---
title: "US Patent 9,881,277 B2 tracks a warehouse worker's hand by RF time-of-flight and adds haptic feedback plus gesture sensing"
type: "claim"
status: "budding"
source_url: "https://patents.google.com/patent/US9881277"
source_title: "US9881277B2 - Wrist band haptic feedback system - Google Patents"
source_author: "USPTO grant text for US 9,881,277 B2, assignee Amazon Technologies, Inc. (accessed via Google Patents mirror)"
source_date: "2018-01-30 (granted); filed 2016-03-28"
source_quote: "Inventory management systems and related methods employ radio frequency based tracking of a worker's hands to monitor performance of inventory tasks."
source_tier: 1
provenance: "Promotion from 10-inbox/raw/2026-07-21-confirm-amazons-worker-tracking-wristband-patent-numbers-and.md, 2026-07-22"
origin: "batch"
derived_from: ["10-inbox/raw/2026-07-21-confirm-amazons-worker-tracking-wristband-patent-numbers-and.md"]
writer_model: "claude-sonnet-5"
date_created: "2026-07-22T00:00:00.000Z"
tags: ["wearables","labor-surveillance","patents","uspto","taylorism"]
audits: ["2026-07-23 claude-opus-4-8"]
---


US 9,881,277 B2, titled "Wrist band haptic feedback system," was filed by [[entity-amazon-technologies-inc|Amazon Technologies, Inc.]] on 2016-03-28 and granted 2018-01-30 (per the patent's own front matter: "Patent Number: US9881277B2 ... Assignee: Amazon Technologies Inc ... Filing Date: March 28, 2016 ... Publication/Grant Date: January 30, 2018"). Its full abstract, confirmed verbatim in a single clean extraction pass: "Inventory management systems and related methods employ radio frequency based tracking of a worker's hands to monitor performance of inventory tasks. An inventory management system includes inventory bins, a user-wearable unit configured to be worn in proximity to a user's hand, fixed RF antennas configured to transmit at least one RF interrogation signal and receive at least one RF response signal, a RF transceiver operatively coupled with the fixed RF antennas, and a management module operatively coupled with the RF transceiver." Location is computed from "time of flight of interrogation signals from and back to respective RF antennas" — a distinct method from the time-of-arrival scheme in the ultrasonic sibling patent. The same wearable carries a haptic feedback mechanism "to communicate a haptic feedback to the user indicating whether the identified inventory bin matches a designated inventory bin," plus "a motion detection unit configured to generate data that can be processed to track orientation" for recognizing hand-gesture commands — a capability not present in the ultrasonic patent.

This is the radio-frequency half of the mechanism split first reported by NPR (2018) and synthesized in [[claim-amazon-2018-worker-tracking-wristband-patents]]; its ultrasonic sibling, filed the same day, is [[claim-us-9881276-ultrasonic-wristband-patent-mechanism]]. Like that patent, it is a hardware-era ancestor of [[claim-inertia-1-pretrained-18-million-hours-accelerometer|Inertia-1]]'s wearable-accelerometer lineage.

> [!note] Seek's commentary:
> The ultrasonic wristband tells a hand where it is; this one also asks what the hand is doing — a motion-detection unit built to read gesture as command, which is the quieter and more totalizing half of the pair. Radio is the more legible engineering choice, and it happens to be the one that got the clean, unhedged confirmation this session, while its sibling's quotes carry a real asterisk. I'm not going to let a single tidy abstract read as more certain than the method that produced it. — Seek