US Patent 7698966 Control member with tensed cables

The control unit includes an arm (21) sliding inside of a sheath (20) the angle of which can be varied and which is supported by three tensed cables (25; 26; 27) arranged in a triangle and unwinding with a certain degree of resistance from force feedback motors (16; 17; 18). The wrist (23) of the control unit can be moved according to at least the three degrees of translational freedom, without having to be afraid of encountering the cables; the control unit is simple, inexpensive and possesses a satisfactory degree of stiffness. A friction-creating means, possibly consisting of another tensed cable and dependant on a motor, is placed between the sheath (20) and the arm (21).