ados-swarm

Swarm control laws for multirotors: separation, braking-aware barriers, alpha-lattice flocking, formations, CBBA task allocation and a deterministic point-mass simulator.

Flying several multirotors near each other needs three things at once: never let two aircraft close inside a safety floor, keep the group moving together or holding a shape, and agree on who does which task without a central coordinator. This crate is those control laws as plain Rust, plus a deterministic simulator to test them on a laptop. Reach for it when you are building swarm autonomy on top of any autopilot that accepts position or velocity setpoints.

use ados_swarm::separation::SEPARATION_HARD_M;
use ados_swarm::sim::{SimDrone, SimWorld};
use ados_swarm::{GeoOrigin, Ned, SwarmControlConfig};

// Three drones in flocking mode, launched 12 m apart at 30 m altitude.
let cfg = SwarmControlConfig {
    enabled: true,
    mode: "flocking".into(),
    ..Default::default()
};
let slots = [1, 2, 3];
let drones = vec![
    SimDrone::new(1, Ned::new(0.0, 0.0, -30.0), &cfg, &slots),
    SimDrone::new(2, Ned::new(12.0, 0.0, -30.0), &cfg, &slots),
    SimDrone::new(3, Ned::new(0.0, 12.0, -30.0), &cfg, &slots),
];
let mut world = SimWorld::new(GeoOrigin::new(47.397, 8.545, 0.0), drones);

// 30 simulated seconds at the 10 Hz control rate.
let report = world.run(300);
println!("closest approach: {:.1} m", report.min_pairwise_m);
assert!(report.min_pairwise_m > SEPARATION_HARD_M);

Highlights

• Every control law is a pure function over a slice of neighbours in a local NED frame: no clock, no socket, no radio.
• One dependency (serde, for the configuration structs).
• Deterministic simulator with a first-order velocity plant, 2 Hz beacon quantisation and dead reckoning; four flight scenarios (collision course, 8-drone flocking to a target, wedge station keeping, beacon loss) run as ordinary tests and as cargo run --example swarm_scenarios.
• A fixed precedence ladder decides which law flies, and the active level packs into three bits of a one-byte beacon status field.
• Bounded work per tick: nearest-neighbour search is allocation-free and every law weights at most a fixed number of neighbours.

How it works

Shape

Every law takes a slice of NeighborState and returns a velocity or position intent. The only stateful piece is SwarmController, which holds the latches a safety layer needs (the hard-override dwell, the staleness deadline, the climb datum) and converts between geodetic coordinates and the local frame at the boundary. Its tick consumes this drone's own state plus geodetic neighbour fixes and returns at most one Setpoint, the field set of MAVLink SET_POSITION_TARGET_GLOBAL_INT. Encoding and sending it is left to the host.

Modules

The precedence ladder

Highest first: hard separation, operator directive, formation, flocking, hold. The ACTIVE level, not the commanded one, is what SwarmController::precedence reports and what ModePrecedence::as_status_bits packs into status bits 5..7. A drone whose separation layer has taken over reads hard-separation, never the mode somebody asked for. Hold is encoding zero, so a node with no control layer running reads hold truthfully.

Staleness

NEIGHBOR_STALE (3 s) is how long a silent neighbour is kept and how long an empty table is tolerated before the controller stops commanding. OWN_STATE_STALE (1 s) is tighter, because a frozen own fix stays plausible while every neighbour is measured from it. A transport that prunes its table or gates its own beacon should use the same constants.

What is deliberately not here

• No leader election. Electing a leader among drones over a lossy broadcast invites a split brain for no benefit; the operator is the single authority.
• No failsafe of its own. The autopilot's own failsafes and geofence are the backstop. When the controller has nothing trustworthy to fly on it emits nothing and lets the flight controller hold.

Part of ADOS

Used in production by the ADOS Drone Agent, the onboard software of the ADOS software-defined drone platform. All ADOS crates · Docs · Discord

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Platform (versioned with the ADOS Drone Agent)

Standalone

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License

Licensed under either of Apache License, Version 2.0 or MIT license at your option.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this crate by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.