cobot-safety 0.1.0

Geometric human safety enforcement for robotic workspaces — zero dependencies

cobot-safety

Geometric human safety enforcement for robotic workspaces.

Zero dependencies. Drop into any Python robotics project and get four-layer collision-free path validation in five lines of code.

pip install cobot-safety

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What it does

cobot-safety validates robot pick-and-place plans against human safety zones after any AI or heuristic planner has run. Four independent mechanisms — no single failure can produce a dangerous path:

Mechanism	What it checks
Point-in-polygon (ray-casting)	No destination lands inside a human zone
Path intersection (2D segment math)	No carry path crosses a human zone, even diagonally
Occupancy check	No two objects are placed at the same position
Safe-area computation	Candidate positions are always generated outside all zones

Safety is enforced in Python — the AI cannot override it.

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Quick start

from cobot_safety import enforce_safety, make_safety_polygon, ROBOT_BASE_ZONE

# Define where humans are (from your camera or sensor)
human_zone = {
    "polygon": make_safety_polygon(
        {"x_min": 0.5, "y_min": 0.6, "x_max": 0.9, "y_max": 1.0},
        margin=0.05,
    )
}

# Your plan (from any planner — Gemini, MoveIt, custom A*)
plan = {
    "sequence": [
        {"step": 1, "object_id": "bottle",
         "from": {"x": 0.2, "y": 0.3}, "to": {"x": 0.8, "y": 0.8}},
        {"step": 2, "object_id": "cup",
         "from": {"x": 0.3, "y": 0.4}, "to": {"x": 0.1, "y": 0.1}},
    ],
    "clusters": [],
}

zones = [ROBOT_BASE_ZONE, human_zone]
plan, relocated = enforce_safety(plan, zones)

for step in plan["sequence"]:
    if step.get("skip"):
        print(f"Step {step['step']} skipped — no safe path")
    else:
        print(f"Step {step['step']} → {step['to']}")

Try it

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API

enforce_safety(plan, safety_zones, objects=None)

Main enforcement function. Mutates plan["sequence"] in place.

Parameters:

• plan — dict with "sequence" (list of step dicts) and optional "clusters"
• safety_zones — list of zone dicts, each with a "polygon" key
• objects — optional list of {"id": str, "category": str} for cluster-aware relocation

Returns: (plan, relocated) — the mutated plan and the number of steps relocated.

Steps that could not be made safe have step["skip"] = True.

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Geometry primitives

from cobot_safety import (
    point_in_polygon,      # ray-casting test
    in_any_zone,           # checks against a list of zones
    segments_intersect,    # p1-p2 vs p3-p4 (tuple args)
    path_crosses_any_zone, # straight-line carry path check
)

Zone construction

from cobot_safety import make_safety_polygon

polygon = make_safety_polygon(
    {"x_min": 0.3, "y_min": 0.6, "x_max": 0.7, "y_max": 0.9},
    margin=0.05,  # outward buffer, default 0.05
)

Safe-area helpers

from cobot_safety import compute_safe_area, generate_grid_positions

sx_min, sx_max, sy_min, sy_max = compute_safe_area(safety_zones)
positions = generate_grid_positions(20, sx_min, sx_max, sy_min, sy_max)

Constants

from cobot_safety import (
    ROBOT_BASE_ZONE,        # default robot base exclusion zone
    DEFAULT_MARGIN,         # 0.05 — safety polygon buffer
    MIN_SPACING,            # 0.11 — grid position spacing
    OCCUPANCY_THRESHOLD,    # 0.08 — minimum distance between objects
)

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Coordinate system

All coordinates are normalized to [0, 1]. (0, 0) is the top-left corner of the workspace, (1, 1) is the bottom-right.

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Tunable constants

Override by importing and reassigning before calling enforce_safety:

import cobot_safety.enforce as se
se.MIN_SPACING = 0.15          # wider grid spacing
se.OCCUPANCY_THRESHOLD = 0.10  # larger personal space per object

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Part of SafeArc

cobot-safety is extracted from the SafeArc hackathon project — a browser-based AI pipeline for human-safe robotic workspace sorting.

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License

Apache 2.0 — see LICENSE.