Dual Check Safety (DCS) Explained

Four Primary DCS Functions

Using DCS decreases floor space needed for safe robot operation, keeps operators safe and allows robots to move at optimal efficiency. The DCS software functions reside in the FANUC controller and are integrated into FANUC’s ROBOGUIDE simulation software. Four primary software tools available within Dual Check Safety for the robot cell designer include:

Position Check

This allows the robot to be setup using a three dimensional (3D) defined workspace. DCS software allows the system designer and robot programmer to define the space where the robot operates while performing its required work. With this approach, less total actual working area needs to be blocked off for the robot cell.

Safe Zones

Safety Zones for operators helps assure the operator’s safety in a Robotic Industries Association (RIA) safety compliant manner, while keeping the robot moving.

When the operator enters a workspace that the robot normally occupies, he triggers an input and a zone is blocked off where the robot can no longer enter. While the robot may, at this point, be using a less efficient path, this eliminates the need for robot cell downtime.

The illustration above shows the operator on a safety mat. The safety mat sends a signal to the robot controller which causes a Safety Zone to be activated within the controller. The controller prevents the robot from entering the area where it would violate safety specifications for clearance with the operator, all in a fail-safe, safety rated manner.

Safety Speed Check

The Safety Speed Check function can be used to slow down a robot under specific conditions, in a fail-safe, safety rated manner. This function could be used to reduce the minimum distance from an operator to the robot under specific conditions.

For example if a quality check needs to occur, an operator could be allowed to perform the check in an area that is acceptable if the robot is moving at a slower speed, but unacceptable if the robot is running at a higher speed. A safety rated mat or laser scanner could be used to signal to the robot controller that an operator is present at the quality check station. The robot controller would slow the robot down so the operator is outside the acceptable limit of robot motion at the slower speed, where the operator would otherwise be in an unacceptable area if the robot was operating at full speed.

Safety mats, light curtains or laser scanners can also be used to provide a signal to the robot controller to slow the robot down and/or limit robot motion so that maintenance can be performed in specific areas of the robot cell while other areas of the robot cell are still in operation.

Cartesian Position Check

Cartesian Position Check can be used by the robot cell designer and programmer to simply and quickly define the physical envelope of the robot and its end of arm tool. The designer/programmer can in turn use this physical envelope to restrict motion of the robot.

The movement of the tooling can be defined using up to 32 zones that all have on/off switches defined in DCS.

Recent Enhancements in Dual Check Safety

FANUC continues to expand DCS capabilities with new features on modern controllers:

• Stop Type by Direction (New with R-50iA controllers)
  Allows the robot to apply different stop categories depending on motion direction. This fine-tunes safety response, enabling faster stops in critical directions and smoother behavior in others.
• Stop Position Prediction (SPP) & Expand Point as Line
  Improves how the robot predicts its stopping envelope. Instead of expanding in all directions, DCS calculates only along the actual motion vector, tightening the safety zone and maximizing usable space.
• Advanced DCS Package & 4D Graphics
  Bundles commonly used DCS options with enhanced visualization tools. Designers can view safety zones and stop predictions in four dimensions, making validation and troubleshooting easier.
• Controller Integration
  DCS is available on R-30iA, R-30iB, R-30iB Plus, and now R-50iA controllers. Each new generation adds refinements in redundancy, prediction accuracy, and zone definition flexibility.

Implementation Tips for DCS

When implementing DCS, designers should:

• Use ROBOGUIDE to simulate zones and validate reach before deployment.
• Combine DCS with external devices (light curtains, scanners, mats) for layered protection.
• Reserve time during commissioning for zone calibration and verification.
• Train operators on DCS behavior like – what happens when entering a Safe Zone or triggering a speed reduction. (Refer to another DCS article –Resetting a Dual Check Safety DCS Alarm)
• Periodically re-validate DCS zones during maintenance, especially after EOAT or layout changes.

DCS Application Examples for Industries

• Food & Beverage Packaging – DCS allows large-reach robots to palletize in tight spaces without oversized fencing.
• Cold Room Palletizing – Safe zones and speed checks let operators enter the cell for checks while robots continue running nearby.
• Medical Device Assembly – Cartesian checks protect delicate tooling paths and limit operator exposure.
• Collaborative Workspaces – DCS combines with sensors to create flexible fenceless cells where human and robot tasks overlap safely.