Checklist v3: IMU calibration (level twice, straight pull-aways and stops); yukart/raw/imu

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DDwfd6Ki8UfG4hK6W5YpJz

checklists/z27ag-captures.json

@@ -1,6 +1,6 @@
 {
   "id": "z27ag-captures",
-  "version": 2,
+  "version": 3,
   "title": "Z27AG decoding captures",
   "about": "docs/impl/plans/Z27AG-CAPTURES.md",
   "mark_format": "<step> <action>[ #<n>] start|end for a span, <step> <action>[ #<n>] for a point",
@@ -447,6 +447,59 @@
           ]
         }
       ]
+    },
+    {
+      "title": "IMU calibration (module fixed in its final place)",
+      "steps": [
+        {
+          "id": "27",
+          "title": "IMU level, facing one way",
+          "do": "Parked on the flattest ground at hand, engine off or idling, nobody moving inside. Start, keep still 15 s, end.",
+          "finds": "which way is down for the IMU (with step 28, cancelling the ground's slope)",
+          "actions": [
+            {
+              "label": "imu level A",
+              "hold_s": 15
+            }
+          ]
+        },
+        {
+          "id": "28",
+          "title": "IMU level, turned round",
+          "do": "The same spot, nose the other way: a rough 180° will do. Still again, 15 s.",
+          "finds": "the second half of the level: the slope's tilt reverses, the mounting's does not",
+          "actions": [
+            {
+              "label": "imu level B",
+              "hold_s": 15
+            }
+          ]
+        },
+        {
+          "id": "29",
+          "title": "IMU pull-away, straight",
+          "do": "A straight, flat section. From standstill, a firm pull-away in 1st to about 30. Start as the clutch bites, end as you lift.",
+          "finds": "which way is forward for the IMU",
+          "actions": [
+            {
+              "label": "imu pull away",
+              "repeat": 3
+            }
+          ]
+        },
+        {
+          "id": "30",
+          "title": "IMU braking, straight",
+          "do": "The same section. From about 40, a firm (not emergency) stop. Start as you brake, end when stopped.",
+          "finds": "forward again, from the other side; also braking g",
+          "actions": [
+            {
+              "label": "imu brake",
+              "repeat": 3
+            }
+          ]
+        }
+      ]
     }
   ]
 }

docs/BOUNDARY.md

@@ -37,7 +37,7 @@ The two channels from decision 24 share the socket but keep different guarantees
 | `ack` | reply to a `cmd` | `id`, `ok`, `detail`, `dup` (true when answered from the cache) |
 
 With `source: bus`, `signals` is the newest envelope of every signal svc-gw has
-seen on `yukart/vehicle/+` and `yukart/host/+`. svc-gw marks one
+seen on `yukart/vehicle/+`, `yukart/host/+`, `yukart/gnss/+` and `yukart/imu/+`. svc-gw marks one
 `quality: "stale"` when it has not been refreshed for 5 s, or is known only from
 the broker's retained copy (which may predate a reboot). A signal once seen is
 never removed.
@@ -66,18 +66,20 @@ tablet, or an Orin behind a replugged hub, looks connected at the link layer.
 |---|---|---|
 | `ping` | — | `ack` with `detail: "pong"` |
 | `mark` | `text`, `delay_ms` (optional: how long the command waited before this send) | stamped into the open recording; fails with no session open |
-| `poweroff` | `confirm: "poweroff"`, `boot_id` (from this connection's `hello`) | acks, then shuts the host down cleanly (`systemctl poweroff`) about 2 s later. Refused unless svc-gw runs with `--allow-poweroff` (the Orin's unit only), and when `boot_id` is not the current boot's |
+| `poweroff` | `confirm: "poweroff"`, `boot_id` (from this connection's `hello`) | acks, then shuts the host down cleanly (`systemctl poweroff`) about 2 s later. Refused unless svc-gw runs with `--allow-power` (the Orin's unit only), and when `boot_id` is not the current boot's |
+| `reboot` | `confirm: "reboot"`, `boot_id` | the same, with `systemctl reboot`; the same flag and refusals |
 
 A repeated `id` returns the original `ack` (last 256 kept, shared across
 connections) and never re-runs the command.
 
