Files
solver/kindred_solver/solver.py
forbes-0023 533ca91774 feat(solver): full constraint vocabulary — all 24 BaseJointKind types (phase 2)
Add 18 new constraint classes covering all BaseJointKind types from Types.h:
- Point: PointOnLine (2r), PointInPlane (1r)
- Orientation: Parallel (2r), Perpendicular (1r), Angle (1r)
- Surface: Concentric (4r), Tangent (1r), Planar (3r), LineInPlane (2r)
- Kinematic: Ball (3r), Revolute (5r), Cylindrical (4r), Slider (5r),
  Screw (5r), Universal (4r)
- Mechanical: Gear (1r), RackPinion (1r)
- Stubs: Cam, Slot, DistanceCylSph

New modules:
- geometry.py: marker axis extraction, vector ops (dot3, cross3, sub3),
  geometric primitives (point_plane_distance, point_line_perp_components)
- bfgs.py: L-BFGS-B fallback solver via scipy for when Newton fails

solver.py changes:
- Wire all 20 supported types in _build_constraint()
- BFGS fallback after Newton-Raphson in solve()

183 tests passing (up from 82), including:
- DOF counting for every joint type
- Solve convergence from displaced initial conditions
- Multi-body mechanisms (four-bar linkage, slider-crank, revolute chain)
2026-02-20 21:15:15 -06:00

