Instrument mounting system with dual encoders

A method for measuring the position of an instrument, comprising:

• (a) mounting the instrument on an instrument shaft for rotation thereabout;
• (b) linking the instrument shaft to a motor shaft adapted to receive torque from a motor, such that:
• (i) in a first operating mode, the instrument shaft is engaged with the motor shaft and operable to rotate upon the urging of torque received from the motor shaft;
• and
• (ii) in a second operating mode, the instrument shaft is disengaged from the motor shaft and operable to rotate independently of the motor shaft;
• (d) generating a motor shaft position signal (“MSP signal”) responsive to the position of the motor shaft;
• (e) generating an instrument shaft position signal (“ISP signal”) responsive to the position of the instrument shaft;
• and
• (f) measuring the position of the instrument as a function of the MSP signal and the ISP signal.

An apparatus for measuring the position of an instrument, comprising:

• (a) means for mounting the instrument for rotation;
• (b) means for mounting a motor, the motor mounting means being adapted to transmit torque received from the motor;
• (b) means for linking the instrument mounting means to the motor mounting means, the linking means having first and second operating modes, such that:
• (i) in the first operating mode, the instrument mounting means is engaged with the motor mounting means and operable to rotate upon the urging of torque received from the motor mounting means;
• and
• (ii) in the second operating mode, the instrument mounting means is disengaged from the motor mounting means and operable to rotate independently of the motor mounting means;
• (d) means for generating a motor mounting means position signal (“MMMP signal”) responsive to the position of the motor mounting means;
• (e) means for generating an instrument mounting means position signal (“IMMP signal”) responsive to the position of the instrument mounting means;
• and
• (f) means for measuring the position of the instrument as a function of the MMMP signal and the IMMP signal.

A computer program embodied in a processor-readable medium for measuring the position of an instrument mounted on an instrument shaft for rotation thereabout, the instrument shaft being linked to a motor shaft adapted to receive torque from a motor such that in a first operating mode the instrument shaft is engaged with the motor shaft to rotate upon the urging of torque received from the motor shaft and in a second operating mode the instrument shaft is disengaged from the motor shaft and free to rotate independently of the motor shaft, comprising code segments that direct a processor to:

• (a) generate a motor shaft position signal (“MSP signal”) responsive to the position of the motor shaft;
• (b) generate an instrument shaft position signal (“ISP signal”) responsive to the position of the instrument shaft;
• and
• (c) measure the position of the instrument as a function of the MSP signal and the ISP signal.

A computer data signal embodied in a carrier wave for measuring the position of an instrument mounted on an instrument shaft for rotation thereabout, the instrument shaft being linked to a motor shaft adapted to receive torque from a motor such that in a first operating mode the instrument shaft is engaged with the motor shaft to rotate upon the urging of torque received from the motor shaft and in a second operating mode the instrument shaft is disengaged from the motor shaft and free to rotate independently of the motor shaft, comprising code segments that direct a processor to:

• (a) generate a motor shaft position signal (“MSP signal”) responsive to the position of the motor shaft;
• (b) generate an instrument shaft position signal (“ISP signal”) responsive to the position of the instrument shaft;
• and
• (c) measure the position of the instrument as a function of the MSP signal and the ISP signal.