The controller or Safety PLC does this by evaluating the signals from the sensor and light curtain to ensure they are turning on and off in a specific sequence within a specific time frame. A Muting Controller or Safety PLC can accomplish this muting function by using sensors and the light curtain to safely suspend the light curtains safety function for product to move through the light curtain without stopping the system. pallets with product) must travel on a conveyor through the light curtain. One example of light curtain muting is where there is an opening in guarding that’s protected by a light curtain, but product (i.e. This operation is called light curtain muting. Another positive feature about light curtains is they can be programmed to distinguish between humans and product. These beams can sense even small intrusions into the space – such as fingers. This means light curtains are the best option for very fast response time. When the beam is broken, hazardous motion comes to a stop. Light curtains work by sending optical beams from an emitter across a work area to a receiver unit. Area Scanners vs Light CurtainsĪnother common safety feature in robot systems is light curtains. These can be used when there are multiple moving hazards and it is safe to enter one area but not another. Some operations will automatically restart, but others may require the operator to initiate a restart of the system.Ĭertain Area scanners can be set up for multiple protection and warning zones. The moving hazard stops completely so the person or object can safely work in the area and then restarts when the protection area is clear.If the scanner detects an object in the specified protection zone, the OSSD (output signal-switching device) changes to the OFF-state to stop the machine hazard.The protection zone begins when the person or object moves to within 13.78 feet (4.2m).If the scanner detects an object in the specified warning zone, a light can flash, warning message be displayed, or audible tone can be heard.The warning zone in this example is anytime the person or object is within 32.81 feet (10m) of the hazard.Can be configured and drawn around permanent or predicted obstacles.An area scanner monitors a 2D area of a 190-degree angle with several meter radius. Scanners can be mounted vertically or horizontally and the graphic to the right shows a general coverage of an area scanner. The scanner calculates the time it takes for a laser to bounce off an object and return to the sensor. Protection and warning zones can be configured with flexibility and adapted to structural conditions.Īrea scanners use time-of-flight technology to calculate the protection zones. Area Scanner SetupĪrea scanners keep both people and equipment safe. This takes more time because the robot isn’t able to stop at the known stopping point, and has to cycle back to the correct position. If the operator does not request access and enters the area the system will fault and come to a stop. Robot and system movement only resume once the someone or something has left the area. One can work safely, and the scanner slows or stops the operation at a known stopping point only when someone or something is in a defined zone. The operator requests access to the area, enters, finishes work, and then resets once they leave the area. Likewise, area scanners allow for protection zones to be defined, but without fencing. Area scanners prevent specified machine hazards from operating when someone or something is in the defined area. The fenced-in area has an entry gate process that requires an access request from the operator, the robot stops at a good stopping point, the operator enters the fenced area, works, leaves, resets the system, and the robot starts moving again. These barriers may solve the safety issue but bring new issues that cost manufacturers downtime and efficiency.įences must contain the entire robot system. In the past, this was predominantly done with physical barriers, such as fencing and gates, that restrict access to an area with the potential hazard. When there is a moving robot, equipment or machinery in a system, it is important to identify, define, and protect against all hazards.
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