| """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() |
|
|
