A mixed reality presentation apparatus and control method thereof which can allow for suitable display of a virtual object depending on tone, brightness, and lighting conditions of a physical space on which the virtual object is superimposed and displayed is disclosed. A adapter is fitted onto the prongs of the cord, and semi-permanently attached with a connector including two half housings that fasten over the plug and a clamp that holds the cord. The compliance mechanism is coupled to the client system. In various embodiments, the end effector also includes a gripper, for gripping tissue in cooperation with the ultrasound probe tip. The method includes generating at least one access request based upon at least one first sequence number associated with the mobile unit and receiving at least one message formed based upon the access request, the message including at least one second sequence number associated with the authentication center, the second sequence number selected to be acceptable to the mobile unit.