  The aim of this paper is to present a new six degree-of-freedom (dof) haptic
device using two parallel mechanisms. The first one, called orthoglide,
provides the translation motions and the second one produces the rotational
motions. These two motions are decoupled to simplify the direct and inverse
kinematics, as it is needed for real-times 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. The main feature of the orthoglide and of the agile eye mechanism
is the existence of an isotropic configuration. The length of the legs and the
range limits of the orthoglide are optimized to have homogeneous performance
throughout the Cartesian workspace, which has a nearly cubic workspace. These
properties permit to have a high stiffness throughout the workspace and
workspace limits that are easily understandable by the user.
