- Email: [email protected]
Application of ultrasonic velocity measurement and capacitive pressure distribution measurements in gait analysis
Abstracts
500
daily sessions of at least 30 min at treadmill speeds of from 0.2 to 2.0 m/set at graded increments. At 4-6 months post-spinalization the locomotor patterns of the hind limbs of the exercised groups were documented with 16 mm cinematography. Only the exercised groups were filmed as the non-exercised were not able to walk on the treadmill. Paw contact patterns, interlimb temporal patterns, and gait conversions were determined. Intralimb step cycle characteristics weie analyzed via traditibnal Philippson step cycle and angle-angle plots. The exercised animals evidenced coordinated variations in gait kinematics with increases in speed ofwalking. Gait conversions and significant alterations in the temporal phases of the step cycle were also noted.
K. METHODOLOGY
A TAXONOMY
AND COMPARISOS
OF DATA SMOOTHING
AND FUSCTION
APPROXIMATION
METHODS LEBERT R. ALLEY
and
JAMES L.
SWTH (Department of Industrial University, TX)
Engineering, Texas Tech.
This paper summarizes the results of a comparison of the several more popular methods for biomechanical data smoothing and function approximation. Performance was found to be a function of the characteristics of data faultiness and the particular criterion used for measuring performance quality. A formally defined set of (1) performance criteria, and (2) data (faultiness) characteristics are described, corresponding lo the various conditions and research objectives normally found in practical biomechanics experiments. The several smoothing and approximation methods were ranked, according to each combination of a particular performance criterion paired with a given set of ‘faulty’ data or ill-behaved function. The results are a comprehensive and uniform evaluative comparison of smoothing and approximation methods, under well defined and controlled conditions. These results will aid biomechanics researchers in selecting the’best’smoothing method. based on a logical characterization of their particular data conditions and criterion for ‘quality’ results.
A TECHNIQUE
FOR MEASLIISG
FORCE-POSITION-VELOCITY
RELATIOSSHIPS
DURING JUMPING
MOVEMESTS DAVID
F. ENZLERand A. DAISIS (Department of Physical Education, University of Maryland, College Park, MD)
A method utilizing a two-segment electrogoniometer system in conjunction with a force platform and a minicomputer has been developed to rapidly measure force and position of the whole body center of gravity during jumping movements. The electrogoniometer system operates in the sagittal plane and is capable of measuring the 2dimensional coordinate of its free end which is attached to the subject. A PDP 1l/34 minicomputer has been programmed to sample and convert to digital form the output of the potentiometers and force platform, carry out the necessary difTerentiation, normalize the data for each subject’s height and weight, and graphically display the results. The technique was applied in an investigation of the vertical jump. Different velocities throughout the take-off were achieved by varying the starting position of the subjects, and data from the different trials enabled force-position-velocity and power-position curves to be generated for each individual. Results from a variety of subjects are presented. Such data should be valuable in modelling situations involving the interaction of the human body with all types of take-off surfaces. APPLICATION
OF ULTRASONIC DISTRIBUTIOS
EWALD
VELOCITY
MEASUREMENT
MEASUREMENTS
M. HEWJG (Biomechanics
Laboratory,
AND CAPACITIVE
PRESSURE
IS GAIT ANALYSIS
Pennsylvania
State University, PA)
On the basis of the acoustical Doppler-principle a low cost device was built, to register directly the velocity of a moved ultrasonic transmitter towards a stationary receiver. Using air as carrier of acoustic waves, no wired connection is necessary between the light weight transmitter (m = 20 g) and the receiver (range= 50 m). This method was used to analyze velocity, acceleration (by dinerentiation) and displacement (by integration) of the movement of ankle, knee and hip. Force and pressure distribution measurements can be done by flexible capacitive type transducers, using rubber material as a compressible dielectric. Besides the construction of a variety of different force-platforms, measuring soles were built as part of a biofeedback device to control the load under the foot after lower extremity surgery. A matrix-like arrangement of capacitors (typically 2048 single elements) enables time dependent pressure distribution measurements under the foot.
