MAGNETIC BEARINGS TO REMOVE STICTION AND REDUCE VIBRATIONS IN MOMENTUM WHEELS

THIS PROJECT ADDRESSES MEANS TO IMPROVE THE OPERATIONAL PERFORMANCE AND LIFETIME OF EXISTING REACTION AND MOMENTUM WHEEL ASSEMBLIES ON SPACECRAFT. INSTRUMENTATION CARRIED ON SPACECRAFT IS BECOMING EVER MORE SENSITIVE AND INTOLERANT TO VIBRATIONS CAUSED BY MASS UNBALANCE ON REACTION-MOMENTUM WHEELS. RESONANT STRUCTURAL MODES OF THE SPACECRAFT CAN CAUSE UNEXPECTED AMPLIFICATION OF THE VIBRATIONS LEADING TO SERIOUS DEGRADATION IN INSTRUMENT PERFORMANCE. STICTION IN THE BALL BEARINGS OF REACTION WHEELS IS AN EVEN MORE SERIOUS PROBLEM ON EXTENDED MISSIONS. STICTION IN THE BEARINGS HAS BEEN SERIOUS ENOUGH TO COMPLETELY DISABLE SOME OF THE GPS SATELLITES. USE OF MAGNETIC BEARINGS ELIMINATES STICTION AND ALLOWS ACTIVE CONTROL IN ORDER TO MINIMIZE FORCES GENERATED BY THE MASS UNBALANCE. BOTH VIBRATION AND STICTION ISSUES ARE ADDRESSED AND A PHASE I PROGRAM IS OUTLINED FOR DESIGNING MAGNETIC BEARINGS AND A CONTROLLER TO ELIMINATE STICTION AND TO MINIMIZE VIBRATIONS IN REACTION/MOMENTUM WHEELS. PHASE II WILL BE TARGETED FOR PROTOTYPE DEVELOPMENT AND EVENTUALLY FLIGHT TESTING. THIS PROJECT ADDRESSES MEANS TO IMPROVE THE OPERATIONAL PERFORMANCE AND LIFETIME OF EXISTING REACTION AND MOMENTUM WHEEL ASSEMBLIES ON SPACECRAFT. INSTRUMENTATION CARRIED ON SPACECRAFT IS BECOMING EVER MORE SENSITIVE AND INTOLERANT TO VIBRATIONS CAUSED BY MASS UNBALANCE ON REACTION-MOMENTUM WHEELS. RESONANT STRUCTURAL MODES OF THE SPACECRAFT CAN CAUSE UNEXPECTED AMPLIFICATION OF THE VIBRATIONS LEADING TO SERIOUS DEGRADATION IN INSTRUMENT PERFORMANCE. STICTION IN THE BALL BEARINGS OF REACTION WHEELS IS AN EVEN MORE SERIOUS PROBLEM ON EXTENDED MISSIONS. STICTION IN THE BEARINGS HAS BEEN SERIOUS ENOUGH TO COMPLETELY DISABLE SOME OF THE GPS SATELLITES. USE OF MAGNETIC BEARINGS ELIMINATES STICTION AND ALLOWS ACTIVE CONTROL IN ORDER TO MINIMIZE FORCES GENERATED BY THE MASS UNBALANCE. BOTH VIBRATION AND STICTION ISSUES ARE ADDRESSED AND A PHASE I PROGRAM IS OUTLINED FOR DESIGNING MAGNETIC BEARINGS AND A CONTROLLER TO ELIMINATE STICTION AND TO MINIMIZE VIBRATIONS IN REACTION/MOMENTUM WHEELS. PHASE II WILL BE TARGETED FOR PROTOTYPE DEVELOPMENT AND EVENTUALLY FLIGHT TESTING.