Wrist mechanism

A wrist mechanism comprising:

• at least three tubular rigid elements, said rigid elements being rotatively connected in series to form a tubular wrist so that adjacent two elements are rotatable relative to each other about a rotation axis, any two adjacent rotation axes intersecting each other;
• a first drive connected to a first rigid element in said rigid element series for rotating both said first rigid element and every second rigid element;
• a second drive for rotating every other rigid element, the latter having an opening extending therethrough from end to end thereof defined by a tubular wall;
• first transmission means connecting both said first rigid element and said every second rigid element in a movement-locking manner, for transmitting rotation from said first rigid element to said every second rigid element, said first transmission means extending through said opening in said every other rigid element within the confines of said tubular wall;
• and
• second transmission means, connecting both said second drive and said every other rigid element in a movement-locking manner, for transmitting rotation from said second drive to said every other rigid element, said second transmission means being arranged to be within said tubular wrist, whereby said first drive rotates both said first rigid element and every second rigid element in synchronous rotation relative to said every other rigid element, and said second drive rotates said every other rigid element in independent synchronous rotation relative to both said first rigid element and said every second rigid element.