How does PFL differ from STO in cobot safety?

How does PFL differ from STO in cobot safety?

• A. PFL and STO are identical functions.
• B. PFL deactivates power; STO reduces speeds.
• C. PFL reduces contact forces by limiting allowable forces/impacts during interactions; STO completely disables power/torque within safety limits.
• D. PFL increases safety via emergency stop; STO triggers maintenance.

Answer: (C)

Power and Force Limiting is about keeping human-robot contact safe by capping the energy in the interaction. It limits the allowable contact forces (and often slows the robot) so that any touch between the robot and a person stays within a safe range. Safe Torque Off, in contrast, disables the robot’s drive power so no torque can be produced and the robot cannot move, ensuring no motion occurs while the safety state is active. These are different approaches: PFL enables controlled contact within safe limits, while STO completely prevents motion by cutting power to the actuators. Therefore, the best description is that the system reduces contact forces by limiting allowable forces and impacts during interactions, whereas STO completely disables power/torque within safety limits.

Power and Force Limiting is about keeping human-robot contact safe by capping the energy in the interaction. It limits the allowable contact forces (and often slows the robot) so that any touch between the robot and a person stays within a safe range. Safe Torque Off, in contrast, disables the robot’s drive power so no torque can be produced and the robot cannot move, ensuring no motion occurs while the safety state is active. These are different approaches: PFL enables controlled contact within safe limits, while STO completely prevents motion by cutting power to the actuators. Therefore, the best description is that the system reduces contact forces by limiting allowable forces and impacts during interactions, whereas STO completely disables power/torque within safety limits.