-`poweroff` is the exception to retry-until-acked: the ack cache does not survive
+`poweroff` and `reboot` are the exception to retry-until-acked: the ack cache does
-the reboot it causes, so a resend could shut the next boot down too. The client
+not survive the restart they cause, so a resend could shut the next boot down (or
-sends it once and does not resend it; `boot_id` makes svc-gw refuse one from a
+reboot it again). The client sends them once and does not resend; `boot_id` makes
-previous boot regardless.
+svc-gw refuse one from a previous boot regardless.
 
 ## Not yet
 
 - TTS utterances (id, chunk sequence, terminator, expiry) — when there is a TTS.
-- `gnss`: its fix is an object, which the envelope's `value` does not allow yet.
+- `gnss/fix` as one object (navigation's input): the envelope's `value` does not allow
+  one yet. Displays get the fix as single values on `yukart/gnss/<signal>` instead.
 - Any version beyond `proto: 0`. A breaking change bumps it; the client checks it.

docs/GUIDELINES.md

@@ -9,7 +9,7 @@ type: guidelines
 - ⚠ **The unit appears in both the topic name and the payload, so they can
   contradict each other.** Generating both from one entry is what stops that; a
   hand-written `"unit"` reintroduces the failure it was meant to prevent.
-- Signal names carry their unit (`vehicle_speed_kph`, `coolant_temp_c`), so a unit
+- Signal names carry their unit (`gnss_speed_kph`, `obd_coolant_temp_c`), so a unit
   mismatch is visible at the call site rather than one registry lookup away.
 
 ## 2. Two clocks, and they answer different questions

docs/impl/plans/Z27AG-CAPTURES.md

@@ -1,7 +1,7 @@
 ---
 type: plan
 status: ready
-updated: 2026-10-13
+updated: 2026-10-14
 ---
 # Z27AG decoding captures: what to do in the car
 
@@ -13,10 +13,11 @@ ground truth. Prior art and first candidates: [the prior-art report](../reports/
 
 | In the session directory | From | Use |
 |---|---|---|
-| `can-*.log(.zst)` | the PEAK, every frame, kernel timestamps | what gets decoded; also holds every OBD request (`7DF`) and reply (`7E8`) |
+| `can-*.log(.zst)` | the PEAK, every frame, kernel timestamps | what gets decoded (nothing transmits on CAN: OBD-II is on the K-line) |
-| `vehicle.ndjson` | `obd-poller` via the bus | the same OBD replies as values (rpm, speed, throttle, load, MAP, MAF ~10 Hz; coolant, intake air, fuel 1 Hz); `env.timestamp` equals the reply frame's timestamp |
+| `vehicle.ndjson` | `decoder` and `obd-poller` via the bus | decoded CAN signals, and the `obd_*` references from the K-line through the ELM327 (rpm, speed, throttle, load, MAF, timing, O2 every round; coolant, intake air, trims every 5 s); `env.timestamp` is the reply's arrival at the Orin |
 | `events.ndjson` | marks from the app | when each step happened |
 | `gnss.ndjson` | gpsd (SIM7600) | speed and position for the drive |
+| `imu.ndjson` | `imu` via the bus (`yukart/raw/imu`) | every IMU sample, raw module axes, Orin receive time: calibration (27–30) and, once calibrated, motion for the drive |
 
 ## Operating it from the app
 
@@ -33,8 +34,9 @@ ground truth. Prior art and first candidates: [the prior-art report](../reports/
   session` when there is no traffic yet (ignition on, PEAK plugged). A mark sent with
   the link down waits (`unacked`) and goes when it is back, with its delay noted.
 - The **Mark** button on the main screen is still there for anything off-plan.
-- **OBD is working** when `engine_rpm`, `vehicle_speed_kph` and the rest appear in
+- **OBD is working** when `obd_engine_rpm`, `obd_coolant_temp_c` and the rest appear
-  the signal list and move. If they never appear, see *If OBD stays silent*.
+  in the signal list and move (the ELM on the OBD port, through the Y harness beside
+  the PEAK). If they never appear, see *If OBD stays silent*.
 
