FA-88310 / Inverse kinematics solvers / Member archive

Encoder counts use banker's rounding · case 05

Exact half counts round to even, so +0.5 counts sometimes round down.

Member previewVariant 5 · 3 implementations · 7 checks per implementation

Case contract

Input [geo,off,dirs,ratio,lines,lims], all per-joint lists: IK joint angles (degrees) become encoder counts per joint as counts = floor(dirs*(geo-off)*ratio/360*lines*4 + 0.5) (quadrature gives 4 counts per line, half rounds up). lims holds inclusive [lo,hi] count limits; the first violating joint returns ["limit", i, counts].

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
half count rounding up	`[2]`	`[3]`	Failed

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