Classification of errors in locating a rigid body

Ball, Kevin; Pierrynowski, Michael R.

doi:10.1016/0021-9290(96)00008-5

Cited by 12 publications

(5 citation statements)

References 15 publications

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“…Following the methods described by Ball and Pierrynowski (1996), for each data frame the XYZ coordinates of each IRED was recorded as a three element column vector. The four IRED vectors that form a cluster were combined to form a 3×4 matrix.…”

Section: Methodsmentioning

confidence: 99%

“…This cycle was then broken down into fifty time steps. For each subject, a spatial average (Ball and Pierrynowski, 1996; Ball and Greiner, 2012) of the F [ i ] rotation matrices associated with each two-percentile step was calculated. Then each average rotation matrix was subjected to Cardan angle decomposition to derive a simultaneous assessment about three rotational axes.…”

Section: Methodsmentioning

confidence: 99%

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Kinematics of primate midfoot flexibility

Greiner

Ball²

2014

Am. J. Phys. Anthropol.

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This study describes a unique assessment of primate intrinsic foot joint kinematics based upon bone pin rigid cluster tracking. It challenges the assumption that human evolution resulted in a reduction of midfoot flexibility, which has been identified in other primates as the “midtarsal break.” Rigid cluster pins were inserted into the foot bones of human, chimpanzee, baboon and macaque cadavers. The positions of these bone pins were monitored during a plantarflexion-dorsiflexion movement cycle. Analysis resolved flexion-extension movement patterns and the associated orientation of rotational axes for the talonavicular, calcaneocuboid and lateral cubometatarsal joints. Results show that midfoot flexibility occurs primarily at the talonavicular and cubometatarsal joints. The rotational magnitudes are roughly similar between humans and chimps. There is also a similarity among evaluated primates in the observed rotations of the lateral cubometatarsal joint, but there was much greater rotation observed for the talonavicular joint, which may serve to differentiate monkeys from the hominines. It appears that the capability for a midtarsal break is present within the human foot. A consideration of the joint axes shows that the medial and lateral joints have opposing orientations, which has been associated with a rigid locking mechanism in the human foot. However, the potential for this same mechanism also appears in the chimpanzee foot. These findings demonstrate a functional similarity within the midfoot of the hominines. Therefore, the kinematic capabilities and restrictions for the skeletal linkages of the human foot may not be as unique as has been previously suggested.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Kinematics of primate midfoot flexibility

Greiner

Ball²

2014

Am. J. Phys. Anthropol.

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“…Defined in this manner, H and S can be combined to create, D=HS, (8) where the matrix elements of D are, sx sy hxy sz hxz D = sx hyx sy sz hyz . (9) L sx hzx sy hzy sz In constructing (14) it was recognized that S and H could be combined in a different order (H would have to be transposed), but this choice was made since it was felt that S should be placed rightmost (see 8). This was done in preparation for concatenation of the deformation matrix with the target matrix, Pc.…”

Section: Towards a Pliant Surface Modelmentioning

confidence: 99%

Modeling of the pliant surfaces of the thigh and leg during gait

Ball

Pierrynowski

1998

SPIE Proceedings

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Rigid Body Modeling, a 6 degree of freedom (DOF) method, provides state of the art human movement analysis, but with one critical limitation; it assumes segment rigidity. A non-rigid 12 DOF method, Pliant Surface Modeling (PSM) was developed to model the simultaneous pliant characteristics (scaling and shearing) of the human body's soft tissues. For validation, bone pins were surgically inserted into the tibia and femur of three volunteers. Infrared markers (44) were placed upon the thigh, leg and bone pin surfaces. Two synchronized OPTOTRAKI3O2OTM cameras (Northern Digital Inc., Waterloo, ON) were used to record 120 seconds of treadmill gait per subject. In comparison to the "gold standard" bone pin rotational results, PSM located the tibia, femur and tibiofemoral joint with root mean square (RMS) errors of 2.4°, 4.0° and 4.6°, respectively. These performances met or exceeded (P<.0l) the current state of the art for surface data, Rigid Surface Modeling. The thigh's measured surface experienced uniform repeatable changes in scale: 40% mediolateral, 5% anterioposterior, 5% superioinferior, and planar shears of: 25° transverse, 1 5° sagittal, 5°f rontal. With the brief exception of push-off, the lower leg demonstrated much greater rigidity: <5% scaling and <5° shearing. Thus, PSM offers superior "rigid" estimates of knee motion with the ability to quantify "pliant" surface changes.

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“…One way to minimise the marker error's effect, when estimating the helical angle, is to use smoothing techniques (described and compared in Cappello et al 1996). The measurement error can be classified into precision and accuracy as described by Ball and Pierrynowski (1996). The factor that has the biggest effect on kinematical measurements is the relative movement between markers on the skin and the underlying bone .…”

Section: Introductionmentioning

confidence: 99%

The effect of anisotropic systematic errors in estimating helical angles

Öhberg

2008

Computer Methods in Biomechanics and Biomedical Engineering

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A common question in movement studies is how the results should be interpreted with respect to systematic and random errors. In this study, simulations are made in order to see how a rigid body's orientation in space (i.e. helical angle between two orientations) is affected by (1) a systematic error added to a single marker (2) a combination of this systematic error and Gaussian white noise. The orientation was estimated after adding a systematic error to one marker within the rigid body. This procedure was repeated with Gaussian noise added to each marker. In conclusion, results show that the systematic error's effect on estimated orientation depends on number of markers in the rigid body and also on which direction the systematic error is added. The systematic error has no effect if the error is added along the radial axis (i.e. the line connecting centre of mass and the affected marker).

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Classification of errors in locating a rigid body

Cited by 12 publications

References 15 publications

Kinematics of primate midfoot flexibility

Kinematics of primate midfoot flexibility

Modeling of the pliant surfaces of the thigh and leg during gait

The effect of anisotropic systematic errors in estimating helical angles

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