Attitude control system with independent controllers for controlling onboard units

An attitude control system for onboard units comprising:

• a plurality of attitude adjusting means each including electric drive means operable to adjust the attitude of each of mutually different onboard units;
• at least one master switch means for delivering a primary attitude control command related to all of the plurality of attitude adjusting means;
• master electronic control means operable in accordance with a given control program and connected to the master switch means and at least one of the plurality of attitude adjusting means for controlling the at least one connected attitude adjusting means in response to the primary attitude control command and for delivering a secondary attitude control command in response to the primary attitude control command;
• and
• slave electronic control means operable in accordance with an independent control program which is separate from the program associated with the master electronic control means and connected to the remaining ones of the plurality of attitude adjusting means and the master electronic control means for controlling the connected ones of the plurality of attitude adjusting means in response to the secondary attitude control command delivered by the master electronic control means;
• said master electronic control means delivers information which depends on the attitude or attitudes of a first set of attitude adjusting means which is or are controlled by the master electronic control means, to be transmitted to the slave electronic control means;
• said slave electronic control means delivers information which depends on the attitude or attitudes of a second set of attitude adjusting means which are controlled by the slave electronic control means, to be transmitted to the master electronic control means;
• said master electronic control means responding to the attitude information from the second set of attitude adjusting means which is delivered by the slave electronic control means by controlling the first set of attitude adjusting means;
• and
• said slave electronic control means responding to the attitude information of the first set of attitude adjusting means which is delivered by the master electronic control means by controlling the second set of attitude adjusting means.