Correcting a robotic surgery user interface device tracking input
A sequence of tracking input samples that are measures of position or orientation of a user interface device, UID, being held by a user, are received. In a prediction phase, a current output sample of a state of linear quadratic estimator, LQE, is computed that is an estimate of the position or orientation of the UID. The current output sample is computed based on i) a previously computed output sample, and ii) a velocity term. In an update phase, an updated output sample of the state of the LQE is computed, based on i) a previously computed output sample from the prediction phase, and ii) a most recent tracking input sample. Other embodiments are also described and claimed.
1. A method for correcting a user interface device, UID, tracking input in a robotic surgery system, the method comprising:
producing an output sequence that is an estimate of position or orientation of the UID, by
receiving an input sequence of tracking input samples that are measures of position or orientation of the UID,
while a new tracking input sample in the input sequence has not been received, computing a current output sample in the output sequence, wherein the current output sample is computed based on i) a previously computed output sample, and ii) a velocity term, and
when the new tracking input sample is received, compute a new output sample in the output sequence, based on i) a previously computed output sample, and ii) the new tracking input sample.
2. The method of claim 1 wherein computing the current output sample is based on a tuning parameter that adjusts a sample-to-sample time interval used in a system model of the UID.
3. The method of claim 2 wherein the sample-to-sample time interval used in the system model comprises a sum of i) the tuning parameter and ii) a nominal sampling period of the output sequence.
4. The method of claim 1 wherein when the new tracking input sample is received, the new output sample is computed by computing a Kalman filter gain.
5. The method of claim 1 wherein the input sequence has a sampling rate that is lower than that of the output sequence.
6. The method of claim 1 wherein the input sequence of tracking input samples is a sequence of orientation vectors, and the output sequence is an estimate of the orientation of the UID.
7. The method of claim 1 wherein while the new tracking input sample in the input (original) sequence has not been received, the current output sample in the output sequence is computed from a window of a plurality of previously computed output samples, by a) fitting a line to the previously computed output samples in the window, and b) taking a derivative of the line to be the velocity term.
8. The method of claim 7 further comprising
wherein while the new tracking input sample in the input sequence has not been received; computing a next output sample in the output sequence based on i) another previously computed output sample, and ii) another velocity term, by
moving the window forward so that another plurality of previously computed output samples are within the window, and
repeating a) and b) using the moved window to compute said another velocity term.
9. The method of claim 7 wherein while the new tracking input sample has not been received, the current output sample is computed based on the velocity term, and when the new tracking input sample is received the new output is computed using only a previously computed output sample and not a velocity term.
10. The method of claim 1 wherein while the new tracking input sample has not been received the current output sample is computed based on the velocity term, and when the new tracking input sample is received the new output is computed using only a previously computed output sample and not a velocity term.
11. An article of manufacture comprising:
a machine-readable medium having stored therein instructions that when executed by a processor correct a user interface device, UID, tracking input in a robotic surgery system, by producing an output sequence that is an estimate of position or orientation of the UID, wherein the processor is to
receive an input sequence of tracking input samples that are measures of the position or the orientation of the UID,
while a new tracking input sample in the input sequence has not been received, compute a current output sample in the output sequence, wherein the current output sample is computed based on i) a previously computed output sample, and ii) a velocity term, and
when the new tracking input sample is received, compute a new output sample in the output sequence, based on i) a previously computed output sample, and ii) the new tracking input sample.
12. The article of manufacture of claim 11 wherein the instructions, when executed by the processor, compute the current output sample based on a tuning parameter that adjusts a sample-to-sample time interval used in a system model of the UID.
13. The article of manufacture of claim 12 wherein the sample-to-sample time interval used in the system model comprises a sum of i) the tuning parameter and ii) a nominal sampling period of the output sequence.
14. The article of manufacture of claim 11 wherein when the new tracking input sample is received, the new output sample is computed by computing a Kalman filter gain.
15. The article of manufacture of claim 11 wherein the input sequence has a sampling rate that is lower than that of the output sequence.
16. The article of manufacture of claim 11 wherein the input sequence of tracking input samples is a sequence of orientation vectors, and the output sequence is an estimate of the orientation of the UID.
17. The article of manufacture of claim 11 wherein while the new tracking input sample in the input sequence has not been received, the current output sample in the output sequence is computed from a window of a plurality of previously computed output samples, by a) fitting a line to the previously computed output samples in the window, and b) taking a derivative of the line to be the velocity term.
18. The article of manufacture of claim 17 wherein the instructions configure the processor to
while the new tracking input sample in the input sequence has not been received, compute a next output sample in the output sequence based on i) another previously computed output sample, and ii) another velocity term, by,
moving the window forward so that another plurality of previously computed output samples are within the window, and
repeating a) and b) with the moved window to compute said another velocity term.
19. A robotic surgery system comprising:
a processor; and
a machine-readable medium having stored therein instructions that when executed by the processor correct a user interface device, UID, tracking input, by producing an output sequence that is an estimate of a position or an orientation of the UID, wherein the processor is to receive an input sequence that are measures of the position or the orientation of the UID,
compute a current output sample of the output sequence, wherein the current output sample is computed based on i) a previously, computed output sample, and ii) a velocity term, and
when a new tracking input sample of the input sequence is received, compute a new output sample of the output sequence, based on i) previously computed output sample, and ii) the new tracking input sample.
20. The system of claim 19 wherein while the new tracking input sample has not been received, the current output sample in the output sequence is computed from a window of a plurality of previously computed output samples, by a) fitting a line to the previously computed output samples in the window, and b) taking a slope of the line to be the velocity term.