Validation of the protective zone of electro-sensitive protective equipment (ESPE)

Status:

completed 12/2000

Aims:

The testing of new types of electro-sensitive protective equipment (ESPE) employing a range of sensor technologies - passive and active infrared, ultrasonics, video sensors - requires that the protective zones be assessed in consideration of dynamic aspects (proximity reaction, dynamic/adaptive protective zone boundaries), in particular when used on vehicles and moving parts of machinery. Comprehensive test procedures are standardized in EN 61496, "Safety of machinery: Electro-sensitive protective equipment, Parts 1 to 3". These test procedures require considerable manual activity in some cases. The purpose of the test equipment is to permit an automated test procedure for the reproducible validation of both static and dynamic protective zones of ESPE, together with documentation of the results.

Activities/Methods:

The test equipment was first specified (list of requirements for functions, linear axes, control system, etc.) and costed. The test equipment was fitted with two mechanical linear axes (11 and 6 metres in length respectively) and a 4 metre gantry portal. A commercially distributed safe machining tool control system was employed for motion control. A software application was written externally to specification and adapted to the standardized test processes. The functions of control and automatic documentation were assumed by a well known measured value acquisition program. An appropriate arrangement of tested ESPE (a laser scanner interfaced through a safety bus) provides safeguarding of access to the test equipment.

Results:

Following installation of all components, the test equipment was tested for correct operation and accuracy (to < 4 cm). Four different ESPE were tested systematically on the test equipment. The high degree of reproducibility together with the small amount of work involved enabled weak points in the probability of detection to be traced on a number of systems. These results assisted the manufacturers in improving their products.

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