2. The role of a coupling

The coupling located after the actuator transmits the rotary motion to the end effector. In the kinematic chain of the mechanism to be designed, it can have the following different roles (figure 2 ):

— rotational motion transmitter: angular information at the system input is transmitted (distorted or not) to the system output;

— torque transmitter: the speeds of rotation on either side of the coupling can be different. However, the torque on the input shaft is fully transmitted to the output shaft;