 ## The steps
 
@@ -52,14 +54,20 @@ recorder refuses marks with "no session" otherwise); engine off, doors shut.
 - **Engine running, parked** (14–18): start and idle, held revs in neutral (no OBD
   on this car's CAN: the revs are approximate, read off the tacho), blips, A/C load, radiator fan.
 - **Driving** (19–22): steady speeds, stops, corners, each gear. A passenger presses,
-  or skip the marks: GNSS speed is recorded continuously, and gear comes from
+  or skip the marks: GNSS speed is recorded continuously. The gear is not on CAN and
-  rpm ÷ speed.
+  is not inferred (decode report).
 - **On jack stands** (23–26, since v2): front wheels up, rears chocked, handbrake
   off. Unpowered steering; speedometer readings held in 2nd and 3rd (fronts turn,
   rears stay still, which tells the wheels apart); braking from speed with vacuum
   assist; reverse. Stands replace the driving speeds where a drive is not practical.
+- **IMU calibration** (27–30, since v3): once the IMU is fixed in its final place. Level
+  twice on the same spot, facing one way and then turned round (a rough 180° is fine:
+  the ground's slope reverses and cancels, the mounting's tilt does not); then three
+  firm pull-aways and three firm stops on a straight, flat section (forward, signed by
+  which kind of stretch it is). Any session holds raw IMU samples (`imu.ndjson`), so
+  these can go in their own short session or with anything else.
 
-Version 2 (2026-10-13) adds the stands section and writes down the conditions the
+Version 3 (2026-10-14) adds the IMU calibration section. Version 2 (2026-10-13) adds the stands section and writes down the conditions the
 first run showed matter: engine off and handbrake on for 1–13, foot brake held for
 the handbrake step, neutral with the clutch up for the revs.
 
@@ -80,18 +88,33 @@ The parked steps can be split over several sessions; the drive is the important
 ## If OBD stays silent
 
 `yukart/system/obd-poller` says why (visible in `mosquitto_sub -v -t 'yukart/system/#'`
-on the Orin):
+on the Orin), and the signal list's `elm_connected` shows the Bluetooth link:
 
-- `bus idle: not polling`: no traffic: ignition off or PEAK unplugged.
+- `ELM …: … (unplugged, asleep or out of range)`: no Bluetooth link. The ELM in the
-- `no ECU answers 01 00`: the engine ECU does not do standard mode 01 on this bus.
+  port? Its light on? A phone app holding it (it takes one connection)? Retried
-  Then OBDb's MUT-III (`21 xx`) requests are the next thing to try.
+  every minute.
+- `ECU not answering (…): ignition off?`: the ELM is there, the car is not. The
+  adapter's own words are in the brackets (`BUS INIT: ...ERROR`, `NO DATA`).
+- `ECU silent for 60 s: adapter released`: ignition off for a minute; the poller let
+  go so the ELM can sleep, and tries again every minute.
 - To see what answers, on the Orin: `sudo systemctl stop yukart-obd-poller`,
-  `yukart-obd-poller --once` (supported PIDs and one value each, with reply times),
+  `yukart-obd-poller --elm $(. /etc/default/yukart-elm; echo $ELM_ADDR) --once`
-  `sudo systemctl start yukart-obd-poller`. Never two pollers at once: their
+  (adapter, protocol, supported PIDs and one value each, with reply times), then
-  replies would cross.
+  `sudo systemctl start yukart-obd-poller`.
 
 ## Afterwards
 
+**IMU calibration**, on the car Orin, from the session that holds steps 27–30:
+
+```bash
+yukart-imu --calibrate /var/lib/yukart/recordings/<session>           # print: down, forward, slope, spread
+yukart-imu --calibrate /var/lib/yukart/recordings/<session> --write   # and save /var/lib/yukart/imu/mount.json
+```
+
+The service picks the new mounting up within seconds; roll and pitch should then read
+about 0 parked on level ground. Steps 27–28 alone also work: forward then stays the
+`--forward` axis, laid flat, until a session with 29–30 is calibrated.
+
 Sessions are in `/var/lib/yukart/recordings/` on the car Orin. Copy one off with
 `rsync -a mikkeli-orin-nano:/var/lib/yukart/recordings/<session>/ …` into
 `yukart-data`, with a line in its README of what was done.

docs/impl/reports/Z27AG-DECODE-1.md

@@ -46,10 +46,15 @@ jack-stands session and a GNSS-matched drive settle both the byte order and the
 
