What kinds of anti-falling safety devices are there in mechanical three-dimensional garage?

There are two kinds of electromagnetic hook and anti-falling frame (invention patent number: ZL2009 10005025. X), in which each parking space is equipped with four electromagnetic hooks, and the anti-falling frame is of tracking type, and each parking space is equipped with one except the top parking space. From the aspects of safety performance, cost and later maintenance cost, the anti-falling frame is much more cost-effective. As shown in the figure:?