indoor.parm — line-by-line for SITL without GPS

Complement to arducopter_params — a concrete breakdown of the production indoor.parm for GPS-less SITL.

Full `indoor.parm`

# GPS off — correct, we're indoor
GPS1_TYPE 0

# Arming without checks — needed for simulation
ARMING_SKIPCHK 1

# Altitude from rangefinder — doesn't work without the bridge yet
# Can be left for the future when we wire up the MAVROS→ArduPilot bridge
EK3_SRC1_POSZ 2

# Optical flow — also for the future
FLOW_TYPE 6
EK3_SRC1_VELXY 5
EK3_SRC1_POSXY 0

# Slow indoor flight — keep it
LOIT_SPEED_MS 3.0
PILOT_SPD_UP 1.0

# Fence — keep, doesn't work yet without GPS/rangefinder
FENCE_ENABLE 1
FENCE_TYPE 2
FENCE_ALT_MAX 2.5
FENCE_ACTION 4

# Battery off — KEEP for simulation
BATT_MONITOR 0

Line-by-line breakdown

Parameter	Purpose	Why this value
`GPS1_TYPE 0`	GPS driver off	Indoor — GPS doesn’t work; ArduPilot won’t wait for a fix
`ARMING_SKIPCHK 1`	Skip prearm checks	Simulation; real checks (compass, battery, baro) interfere with bring-up
`EK3_SRC1_POSZ 2`	EKF3 Z source — rangefinder	Future-proofing for the rangefinder MAVROS bridge
`EK3_SRC1_VELXY 5`	EKF3 XY-velocity source — optical flow	Future-proofing for CXOF / PMW3901
`EK3_SRC1_POSXY 0`	EKF3 XY-position source — none	Without GPS / fiducial — XY position isn’t available
`FLOW_TYPE 6`	Optical-flow type = MAVLink message-based	Connection via MAVROS
`LOIT_SPEED_MS 3.0`	LOITER max speed = 3 m/s	Indoor-safe (default was 12.5 — too much for a room)
`PILOT_SPD_UP 1.0`	Takeoff speed 1 m/s	Smooth takeoff, minimal overshoot
`FENCE_ENABLE 1`	Geofence on	Out-of-bounds protection (requires position)
`FENCE_TYPE 2`	Altitude limit only	Without GPS the round fence doesn’t work
`FENCE_ALT_MAX 2.5`	2.5 m ceiling	Indoor (no ceiling — for testing)
`FENCE_ACTION 4`	On fence breach → LAND	Safer than RTL for indoor
`BATT_MONITOR 0`	Battery monitoring off	Simulation — no battery; otherwise ArduPilot complains “no battery”

Notes

`ARMING_CHECK` vs `ARMING_SKIPCHK` (ArduPilot 4.7)

The old name ARMING_CHECK was renamed to ARMING_SKIPCHK in 4.7:

libraries/AP_Arming/AP_Arming.cpp:128 — // 2 was the CHECK paramter
libraries/AP_Arming/AP_Arming.cpp:201 — AP_GROUPINFO("SKIPCHK", 13, ...)
init() has PARAM_CONVERSION - 4.7 CHECK -> SKIPCHK.

If you accidentally use the old name — ArduPilot ignores it (unknown param) → done_all_default_params = false → reload loop. See SITL “Waiting for heartbeat” cause 2.

Encoding gotcha — ASCII only in `.parm`

AP_Param.cpp uses a char line[100] buffer and fgets. UTF-8 comments longer than 99 bytes (~50 Cyrillic chars) split across chunks → unknown-param → reload loop. All comments must be ASCII, line length ≤ 78 chars (wc -L = 78).

What to add once sensors are in

Rangefinder MAVROS bridge → RNGFND1_TYPE, RNGFND1_ORIENT 25 (downward)
Optical flow → FLOW_ENABLE 1, CXOF/PMW3901 options already reserved above
Battery (real drone) → BATT_MONITOR 4 (analog voltage + current), BATT_VOLT_PIN, BATT_CURR_PIN per distro

Sources

ArduPilot Tools/autotest/default_params/copter.parm — base defaults
ardupilot_gazebo worlds/iris_runway.sdf → home location Canberra (-35.363262, 149.165237, 584 m) — inherited via SITL defaults

Full indoor.parm