Machine guarding by electromagnetic field distortion

The effective guarding of machines against human injury is an enormous problem already with many available solutions. Guarding procedures generally fall into one of three classes: (1) Physical guards which prevent the placing of limbs and personnel in potential crush points. (2) Those devices which require the removal of the human from the device so that they can be activated, e.g. switches for activation. (3) Sensor, such as light sheets which shut down the machinery when the presence of an object, such as a hand, is detected in a hazardous position. We have developed a novel machine guarding technique based on the measurement of electromagnetic field distortion. There are no physical connections between the operator and the machine. The machine guarding is accomplished by merely sensing operator presence/absence through the capacitance change caused by the operator themself. As such we see few easy ways in which such a machine guard may be deactivated.