In safe hands with the world market leader
Altendorf and partners develop innovative hand detection sensor.
Hands are the most important tool anyone working in the wood processing industries can have and for this reason they deserve special protection. Altendorf, the world market leader for sliding table saws based in Minden, Germany, is exploring a new approach to user safety – a sensor that can distinguish between human skin and typical workpieces - in collaboration with Bonn-Rhein-Sieg University of Applied Sciences and IFA, the Institute for Occupational Safety and Health of the German Social Accident Insurance.
Conventional safety devices for wood processing machinery rely on light curtains that create an invisible protected zone in the danger area in front of the saw blade. The machine sounds and audible warning or stops as soon as this protected zone is penetrated. These light-curtain-based solutions, however, cannot tell the difference between innocent workpieces and a hand in jeopardy.
An industry first: a sensor that can distinguish between skin and workpiece
Minden-based Altendorf and its partners have achieved a major breakthrough: a near-infrared sensor that can tell the difference between human skin and wood and other materials. Installed ahead of the safety hood, the sensor can trigger a deflector in a matter of milliseconds. This deflector, which is known as a shutter, prevents any chance of injury by stopping the stray hand from ever reaching the saw blade – and it only operates if the object in the danger zone really is a hand. The saw itself is stopped as soon as the shutter is triggered. If the object picked up by the sensor is just an ordinary workpiece, the sawing operation continues as usual.
Modern infrared technology for unparalleled safety
The innovative sensor uses a method patented by the Bonn-Rhein-Sieg University of Applied Sciences that takes advantage of one very simple factor: our eyes can often see quite significant differences in skin characteristics from person to person, but skin brightness in the near infrared band is almost identical across all people irrespective of skin colour, age and gender. Human skin also appears quite different to other materials, so a near-infrared sensor can definitively identify skin. The associated measurement can be carried out quickly and easily using straightforward hardware and software and is unaffected by environmental factors like humidity, dirt, temperature and light levels.
The hand detection sensor uses integral light-emitting diodes to create infrared beams that strike the workpiece or hand. Each material interacts with the beams in a different way, allowing them to pass through, absorbing them or reflecting them back. The sensor uses a photodiode to determine the material’s response and hence identify it. If the material turns out to be human skin, the safety device is triggered in a fraction of a second to keep the hand or hands safely away from the saw blade.
Technology to go into production shortly
The prototype hand detection sensor is currently undergoing exhaustive field testing. The results so far are encouraging and everyone involved is optimistic that the technology will soon be ready to go into production.
Further information:
Wilhelm Altendorf Maschinenbau GmbH & Co. KG
Simone Bergmann, Wettinerallee 43/45
32429 Minden, Germany
Tel. +49(0)571 9550 134, Fax +49(0)571 9550 133
s.bergmann@altendorf.de, www.altendorf.com