500
daily sessions of at least 30 min at treadmill speeds of from 0.2 to 2.0 m/set at graded increments. At 4-6 months post-spinalization the locomotor patterns of the hind limbs of the exercised groups were documented with 16 mm cinematography. Only the exercised groups were filmed as the non-exercised were not able to walk on the treadmill. Paw contact patterns, interlimb temporal patterns, and gait conversions were determined. Intralimb step cycle characteristics weie analyzed via traditibnal Philippson step cycle and angle-angle plots. The exercised animals evidenced coordinated variations in gait kinematics with increases in speed ofwalking. Gait conversions and significant alterations in the temporal phases of the step cycle were also noted.
K. METHODOLOGY
A TAXONOMY
AND COMPARISOS
OF DATA SMOOTHING
AND FUSCTION
APPROXIMATION
METHODS LEBERT R. ALLEY
and
JAMES L.
SWTH (Department of Industrial University, TX)
Engineering, Texas Tech.
This paper summarizes the results of a comparison of the several more popular methods for biomechanical data smoothing and function approximation. Performance was found to be a function of the characteristics of data faultiness and the particular criterion used for measuring performance quality. A formally defined set of (1) performance criteria, and (2) data (faultiness) characteristics are described, corresponding lo the various conditions and research objectives normally found in practical biomechanics experiments. The several smoothing and approximation methods were ranked, according to each combination of a particular performance criterion paired with a given set of ‘faulty’ data or ill-behaved function. The results are a comprehensive and uniform evaluative comparison of smoothing and approximation methods, under well defined and controlled conditions. These results will aid biomechanics researchers in selecting the’best’smoothing method. based on a logical characterization of their particular data conditions and criterion for ‘quality’ results.
A TECHNIQUE
FOR MEASLIISG
FORCE-POSITION-VELOCITY
RELATIOSSHIPS
DURING JUMPING
MOVEMESTS DAVID
F. ENZLERand A. DAISIS (Department of Physical Education, University of Maryland, College Park, MD)
A method utilizing a two-segment electrogoniometer system in conjunction with a force platform and a minicomputer has been developed to rapidly measure force and position of the whole body center of gravity during jumping movements. The electrogoniometer system operates in the sagittal plane and is capable of measuring the 2dimensional coordinate of its free end which is attached to the subject. A PDP 1l/34 minicomputer has been programmed to sample and convert to digital form the output of the potentiometers and force platform, carry out the necessary difTerentiation, normalize the data for each subject’s height and weight, and graphically display the results. The technique was applied in an investigation of the vertical jump. Different velocities throughout the take-off were achieved by varying the starting position of the subjects, and data from the different trials enabled force-position-velocity and power-position curves to be generated for each individual. Results from a variety of subjects are presented. Such data should be valuable in modelling situations involving the interaction of the human body with all types of take-off surfaces. APPLICATION
OF ULTRASONIC DISTRIBUTIOS
EWALD
VELOCITY
MEASUREMENT
MEASUREMENTS
M. HEWJG (Biomechanics
Laboratory,
AND CAPACITIVE
PRESSURE
IS GAIT ANALYSIS
Pennsylvania
State University, PA)
On the basis of the acoustical Doppler-principle a low cost device was built, to register directly the velocity of a moved ultrasonic transmitter towards a stationary receiver. Using air as carrier of acoustic waves, no wired connection is necessary between the light weight transmitter (m = 20 g) and the receiver (range= 50 m). This method was used to analyze velocity, acceleration (by dinerentiation) and displacement (by integration) of the movement of ankle, knee and hip. Force and pressure distribution measurements can be done by flexible capacitive type transducers, using rubber material as a compressible dielectric. Besides the construction of a variety of different force-platforms, measuring soles were built as part of a biofeedback device to control the load under the foot after lower extremity surgery. A matrix-like arrangement of capacitors (typically 2048 single elements) enables time dependent pressure distribution measurements under the foot.