Robotic Surgery Input Tracking Correction With Low-Latency LQE
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Solution Overview
Problem
Robotic surgery tracking inputs, generated by sensor circuits, are often noisy and imprecise, and may have sampling rates mismatched with the desired rates of the robotic surgery controller, necessitating correction for precision and repeatability in end effector movements.
Innovation Solution
A linear quadratic estimator (LQE) is employed to correct noisy tracking inputs and up-sample them to match the higher sample rate of the robotic surgery control system, incorporating a prediction phase and update phase with a Kalman filter gain, and a latency coefficient tuning to reduce latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensor circuit sampling rate is increased to match controller sample rate, then tracking input precision is improved, but device complexity and data processing burden increase
Solution Approach 1:
A linear quadratic estimator (LQE) is introduced as an intermediary component between the sensor circuit and the robotic surgery controller. The LQE receives lower-rate, noisier tracking input from the sensor circuit and produces higher-rate, corrected tracking output for the controller. This mediator resolves the contradiction by providing precision through algorithmic correction rather than through hardware sampling rate increases, thereby avoiding the complexity and cost of high-speed sensors.
2Measurement precision
If tracking input is corrected using traditional filtering methods, then noise is reduced, but latency increases
Solution Approach 1:
The LQE dynamically adjusts its internal parameters (prediction coefficients, gain values) based on the characteristics of the tracking input and the desired output sample rate. By changing these parameters adaptively, the system achieves effective noise filtering while maintaining minimal latency. The estimator optimizes the balance between smoothing noisy data and responding quickly to actual movement changes, resolving the contradiction between noise reduction and latency.
3Productivity
If LQE prediction phase runs at higher rate than input sample rate, then up-sampling is achieved, but computational load increases
Solution Approach 1:
The LQE computation is segmented into distinct phases: a prediction phase that runs continuously at the higher output sample rate, and an update phase that executes only when new sensor data arrives. This segmentation allows the system to maintain high output productivity through frequent predictions while reducing computational energy consumption by limiting expensive update calculations to only when necessary. The prediction phase uses lightweight recursive formulas that are computationally efficient.
Data Source
AI summary
A sequence of input samples that are measures of position or orientation of an input device being held by a user are received. 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 input device. The current output sample is computed based on i) a previously computed output sample, and ii) a velocity term. An updated output sample of the state of the LQE is computed, based on i) a previously computed output sample, and ii) a new input sample. Other embodiments are also described and claimed.


