Device for simultaneous continuous and separate recording and measurement of head and body movements during standing, walking and stepping

An apparatus and method for the simultaneous, continuous and separate recording and measurement of head and body movements during standing and walking, including various optical markers mounted upon the head and the trunk of a test person, and a device for continuously receiving and recording optical signals from the markers, which device is stationarily fixed at a distance from the test person. The device being easy to handle, allows a time critical spectral analysis of the movement patterns, avoids overlapping of light tracings during recording of the optical signals, distortions of the measurements due to parallaxes when observing the body at various locations and central scotoma or an area of loss of visibility of the optical markers underneath of the device. At least three photoelectric cells being permanently mounted and fixed in a polygonal relation, and the device successively compares and levels quantitatively the values if the measurements of the photoelectric cells, which are permanently called and transmitted to a central data processing unit by a flow of data. Thus, the device installs a cylindrical vertical projection upon the standing or moving person being recorded.

BACKGROUND OF THE INVENTION 
1. FIELD OF THE INVENTION 
The present invention relates to a method and apparatus for determination 
of a simultaneous, permanent and separate recording and measurement of the 
head and trunk movements of a body in one plane during standing and 
walking. The invention includes optical markers, which are mounted upon 
the head and the trunk of the test person. Such an apparatus also includes 
a device which is stationarily put in operation at a distance above the 
test person, and continuously receives and records the optical signals of 
the markers. 
2. DESCRIPTION OF THE PRIOR ART 
A similar device has been used until now by means of the so-called 
cranio-corpo-graphy (CCG), which has been described in the literature: 
"Ein einfacher, objektiver und quantitativer Gleichgewichstest fur die 
Praxis Forschungsbericht Cranio-CorpoGraphy (CCG), Schritfenreihe des 
Hauptverbandes der gewerblichen Berufsgenossenschaften eV, Lindenstrasse 
78, D 5205 St. Augustin 2, West Germany, Juni 1986." 
However, several disadvantages are adhered to this well-known instrument. 
For obtaining a sufficient distance between the test person and the 
optical receiver and recorder, a mirror is attached to the ceiling into 
which a camera is centrally directed from below. Thus, an area of loss is 
visibly of the optical marker is created centrally underneath the camera, 
within which the markers cannot be observed. Another disadvantage lies in 
the fact that handling the camera involves difficult overhead maneuvering. 
Since all the exposures can only be recorded outside of the central 
scotoma, distortions of the measurements occur due to parallaxes, with an 
increasing impact when moving towards the border of the field of 
observation. Since the photographic recording is two dimensional, a time 
critical spectral analysis of the movement patterns cannot be achieved, 
even though it is diagnostically important, due to the hierarchically 
organized central nervous movement regulation, including the brain 
hemispheres, brain stem and spinal cord. Finally, an analysis of the 
movement patterns of the various marker points upon the head and the body 
is impaired and partly impossible due to overlapping of the light tracings 
during the swaying movements of the head and body, when standing stepping 
or walking. 
Another prior art device is described in U.S. Pat. No. 4,375,674, issued 
Mar. 3, 1983, for "Kinesiometric Method and Apparatus" to William E. 
Thawnton. Disclosed therein are an apparatus and method for the 
determination of functional capability of bodies. Reach, as well as 
velocity, acceleration and force generation at various positions, may be 
determined for parts of the body by a three-dimensional kinesimeter, 
equipped with an ergometer. This invention finds particular application to 
the measurement of human task performing capabilities. A three camera 
video position detector system is positioned equidistant around a 
stationary reference lamp. The test subject, whose anthropometric 
characteristics are to be observed, is regularly positioned within the 
field of view of the camera system. The test person is kept in fixed 
relation to the reference site by body belts, as shown in FIGS. 5 and 10 
thereof. The recorder light fixed to a part of the body, for instance an 
arm or a hand, is then recorded through the cameras when moving. The 
system needs a complicated calibration procedure to be appropriately 
programmed with proper scale factors and locations, as well as zero 
references used in calculations of position for accurate dimensional 
measurements, in which one of the lamps serves as a reference lamp. This 
invention does not allow recording of locomotor tracings over the plain 
field of visibility, as the body must be kept close to the reference lamp. 
