When it comes to robotics applications, “safety” has always been a hot topic. For lightweight cobots, “safety” and “human-robot collaboration without fencing” have always been a major technical advantage. However, in practice, there is no absolutely safe robot, we need to assess the systemic risk of the entire robotics solution. Human operator is a crucial factor when using robots!
On July 4, 1981, a repairman
at the Akashi plant of Kawasaki Heavy Industries Ltd. in Japan accidentally
touched the start button of the robot next to him, and the robot, which was
used to process gears, regarded the repairman as a gear and picked him up,
resulting in a tragic accident.
On January 25, 1979, Robert Williams, a 25-year-old assembly line worker at a Ford plant in the United States, was struck and killed by the arm of an industrial robot at the Ford Foundry in Michigan. Official figures released by the U.S. show that for every 100,000 full-time employees in American manufacturing industry, 2.1 fatal accidents occurred in 2013, down from 2.7 in 2006. In the transportation equipment industry, the figure was just 0.9. As for“man-made calamity”, an “obedient” may also make mistakes because of man-made calamity
How can we prevent a working robot colliding with a person? In this issue, we’ll take a look at the ELITE cobot and collision detection related contents in this video.
ISO standards define safety requirements for cobots: from ISO 12100, ISO 13849, to 10218 and 15066, all of which are official ISO standards (except for 15066, which is a TS (Technical specification)). The formal ISO standards serve as a reference for designing our products and as a benchmark for verifying product safety functions. But for the robot itself, we call the function to ensure safety without external sensors as passive measure.
The current mainstream approach is to use joint torque detection (current or direct torque sensing):
1. As it is passive detection, it will only be detected if a collision occurs.
2. Limited by the accuracy of the dynamics itself, its detection accuracy can not reach a high level, so there is a contradiction between sensitivity and speed.
Can the collision level of ELITE robot be turned off? Yes. But you must have the password of the highest authority. On the practical level: Based on ELITE’s understanding of the site, clients may have different needs on site, so we have different targeted solutions. Some customers give prominence to compactness and easy programming, so they don’t attach great importance to collision and safety. Second, based on the efficiency, we set acceleration limit. We can slash the chance of false alarm while achieving highest collision sensitivity. At present, the accuracy of recognition is inconsistent throughout the working area, which is caused by the mechanism, as joint sensitivity is not consistent throughout the space. Based on the client’s requirements, ELITE can provide experience to help the client debug the robot.
Are cobots really safe? Will they really not hurt anyone? It’s hard to answer such questions. For example, can a child hurt anyone? No. But what about a child with a knife? Is it still safe? Is there any way to make a child with a knife safe? Yes, by conducting safety assessment. When there are safety risks in an application, measures must be taken to eliminate or mitigate such risks, and we must ensure risks have been distinctly identified. The process is an iterative course, we need to continually eliminating risks, discovering the risks that are introduced by the measures, and eliminate those risks again. For more questions about cobots, please feel free to contact us!