Inventory of the mechanical principles behind the linkage of robot walking

The concept of robots has been thriving for many years, and there are indeed many companies that have developed high-performance robot products. The ones we are familiar with may be the robots that used to flip over. These robots are so agile, but what high-tech is hidden behind them? The control technology is too complex and generally not easy to understand, but the mechanical principles are relatively simple, mostly consisting of some linkage mechanisms.