AAmogh·Panhale
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RoboticsNumerical2026

MuJoCo Ackermann Steering

Finds the least-error polynomial fit for Ackermann steering geometry in MuJoCo.

Problem

MuJoCo cars approximate Ackermann steering with a quartic joint-equality polynomial; picking the coefficients badly causes visible steering misalignment across the range.

What I built

  • Derived the quartic polycoef two ways — Taylor expansion of the exact geometry and a least-squares fit over the steering range.
  • Built an error table (SSE / RMSE / max error) and argued why RMSE is the right metric to optimize (sample-count-independent, whole-range, in degrees).
  • Exposed wheelbase, track width, steering lock, and sample count as CLI parameters with a comparison plot.

Impact

  • Produces a ready-to-paste MuJoCo `polycoef` vector for a given car geometry.
  • The least-squares fit minimizes typical (RMSE) steering error across the full lock range.

Stack

PythonNumPyMuJoCoMatplotlib