Wrench capabilities of planar parallel manipulators. Part I: Wrench polytopes and performance indices

Firmani, Flavio; Zibil, Alp; Nokleby, Scott B.; Podhorodeski, Ron P.

doi:10.1017/s0263574708004384

Cited by 36 publications

(21 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Hence the dimension of the generalized forces is n ≤ 6 (see below). Generalized force is also commonly referred to as wrench (Firmani et al 2008). Leg configuration is described by m generalized angles, θ (mx1).…”

Section: Methodsmentioning

confidence: 99%

Transducer and base compliance alter the in situ 6 dof force measured from muscle during an isometric contraction in a multi-joint limb

Sandercock

Yeo

Pai

et al. 2012

Journal of Biomechanics

View full text Add to dashboard Cite

Although musculoskeletal models are commonly used, validating the muscle actions predicted by such models is often difficult. In situ isometric measurements are a possible solution. The base of the skeleton is immobilized and the endpoint of the limb is rigidly attached to a 6-axis force transducer. Individual muscles are stimulated and the resulting forces and moments recorded. Such analyses generally assume idealized conditions. In this study we have developed an analysis taking into account the compliances due to imperfect fixation of the skeleton, imperfect attachment of the force transducer, and extra degrees of freedom (dof) in the joints that sometimes become necessary in fixed end contractions. We use simulations of the rat hindlimb to illustrate the consequences of such compliances. We show that when the limb is overconstrained, i.e. when there are fewer dof within the limb than are restrained by the skeletal fixation, the compliances of the skeletal fixation and of the transducer attachment can significantly affect measured forces and moments. When the limb dofs and restrained dofs are matched, however, the measured forces and moments are independent of these compliances. We also show that this framework can be used to model limb dofs, so that rather than simply omitting dofs in which a limb does not move (e.g. abduction at the knee), the limited motion of the limb in these dofs can be more realistically modeled as a very low compliance. Finally, we discuss the practical implications of these results to experimental measurements of muscle actions.

show abstract

Section: Methodsmentioning

confidence: 99%

Transducer and base compliance alter the in situ 6 dof force measured from muscle during an isometric contraction in a multi-joint limb

Sandercock

Yeo

Pai

et al. 2012

Journal of Biomechanics

View full text Add to dashboard Cite

show abstract

“…The concept of a wrench workspace has been studied in [5], [9]- [12], [20], [21]. An interval-based method [13], [15] and a convex-hull method [4], [5], [9], [10] are two current techniques for numerically obtaining the wrench workspace.…”

Section: Workpacesmentioning

confidence: 99%

“…An interval-based method [13], [15] and a convex-hull method [4], [5], [9], [10] are two current techniques for numerically obtaining the wrench workspace. A comparison of the two techniques applied to the 3-RPR CDPM is provided in [19].…”

Section: Workpacesmentioning

confidence: 99%

Task-optimized cable-actuated planar parallel manipulator architecture and its concurrent implementation

Pickard

Carretero

Bhavsar

2014

2014 International Conference on High Performance Computing &Amp; Simulation (HPCS)

View full text Add to dashboard Cite

This work presents an initial framework for an efficient new technique for obtaining task-optimized parallel manipulators with the aid of parallel computing through OpenMP directives. A cable-driven parallel manipulator is an architecture whose actuated limbs are cables. All of the cables must remain in constant positive tension to constrain the motion of the moving end-effector. A Differential Evolution algorithm is applied in order to optimize the topology and actuator specifications of a cable-driven parallel manipulator. The algorithm's intrinsic parallelism is exploited using OpenMP directives to evaluate the manipulator's associated reachable and wrench workspaces. The results show that this algorithm is effective at obtaining a taskoptimized architecture for the cable-driven parallel manipulator. Parallel implementation is shown to improve the algorithm's performance with a speedup of 7.4 times using ten cores on the Atlantic Computational Excellence Network (ACEnet) Fundy compute resource which utilizes Parallel Sun x4600 and x2200 AMD Opteron (dual-core) clusters.

show abstract

“…Krut et al (2004b) also studied force performance indices of redundant parallel manipulators and determined the isotropic wrench workspaces of planar wire-driven manipulators with multiple actuated limbs. Firmani et al (2007a and) derived a set of wrench performance indices for PPMs. Merlet (1996) described that the inclusion of redundancy may lead to improvements in various analyses such as forward kinematics, singular configurations, optimal force control, and calibration.…”

Section: Wwwintechopencommentioning

confidence: 99%

Wrench Capabilities of Planar Parallel Manipulators and their Effects Under Redundancy

Firmani¹,

Nokleby²,

Podhorodeski³

et al. 2008

Parallel Manipulators, Towards New Applications

Self Cite

View full text Add to dashboard Cite

Wrench capabilities of planar parallel manipulators. Part I: Wrench polytopes and performance indices

Cited by 36 publications

References 29 publications

Transducer and base compliance alter the in situ 6 dof force measured from muscle during an isometric contraction in a multi-joint limb

Transducer and base compliance alter the in situ 6 dof force measured from muscle during an isometric contraction in a multi-joint limb

Task-optimized cable-actuated planar parallel manipulator architecture and its concurrent implementation

Wrench Capabilities of Planar Parallel Manipulators and their Effects Under Redundancy

Contact Info

Product

Resources

About