*2.1.1 Mechanical system*

Mechanical structure (surgical drill) with two degrees of freedom is proposed (**Figure 2**). It has one translation and one revolute joint with co-linear axes, where q1 and q2 are corresponding generalized coordinates. The new assembly drawing which corresponds to the new construction is shown in **Figure 3**.

Both actuators are mounted inside the drilling module. All parts of the mechanical module are made by stainless steel material for assuring the sterility requirements. The machine allows gas chemical sterilization before every manipulation.