It is therefore used for establishing maximum reach envelopes. A 
simultaneous recording of several head and body marker points during 
walking consequently cannot be achieved since always only the coordinates 
of one marker point are put into relation with the central coordinates of 
the reference lamp. Also, the ergometer needs to keep the body stationary, 
as depicted in the figures. 
A further variety of techniques, which have been developed to attempt to 
measure one aspect or another of human activities, have also been 
described and discussed in the background of the invention section of U.S. 
Pat. No. 4,375,674. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a method and apparatus 
for recording head and body movements during standing and walking, as 
described above, which avoids overlapping of the light tracings during 
recording and distortions of the measurements due to parallaxes, when 
observing the body at various locations, and avoids central scotoma or an 
area of loss of visibility of the optical markers underneath the recording 
device. The present invention achieves this objective with a device having 
at least three photoelectrical cells which are stationarily fixed in a 
polygonal shape above the test person or object. The values of 
measurements of different intensities at the different photoelectric cells 
are regularly successively compared with each other, and are input into a 
central data processing unit by a flow data. 
By means of the polygonal arrangement of the photoelectric cells, the 
present invention avoids a central area of loss of visibility of the 
optical markers underneath the device, and all the optical distortions of 
the measurements at varying positions of the test person, since the object 
viewed is inside of a cylinder of the "electronic objective". The 
invention also includes that the values of measurement of the 
photoelectric cells of different light intensities are regularly 
successively compared with each other, and they are permanently input into 
a central data processing unit by means of a series of data. The 
comparison of the measurements rotates successively and regularly between 
all the photoelectric cells and several generations of virtual values. 
Thus, a temporal and spatial structure of the movement patterns of the 
various head and body marker points is achieved. The resulting data series 
and curves additionally allow a spectral analysis of the movements of the 
head and body points being marked. Thus, whose body movements as well as 
the movements of parts of the body and the differences between the 
movements of various parts of the body, for instance, between head and 
trunk, can be calculated and graphed. All these calculations can be 
executed simultaneously upon all the body points recorded. The differences 
in the movement patterns of various parts of the human body, which are 
important for medical diagnostics, can be displayed in digital time series 
of the measurements, as well as by means of graphical curves for each of 
the points being recorded, as well as by statistical plots. 
A preferred polygonal arrangement of the photoelectric cells, with respect 
to this invention, is a hexagon. The hexagon of photoelectrioal cells 
delivers a sufficient amount of data for a precision measurement. 
Additionally, the hexagon makes it possible to closely attach several 
polygons of photoelectric cells in a honeycombed manner for surveying the 
complete surface of an entire room. Such a complete viewing of a whole 
room without any optical distortions in the plane of observations cannot 
be achieved with the procedures known prior to the present invention and 
cited above. 
According to a further embodiment of the invention, the central data 
processing unit is a digital computer. This computer compares and 
calculates the bit coded measurements of light differences between the 
photoelectric cells in a successively rotating manner on real and virtual 
point comparisons. Thus, the points of maximal marker lights are 
determined in the plane. Additionally, the computer calculates the 
synthesis of the light tracings in the plane, the spectral analysis of the 
marker movements with respect to frequency and amplitude etc., as well as 
the numerical and graphical display of the parameters and the curves. 
Important clinical and diagnostic parameters are also evaluated 
numerically and graphically, like longitudinal displacement, longitudinal 
sway, lateral sway, angular deviation, whole body spin, angular distortion 
of the head with respect to the trunk, differences in the sways between 
head and trunk, and configurations of preferential zones of movements. 
