Occupancy Sensor

I want to use occupancy sensors to disable movement of racks in a mobile rack storage system if somebody is standing in the passage between two consecutive racks (and also to stop a moving rack if somebody enters the passage). The racks are 15 m long, 4 m high and 3 m wide. The empty passage is 3 m wide.

On Internet I found some sensors which seem to be motion sensors which will not only sense human beings but also any moving object.

Are there any sensors which can sense only human beings and not moving racks?

SVN

As you describe it, you want to use the sensor as a safety device.
I suggest that you monitor the area where people can enter or leave the passage. This can be with a safety relay in combination with a door, a light curtain, or an area sensor.
The important bit is, if someone enters the area and thus stops the moving equipment, in order to reset the safety relay there must be a locally placed reset button outside the dangerous area. The button shall be activated by a person with full view of the passage.
If a person can hide in the passage somehow, then I believe the only viable solution is with a "trapped key" lock.

JesperMP, thanks for the suggestions.

The areas to be monitored are very large. Since all the racks are movable and the desired empty space can be in place of any rack, doors to the passage are not feasible. I already thought of area scanners, light curtains and pressure mats but to cover the large areas I need many sensors and they turn out to be very expensive for the application. I just want to know whether there are any cheaper alternatives to cover large areas.

Best regards
SVN

Hi svn.

There does not exist a safety-approved sensor that can reliably distinguish between a human object and a non-human object.

What you describe is a typical application. There is nothing special about it. You must monitor the area where people can enter the dangerous area, not the entire area.

Another solution is to install area sensors on each of the moving devices. The area sensor then checks the area immediately in front of the car or whatever it is. However, that can be expensive if you need a lot of them. And it gets complicated if the covered area includes places where the area in front of the car can be intentionally blocked. You must then mute the area sensor in certain cases.

JesperMP, thanks for the info.

Best regards
SVN