403 lines
11 KiB
Python

"""KindredSolver — IKCSolver implementation bridging KCSolve to the
expression-based Newton-Raphson solver."""
from __future__ import annotations
import kcsolve
from .bfgs import bfgs_solve
from .constraints import (
AngleConstraint,
BallConstraint,
CamConstraint,
CoincidentConstraint,
ConcentricConstraint,
ConstraintBase,
CylindricalConstraint,
DistanceCylSphConstraint,
DistancePointPointConstraint,
FixedConstraint,
GearConstraint,
LineInPlaneConstraint,
ParallelConstraint,
PerpendicularConstraint,
PlanarConstraint,
PointInPlaneConstraint,
PointOnLineConstraint,
RackPinionConstraint,
RevoluteConstraint,
ScrewConstraint,
SliderConstraint,
SlotConstraint,
TangentConstraint,
UniversalConstraint,
)
from .dof import count_dof
from .entities import RigidBody
from .newton import newton_solve
from .params import ParamTable
from .prepass import single_equation_pass, substitution_pass
# All BaseJointKind values this solver can handle
_SUPPORTED = {
# Phase 1
kcsolve.BaseJointKind.Coincident,
kcsolve.BaseJointKind.DistancePointPoint,
kcsolve.BaseJointKind.Fixed,
# Phase 2: point constraints
kcsolve.BaseJointKind.PointOnLine,
kcsolve.BaseJointKind.PointInPlane,
# Phase 2: orientation
kcsolve.BaseJointKind.Parallel,
kcsolve.BaseJointKind.Perpendicular,
kcsolve.BaseJointKind.Angle,
# Phase 2: axis/surface
kcsolve.BaseJointKind.Concentric,
kcsolve.BaseJointKind.Tangent,
kcsolve.BaseJointKind.Planar,
kcsolve.BaseJointKind.LineInPlane,
# Phase 2: kinematic joints
kcsolve.BaseJointKind.Ball,
kcsolve.BaseJointKind.Revolute,
kcsolve.BaseJointKind.Cylindrical,
kcsolve.BaseJointKind.Slider,
kcsolve.BaseJointKind.Screw,
kcsolve.BaseJointKind.Universal,
# Phase 2: mechanical
kcsolve.BaseJointKind.Gear,
kcsolve.BaseJointKind.RackPinion,
}
class KindredSolver(kcsolve.IKCSolver):
"""Expression-based Newton-Raphson constraint solver."""
def name(self):
return "Kindred (Newton-Raphson)"
def supported_joints(self):
return list(_SUPPORTED)
def solve(self, ctx):
params = ParamTable()
bodies = {} # part_id -> RigidBody
# 1. Build entities from parts
for part in ctx.parts:
pos = tuple(part.placement.position)
quat = tuple(part.placement.quaternion) # (w, x, y, z)
body = RigidBody(
part.id,
params,
position=pos,
quaternion=quat,
grounded=part.grounded,
)
bodies[part.id] = body
# 2. Build constraint residuals
all_residuals = []
constraint_objs = []
for c in ctx.constraints:
if not c.activated:
continue
body_i = bodies.get(c.part_i)
body_j = bodies.get(c.part_j)
if body_i is None or body_j is None:
continue
marker_i_pos = tuple(c.marker_i.position)
marker_j_pos = tuple(c.marker_j.position)
obj = _build_constraint(
c.type,
body_i,
marker_i_pos,
body_j,
marker_j_pos,
c.marker_i,
c.marker_j,
c.params,
)
if obj is None:
continue
constraint_objs.append(obj)
all_residuals.extend(obj.residuals())
# 3. Add quaternion normalization residuals for non-grounded bodies
quat_groups = []
for body in bodies.values():
if not body.grounded:
all_residuals.append(body.quat_norm_residual())
quat_groups.append(body.quat_param_names())
# 4. Pre-passes
all_residuals = substitution_pass(all_residuals, params)
all_residuals = single_equation_pass(all_residuals, params)
# 5. Newton-Raphson (with BFGS fallback)
converged = newton_solve(
all_residuals,
params,
quat_groups=quat_groups,
max_iter=100,
tol=1e-10,
)
if not converged:
converged = bfgs_solve(
all_residuals,
params,
quat_groups=quat_groups,
max_iter=200,
tol=1e-10,
)
# 6. DOF
dof = count_dof(all_residuals, params)
# 7. Build result
result = kcsolve.SolveResult()
result.status = (
kcsolve.SolveStatus.Success if converged else kcsolve.SolveStatus.Failed
)
result.dof = dof
env = params.get_env()
placements = []
for body in bodies.values():
if body.grounded:
continue
pr = kcsolve.SolveResult.PartResult()
pr.id = body.part_id
pr.placement = kcsolve.Transform()
pr.placement.position = list(body.extract_position(env))
pr.placement.quaternion = list(body.extract_quaternion(env))
placements.append(pr)
result.placements = placements
return result
def is_deterministic(self):
return True
def _build_constraint(
kind,
body_i,
marker_i_pos,
body_j,
marker_j_pos,
marker_i,
marker_j,
c_params,
) -> ConstraintBase | None:
