When performing measurement of the balance through the COP can try to estimate the location and the CoM shifts through different techniques. What is the best technique? What is the most reliable for analysis?
Dear Silva , I think if you have motion analysis is very good technique, Also CoP recording by force plate and use of some equations (winter equations) is very simple approach for CoM estimation.
You need to check out the work by David Winter - the very early reference/go to guide on physiological measurement: Biomechanics and Motor Control of Human Movement and review article from 1995, human balance and posture control during standing and walking (widely available via Google!). There he discusses the misunderstanding between COP and CoM. Measuring one doesn't inform the other!
CoM trajectories may be quantified by accelerometers placed on the lower back, typically L5. There is an abundance of literature than has used such techniques in pathology and ageing. Fay Horak and Martina Mancini (again Google will point to their work), my colleague Silvia Del Din (Journal article: Time‑dependent changes in postural control in early Parkinson’s disease: what are we missing? Med Biol Eng Computing, 2015). As well as those associated with the NIH Toolbox work: Whitney (A comparison of accelerometry and center of pressure measures during computerized dynamic posturography: A measure of balance. Gait & Posture) and RoseMarie Rine (Vestibular function assessment using the NIH Toolbox).
Hope that helps
Hi
You need to read up on the work by David winter from the early to mid 90's. For instance his review: Human Balance and posture control during standing and walking. For instance how previous COP measurement been misinterpreted as CoM displacement.
Moreover, accelerometers worn on the lower back near the:CoM to quantify trajectories Fay Horak and Martina Mancini have published a lot in this area (Google will throw up many papers). Also my colleague Silvia Del Din has a recent twist on that type of analysis and change in CoM trajectories over time, Time‑dependent changes in postural control in early Parkinson’s disease: what are we missing? Med Biol Eng Comp, 2015. Also of interest might be the work relating to the NIH Toolbox and vestibular functioning. Whitney et al. A comparison of accelerometry and center of pressure measures during computerized dynamic posturography: A measure of balance and applied in the work by Rine et al Vestibular function assessment using the
NIH Toolbox (Neurology)
Hope that helps
For single body segment under static situations, its CoM location can be estimated through moment-subtraction methods described by Williams and Lissner (Leveau, 1997, p214). For CoM location of whole body, motion capture technique could be used for estimation. Another simpler way for your study could be just attach an IMU sensor on the lower back (approximate CoM) to record the CoM trajectories, as suggested by Alan Godfrey.
the most complete measure of COM to date a 21 marker, 14 segment model that has been used to determine the mechanisms of balance during quiet standing (Winter et al., 1998)
Hi everyone,
Thanks for your response. I will apply the classic Winter's method, which I think it will be the most appropriate for my case. The accelerometer technique is interesting, but I didn't use this instrumentation to obtain the CoM in my research, however I believe that I will use in future studies, it seems very interesting measure technique.
Hi Marcelo. We are trying something new out in this area. You might want to take a look at http://academic.udayton.edu/murray/DIMLAB/pubs/conference/2015/T2OC-3.pdf. Unfortunately, this isn't our most recent work which streamlines the process significantly compared to the work presented in that paper. That publication is currently under preparation, but you can find most of it in an upcoming dissertation. I can supply a draft if interested.
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