Abstract: An angle adjustment assembly includes a first connecting piece including first side plates, a second connecting piece including second side plate, and a limiting rod. The first side plates are hinged to the second side plates. The first side plates include a through hole that is arc-shaped and centered at a hinge joint of the first side plates and the second side plates. A path of the through hole has at least one expansion groove. The limiting rod is axially movably connected with a corresponding second side plate. The limiting rod includes a first sections and a second section. A diameter of the first section is smaller than a diameter of the second section. A size of the first section matches a size of the through hole. A size of the second section matches a size of the at least one expansion groove.