How many degrees-of-freedom does a biped need?

Sias, F.R.; Zheng, Yuan F.

doi:10.1109/iros.1990.262401

Cited by 16 publications

(8 citation statements)

References 3 publications

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“…The head‐arms‐trunk complex (HAT) was represented as a single rigid body with a constant mass and moment of inertia. Each leg consisted of six DOF (total of 12 DOF), which has been shown to be a sufficient approximation of the double‐support (ie, bipedal) characteristics of quiet stance (24). The feet were not included in the model because it was assumed that they were fully in contact with the ground.…”

Section: Methodsmentioning

confidence: 99%

Closed-Loop Control of Functional Electrical Stimulation-Assisted Arm-Free Standing in Individuals With Spinal Cord Injury: A Feasibility Study

Vette

Masani

Kim

et al. 2009

Neuromodulation: Technology at the Neural Interface

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Section: Methodsmentioning

confidence: 99%

Closed-Loop Control of Functional Electrical Stimulation-Assisted Arm-Free Standing in Individuals With Spinal Cord Injury: A Feasibility Study

Vette

Masani

Kim

et al. 2009

Neuromodulation: Technology at the Neural Interface

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“…The stifflegged stilt character must remain in a continual state of motion to maintain balance (see Sias [14] for further details on why we need feet).…”

Section: ) Do We Need Feet?mentioning

confidence: 99%

Responsive Biped Character Stepping: When Push Comes to Shove

Kenwright

2012

2012 International Conference on Cyberworlds

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In this paper, we propose a real-time approximation method for generating intelligent foot placement information for interactive biped characters. Our model uses an uncomplicated and efficient physics-based mechanism for generating fundamental pose information that can be used to construct the motions of a fully articulated dynamic character. The focus of this paper is a foot placement approximation method capable of producing balancing characters with dynamic characteristics. Furthermore, our model is straightforward to implement, computationally efficient, practical and robust, and ideal for time critical applications such as games.

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“…The HAT (Head-Arms-Trunk) was modeled as a rigid body with a constant mass and moment of inertia. Each leg consisted of six DOF, which has been shown to be a reasonable approximation of the double-support stance in humans [19]. The feet were not included in the model since it was assumed that the feet were fully in contact with the ground.…”

Section: A Three-dimensional Dynamic Modelmentioning

confidence: 99%

Optimal Combination of Minimum Degrees of Freedom to be Actuated in the Lower Limbs to Facilitate Arm-Free Paraplegic Standing

Kim

Mills

Vette

et al. 2007

Journal of Biomechanical Engineering

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Arm-free paraplegic standing via functional electrical stimulation (FES) has drawn much attention in the biomechanical field as it might allow a paraplegic to stand and simultaneously use both arms to perform daily activities. However, current FES systems for standing require that the individual actively regulates balance using one or both arms, thus limiting the practical use of these systems. The purpose of the present study was to show that actuating only six out of 12 degrees of freedom (12-DOFs) in the lower limbs to allow paraplegics to stand freely is theoretically feasible with respect to multibody stability and physiological torque limitations of the lower limb DOF. Specifically, the goal was to determine the optimal combination of the minimum DOF that can be realistically actuated using FES while ensuring stability and able-bodied kinematics during perturbed arm-free standing. The human body was represented by a three-dimensional dynamics model with 12-DOFs in the lower limbs. Nakamura's method (Nakamura, Y., and Ghodoussi, U., 1989, "Dynamics Computation of Closed-Link Robot Mechanisms With Nonredundant and Redundant Actuators," IEEE Trans. Rob. Autom., 5(3), pp. 294-302) was applied to estimate the joint torques of the system using experimental motion data from four healthy subjects. The torques were estimated by applying our previous finding that only 6 (6-DOFs) out of 12-DOFs in the lower limbs need to be actuated to facilitate stable standing. Furthermore, it was shown that six cases of 6-DOFs exist, which facilitate stable standing. In order to characterize each of these cases in terms of the torque generation patterns and to identify a potential optimal 6-DOF combination, the joint torques during perturbations in eight different directions were estimated for all six cases of 6-DOFs. The results suggest that the actuation of both ankle flexionextension, both knee flexionextension, one hip flexionextension, and one hip abductionadduction DOF will result in the minimum torque requirements to regulate balance during perturbed standing. To facilitate unsupported FES-assisted standing, it is sufficient to actuate only 6-DOFs. An optimal combination of 6-DOFs exists, for which this system can generate able-bodied kinematics while requiring lower limb joint torques that are producible using contemporary FES technology. These findings suggest that FES-assisted arm-free standing of paraplegics is theoretically feasible, even when limited by the fact that muscles actuating specific DOFs are often denervated or difficult to access.

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How many degrees-of-freedom does a biped need?

Cited by 16 publications

References 3 publications

Closed-Loop Control of Functional Electrical Stimulation-Assisted Arm-Free Standing in Individuals With Spinal Cord Injury: A Feasibility Study

Closed-Loop Control of Functional Electrical Stimulation-Assisted Arm-Free Standing in Individuals With Spinal Cord Injury: A Feasibility Study

Responsive Biped Character Stepping: When Push Comes to Shove

Optimal Combination of Minimum Degrees of Freedom to be Actuated in the Lower Limbs to Facilitate Arm-Free Paraplegic Standing

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