajectory from the planned trajectory (set for the X, Y, and Z directions on the UI, in mm). During Soft Float, the deviation between the actual and planned trajectories should not exceed this range.

When the robot speed is relatively high, or when the working conditions (payload, friction, external-force variation, and so on) differ significantly from the commissioning conditions, the actual deviation may slightly exceed the configured maximum deviation range. Set the range according to the actual application and verify it thoroughly.

Configuration and enablement steps

  1. Select a process number (1–16).

  2. Set the coordinate system, Soft Float ratios for each direction, and the X/Y/Z maximum deviation ranges.

  3. Click Save in the lower-right corner to write the current process to the controller.

  4. Repeat the steps above as needed to configure other process numbers.

  5. After configuration, turn on the Enable switch in the upper-right corner.

  6. Call SoftFloatStart(process number) in the program to enable Soft Float with the corresponding process.

16.1.2.2 SoftFloatStop

Explanation

Disable Soft Float. When the program reaches this command, Soft Float ends and the robot no longer responds to external forces in a compliant manner.

Definition

SoftFloatStop();
No parameters.

Example

Example 1
SoftFloatStart(1);
MoveL(p2, v100, z50, tool0);
SoftFloatStop();
After Soft Float is disabled, subsequent motion follows the normal rigid trajectory.

Attention

  • If SoftFollow is not executed before stopping, the robot attempts to return to the planned trajectory when Soft Float is disabled. If a large external force is still applied at that moment, the robot may fail to return and may even trigger errors such as overcurrent.

  • It is recommended to remove the external force before executing SoftFloatStop.
16.1.2.3 SoftFollow

Explanation

Soft Float follow command. After execution, the current actual position is reset as the new planned start point, so subsequent trajectories are planned based on the current position.

Definition

SoftFollow();
No parameters.

Example

Example 1 (reset the planned start point before stopping)
SoftFloatStart(1);
MoveL(p2, v100, z50, tool0);
MoveL(p3, v100, z50, tool0);
SoftFollow();
SoftFloatStop();
MoveL(p4, v100, z50, tool0);
After an external-force offset on the segment to p3, execute SoftFollow to set the current position (assumed as p100) as the new planned start point. Then SoftFloatStop no longer attempts to return to the original planned point p3, and the next MoveL is planned from p100 to p4.

Example 2 (continue motion after follow)
SoftFloatStart(1);
MoveL(p2, v100, z50, tool0);
SoftFollow();
MoveL(p3, v100, z50, tool0);
SoftFloatStop();
After SoftFollow, the next motion command starts from the reset position. If the external force still exists, another offset occurs relative to the new planned baseline.

Attention

  • Without SoftFollow: after Soft Float is stopped or the external force is removed, the robot attempts to return to the original planned position.

  • With SoftFollow: the planned position is reset to the current position; when Soft Float is stopped or the external force is removed, the robot no longer attempts to return to the planned position before the reset.

  • If the command immediately before SoftFloatStop is SoftFollow, the robot is already on the new planned trajectory when Soft Float is stopped, and generally does not rebound toward the old planned point.

Typical usage comparison:

  • Return to the original planned trajectory: SoftFloatStart → motion → SoftFloatStop

  • Continue subsequent processes from the offset actual position: SoftFloatStart → motion → SoftFollow → SoftFloatStop → subsequent motion
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