MAGNETOSTRICTIVE ACTIVE-MEMBER FOR CONTROL OF SPACE STRUCTURES

NEW SPACECRAFT DESIGNS FEATURE LARGE STRUCTURES CHARACTERIZED BY LOW NATURAL FREQUENCIES, LIGHTLY DAMPED STRUCTURAL MODES, AND STRINGENT SHAPE CONTROL REQUIREMENTS. THESE LARGE SPACE STRUCTURES (LSS) POSE UNIQUE AND DIFFICULT CONTROL PROBLEMS. AN IMPORTANT PART OFTHE SOLUTION TO THIS CONTROL PROBLEM IS THE DEVELOPMENT OF ACTUATORS NECESSARY TO IMPLEMENT ACTIVE STRUCTURAL CONTROL. ONE PROMISING APPROACH TO THE PRECISION CONTROL OF LARGE SPACE STRUCTURES IS THE USE OF ACTIVE TRUSS MEMBERS. THESE ACTIVE TRUSSES ARE STRUCTURAL MEMBERS THAT INCORPORATE SENSORS AND ACTUATORS, ALLOWING CLOSED LOOP CONTROL OF BOTH THE SPACE STRUCTURE SHAPE AND SUPPRESSION OF UNWANTED STRUCTURAL VIBRATIONS. IN THE PAST, THESE ACTIVE TRUSS MEMBERS HAVE INCORPORATED PIEZOELECTRIC OR ELECTRODYNAMIC ACTUATORS. RECENT DEVELOPMENTS IN MAGNETOSTRICTIVE MATERIALS, HOWEVER, OFFER THE OPPORTUNITY FOR INCREASED STRAIN, INCREASED POWER DENSITY, AND DECREASED HYSTERESIS COMPARED TO PIEZOELECTRIC MATERIALS. FOR EXAMPLE, MAXIMUM STRAINS AND POWER DENSITIES CAN BE OVER A ORDER OF MAGNITUDE HIGHER THAN FOR PIEZOELECTRICS. INNOVATIONS ARE NEEDED, HOWEVER, TO INTEGRATE THESE HIGH PERFORMANCE MAGNETOSTRICTIVE MATERIALS INTO ACTIVE TRUSS MEMBERS. THIS PROPOSED RESEARCH EFFORT WILL DEVELOP ADVANCED ACTIVE TRUSS MEMBERS BASED ON MAGNETOSTRICTIVE MATERIALS, INCLUDING THE ASSOCIATED SENSORS AND CONTROLLER.