FA-88117 / Inverse kinematics solvers / Member archive

Stewart platform composes roll, pitch and yaw in reverse order · case 02

Poses with more than one non-zero attitude angle produce wrong leg lengths.

Member previewVariant 2 · 3 implementations · 7 checks per implementation

Case contract

Input [A,B,pose,lmin,lmax]: base anchors A and platform anchors B (platform frame), pose [x,y,z,roll,pitch,yaw] in degrees with R = Rz(yaw) Ry(pitch) Rx(roll). Leg i length is |p + R b_i - a_i|. Return lengths rounded to 4, or ["limit", i, length] for the first leg outside the inclusive range [lmin,lmax].

Why this case matters

Inverse kinematics code turns task-space goals into joint commands; a wrong branch, sign, limit or update order sends a real arm to the wrong pose.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
combined attitude	`[9.2584, 7.7756, 8.311]`	`[9.2131, 8.0316, 8.1298]`	Failed

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