Vision-Based Protective Devices

Introduction

In the manufacturing industry context, production consists of processing, assembling, and transporting materials. In the last decades, industrial machines have been increasingly used to reduce the burden from workers to assist in production. As a result, a wider range of machines are currently designed, produced, marketed and used for multiple industrial purposes on a global-scale, networked scenario. However, manufacturing is still not possible without the intended action of a trained worker who operates a machine. Since humans are prone to make mistakes, ensuring safety irrespective of worker operating experience on a machine is mandatory. The same applies to machines (and their hardware and software components), given that they also fail specially during machine maintenance and setup operations.

In the context of machinery, the purpose of safety is to protect persons from harm (i.e. physical injury or damage to health). A machine must be safe since its design. As stated in Machinery Directive 2006/42/EC (European Commission, 2006), it is responsibility of both builder and supplier to ensure that a machine is designed and constructed to be safe, so that it can be used in its intended manner, configured and maintained throughout all phases of its life, causing minimal risk to persons and the environment. For this purpose, the machine designer must carry out a technical procedure to identify both hazards (i.e. potential source of harm) and risks (i.e. severity and probability of occurrence of a harm) associated with the machinery. In turn, these hazards and risks determine the so-called machine danger zone (i.e. any space within and/or around the machinery in which a person can be exposed to risk of injury or damage to health), in order to assess which measures are suitable and where they should be installed. Optionally, a warning zone (i.e. any space which surrounds the danger zone in which a person is close but not exposed to a hazard) may also be considered in the installation and utilization of some measures. From a Machine Safety viewpoint, this technical procedure —known as Risk Management— must only be finished when the machine is safe.

In general terms, a Safety Measure is a measure (i.e. a particular action which is intended to achieve an effect) that is taken to increase or ensure safety, or protection from danger. In the Machine Safety context, Safety Measures are those measures intended to achieve the necessary risk reduction for a particular machine, according to a standardized Risk Assessment procedure, which must be implemented by the machine designer and/or by the user. Plainly stated, Safety Measures are thus responsible to ensure that machines are mechanically and functionally safe. As for the machine designer, the Safety Measures under consideration include:

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  Inherently Safe Design Measures,

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  Safeguarding Devices,

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  Complementary Safety Measures, and

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  Information for Use.

On the other hand, Safety Measures applied by the user include organizational issues such as:

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  Safe working procedures,

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  Supervision and maintenance plans,

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  Permit-to-work systems,

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  The provision and use of additional Safeguarding Devices,

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  Personal Protective Equipment (PPE), and

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  Personnel training.