Active torque reduction for hydraulically filled joints

A system for reducing starting torque and assuring smoothness of motion comprising:

• a rotary joint having first annular joint member and a second annular joint member separated by a fluid-filled annulus, said second annular joint member being adapted for rotary motion with respect to said first annular joint member;
• a motion module fluidly communicating with said fluid-filled annulus for creating vibratory motions in said fluid of said fluid-filled annulus, said motion module comprising:
• a cavity in one of said annular joint members, said cavity being in fluid communication with said fluid of said fluid-filled annulus;
• a magnetostrictive element in said cavity;
• and
• a control section connected to said magnetostrictive element to create and couple AC signals to displace said magnetostrictive element and create responsive vibratory motions of said fluid of said fluid-filled annulus;
• and
• a pair of seals extending between said first annular joint member and said second annular joint member, said seals having said fluid-filled annulus therebetween, said vibratory motions inducing motions in said seals of said rotary joint and said motions in said seals reducing initial torque for initial rotational displacement of at least one of said annular joint members and assuring smoothness of continuing displacement of at least one of said annular joint members.