"""Create the appropriate constraint object from a BaseJointKind."""
marker_i_quat = tuple(marker_i.quaternion)
marker_j_quat = tuple(marker_j.quaternion)
# -- Phase 1 constraints --------------------------------------------------
if kind == kcsolve.BaseJointKind.Coincident:
return CoincidentConstraint(body_i, marker_i_pos, body_j, marker_j_pos)
if kind == kcsolve.BaseJointKind.DistancePointPoint:
distance = c_params[0] if c_params else 0.0
return DistancePointPointConstraint(
body_i,
marker_i_pos,
body_j,
marker_j_pos,
distance,
)
if kind == kcsolve.BaseJointKind.Fixed:
return FixedConstraint(
body_i,
marker_i_pos,
marker_i_quat,
body_j,
marker_j_pos,
marker_j_quat,
)
# -- Phase 2: point constraints -------------------------------------------
if kind == kcsolve.BaseJointKind.PointOnLine:
return PointOnLineConstraint(
body_i,
marker_i_pos,
marker_i_quat,
body_j,
marker_j_pos,
marker_j_quat,
)
if kind == kcsolve.BaseJointKind.PointInPlane:
offset = c_params[0] if c_params else 0.0
return PointInPlaneConstraint(
body_i,
marker_i_pos,
marker_i_quat,
body_j,
marker_j_pos,
marker_j_quat,
offset=offset,
)
# -- Phase 2: orientation constraints -------------------------------------
if kind == kcsolve.BaseJointKind.Parallel:
return ParallelConstraint(body_i, marker_i_quat, body_j, marker_j_quat)
if kind == kcsolve.BaseJointKind.Perpendicular:
return PerpendicularConstraint(body_i, marker_i_quat, body_j, marker_j_quat)
if kind == kcsolve.BaseJointKind.Angle:
angle = c_params[0] if c_params else 0.0
return AngleConstraint(body_i, marker_i_quat, body_j, marker_j_quat, angle)
# -- Phase 2: axis/surface constraints ------------------------------------
if kind == kcsolve.BaseJointKind.Concentric:
distance = c_params[0] if c_params else 0.0
return ConcentricConstraint(
body_i,
marker_i_pos,
marker_i_quat,
body_j,
marker_j_pos,
marker_j_quat,
distance=distance,
)
if kind == kcsolve.BaseJointKind.Tangent:
return TangentConstraint(
body_i,
marker_i_pos,
marker_i_quat,
body_j,
marker_j_pos,
marker_j_quat,
)
if kind == kcsolve.BaseJointKind.Planar:
offset = c_params[0] if c_params else 0.0
return PlanarConstraint(
body_i,
marker_i_pos,
marker_i_quat,
body_j,
marker_j_pos,
marker_j_quat,
offset=offset,
)
if kind == kcsolve.BaseJointKind.LineInPlane:
offset = c_params[0] if c_params else 0.0
return LineInPlaneConstraint(
body_i,
marker_i_pos,
marker_i_quat,
body_j,
marker_j_pos,
marker_j_quat,
offset=offset,
)
# -- Phase 2: kinematic joints --------------------------------------------
if kind == kcsolve.BaseJointKind.Ball:
return BallConstraint(body_i, marker_i_pos, body_j, marker_j_pos)
if kind == kcsolve.BaseJointKind.Revolute:
return RevoluteConstraint(
body_i,
marker_i_pos,
marker_i_quat,
body_j,
marker_j_pos,
marker_j_quat,
)
if kind == kcsolve.BaseJointKind.Cylindrical:
return CylindricalConstraint(
body_i,
marker_i_pos,
marker_i_quat,
body_j,
marker_j_pos,
marker_j_quat,
)
if kind == kcsolve.BaseJointKind.Slider:
return SliderConstraint(
body_i,
marker_i_pos,
marker_i_quat,
body_j,
marker_j_pos,
marker_j_quat,
)
if kind == kcsolve.BaseJointKind.Screw:
pitch = c_params[0] if c_params else 1.0
return ScrewConstraint(
body_i,
marker_i_pos,
marker_i_quat,
body_j,
marker_j_pos,
marker_j_quat,
pitch=pitch,
)
if kind == kcsolve.BaseJointKind.Universal:
return UniversalConstraint(
body_i,
marker_i_pos,
marker_i_quat,
body_j,
marker_j_pos,
marker_j_quat,
)
# -- Phase 2: mechanical constraints --------------------------------------
if kind == kcsolve.BaseJointKind.Gear:
radius_i = c_params[0] if len(c_params) > 0 else 1.0
radius_j = c_params[1] if len(c_params) > 1 else 1.0
return GearConstraint(
body_i,
marker_i_quat,
body_j,
marker_j_quat,
radius_i,
radius_j,
)
if kind == kcsolve.BaseJointKind.RackPinion:
pitch_radius = c_params[0] if c_params else 1.0
return RackPinionConstraint(
body_i,
marker_i_pos,
marker_i_quat,
body_j,
marker_j_pos,
marker_j_quat,
pitch_radius=pitch_radius,
)
# -- Stubs (accepted but produce no residuals) ----------------------------
if kind == kcsolve.BaseJointKind.Cam:
return CamConstraint()
if kind == kcsolve.BaseJointKind.Slot:
return SlotConstraint()
if kind == kcsolve.BaseJointKind.DistanceCylSph:
return DistanceCylSphConstraint()
return None