 ## Not on this bus (or not seen)
 
-- **Clutch pedal:** nothing changed in 3 presses, engine off.
+- **Clutch and transmission are not on this bus.** Nothing changed for the clutch
-- **Gear position:** nothing in 5 gears, reverse or neutral. Expected for a manual. The
+  (3 presses), any of the 5 gears, neutral or reverse: nothing on the car consumes
-  gear can be computed from rpm ÷ wheel speed once the scale is known.
+  them, so no frame carries them. Reverse was rechecked against both reverse
-- **Reverse:** no reverse bit found. The reverse lamp is probably wired directly.
+  stretches (engine off and engine on) versus every other position: no bit
+  separates them.
+- **Gear is not inferred from rpm ÷ wheel speed** (owner's call, 2026-10-13): the
+  clutch is invisible, so the ratio lies whenever it is down or slipping, and the
+  gear matters most at a standstill, where the ratio says nothing. A *recommended*
+  gear from speed and rpm is the useful form, if any.
 - **Steering angle:** not analysed yet (step 5 was done with the engine on, at the end).
 
 ## Not analysed yet

schema/signals.json

@@ -1,6 +1,136 @@
 {
-  "$comment": "Single source for signal identity. Topic name and envelope unit are both derived from these entries and are never authored separately. source=obd2 is standardised; source=host is the Orin itself (orin-status), not the car. source=z27ag is reverse-engineered from the car's own broadcast frames, and its 'can' block is the only place its layout is written down: id (11-bit, hex string), byte (first data byte, 0-7), length in bits (1, 8 or 16), bit (length 1 only: 0 = LSB of that byte), order (length 16: big = byte first is most significant, little = the reverse), scale and offset (value = raw * scale + offset; booleans are raw != 0). 'evidence' names the contracts report that found it.",
+  "$comment": "Single source for signal identity. Topic name and envelope unit are both derived from these entries and are never authored separately. source=obd2 is standardised (OBD-II mode 01 over the K-line, through the ELM327): calibration references, every name prefixed obd_ (project-yukart decision 30); source=host is the Orin itself (orin-status), not the car. source=gnss is the receiver (svc-core gnss), on yukart/gnss/<signal>. source=imu is the WT61 IMU, already turned into the car's frame (mounting and gravity handled by its publisher), on yukart/imu/<signal>. source=z27ag is reverse-engineered from the car's own broadcast frames, and its 'can' block is the only place its layout is written down: id (11-bit, hex string), byte (first data byte, 0-7), length in bits (1, 8 or 16), bit (length 1 only: 0 = LSB of that byte), order (length 16: big = byte first is most significant, little = the reverse), scale and offset (value = raw * scale + offset; booleans are raw != 0). 'evidence' names the contracts report that found it.",
   "signals": {
+    "obd_vehicle_speed_kph": {
+      "unit": "kph",
+      "type": "number",
+      "source": "obd2",
+      "description": "Road speed",
+      "range": [
+        0,
+        255
+      ]
+    },
+    "obd_coolant_temp_c": {
+      "unit": "celsius",
+      "type": "number",
+      "source": "obd2",
+      "description": "Engine coolant temperature",
+      "range": [
+        -40,
+        215
+      ]
+    },
+    "obd_intake_air_temp_c": {
+      "unit": "celsius",
+      "type": "number",
+      "source": "obd2",
+      "description": "Intake air temperature",
+      "range": [
+        -40,
+        215
+      ]
+    },
+    "obd_throttle_pct": {
+      "unit": "percent",
+      "type": "number",
+      "source": "obd2",
+      "description": "Throttle position",
+      "range": [
+        0,
+        100
+      ]
+    },
+    "obd_engine_load_pct": {
+      "unit": "percent",
+      "type": "number",
+      "source": "obd2",
+      "description": "Calculated engine load",
+      "range": [
+        0,
+        100
+      ]
+    },
+    "obd_fuel_level_pct": {
+      "unit": "percent",
+      "type": "number",
+      "source": "obd2",
+      "description": "Fuel tank level",
+      "range": [
+        0,
+        100
+      ]
+    },
+    "obd_intake_pressure_kpa": {
+      "unit": "kpa",
+      "type": "number",
+      "source": "obd2",
+      "description": "Intake manifold absolute pressure",
+      "range": [
+        0,
+        255
+      ]
+    },
+    "obd_maf_gps": {
+      "unit": "g/s",
+      "type": "number",
+      "source": "obd2",
+      "description": "Mass air flow rate",
+      "range": [
+        0,
+        656
+      ]
+    },
+    "obd_engine_rpm": {
+      "unit": "rpm",
+      "type": "number",
+      "source": "obd2",
+      "description": "Engine speed (OBD-II 0C): the reference for the decoded engine_rpm",
+      "range": [
+        0,
+        8000
+      ]
+    },
+    "obd_timing_advance_deg": {
+      "unit": "degree",
+      "type": "number",
+      "source": "obd2",
+      "description": "Ignition timing advance before TDC, cylinder 1",
+      "range": [
+        -64,
+        64
+      ]
+    },
+    "obd_stft_pct": {
+      "unit": "percent",
+      "type": "number",
+      "source": "obd2",
+      "description": "Short-term fuel trim, bank 1: positive adds fuel",
+      "range": [
+        -100,
+        100
+      ]
+    },
+    "obd_ltft_pct": {
+      "unit": "percent",
+      "type": "number",
+      "source": "obd2",
+      "description": "Long-term fuel trim, bank 1: positive adds fuel",
+      "range": [
