Command generation is codified by a state machine defining the time-dependent state (command) of the system, as shown in Fig. 5(b). With the semiautomatic guidance strategy, the users themselves have to scan the various commands and also effect a certain “action.” The user can thus move over the active commands until settling on the desired one. Once selected, it has to be validated, by an action or by simple lapse of time. In this case, it has been opted for time-validation, i.e., if a given command remains selected for a given period of time, it is then validated and the associated control action is executed. The validation time interval has to be adapted to the characteristics of each user. The command is deactivated when another movement action is executed.