Method and system for assessing orthopedic alignment using tracking sensors

A system for positional measurements, comprising:

• three or more ultrasonic transmitters on a first device for transmitting at a first location a first sequence of ultrasonic signals through air, and
• three or more receivers on a second device for receiving the first sequence of ultrasonic signals and thereafter receiving a second sequence of ultrasonic signals transmitted by the first device;
• a phase detector on the second device operatively coupled to the receivers for identifying a series of phase differences between the first sequence of ultrasonic signals and the second sequence of ultrasonic signals;
• and
• a processor operatively coupled to the phase detector and the sensing unit to:
• measure a first series of Time of Flights (TOF) for the first sequence of received ultrasonic signals to produce an expected location of the object at a first location,
• measure a second series of Time of Flights (TOF) for the second sequence of received ultrasonic signals to produce an estimated location of the object at a second location,
• apply a weighted difference of the expected location and the estimated location to the phase difference to produce a relative displacement,
• update the expected location of the first device with the relative displacement, and
• report the expected location of a cutting jig coupled to the first device.

A method resolving object movement and position, the method comprising the steps of:

• monitoring a movement of a first device from a first sequence of Time of Flight (TOF) measurements from ultrasonic signals transmitted from the first device to a second device to produce an expected location of the first device;
• estimating a location of the first device to produce an estimated location from a second sequence of Time of Flight (TOF) measurements from ultrasonic signals transmitted from the first device to the second device;
• calculating a set of phase differences between the first sequence of Time of Flight (TOF) measurements and the second sequence of Time of Flight (TOF) measurements;
• weighting a difference of the expected location and estimated location with the set of phase differences to produce a relative displacement of the first device;
• updating the expected location of the first device in view of the estimated location with the relative displacement;
• and
• reporting a position of a cutting jig coupled to the first device at the expected location.

A system for positional measurements, comprising:

• three ultrasonic transmitter on a first device for transmitting at a first location a first sequence of ultrasonic signals through air;
• a receiver on a second device for capturing the first sequence of ultrasonic signals and a second sequence of ultrasonic signals transmitted by the ultrasonic transmitter on the first device during movement to a second location;
• a phase detector on the second device operatively coupled to the receiver for identifying a series of phase differences between the first sequence of ultrasonic signals and the second sequence of ultrasonic signals;
• and
• a processor on the second device operatively coupled to the phase detector and a sensing unit comprising the receiver for updating an expected location of the first device using the series of phase differences for:
• measuring a first series of Time of Flights (TOF) between the transmitting of the first sequence of ultrasonic signals and the capturing of the second sequence of ultrasonic signals, and producing therefrom the expected location of the first device at the first location,
• measuring a second series of Time of Flights (TOF) between the transmitting of the first sequence of ultrasonic signals and the capturing of the second sequence of ultrasonic signals, and producing therefrom an estimated location of the first device at the second location,
• determining a relative displacement of the first device by weighting a difference of the expected location and estimated location with the phase difference, and
• reporting a position of a cutting jig coupled to the first device in accordance with the relative displacement wherein the estimated location is determined from the second series of Time of Flight (TOF) measurements, and the relative displacement is evaluated within a minimized error region determined from a series of differential time of flight (dTOF) measurements.

A system for positional measurements, comprising:

• an ultrasonic transmitter on a first device for transmitting at a first location a first sequence of ultrasonic signals through air;
• a receiver on a second device for capturing the first sequence of ultrasonic signals and a second sequence of ultrasonic signals transmitted by the ultrasonic transmitter on the first device during movement to a second location;
• a phase detector on the second device operatively coupled to the receiver for identifying a series of phase differences between the first sequence of ultrasonic signals and the second sequence of ultrasonic signals;
• and
• a processor on the second device operatively coupled to the phase detector and a sensing unit comprising the receiver for updating an expected location of the first device using the series of phase differences for:
• measuring a first series of Time of Flights (TOF) between the transmitting of the first sequence of ultrasonic signals and the capturing of the second sequence of ultrasonic signals, and producing therefrom the expected location of the first device at the first location,
• measuring a second series of Time of Flights (TOF) between the transmitting of the first sequence of ultrasonic signals and the capturing of the second sequence of ultrasonic signals, and producing therefrom an estimated location of the first device at the second location,
• determining a relative displacement of the first device by weighting a difference of the expected location and estimated location with the phase difference, and
• reporting a position of a prosthetic insert having at least one articular surface coupled to the first device in accordance with the relative displacement wherein the estimated location is determined from the second series of Time of Flight (TOF) measurements, and the relative displacement is evaluated within a minimized error region determined from a series of differential time of flight (dTOF) measurements.