+        -100,
+        100
+      ]
+    },
+    "obd_o2_b1s1_v": {
+      "unit": "V",
+      "type": "number",
+      "source": "obd2",
+      "description": "Upstream oxygen sensor voltage (narrowband: ~0.1 lean … ~0.9 rich)",
+      "range": [
+        0,
+        1.275
+      ]
+    },
     "engine_rpm": {
       "unit": "rpm",
       "type": "number",
@@ -20,86 +150,6 @@
         "evidence": "Z27AG-DECODE-1"
       }
     },
-    "vehicle_speed_kph": {
-      "unit": "kph",
-      "type": "number",
-      "source": "obd2",
-      "description": "Road speed",
-      "range": [
-        0,
-        255
-      ]
-    },
-    "coolant_temp_c": {
-      "unit": "celsius",
-      "type": "number",
-      "source": "obd2",
-      "description": "Engine coolant temperature",
-      "range": [
-        -40,
-        215
-      ]
-    },
-    "intake_air_temp_c": {
-      "unit": "celsius",
-      "type": "number",
-      "source": "obd2",
-      "description": "Intake air temperature",
-      "range": [
-        -40,
-        215
-      ]
-    },
-    "throttle_pct": {
-      "unit": "percent",
-      "type": "number",
-      "source": "obd2",
-      "description": "Throttle position",
-      "range": [
-        0,
-        100
-      ]
-    },
-    "engine_load_pct": {
-      "unit": "percent",
-      "type": "number",
-      "source": "obd2",
-      "description": "Calculated engine load",
-      "range": [
-        0,
-        100
-      ]
-    },
-    "fuel_level_pct": {
-      "unit": "percent",
-      "type": "number",
-      "source": "obd2",
-      "description": "Fuel tank level",
-      "range": [
-        0,
-        100
-      ]
-    },
-    "intake_pressure_kpa": {
-      "unit": "kpa",
-      "type": "number",
-      "source": "obd2",
-      "description": "Intake manifold absolute pressure",
-      "range": [
-        0,
-        255
-      ]
-    },
-    "maf_gps": {
-      "unit": "g/s",
-      "type": "number",
-      "source": "obd2",
-      "description": "Mass air flow rate",
-      "range": [
-        0,
-        656
-      ]
-    },
     "accel_pedal_pct": {
       "unit": "percent",
       "type": "number",
@@ -477,6 +527,12 @@
         10000
       ]
     },
+    "elm_connected": {
+      "unit": "",
+      "type": "boolean",
+      "source": "host",
+      "description": "Bluetooth link to the OBD-II adapter (the ELM327 on the K-line) is up: obd-poller holds it while the ECU answers"
+    },
     "ups_battery_v": {
       "unit": "V",
       "type": "number",
@@ -512,6 +568,122 @@
       "type": "string",
       "source": "host",
       "description": "charging, discharging (running on battery) or idle (on input power, not charging)"
+    },
+    "gnss_fix": {
+      "unit": "",
+      "type": "string",
+      "source": "gnss",
+      "description": "Fix quality: none, 2d or 3d (gpsd TPV mode)"
+    },
+    "gnss_speed_kph": {
+      "unit": "kph",
+      "type": "number",
+      "source": "gnss",
+      "description": "Speed over ground; null without a fix",
+      "range": [
+        0,
+        300
+      ]
+    },
+    "gnss_heading_deg": {
+      "unit": "degree",
+      "type": "number",
+      "source": "gnss",
+      "description": "Course over ground, true north; null without a fix or at a standstill",
+      "range": [
+        0,
+        360
+      ]
+    },
+    "gnss_lat": {
+      "unit": "degree",
+      "type": "number",
+      "source": "gnss",
+      "description": "Latitude, WGS84",
+      "range": [
+        -90,
+        90
+      ]
+    },
+    "gnss_lon": {
+      "unit": "degree",
+      "type": "number",
+      "source": "gnss",
+      "description": "Longitude, WGS84",
+      "range": [
+        -180,
+        180
+      ]
+    },
+    "gnss_alt_m": {
+      "unit": "m",
+      "type": "number",
+      "source": "gnss",
+      "description": "Altitude above mean sea level; null without a 3D fix",
+      "range": [
+        -500,
+        9000
+      ]
+    },
+    "gnss_satellites": {
+      "unit": "",
+      "type": "number",
+      "source": "gnss",
+      "description": "Satellites used in the fix",
+      "range": [
+        0,
+        64
+      ]
+    },
+    "imu_roll_deg": {
+      "unit": "degree",
+      "type": "number",
+      "source": "imu",
+      "description": "Body roll in the car's frame: positive leaning right (right side down)",
+      "range": [
+        -180,
+        180
+      ]
+    },
+    "imu_pitch_deg": {
+      "unit": "degree",
+      "type": "number",
+      "source": "imu",
+      "description": "Body pitch in the car's frame: positive nose up",
+      "range": [
+        -90,
+        90
+      ]
+    },
+    "imu_accel_lon_g": {
+      "unit": "g",
+      "type": "number",
+      "source": "imu",
+      "description": "Longitudinal acceleration in the car's frame, gravity removed: positive forward (speeding up), negative braking",
+      "range": [
+        -4,
+        4
+      ]
+    },
+    "imu_accel_lat_g": {
+      "unit": "g",
+      "type": "number",
+      "source": "imu",
+      "description": "Lateral acceleration in the car's frame, gravity removed: positive to the right (a right turn reads positive)",
+      "range": [
+        -4,
+        4
+      ]
+    },
+    "imu_yaw_rate_dps": {
+      "unit": "degree/s",
+      "type": "number",
+      "source": "imu",
+      "description": "Yaw rate: positive turning left (counter-clockwise from above)",
+      "range": [
+        -500,
+        500
+      ]
     }
   }
 }

