  This paper is devoted to the kinematic design of a new six degree-of-freedom
haptic device using two parallel mechanisms. The first one, called orthoglide,
provides the translation motions and the second one, called agile eye, produces
the rotational motions. These two motions are decoupled to simplify the direct
and inverse kinematics, as it is needed for real-time control. To reduce the
inertial load, the motors are fixed on the base and a transmission with two
universal joints is used to transmit the rotational motions from the base to
the end-effector. Two alternative wrists are proposed (i), the agile eye with
three degrees of freedom or (ii) a hybrid wrist made by the assembly of a
two-dof agile eye with a rotary motor. The last one is optimized to increase
its stiffness and to decrease the number of moving parts.
