accuracy of ±0.03 mm, and a maximum speed of the tool end of 3 meters per second (m/s), 12 times faster than the maximum allowed by ISO/TS 15066 when a person is in the collaborative workspace (Figure 2).
In many applications, the cobot can be operating alone for long periods. So, sensing the presence or absence of people in the collaborative workspace can enable much faster operation and higher efficiency when no one is present. Common devices for sensing the presence of people include safety scanners, light curtains, and safety contact floor mats. Each technology offers a different set of benefits, and they are often used in combination. Safety scanners Safety scanners monitor a designated area to detect the presence of people. They can determine how far away a person is and implement various warning zones in addition to the active safety zone. Omron's model OS32C-SP1-4M is a good example of a safety laser scanner designed for use with cobots. It has a safety radius of up to 4 meters (m) and can support multiple warning zones up to 15 m. It includes 70 standard sets of safety zone and warning zone combinations to support complicated collaborative workspaces. In addition, the minimum object resolution can be set to 30, 40, 50, or 70 mm, and the response time can range from 80 milliseconds (ms) up to 680 ms, further increasing application flexibility (Figure 3).
Figure 3: This safety scanner has a safety radius of up to 4 m and can support multiple warning zones up to 15 m. (Image source: DigiKey)
Light curtains Light curtains can measure the presence of people and can be designed to detect objects of various sizes, like fingers or hands. Unlike safety scanners, light curtains don't measure distance. They send a series of light beams between linear emitter and receiver arrays and can sense when an object breaks one or more beams. In terms of safety ratings, there are two primary light curtain classifications: Type 2 and Type 4. They have similar outward appearances but are designed to provide different levels of safety. Type 4 monitors the safeguarded space that defines a collaborative workspace. Type 2 light curtains are designed for lower-risk applications.
Figure 2: This cobot can move 12 times faster than the maximum allowed by ISO/TS 15066 when a person is in the collaborative workspace. (Image source: Schneider Electric)
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