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View Full Version : Re: Measurement of the position of a c hopstick's tip usingaccelerometer



Van Den Bogert, Ton
05-21-2008, 01:48 AM
Gyusung Lee asked:

> Q1. What would be the best way to calculate relative position
> of the sensor from the acceleration data? Does a simple
> routine of double integration of acceleration provide with
> good data of relative position?

I doubt that this will work for your application. First, accelerometers
are sensitive to tilt, and to compensate for this, you need an
integrated sensor with accelerometer, gyroscope and magnetic field
sensor, such as the devices from Xsens, Intersense, or Microstrain.
Then you can measure true acceleration. The next problem is that double
integration leads to drift so you can only get information about
relative motion on a short time scale. If absolute position or longer
time scale is important for your application, accelerometers would
probably not work. If anyone from these companies subscribes to
Biomch-L, additional comments would be welcome (me speaking as Biomch-L
moderator here). It would be nice to have some information about
precision of actual devices.

You might consider optical tracking technology that is more suitable
(than Vicon) for the operating room, such as Optotrak which is used in
surgical navigation. Your hospital may already have one.

Our department of obstretrics and gynaecology is starting to do movement
analysis during laparoscopy, but related to performance (speed and
precision) rather than ergonomics. They are using standard video and
manual digitization. We just submitted an abstract to the American
Uro-Gynaecological Society. While searching for related work, I came
across a publication describing the use of gyroscopic sensors to
quantify angular motion (not position!) during laparoscopy:

Kondraske GV, Hamilton EC, Scott DJ, Fischer CA, Tesfay ST, Taneja R,
Brown RJ, Jones DB. Surgeon workload and motion efficiency with robot
and human laparoscopic camera control. Surg Endosc. 2002
Nov;16(11):1523-7.

Considering you are at U of Maryland, you are probably familiar with the
work at Johns Hopkins, but here is the link anyway for the archives:
http://www.cs.jhu.edu/CIRL/projects/SurgicalModeling/

--

Ton van den Bogert
Department of Biomedical Engineering
Cleveland Clinic Foundation
http://www.lerner.ccf.org/bme/bogert/


> -----Original Message-----
> From: * Biomechanics and Movement Science listserver
> [mailto:BIOMCH-L@NIC.SURFNET.NL] On Behalf Of Gyusung Lee
> Sent: Tuesday, May 20, 2008 4:10 PM
> To: BIOMCH-L@NIC.SURFNET.NL
> Subject: [BIOMCH-L] Measurement of the position of a c
> hopstick's tip using accelerometer
>
> Dear all subscribers,
>
>
> Well... it is not really with chopstick but the idea is the
> same. For ergonomic studies in laparoscopy, I am using Vicon
> MX system with a cluster of markers attached to the handles
> of a laparoscopic long-shaft instrument to measure the
> movement of the surgical instrument. By creating a virtual
> marker at the tip location using BodyBuilder model, I had a
> good tracking data. Now, I would like to do it in real OR
> during cases. As you can imagine, bring down my Vicon system
> into OR is not be an easy job so I started thinking of
> alternatives. I just remembered some discussions about 3d
> accelerometers a few days ago from Biomch-L. I am trying to
> check the feasibility of this technology on my application
> but do not have any personal experience with accelerometer.
> Here are my two questions. Your explanations and suggestions
> will be very appreciated.
>
>
>
> Q1. What would be the best way to calculate relative position
> of the sensor from the acceleration data? Does a simple
> routine of double integration of acceleration provide with
> good data of relative position?
>
>
>
> Q2. Any recommendations of small accelerometers with a good
> precision? I have started checking the information from
> previous discussion on accelerometers.
>
> Sincerely,
>
> Gyusung Lee, Ph.D.
> ------------------------------------------------
> Faculty Research Associate
> Director, Surgical Ergonomics Laboratory Maryland Advanced
> Simulation, Training, Research and Innovation Center
>
> University of Maryland
> School of Medicine
> Department of Surgery
> 22 South Greene St. Room S7B15
> Baltimore, MD 21201
> Phone: (410) 328-0185
> Fax: (410) 328-4084
> ------------------------------------------------
>
> ---------------------------------------------------------------
> Information about BIOMCH-L: http://www.Biomch-L.org
> Archives: http://listserv.surfnet.nl/archives/Biomch-L.html
> ---------------------------------------------------------------
>
>


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