A capacitive sensor for the detection of humans in a robot cell

To increase operator safety in robotic work cells, a capacitive sensor for detection of humans has been developed. The capacitive sensor has an antenna above the robot. The antenna covers the entire area of the robot cell. The floor of the robot cell is covered with an electrically insulated, conducting sheet. The sensor detects objects roughly in the shape of humans, placed between the antenna and the floor, and with an electrical conductivity similar to that of seawater. A person entering the cell causes a change of capacitance between the sheet and the antenna. This change is measured with a capacitance-voltage converter. The output voltage is used as a signal for human presence. The floor can be sectioned into several sheets separated from each other by guards. If the area is sectioned the sensor is not only able to give information about the presence of a person in the cell but also about the location of that person