"""Check ball containment under lateral vibration in a STEP-derived tray.""" import argparse import hashlib import json import math import subprocess import sys from pathlib import Path ROOT = Path(__file__).resolve().parent def measure(step: Path, setup: dict) -> dict: import cadquery as cq shape = cq.importers.importStep(str(step)).val() if shape.ShapeType() != "Solid" or not shape.isValid() or len(shape.Solids()) != 1: raise ValueError(f"Expected one valid solid: {step}") bounds = shape.BoundingBox() envelope = cq.Solid.makeBox(300, 100, 60, cq.Vector(-150, -100, -30)) floor = cq.Solid.makeBox(300, 20, 60, cq.Vector(-150, -100, -30)) mounts = [cq.Solid.makeBox(2.5, 80, 15, cq.Vector(x, -80, z)) for x in (-150, 147.5) for z in (-30, 15)] vertices, faces = shape.tessellate(1.0) if not vertices or not faces: raise ValueError("STEP tessellation has no triangles") return { "step_sha256": hashlib.sha256(step.read_bytes()).hexdigest(), "volume_mm3": shape.Volume(), "mass_kg": shape.Volume() * setup["material_density_kg_m3"] * 1e-9, "bounds_mm": [bounds.xmin, bounds.xmax, bounds.ymin, bounds.ymax, bounds.zmin, bounds.zmax], "external_added_mm3": shape.cut(envelope).Volume(), "floor_missing_mm3": floor.cut(shape).Volume(), "mount_missing_mm3": sum(mount.cut(shape).Volume() for mount in mounts), "collision_vertices_m": [[v.x / 1000, v.y / 1000, v.z / 1000] for v in vertices], "collision_triangles": faces, } def dynamics(properties: dict, setup: dict) -> dict: import pychrono as ch ch.ChCollisionModel.SetDefaultSuggestedEnvelope(1e-5) ch.ChCollisionModel.SetDefaultSuggestedMargin(1e-5) material = ch.ChContactMaterialNSC() material.SetFriction(setup["contact_friction"]) material.SetRestitution(setup["contact_restitution"]) mesh = ch.ChTriangleMeshConnected() vertices = properties["collision_vertices_m"] for a, b, c in properties["collision_triangles"]: mesh.AddTriangle(ch.ChVector3d(*vertices[a]), ch.ChVector3d(*vertices[b]), ch.ChVector3d(*vertices[c])) dt = setup["time_step_s"] steps = round(setup["duration_s"] / dt) if dt <= 0 or abs(steps * dt - setup["duration_s"]) > 1e-12: raise ValueError("Invalid simulation duration or time step") escape_times = [] maximum_excursions = [] for release_x in setup["release_x_m"]: system = ch.ChSystemNSC() system.SetCollisionSystemType(ch.ChCollisionSystem.Type_BULLET) system.SetGravitationalAcceleration(ch.ChVector3d(0, -setup["gravity_m_s2"], 0)) tray = ch.ChBody() tray.SetFixed(True) tray.AddCollisionShape(ch.ChCollisionShapeTriangleMesh( material, mesh, True, False, 0)) tray.EnableCollision(True) system.Add(tray) ball = ch.ChBodyEasySphere(setup["ball_radius_m"], setup["ball_density_kg_m3"], False, True, material) ball.SetPos(ch.ChVector3d(release_x, setup["release_y_m"], 0)) system.Add(ball) planar = ch.ChLinkMateGeneric() planar.SetConstrainedCoords(False, False, True, False, False, False) planar.Initialize(ball, tray, ch.ChFramed( ch.ChVector3d(release_x, setup["release_y_m"], 0))) system.Add(planar) forcing = ch.ChForce() ball.AddForce(forcing) forcing.SetMode(ch.ChForce.FORCE) forcing.SetDir(ch.ChVector3d(1, 0, 0)) maximum_x = abs(release_x) escaped = None for i in range(steps): t = i * dt forcing.SetMforce(ball.GetMass() * setup["lateral_acceleration_m_s2"] * math.cos(2 * math.pi * setup["vibration_frequency_hz"] * t)) system.DoStepDynamics(dt) pos = ball.GetPos() if not math.isfinite(pos.x + pos.y): raise ValueError("Nonfinite ball trajectory") maximum_x = max(maximum_x, abs(pos.x)) if abs(pos.x) >= setup["escape_center_x_m"]: escaped = (i + 1) * dt break escape_times.append(escaped) maximum_excursions.append(maximum_x) return {"escape_times_s": escape_times, "escaped_count": sum(value is not None for value in escape_times), "maximum_center_excursions_m": maximum_excursions} def invoke(python: str, phase: str, payload: dict) -> dict: run = subprocess.run( [python, str(Path(__file__).resolve()), "--phase", phase], input=json.dumps(payload), text=True, capture_output=True, check=False, ) if run.returncode: raise RuntimeError(f"{phase} failed:\n{run.stderr[-1600:]}") return json.loads(run.stdout) def main() -> None: parser = argparse.ArgumentParser() parser.add_argument("--cad-python", default=sys.executable) parser.add_argument("--physics-python", default=sys.executable) parser.add_argument("--phase", choices=("measure", "dynamics")) args = parser.parse_args() if args.phase: payload = json.load(sys.stdin) result = (measure(Path(payload["step"]), payload["setup"]) if args.phase == "measure" else dynamics(payload["properties"], payload["setup"])) print(json.dumps(result)) return setup = json.loads((ROOT / "setup.json").read_text()) results = {} for name in ("before", "after"): properties = invoke(args.cad_python, "measure", { "step": str(ROOT / f"{name}.step"), "setup": setup, }) results[name] = { "step_properties": properties, "simulation_result": invoke(args.physics_python, "dynamics", { "properties": properties, "setup": setup, }), } before = results["before"] after = results["after"] bp = before["step_properties"] ap = after["step_properties"] bs = before["simulation_result"] gs = after["simulation_result"] checks = { "baseline_escapes": bs["escaped_count"] == len(setup["release_x_m"]), "all_releases_contained": gs["escaped_count"] == 0, "vibration_moves_ball": min(gs["maximum_center_excursions_m"]) >= setup["minimum_gold_ball_excursion_m"], "mass_fixed": abs(ap["mass_kg"] / bp["mass_kg"] - 1) <= setup["maximum_relative_mass_change"], "envelope_fixed": all(abs(a - b) <= setup["maximum_envelope_change_mm"] for a, b in zip(ap["bounds_mm"], bp["bounds_mm"])), "outer_envelope_kept": ap["external_added_mm3"] <= setup["maximum_external_added_mm3"], "floor_intact": ap["floor_missing_mm3"] <= setup["maximum_floor_missing_mm3"], "mounting_strips_intact": ap["mount_missing_mm3"] <= setup["maximum_mount_missing_mm3"], } after["comparison_to_before"] = {"checks": checks, "passed": all(checks.values())} for name, result in results.items(): (ROOT / f"{name}.results.json").write_text(json.dumps(result, indent=2) + "\n") print(f"Escaped releases: {bs['escaped_count']} -> {gs['escaped_count']}") print(f"Task passed: {after['comparison_to_before']['passed']}") if not after["comparison_to_before"]["passed"]: raise SystemExit(1) if __name__ == "__main__": main()