# Multi-Frequency Tracker for Control of Handheld Surgical Robotic Systems

> **NIH NIH R01** · CARNEGIE-MELLON UNIVERSITY · 2021 · $329,820

## Abstract

Currently available surgical trackers are inadequate for microsurgery, and especially for robotic
microsurgical systems where the tracker is inside the control loop. This problem is exacerbated in the case of
handheld microsurgical systems, where small and rapid (1-20 Hz) disturbances such as physiological tremor
must be correctly tracked and accounted for by the control system. As a result, for the most demanding types
of microsurgery, such as vitreoretinal microsurgery, few suitable tracking systems exist. Available commercial
systems are not designed for microsurgery, and their accuracy is inadequate for the task. More importantly,
their latency makes them unsuitable for inclusion within the control loop of active handheld robotic instruments.
 The two main operating principles used in surgical trackers are optical and electromagnetic (EM). Optical
trackers have better accuracy, but have a serious flaw when used for closed-loop control: any obstruction of
sensor sightlines may cause control to fail. The surgeons who have used “Micron,” a handheld
micromanipulator under development in our laboratory, have repeatedly identified this need for sightlines as
the main factor preventing it from being clinically compatible. Micron is just one example; any handheld
instrument incorporating closed-loop control and optical tracking (e.g., Navio™) faces the same problem.
 We propose to develop an innovative medical tool tracker, the In-Loop Electromagnetic Tracker (ILEMT).
The goal: > 50x improvement in latency, while maintaining the interference rejection of the best existing EMTs.
Dual-path high/low carrier modulation combines the best qualities of AC and pulsed-DC EMTs, while
frequency-domain multiplexing pushes bandwidth and resolution well beyond that of commercial offerings. A
class-D current source will efficiently drive arbitrary signals into the source coil, allowing simultaneous emission
of two or more carriers on each axis for metallic error compensation, with low-noise signal conditioning and
data acquisition will to maximize resolution. A software-defined architecture implements signal processing in
software and FPGA firmware, maximizing flexibility.
 The ultimate goal of this research is to develop a production-quality EMT with an open architecture (under
CC-BY copyright), as a crucial enabling technology for handheld microsurgical robotics. It also has potential
for significant advances in the science of microsurgery, and for microsurgical assessment in vivo. The specific
aims are to:
 1. Develop a three-channel prototype and demonstrate measurement in six degrees of freedom (6DOF).
 2. Develop signal processing algorithms for metallic and EM interference rejection.
 3. Develop a reference ILEMT design and test it to verify performance goals are achieved. We will
compare ILEMT performance with 2 commercial EM trackers.
 4. Integrate ILEMT with the instruments Micron and Navio and test in animals in vivo and in cadavers.

## Key facts

- **NIH application ID:** 10073512
- **Project number:** 5R01EB024564-04
- **Recipient organization:** CARNEGIE-MELLON UNIVERSITY
- **Principal Investigator:** Cameron N Riviere
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $329,820
- **Award type:** 5
- **Project period:** 2018-03-01 → 2023-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10073512

## Citation

> US National Institutes of Health, RePORTER application 10073512, Multi-Frequency Tracker for Control of Handheld Surgical Robotic Systems (5R01EB024564-04). Retrieved via AI Analytics 2026-05-21 from https://api.ai-analytics.org/grant/nih/10073512. Licensed CC0.

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