From 827b7a279247e2637b8bea15299e0652b950bb0c Mon Sep 17 00:00:00 2001 From: Nimrod Gileadi Date: Tue, 2 Apr 2024 03:02:04 -0700 Subject: [PATCH] Solver parameter docs improvements. - Correct the equation for penetration depth. The equation is tested in engine_core_constraint_test.cc. - Add a tip on scaling damping with stiffness. PiperOrigin-RevId: 621111712 Change-Id: I8fcc133cbc638ffef2d0ddf4e298ae402dda7b6a --- doc/modeling.rst | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/doc/modeling.rst b/doc/modeling.rst index 36edf643..490affa8 100644 --- a/doc/modeling.rst +++ b/doc/modeling.rst @@ -421,7 +421,7 @@ and the damping ratio is ignored. Equivalently, in the direct format, the :math: impedance is constant, then the penetration depth at rest is .. math:: - r = \au \cdot (1 - d) \cdot \text{stiffness} + r = \frac{\au (1 - d)}{\text{stiffness}} .. tip:: In the positive-value default format, the :math:`\text{timeconst}` parameter controls constraint **softness**. @@ -431,6 +431,9 @@ and the damping ratio is ignored. Equivalently, in the direct format, the :math: The negative-value "direct" format is more flexible, for example allowing for perfectly elastic collisions (:math:`\text{damping} = 0`). It is the recommended format for system identification. + A :math:`\text{dampratio}` of 1 in the positive-value format is equivalent to + :math:`\text{damping} = 2 \sqrt{ \text{stiffness} }` in the direct format. + .. _CContact: Contact parameters