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Document semantics difference between Pinocchio quantities and iDynTree KinDynComputations quantities #674

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traversaro opened this issue Apr 20, 2020 · 5 comments
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Document semantics difference between Pinocchio quantities and iDynTree KinDynComputations quantities #674

traversaro opened this issue Apr 20, 2020 · 5 comments
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@GiulioRomualdi

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@traversaro
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traversaro commented Apr 20, 2020 •
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Things to check (see #673 (comment)) :

  • DOFs and link serializations
  • Velocity, force and acceleration representations for the base quantities
  • How we need to transform the vector and matrix input and output quantities appropriately given these differences
@traversaro traversaro mentioned this issue Apr 20, 2020
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cc @GiulioRomualdi

@traversaro
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Related issues:

@GiulioRomualdi
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Before I forgot I want to drop here this table of conversion:

iDynTree Pinocchio
MIXED_REPRESENTATION LOCAL_WORLD_ALIGNED
INERTIAL_FIXED_REPRESENTATION WORLD
BODY_FIXED_REPRESENTATION LOCAL

@DanielePucci
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CC @robotology/iit-dynamic-interaction-control

@S-Dafarra S-Dafarra mentioned this issue Jul 16, 2020
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@GiulioRomualdi GiulioRomualdi self-assigned this Jul 16, 2020
This was referenced Jul 17, 2020
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@traversaro traversaro mentioned this issue Jul 17, 2020
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traversaro commented Mar 26, 2022 •
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Before I forgot I want to drop here this table of conversion:

Updated version to be self-contained. Assumptions:

  • we have two frame a and e, and the transform between this two frames is represented by ᵃRₑ ∈ SO(3) ᵃoₑ ∈ ℝ³
  • (.)ᵛ represents the mapping between the skew-symmetrix matrix and the related vector in ℝ³, i.e. such that if u,v ∈ ℝ³, u = (U)ᵛ s.t. U v = u × v
  • the dot represent the usual mathematical analysis dot operator (time derivative) and not the Featherstone one then the different velocities are:
iDynTree Pinocchio Math
MIXED_REPRESENTATION LOCAL_WORLD_ALIGNED (ᵃȯₑ , ( ᵃṘₑ ᵃRₑᵀ )ᵛ ) .
INERTIAL_FIXED_REPRESENTATION WORLD (ᵃȯₑ - (ᵃṘₑ ᵃRₑᵀ) ᵃoₑ , ( ᵃṘₑ ᵃRₑᵀ )ᵛ ) .
BODY_FIXED_REPRESENTATION LOCAL (ᵃRₑᵀ ᵃȯₑ , ( ᵃRₑᵀ ᵃṘₑ )ᵛ ) .

Sources and derivation for the equations:

Related Pinocchio issues:

@traversaro traversaro mentioned this issue Mar 26, 2023
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