Here's the final version of the introductory article. Sorry for the length, but I'm defining an entire level of detail for a very scientific industry. This version contains all of the clinical article, plus extra discussions relevant to tracking.
Future work will expand applications in the various areas where the method is relevant, like robotics, clinical, SAR, multi-ped, etc.
Clinical is the priority right now, since work done in clinical can also be used for SAR and the others, but not vice versa.
I'm right in the middle of making a spreadsheet program to calculate the 8 parameters (and many other new measures) from currently available 3D co-ordinate data. Fortunately, I think direction changes due to each of the parameters is so large that the very minor errors with estimating the 4 minimum points (since they can't be directly marked or defined, being inside the body or on the sole of the foot) are very tolerable. As long as it's noted the data source and estimation method.
...Mike Mouck
From the first contact with the author...
There's probably no need to know all parts of the measurement system in order to apply it to SAR. It's important to realize, though, that absolutely all observed footprint patterns, under any conditions, can be measured using the 8 parameters.
Unfortunately, the 4 points of gait (and foot-line), at the proper time of heel-contact, are not measurable from a footprint pattern, since they're in the air. But, that doesn't mean the system can't be applied. At least now we know the correct body segments and joints which are involved in distance and direction when walking.
And, it's all about distance and direction. That's why humans evolved the ability to walk. If this is indeed true, then it's reasonable to assume that muscular and other controls developed to facilitate these, and so should be definable as specific sets associated with each parameter. This will simplify the application to SAR.
Also, you should realize that there's nothing to validate in this system. There are no theories and nothing to prove. This is a series of measurements which are based on the 2D projection of the 4 minimum points and foot-line. The appropriate question is how useful are these measurements, not whether they're right or wrong. There is no right or wrong.. The big job now is to use the measurements to study how people walk.
But, I believe these parameters are very important for all aspects of gait analysis, even critical, since they show, for a single step, the contributions to distance and direction from specific body segments and joint rotations. The rotating reference grid is also a very important element. Currently, inappropriate reference lines (like "line of progression") are used for gait measurements, which don't take into account the specific direction elements of a step.
I've scanned the internet and been in contact with a clinical gait researcher, so I know 1) this entire level of detail in gait analysis currently does not exist, and the step, stride, etc. measures which are currently used are very poorly defined and inaccurately measured, and 2) it's a revolutionary advancement for clinical analysis, as well as any other area that depends on understanding how people walk (and run, jump, etc., since this system can be used to study those, too.), like sports, prosthetics and SAR (for path deviation mainly).
It's important to SAR for 2 main reasons. It allows the production of realistic footfall plots, in order to study distance and direction relationships between footfalls which couldn't be studied without it, and it shows how the different body segments and joints contribute, via the parameters, to the observed footfall pattern.
This means that tables can be created which show how each parameter affects the position of the footprint, so variations for each can be correlated in order to produce a "most likely" Step Model for each step. A part of this is lab study of how people walk, in order define limits of motion and show how each parameter is related to the others.
The relationship of pelvic stretch and straddle-line doesn't have to be studied, since they're the sides of a right triangle with the pelvis-line as hypotenuse, but all others have to be determined. The step-out-line and rear-leg-line, for eg., have a relationship through ground contact and the pelvis-line. A change in step-out-line will virtually always cause a change in rear-leg-line (at heel-contact, not for the snapshots when one or both are in the air), but the exact variations would have to be studied, since pelvic tilt, pelvic stretch and several other factors affect this relationship. Understanding these will help determine what simplifications can be applied.
Up to now, I've concentrated on developing the clinical applications, since they have the most equipment. 3D gait analysis should give all the info needed for this method, although some of the positions (like heel-point) and values may have to be estimated. But, as long as the same method is used every time, any potential errors should be very small, most likely negligible. I'm waiting for the first set of real data, which is being extracted from an unrelated 3D run.
Hopefully, the clinicians will provide the vast amount of the data for this, and we can do a lot with what's already on file. Do you know of anyone with a 3D gait analysis set-up who would be willing to work with us and/or provide data?
I've been told I write a long e-mail, so I'll cut to the chase. I think application to SAR should involve 2 main areas, one of which requires real data input.
The first area is 2 computer programs and a database. The initial program would be for creating Step Models from specific input, taking relevant measurements on the Model, using the Model (with any others) to create footfall plots, taking relevant measurements on the plot, showing the acquired data via figures and graphs, and tabulating the data in a standard format (which we'd have to determine).
The stage 2 program would use the previous for the base, but be enhanced to facilitate SAR in the field (see Foreword, One Plausible Scenario). This would require the input of physical data and it's use to estimate Step Models, the plotting of wander paths, the evaluation of terrain if such data is available (popular areas could have a detailed topographical map), the calculation and display of potential error path regions, allow input of field determined factors like rockiness or moisture, create logs of input and all analyses, etc.
The world database would be to tabulate real data, and would be truly universal.
The second main area is the study of normal walking patterns, as well as changes in the parameters due to specific stresses (such as wearing a heavy backpack) and limb dominance. This would require the definition of a standard method to determine limb dominance (which there currently isn't, I believe), as well as the analysis of parameter data.
Each area could turn out to be very large and detailed.
More information received...
I finally got some real data to apply the method to, and with great success. The gait analyst who provided the data is very excited, because I think he finally sees the great potential to expand the research capacity and quality in the clinical gait industry.
From consideration of this application, I made a slight re-organization of the direction changes over a step, and now consider the order as: 1) aberration, 2) push-off angle, 3) and 4) foot offset and foot angle at the same time. This is much more logical and facilitates the representation of all the parameters on a single model.
Some definitions and discussions are changed by this, but only in the order of events, like for the straight lines over the step. Nothing fundamental is changed. But, this shows the importance of co-ordinating with members of each different area, since many decisions are arbitrary, and any of many other different approaches would be just as good, depending on what you want to look at.
The only things that can't change are the 4 minimum points of gait (and foot-line) and the 8 fundamental parameters. Though other points, lines and values can be used, only these give accurate determinations of distance and direction changes over the step, as is.
These changes have been made in this current version.
Clinical Gait Analysis - Forward
Clinical Gait Analysis - Part 1
Clinical Gait Analysis - Part 2
Clinical Gait Analysis - Part 3
Clinical Gait Analysis - Part 4
Clinical Gait Analysis - Part 5
Clinical Gait Analysis - JPG figures zipped
