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Error in kinematic data due to marker attachment methods
172
Abstracts--International
Society of Biomechanics XIII Congress 1991
STOCHASTIC SIMULATION FOR ESTIMATION OF SENSITIVITY OF THE HUMAN BODY MODEL TO ERRORS IN INPUT PARAMETERS Boris I. Prilutsky, Ludmila N. Petrova and Nikita V. Poltorapavlov Biomechanics Laboratory, Central Institute of Physical Culture, Moscow 105483, USSR. The purpose of the study was to: 1) introduce a new method based on stochastic simulation and developed to estimate the sensitivity of the mode 1; 2) evidence potentialities of the method by applying it to determine mechanical work done by the joint moments of the 14-link man’s model at landing. The work of joint moments of the model served as an output and coordinates of the body landmarks, ground reaction forces, parameter, and mass-inertial characteristics of the body segments were used as input parameters (total 22848). A random error (its distribution characteristics were evaluated experimentally) of every parameter is added to its appropriate averaged input parameter, and then the output parameter is computed. The procedure is repeated as many times as required for subsequent statistical analyses. By comparing the variance coefficients of input and output parameters the conclusion on the model sensitivity is being made. The method demonstrated acceptable reasons to employ it for estimation of sensitivity of models having practically any quantity of input parameters.
ERROR IN KINEMATIC DATA DUE TO MARKER ATTACHMENT METHODS
Janet L. Ronsky and Benno M. Nigg Human Performance Laboratory The University of Calgary, Calgary, Alberta, Canada T2N lN4 Three dimensional motion analysis measurements were obtained to quantify, non-invasively, the error in kinematic data due to various marker attachment methods. Five marker attachment methods for the lower leg were compared using skin or external frames as the base for mounting the marker arrays. Standing, quasidynamic and running (4.5 m/s) conditions were assessed. Errors due to relative marker movement were quantified by measuring the change in length between markers occurring during the dynamic conditions with respect to.the length obtained during standing. Errors due to movement between the skin and the underlying skeletal structures were assessed indirectly by quantifying deviations between the vertical displacement trajectories for the quasidynamic and running conditions. Skin mounted marker arrays produced substantially greater relative length changes between markers, ranging from 1.2 to 12.3 times greater than changes exhibited with external frames or marginally Markers mounted on external frames produced than es in marker lengths within deviations in the vertical greater than the system measurement error (0.3cm B . Additionally, displacement trajectories were smaller for markers mounted on external frames. The results suggest that significant reductions in relative movement between markers can be achieved by utilizing marker arrays mounted on external frames. Artefacts in vertical displacement trajectories, speculated to be caused by soft tissue motion during dynamic loading of the leg, can also be reduced by attaching markers to external frames.
AN AUDIOHJBRICHE!J!WDFORORTAIwIAlGTHE MBZANICAL RESONAM!CHARA~ISTICS OF TRE RUIW RRAD au Vladimir V. Shorokhov and Robert E. Ti Institute of Theoretical and Experimental F lo sic8 of the USSRAcad. Sci.Puehchino, MoscowRegion, 1 Pr2 92, USSR An audiometric method for obtaining IN VIVO acoustic resonant characteristics of the human head Is proposed. The method 16 baaed on the idea that the sound perception through the cranium boma Is to be affected by the resonant properties of the head. Six observem wem teeted with the cylindrical transducer applied to the forehead by the flat bottom. The mmaummnts were performed at frequencies ranged from 4 to 12 Wz with a ete of 200 Hz. The audlogmns are shown to have fmne coimon feature6 in thaP they have a e$Wlar s*e of i% BeEiSitiVity. However, peak3 and values are very B clflc. The tke m may be Interpret et? 88 frequenoy I-e 1: acoustic resonator. It is essent appear only at the audiograms obtained with 8 !@Wval frequmc~ ate?-
Abstracts--International
Society of Biomechanics XIII Congress 1991
STOCHASTIC SIMULATION FOR ESTIMATION OF SENSITIVITY OF THE HUMAN BODY MODEL TO ERRORS IN INPUT PARAMETERS Boris I. Prilutsky, Ludmila N. Petrova and Nikita V. Poltorapavlov Biomechanics Laboratory, Central Institute of Physical Culture, Moscow 105483, USSR. The purpose of the study was to: 1) introduce a new method based on stochastic simulation and developed to estimate the sensitivity of the mode 1; 2) evidence potentialities of the method by applying it to determine mechanical work done by the joint moments of the 14-link man’s model at landing. The work of joint moments of the model served as an output and coordinates of the body landmarks, ground reaction forces, parameter, and mass-inertial characteristics of the body segments were used as input parameters (total 22848). A random error (its distribution characteristics were evaluated experimentally) of every parameter is added to its appropriate averaged input parameter, and then the output parameter is computed. The procedure is repeated as many times as required for subsequent statistical analyses. By comparing the variance coefficients of input and output parameters the conclusion on the model sensitivity is being made. The method demonstrated acceptable reasons to employ it for estimation of sensitivity of models having practically any quantity of input parameters.
ERROR IN KINEMATIC DATA DUE TO MARKER ATTACHMENT METHODS
Janet L. Ronsky and Benno M. Nigg Human Performance Laboratory The University of Calgary, Calgary, Alberta, Canada T2N lN4 Three dimensional motion analysis measurements were obtained to quantify, non-invasively, the error in kinematic data due to various marker attachment methods. Five marker attachment methods for the lower leg were compared using skin or external frames as the base for mounting the marker arrays. Standing, quasidynamic and running (4.5 m/s) conditions were assessed. Errors due to relative marker movement were quantified by measuring the change in length between markers occurring during the dynamic conditions with respect to.the length obtained during standing. Errors due to movement between the skin and the underlying skeletal structures were assessed indirectly by quantifying deviations between the vertical displacement trajectories for the quasidynamic and running conditions. Skin mounted marker arrays produced substantially greater relative length changes between markers, ranging from 1.2 to 12.3 times greater than changes exhibited with external frames or marginally Markers mounted on external frames produced than es in marker lengths within deviations in the vertical greater than the system measurement error (0.3cm B . Additionally, displacement trajectories were smaller for markers mounted on external frames. The results suggest that significant reductions in relative movement between markers can be achieved by utilizing marker arrays mounted on external frames. Artefacts in vertical displacement trajectories, speculated to be caused by soft tissue motion during dynamic loading of the leg, can also be reduced by attaching markers to external frames.
AN AUDIOHJBRICHE!J!WDFORORTAIwIAlGTHE MBZANICAL RESONAM!CHARA~ISTICS OF TRE RUIW RRAD au Vladimir V. Shorokhov and Robert E. Ti Institute of Theoretical and Experimental F lo sic8 of the USSRAcad. Sci.Puehchino, MoscowRegion, 1 Pr2 92, USSR An audiometric method for obtaining IN VIVO acoustic resonant characteristics of the human head Is proposed. The method 16 baaed on the idea that the sound perception through the cranium boma Is to be affected by the resonant properties of the head. Six observem wem teeted with the cylindrical transducer applied to the forehead by the flat bottom. The mmaummnts were performed at frequencies ranged from 4 to 12 Wz with a ete of 200 Hz. The audlogmns are shown to have fmne coimon feature6 in thaP they have a e$Wlar s*e of i% BeEiSitiVity. However, peak3 and values are very B clflc. The tke m may be Interpret et? 88 frequenoy I-e 1: acoustic resonator. It is essent appear only at the audiograms obtained with 8 !@Wval frequmc~ ate?-