Let us examine the manipulator of which the structure is described at Fig. 1. This
manipulator is composed of three identical legs (Fig. 2) linked to both the fixed base and the
moving platform. Each leg is composed of one actuated revolute joint Qi
(i = 1, 2, 3) mounted
onto the base and linked to an articulated parallelogram Ai
Bi
Ci
Di
. Each parallelogram is
connected to a rod Ti
Pi
through a revolute joint. Finally, rods Ti
Pi
are connected to the moving
platform by means of another revolute joint Pi
. Such a structure corresponds to a Delta robot
of which the legs are turned. Therefore, the degrees of freedom of the manipulator are 3
translations of the platform.