Geometry of hinged constructions

I will talk about the geometric properties of the ideal hinge mechanisms and trusses. I'll start with unusual examples of flat hinge mechanisms, such as a mechanism with a variable number of degrees of freedom. The formalization of the basic concepts of the theory of mechanisms for hinge-lever mechanisms, such as the concepts of the kinematic scheme, hinge mechanism and its configuration space, will be given. It will lead both to clarification of the picture and to a number of interesting new questions for mechanics and geometry. It will also be told about the unconventional understanding of hinge mechanisms by algebraic geometers, leading to misunderstandings.