Components#

IMU Trackers#

Each tracker consists of:

  • BNO085 9-axis IMU sensor

  • WeMos D1 Mini (ESP8266) for Wi-Fi streaming

  • 3D-printed enclosure with a rigidly mounted AprilTag

  • LiPo battery (e.g. 503759 1200 mAh, see BOM)

You need 9 trackers in total. The full IMU / AprilTag / SMPL-X mapping is:

IMU ID

Body Part

AprilTag ID

SMPL-X Joint

1

Pelvis

0

0

2

Left Shoulder

1

16

3

Right Shoulder

2

17

4

Left Elbow

3

18

5

Right Elbow

4

19

6

Left Hip

5

1

7

Right Hip

6

2

8

Left Knee

7

4

9

Right Knee

8

5

Project Aria Glasses#

RoSHI uses Project Aria glasses for:

  • 6-DoF head tracking via onboard SLAM

  • Egocentric RGB video capture

  • Machine Perception Services (MPS) for post-processing

Bill of Materials#

Prices below are typical U.S. Amazon retail (before tax/shipping) for the listed packs; buy enough packs to cover nine trackers plus spares where it helps (passives, connectors). PCB Gerbers follow the SlimeVR Hyperion design—see Assembly.

Item

Qty (9 trackers)

List / pack price

Source

WeMos D1 Mini (ESP8266 class)

9 boards (e.g. 5-packs)

$14.99 / 5 boards (~$3.00 ea)

D1 Mini pack

180 kΩ resistor (1/2 W metal film)

9 (buy 100-pack)

$5.99 / 100 pcs

180K resistor pack

Schottky diode 1N5817

9 (buy 125-pack)

$5.99 / 125 pcs

1N5817 diode pack

TP4056 charger (Type-C), dual protection

9 modules (1× 10-pack)

$8.99 / 10 pcs

TP4056 10-pack

BNO085 nine-axis IMU module

9

$17.59 each

BNO085 module

Slide switch SS12D00G3 (SPDT, 3-pin)

9 (40-pack)

$5.59 / 40 pcs

SS12D00G3 40-pack

LiPo 503759, 3.7 V, 1200 mAh, JST-PH 2.0 mm

9

$10.19 each

503759 1200mAh battery

JST-PH 2.0 mm socket kit (side-entry / right-angle, multi-pin)

9× 2P sockets from kit

$9.99 kit (~40× 2P + other sizes)

JST-PH socket kit

Pin headers, strap hardware, filament, AprilTag prints

varies

(local / print lab)

3D-printed tracker case

9

material cost varies

see Assembly

Receiver (host unit) BOM#

These parts match the receiver described in Assembly (ESP32-S3 host, ESP-NOW on 2.4 GHz, small OLED on I²C, external antenna). Prices are Adafruit U.S. list (before tax/shipping). The Feather uses a w.FL / MHF3 / IPEX3 port (not u.FL); pair the RP-SMA dipole antenna with the RP-SMA to w.FL adapter cable. Budget separately for STEMMA QT / Qwiic cables and any I²C multiplexers your receiver PCB uses.

Item

Qty

Price

Source

Adafruit ESP32-S3 Feather 8 MB Flash, w.FL antenna (native USB-C)

1

$17.50

ESP32-S3 Feather w.FL

2.4 GHz dipole swivel antenna, RP-SMA, 2 dBi

1

$7.95

2.4 GHz RP-SMA antenna

RP-SMA to w.FL / MHF3 / IPEX3 adapter cable

1

$2.95

RP-SMA to w.FL adapter

Monochrome 0.91” 128×32 I²C OLED, STEMMA QT / Qwiic

1

$12.50

0.91in OLED STEMMA QT