Fig. 06 · GPS camera · ArduCopter V4.7.2

GPS camera drone

Fly it

Parts: …
Battery: unplugged
Fault: none

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Pick the battery, motors and props. Every number below is recalculated from this craft's own model.

Battery

Motors

Props

Calculated for this build

All-up weight: 1,600 g
Thrust : weight: 2.5 : 1
Hover throttle: 63%
Max current: 80 A
Hover time: 20.0 min
Hard-flying time: 16.0 min

Checks

Parts match: 2.5:1 is plenty for a camera drone, and the low hover current gives long flights. The calculator's hover throttle is pessimistic for this class: real F450s hover at 35 to 50 %, and ArduPilot learns the real value in flight.

WarningIt hovers at 63% throttle: too little headroom to climb out or correct a gust.

Cost

Category	Parts	Cost
Electrical	9	$581
Mechanical	5	$76
Total (approx.)	14	$657

A working emulation of the ArduPilot Copter command line for this craft: real setting names, real limits and real error messages.

Connect tcp:127.0.0.1:5760 source_system=255

Up and down recall earlier commands.

Configuration snippets

Frame, outputs and power after the build

In ArduCopter 4.7.2 you set parameters, not commands: in MAVProxy each param set is stored at once, in Mission Planner it is Write Params. Quad X frame, DShot600 on the MAIN outputs (the 6C's IO chip needs BRD_IO_DSHOT 1 for that), the PM02 as an analog battery monitor, and the pack's full and empty voltage so the thrust doesn't fade as the pack drains.

# ArduCopter 4.7.2 on a Pixhawk 6C: quad X, DShot600 on MAIN 1-4, PM02 on POWER1
param set FRAME_CLASS 1         # Quad
param set FRAME_TYPE 1          # X: M1 front right, M2 rear left, M3 front left, M4 rear right
param set MOT_PWM_TYPE 6        # DShot600: no ESC calibration
param set BRD_IO_DSHOT 1        # DShot on the 6C's IO (MAIN) outputs
param set BATT_MONITOR 4        # PM02: analog voltage and current
param set BATT_CAPACITY 5000    # mAh
param set MOT_BAT_VOLT_MAX 16.8 # 4.2 V x 4 cells: thrust stays the same as the pack drains
param set MOT_BAT_VOLT_MIN 13.2 # 3.3 V x 4 cells
param set AHRS_ORIENTATION 0    # Pixhawk arrow to the nose; 4 = Yaw180 if it points back
# FRAME_CLASS, BRD_IO_DSHOT and AHRS_ORIENTATION take effect after a reboot

Telemetry, receiver and GPS ports after the build

Each serial port gets a protocol: MAVLink2 for the SiK radio on TELEM1, RCIN for the ELRS receiver on TELEM2 at 420 kbaud, GPS on GPS1. COMPASS_ORIENT says which way the puck's compass faces.

# SiK telemetry on TELEM1, ELRS on TELEM2 (not RCIN: CRSF needs a full UART), GPS on GPS1
param set SERIAL1_PROTOCOL 2    # MAVLink2
param set SERIAL1_BAUD 57       # 57600, the SiK radio's default
param set SERIAL2_PROTOCOL 23   # RCIN: the ELRS receiver speaks CRSF here
param set RSSI_TYPE 3           # link quality from the receiver protocol
param set RC_OPTIONS 8192       # bit 13: 420 kbaud for ELRS
param set SERIAL3_PROTOCOL 5    # GPS
param set GPS1_TYPE 1           # auto-detect the u-blox M10
param set COMPASS_ORIENT 0      # GPS puck arrow forward

The mode switch after the build

Channel 5 picks one of six flight modes by its PWM band. The numbers are ArduCopter's mode numbers: 5 Loiter, 2 AltHold, 3 Auto, 0 Stabilize, 9 Land, 6 RTL. Loiter is position 1, so a panicked flick to the end of the switch gives you a drone that stops and holds.

# A 6-position mode switch on channel 5
param set FLTMODE_CH 5
param set FLTMODE1 5            # Loiter
param set FLTMODE2 2            # AltHold
param set FLTMODE3 3            # Auto
param set FLTMODE4 0            # Stabilize
param set FLTMODE5 9            # Land
param set FLTMODE6 6            # RTL

Gimbal on AUX 1 and 2 after the build

Type 7 (BrushlessPWM) is for a gimbal that stabilises itself: ArduPilot just sends the angle it wants on two outputs. Type 1 is for plain servos that ArduPilot must stabilise; on a brushless gimbal both would try to cancel the lean. The tilt knob on channel 6 moves the pitch between -90° and 25°.

# A self-stabilising 2-axis brushless gimbal: ArduPilot only asks for an angle
param set MNT1_TYPE 7           # BrushlessPWM (reboot); 1 = plain servo gimbal
param set SERVO9_FUNCTION 8     # AUX 1: Mount1Roll
param set SERVO10_FUNCTION 7    # AUX 2: Mount1Pitch
param set MNT1_PITCH_MIN -90    # straight down
param set MNT1_PITCH_MAX 25
param set MNT1_ROLL_MIN -30
param set MNT1_ROLL_MAX 30
param set RC6_OPTION 213        # the tilt knob on channel 6 moves the pitch
param set MNT1_RC_RATE 90       # deg/s while the knob is off centre
param set MNT1_DEFLT_MODE 3     # RC targeting

Failsafes and fence after the build

Radio lost: RTL. Battery low (3.5 V a cell, or 1000 mAh left): RTL. Battery critical (3.3 V a cell): land where it is. The defaults are made for 3S, so a 4S drone must set its own voltages. The fence sends it home if it goes above 100 m or 300 m from home.

