Checks and references

A model has to be checkable faster than it can be built. freedyn2 check, the viewer's Checks panel and the assistant's validate and check tools report the same findings:

freedyn2 check model.yaml             # the model alone
freedyn2 check model.yaml --run       # and its results
freedyn2 check model.yaml result.csv  # and these results

The exit status is 1 if there is an error or a failed reference – usable in CI.

Findings

errors	inertia no real body has (I1 + I2 < I3), a spring whose points coincide, non-finite results
likely slips	gravity, lengths or masses not in SI units; a joint far from both its bodies; more constraints than degrees of freedom (redundant joints); a tire deep in the road or in the air at the start; drift of the orientation
good to know	degrees of freedom and total mass; bodies not connected to the ground or not at rest at the start; parameters no expression uses

References

The checks section holds what the results must agree with – from the weight list, a measurement, a test rig:

checks:
  mass: {total: 1430, tolerance: 5}                        # [kg], from the weight list
  values:
    - {name: ride height, channel: chassis1.R_z, time: 0.0, value: 0.536, tolerance: 0.002}
  curves:
    - {name: toe fl, channel: toe_fl, x_channel: travel_fl, file: kc_rig.csv, x: travel, y: toe, tolerance: 0.001}

• values: a channel at a time.
• curves: a channel over time, or over another channel (x_channel) – e.g. toe over wheel travel of a kinematics & compliance rig – against a CSV file. Reported: the largest deviation and where.

Every check is run with every simulation in the viewer; failed references are red in the Checks panel, and a click plots the curve with its reference.

key	value
mass	object	Total mass of the bodies [kg], e.g. from the weight list.
values	list
curves	list