Complete ranging cycle
Target for all 10 pair distances across a five-phone group. Device setup, radio conditions, and retries determine actual cycle time.
HARDWARE BENCHMARK PENDING DISTRIBUTED SPATIAL INTELLIGENCEPosition.
Position.
Without sight.
A shared sense of where everyone is.
Relative positioning for GPS-denied, low-visibility environments—using radio, not cameras.
RELATIVE REFERENCE FRAMEFIG. 01 / GEOMETRY
‖p − pᵢ‖ = rᵢRANGE CONSTRAINTS / SCHEMATIC
0GPS dependencies
5Peers in a ranging group
10Pairwise range constraints
< 5sFull-cycle design target 01
When visibility drops,
awareness shouldn’t.
Dark interiors. Obscured sightlines. Places a satellite signal cannot reach. TactLink reconstructs the group’s relative geometry from peer-to-peer distances, without visual features, installed anchors, or a cloud positioning service.
Designed for these conditions. Radio obstruction, multipath, and motion still affect ranging; low-visibility field performance remains to be validated.
No satellite fix No scene reconstruction No fixed anchor deployment
01 / RELATIVE POSITIONINGDistance becomes
Distance becomes
spatial awareness.
A radio measures a distance.
A network of distances reveals a shape.
RELATIVE REFERENCE FRAMEFIG. 01 / GEOMETRY
‖p − pᵢ‖ = rᵢRANGE CONSTRAINTS / SCHEMATIC
Add a range
ULTRA-WIDEBAND / UWB
A radio ruler.
UWB sends very short radio pulses across a wide frequency band. Their travel time provides a distance estimate between devices. No image, lighting, or visual landmark is needed for that measurement.
distance ≈ propagation time × cRanging accounts for the reply delay.
From ranges to a relative map
Each distance constrains a position to a sphere. Intersections explain the geometry; the implementation reconstructs all peers together from the complete distance matrix using multidimensional scaling.
The illustration uses five range shells to explain an unknown point. The five-phone system instead solves 10 mutual distances. Global position, orientation, and reflection are not determined by distances alone.
PAIR DISTANCES D²CENTERED GRAM MATRIX −½ JD²JTOP 3 EIGENVECTORS X = V₃Λ₃½RELATIVE GROUP SHAPE
DECENTRALIZED BY DEPLOYMENTThe group is
The group is
the infrastructure.
Nearby phones exchange measurements over authenticated, encrypted peer connections. No fixed base station and no internet service calculate your position.
A deterministically elected peer schedules ranging and shares the map. The role can move to another peer; the current prototype is peer-coordinated, not leaderless.
Coordination & recoveryLOCAL PEER NETWORK NO CLOUD DEPENDENCY
UWB · DISTANCEPEER TRANSPORT · COORDINATION
02 / THE RANGING PROTOCOLA hardware limit.
A hardware limit.
A scheduling solution.
Time-share the radio.
Build the complete distance graph.
ONE RADIO · ONE PARTNERFIG. 03
01 / 05 ROUNDS
TIME-DIVISION MULTIPLEXINGOne connection.
One connection.
Every peer.
A phone ranges with one partner at a time. Rotate the pairings; two independent pairs can work in parallel while the fifth phone waits.
5 peers10 unique pairs5 nominal rounds
Actual dispatch is availability-based: a free pair may start without waiting for an entire round. Each attempt exchanges fresh Nearby Interaction tokens.
Prepare fresh sessionExchange tokensCollect 4 valid readings250 ms graceRelease + 300 ms handoff
Failed attempts back off. Local leases release a stuck radio. Incomplete cycles stay out of complete-cycle statistics.
Round-robin implementation03 / FROM HUMAN INTENT TO ACTIONLocate with radio.
Locate with radio.
Command with a gesture.
Two independent pipelines.
One operator state.
POSITION / CAMERA-FREE
UWB rangesRelative geometryPosition + age
OPTIONAL INPUT / LOCAL CAMERA
MediaPipeGesture logicIntent + heading
STATE MERGEOperator state → command mapping → drone simulatorPosition, heading, gesture, confidence. Camera frames stay local.
MEDIAPIPE + CUSTOM GESTURE LAYER
FIG. 04 / MODEL ARCHITECTUREInside the gesture pipeline.
01
Local camera
Frames stay on the device; no image stream to the swarm.
02
MediaPipe recognizer
Palm detection → 21 landmarks → canned gesture scores.
03
Gesture logic
iOS: landmark rules + motion sequences. PC: optional custom k-NN.
04
Stabilize & gate
Confidence rejection, recent-frame voting, and command hold.
05
Command output
Gesture + confidence + heading joins the UWB position stream.
RUN LOCALLY · TRANSMIT INTENT
The iPhone ships the pretrained MediaPipe recognizer plus gesture rules. The desktop can load the optional custom model, falling back to canned gestures when a pose is rejected. Gesture visibility does not determine UWB position.
04 / ENGINEERING ENVELOPESpecific by design.
Specific by design.
Measurable by default.
Protocol constants, design targets,
and real measurements stay distinct.
Valid readings per attempt
The completion milestone before peer grace and teardown. Four samples are a collection threshold, not an accuracy guarantee.
IMPLEMENTEDMeasurement deadline
Default per-attempt measurement window. A separate local lease adds five seconds to release the radio if coordination stalls.
IMPLEMENTEDWHAT A “TICK” MEANS
A complete cycle is a fresh map.
The coordinator checks work every 100 ms. Bridge packets arrive at roughly 10 Hz. Neither means a new position was measured: fresh geometry requires a complete set of ranges. Profiling reports complete-cycle p50/p95, fit residual, and measurement age.
Relative, not geographic
No latitude, longitude, or gravity-aligned height. Nearly planar layouts leave the third axis uncertain.
Freshness is explicit
Motion during a cycle can deform the estimate. The prototype expires positions after eight seconds.
Evidence stays inspectable
Per-attempt timing, failures, and full-cycle statistics export as JSONL. Field navigation performance is not yet validated.