Vibration actuator suitable for use in magnetic field environment and medical system

A medical system including:

• an articulated robot that performs diagnosis or an operation on a subject, said articulated robot having a plurality of joints, and
• a vibration actuator in which a vibration element and a driven element are brought into pressure contact with each other, and vibration is excited in said vibration element to thereby move said driven element and said vibration element relative to each other, said vibration actuator being assembled into each joint for enabling said joint to perform rotational movement,
• said vibration element comprising:
• an elastic body of which a main ingredient comprises a material which is electrically insulating, dielectric, or semi-conductive;
• and
• an electromechanical energy conversion element that is joined to said elastic body,
• said electromechanical energy conversion element comprising:
• a piezoelectric body;
• a first electrode that is provided on a surface of said piezoelectric body, via which surface said piezoelectric body is joined to said elastic body, said first electrode having an open loop structure;
• at least two second electrodes that are provided in a manner opposed to said first electrode via said piezoelectric body;
• and
• a conduction path that electrically connects said first electrode and at least one second electrode of said at least two second electrodes,
• wherein a gap is formed between said at least two second electrodes.