Ball joints for Marker-less human Motion Capture

Moll, Gerard Pons; Rosenhahn, Bodo

doi:10.1109/wacv.2009.5403056

Cited by 7 publications

(4 citation statements)

References 13 publications

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“…An alternative approach is to use measurements that directly yield 3D information, for example RGBD 61 . In parallel, there has been substantial developments in pose estimation of humans, including the possibility to track multiple individuals in real time 60,[62][63][64] , some of which include explicit models of kinematics 65,66 . In general, these approaches triangulate joint positions of readily detectable key points in the images, which has the advantage of not requiring application of surface markers.…”

Section: Discussionmentioning

confidence: 99%

Estimation of skeletal kinematics in freely moving rodents

Monsees¹,

Voit²,

Wallace³

et al. 2022

Nat Methods

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Forming a complete picture of the relationship between neural activity and skeletal kinematics requires quantification of skeletal joint biomechanics during free behavior; however, without detailed knowledge of the underlying skeletal motion, inferring limb kinematics using surface-tracking approaches is difficult, especially for animals where the relationship between the surface and underlying skeleton changes during motion. Here we developed a videography-based method enabling detailed three-dimensional kinematic quantification of an anatomically defined skeleton in untethered freely behaving rats and mice. This skeleton-based model was constrained using anatomical principles and joint motion limits and provided skeletal pose estimates for a range of body sizes, even when limbs were occluded. Model-inferred limb positions and joint kinematics during gait and gap-crossing behaviors were verified by direct measurement of either limb placement or limb kinematics using inertial measurement units. Together we show that complex decision-making behaviors can be accurately reconstructed at the level of skeletal kinematics using our anatomically constrained model.

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Section: Discussionmentioning

confidence: 99%

Estimation of skeletal kinematics in freely moving rodents

Monsees¹,

Voit²,

Wallace³

et al. 2022

Nat Methods

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show abstract

“…However, both parameterizations become identical when only a single type of rotation, e.g. flexion/extension, is present at a vertex, which was the case for the measured joint angles 49 . Parameterizing rotations with Rodrigues vectors therefore allowed us to obtain smooth transitions between different types of bone rotations.…”

Section: Methodsmentioning

confidence: 80%

“…While the published joint angles referred to Euler angles, we used Rodrigues vectors to parameterize rotations (Supplementary Text), since the latter are better suited for pose reconstruction 49 . However, both parameterizations become identical when only a single type of rotation, e.g.…”

Section: Methodsmentioning

confidence: 99%

Anatomically-based skeleton kinetics and pose estimation in freely-moving rodents

Monsees

Voit

Wallace

et al. 2021

Preprint

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Forming a complete picture of the relationship between neural activity and body kinetics requires quantification of skeletal joint biomechanics during behavior. However, without detailed knowledge of the underlying skeletal motion, inferring joint kinetics from surface tracking approaches is difficult, especially for animals where the relationship between surface anatomy and skeleton changes during motion. Here we developed a videography-based method enabling detailed three-dimensional kinetic quantification of an anatomically defined skeleton in untethered freely-behaving animals. This skeleton-based model has been constrained by anatomical principles and joint motion limits and provided skeletal pose estimates for a range of rodent sizes, even when limbs were occluded. Model-inferred joint kinetics for both gait and gap-crossing behaviors were verified by direct measurement of limb placement, showing that complex decision-making behaviors can be accurately reconstructed at the level of skeletal kinetics using our anatomically constrained model.

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“…Ball joints such as the shoulder joint are modeled as three revolute joints in series with orthogonal axes intersecting at the center of the joint. This leads to the ball joint configuration being described with intrinsic Euler angles rotating around a point in space [21], [22]. The elbow joint is modeled as a single revolute joint.…”

Section: A Experiments Description and System Modelingmentioning

confidence: 99%

Constrained Inverse Optimal Control With Application to a Human Manipulation Task

Menner

Worsnop

Zeilinger

2021

IEEE Trans. Contr. Syst. Technol.

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This paper presents an inverse optimal control methodology and its application to training a predictive model of human motor control from a manipulation task. It introduces a convex formulation for learning both objective function and constraints of an infinite-horizon constrained optimal control problem with nonlinear system dynamics. The inverse approach utilizes Bellman's principle of optimality to formulate the infinitehorizon optimal control problem as a shortest path problem and Lagrange multipliers to identify constraints. We highlight the key benefit of using the shortest path formulation, i.e., the possibility of training the predictive model with short and selected trajectory segments. The method is applied to training a predictive model of movements of a human subject from a manipulation task. The study indicates that individual human movements can be predicted with low error using an infinite-horizon optimal control problem with constraints on shoulder movement.

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Ball joints for Marker-less human Motion Capture

Cited by 7 publications

References 13 publications

Estimation of skeletal kinematics in freely moving rodents

Estimation of skeletal kinematics in freely moving rodents

Anatomically-based skeleton kinetics and pose estimation in freely-moving rodents

Constrained Inverse Optimal Control With Application to a Human Manipulation Task

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