Fix flexcomp instability when parent body has non-identity quaternion#3379
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devansh0703 wants to merge 1 commit into
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Fix flexcomp instability when parent body has non-identity quaternion#3379devansh0703 wants to merge 1 commit into
devansh0703 wants to merge 1 commit into
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Fast path for elastic/damper forces assumed body slide joints are world-aligned. When parent body has non-identity quaternion, joint axes are rotated, causing wrong force mapping and NaN in QACC. Fix: project world-frame forces onto body's local frame via mju_mulMatTVec3(R^T, force) before adding to qfrc_spring/damper.
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Fast path in
mj_flexPassiveInterp,mj_flexPassiveBendInterp, andmj_flexPassiveStretchassumed body slide joints are world-aligned. When parent body has a non-identity quaternion, joint axes are rotated, causing wrong force mapping and instability (NaN/Inf in QACC).Fix: project world-frame forces onto body's local frame via
mju_mulMatTVec3(R_body^T, force)before adding to qfrc_spring/damper.Fixes #3364