Displacement mechanism

A displacement mechanism, comprising:

• a base;
• three rails standing on the base;
• three arm assemblies each having a first end and a second end, wherein the first ends of the arm assemblies are respectively slidably connected to the rails, and each of the arm assemblies is configured to swing in a space among the rails;
• a moving platform parallel to the base;
• three parallel linkage assemblies, two ends of each of the parallel linkage assemblies being respectively connected to the second end of the corresponding one of the arm assemblies and the moving platform in a multidirectional rotating way;
• and
• a connecting structure connected to the second ends of the arm assemblies in a multidirectional rotating way, wherein any two of the second ends of the arm assemblies define the same distance,
• wherein each of the arm assemblies substantially extends away from the base from the corresponding one of the rails, and each of the parallel linkage assemblies substantially extends toward the base from the second end of the corresponding one of the arm assemblies.