schema/topics.json

@@ -12,7 +12,7 @@
       "payload": "envelope",
       "retained": true,
       "rate": "1-50/s",
-      "publisher": "decoder, obd-poller",
+      "publisher": "decoder (source z27ag), obd-poller (source obd2)",
       "description": "One topic per signal, named exactly as in signals.json."
     },
     "yukart/gnss/fix": {
@@ -22,6 +22,27 @@
       "publisher": "gnss",
       "description": "value is an object: lat, lon, alt_m, speed_kph, heading_deg, fix, satellites."
     },
+    "yukart/gnss/<signal>": {
+      "payload": "envelope",
+      "retained": true,
+      "rate": "1-10/s",
+      "publisher": "gnss",
+      "description": "The receiver's fix as single values, one topic per signal, named exactly as in signals.json (source=gnss). For displays; yukart/gnss/fix stays the composite for navigation."
+    },
+    "yukart/imu/<signal>": {
+      "payload": "envelope",
+      "retained": true,
+      "rate": "10-50/s",
+      "publisher": "imu",
+      "description": "The IMU (WT61) in the car's frame: attitude, gravity-free acceleration, yaw rate; one topic per signal, named exactly as in signals.json (source=imu)."
+    },
+    "yukart/raw/imu": {
+      "payload": "json",
+      "retained": false,
+      "rate": "10-100/s",
+      "publisher": "imu",
+      "description": "Every IMU sample, raw: module axes, not calibrated. {mono (ns, CLOCK_MONOTONIC), t (µs, realtime), accel [x,y,z] g, gyro [x,y,z] deg/s, angle [roll,pitch,yaw] deg (the module's own)}. Not an envelope; for the recorder (imu.ndjson), so a later calibration can reprocess a session. Displays use yukart/imu/<signal>."
+    },
     "yukart/host/<signal>": {
       "payload": "envelope",
       "retained": true,