In case of preferred high precision marker localization, it is necessary to 
evaluate a maximum of possible light intensity comparisons. Therefore, the 
invention also includes a light source at the very center of the polygon 
of photoelectric cells, controlled by the central processing unit, which 
permits regulation of the intensity and the color of the light during 
continuous light emission, and during intermittent light emission the 
intensity, color and rhythm of the light. The markers, being reflectors in 
this case, can be received separately with short time intervals from 
calculation to calculation. Thus, one marker is only visible at each short 
observation interval. 
For the same purpose, in another embodiment of the invention, the central 
data processing unit is connected with the photoelectric cells through a 
remote control so that the photoelectric cells can be modulated with 
respect to their photoelectric sensitivity and/or with respect to their 
sensitivity in combination with adaptive or controlled modulation of the 
central light emitting system. 
In a further embodiment of the invention, the photoelectric cells are 
constructed with a dual output mode, which can be selected for output of 
analogous signals or output of signals which are directly analogue to 
digital converted. The latter alternative implies the advantage that the 
central processing unit is continuously provided with signals, which can 
be calculated immediately. This excludes the susceptibility to faults, for 
example, due to untoward resistances in the wires, magnetic fields, etc. 
It is also advantageous to provide the digital computer with at least one 
interface for the photoelectric cells with a multiplexer function, as well 
as with an interface for an analogue to digital converter. Of course, each 
of the photocells can have its own input into the central processing unit. 
The detailed description of the invention is given in connection with 
device for medical investigation of head and body instability during 
standing and stepping.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 shows a test person 1, who is moving in a room, of which the floor 2 
and the ceiling 3 are visible. Markers 6a-6d are attached on the shoulders 
4a, 4b of the test person, and on a helmet 5 on the test person's head. 
The markers 6a-6a emit light beams 1. These light beams 1 are received and 
processed by photoelectric cells 7a-7h, which are attached in fixed 
positions to the ceiling 3. 
As shown in FIG. 2, the photoelectric cells 7a-7h are arranged in the shape 
of a regular octagon. FIG. 3 demonstrates the position of the markers 
6a-6d on the shoulders 4a, 4b and the helmet 5. 
FIG. 4 schematically illustrates part of the rotating pair calculation and 
leveling of the light intensities of the photoelectric cells 7a-7h, while 
FIG. 5 illustrates the complete calculation and leveling of light 
intensities. 
FIG. 6 basically illustrates the same arrangement as FIG. 1, with one 
difference. The difference being a light source 8 installed in the very 
center of the polygon of the photoelectric cells 7 for the stimulation of 
the passive, only reflecting markers 6a-6d, which then do not have their 
own light sources. The light beams being released from the central light 
source 8, which are received by the markers 6a-6d, are denoted with 
1.sub.x. 
The position of the photoelectric cells 7a-7h of FIG. 6 are schematically 
shown in FIG. 7, which demonstrates a partial rotating paired calculation 
and leveling of light intensities. 
FIG. 8 demonstrates a body movement pattern, like a cut line of a scythe of 
a test person 1, stepping on a spot, beginning at a starting point 0 and 
moving anteriorly, even though he believes that he is stepping on the 
spot. The movement pattern is taken from a calculated tracing of any 
randomly selected marker 6. 
FIG. 9 demonstrates the said procedure as in FIG. 8, however, for all 4 
markers 6a-6d. Due to separation of the single tracings of the movements 
by computer processing, each of the tracings can be completely inspected 
without any loss of visibility or overlap and/or crossing. 
The invention has been demonstrated above by means of a medical 
application. However, other applications are also considered, for 
instance, the supervision of the movements of personnel in dangerous and 
hazardous working areas, like, for instance, in nuclear power plants. 
Besides, the invention may also be applied in conveying systems of exactly 
localizing and managing movable machineries, tools or parts, as well as 
for an assembly technique. 
The foregoing disclosure and description of the invention is illustrative 
and explanatory thereof, and various changes in the method steps, as well 
as in the details of the illustrated apparatus, may be made within the 
scope of the appended claims without departing from the spirit of the 
invention.