# Radio lost, battery low, battery critical, and a fence round home
param set FS_THR_ENABLE 1       # radio lost: RTL
param set FS_THR_VALUE 975      # throttle PWM below this counts as lost (PWM and SBUS receivers)
param set BATT_LOW_VOLT 14      # 3.5 V per cell on 4S (the default 10.5 is a 3S value)
param set BATT_CRT_VOLT 13.2    # 3.3 V per cell
param set BATT_LOW_MAH 1000     # or 20 % of 5000 mAh left
param set BATT_FS_LOW_ACT 2     # low: RTL
param set BATT_FS_CRT_ACT 1     # critical: land where it is
param set FENCE_ENABLE 1
param set FENCE_ALT_MAX 100     # m
param set FENCE_RADIUS 300      # m round home

Stabilize for Stabilize

The drone levels itself and the throttle stick drives the motors directly, so you hold the height yourself. ATC_ANGLE_MAX caps the lean in every mode; in 4.7 it is in degrees (it was ANGLE_MAX in centi-degrees).

# Stabilize: self-levelling, the throttle stick is the motors
param set ATC_ANGLE_MAX 30      # max lean in every mode, degrees
mode STABILIZE

AltHold for AltHold

The barometer holds the height. Throttle in the middle holds it; up or down asks for a climb or descent, up to PILOT_SPD_UP (2.5 m/s). There is no position hold, so the wind pushes it along.

# AltHold: the barometer holds the height, the throttle stick asks for a climb rate
param set PILOT_SPD_UP 2.5      # m/s at full throttle
mode ALT_HOLD

Loiter for Loiter

GPS and compass hold the position as well as the height: let go and it brakes and stops. The sticks ask for a speed, up to LOIT_SPEED_MS. 4.7 renamed the Loiter parameters to SI units: LOIT_SPEED 500 (cm/s) became LOIT_SPEED_MS 5.

# Loiter: GPS holds the position too; the sticks ask for a speed
param set LOIT_SPEED_MS 5       # m/s at full stick (default 12.5)
param set LOIT_BRK_ACC_M 2.5    # m/s/s braking when the sticks centre
param set LOIT_BRK_DELAY 1      # s before braking starts
mode LOITER

Return to launch for RTL

It climbs to RTL_ALT_M (or stays higher if it already is), flies home at WP_SPD, hovers over home for RTL_LOIT_TIME and lands at LAND_SPD_MS. Set RTL_ALT_M above anything between the drone and home: here the mast is 18 m, so 20 m.

# Return to launch: climb, fly home, wait, land
param set RTL_ALT_M 20          # m above home: higher than the 18 m mast
param set RTL_SPEED_MS 0        # 0 = fly home at WP_SPD
param set RTL_LOIT_TIME 5000    # ms over home before it descends
param set LAND_SPD_MS 0.5       # m/s for the last metres
mode RTL

AUTO: the mast inspection for AUTO mission

AUTO flies the loaded mission: take off to 8 m, four photo points round the mast at 12 m, then RTL. ArduCopter won't arm in AUTO unless AUTO_OPTIONS allows it, so arm in Loiter and switch. The lab's console has no mission loader; the wp line shows what you'd type in MAVProxy.

# The mast inspection: take off to 8 m, four photo points at 12 m, then RTL
param set WP_SPD 4              # m/s between waypoints
param set WP_RADIUS_M 2         # m: how close counts as reached
param set WP_SPD_DN 1.5         # m/s descending
# wp load inspection.txt        (MAVProxy's wp module; Mission Planner: Plan > Load WP File)
mode LOITER
arm throttle                    # it refuses to arm in AUTO itself
mode AUTO

Meet the GPS camera drone

This is the drone most people picture: a mid-size quad that knows where it is. Its Pixhawk runs ArduPilot, whose estimator (EKF3) blends the gyro, accelerometer, barometer, compass and GPS into one position and speed. That is what lets it hold a point in the wind in Loiter, hold only its height in AltHold, fly home and land on its own in RTL, and fly a planned route in AUTO while a gimbal keeps the camera level. It is built for long, smooth flights rather than punch: low-KV motors, big slow 10-inch props and a big 4S pack. Drones like it do aerial photography, roof and mast inspections and mapping, and the same layout is the standard ArduPilot and PX4 learning platform (Holybro's X500 kit is one). Pick the parts and watch the numbers, build it, run the bench checks, then fly the mast inspection by hand or let AUTO fly it.

Practice task

Fly the mast inspection in Loiter first: the drone stops when you let go of the sticks, so you can line up each photo point at your own pace. Then try AltHold and see it drift with the wind, and Stabilize to feel what the GPS was doing for you. Finally switch to AUTO and watch it fly the same route, pausing at each photo point, then RTL and land. On a real build: smoke stopper on the first plug, motor test with the props off (A front right, then clockwise), accelerometer and compass calibration away from metal, a GPS lock outdoors, the failsafe test with the props off, and read every PreArm message before the first flight.

Build a GPS quad, calibrate its compass, then fly a photo mission round a mast

Category

Parts

Cost

Electrical

$581

Mechanical

$76

Total (approx.)

$657

# ArduCopter 4.7.2 on a Pixhawk 6C: quad X, DShot600 on MAIN 1-4, PM02 on POWER1 param set FRAME_CLASS 1 # Quad param set FRAME_TYPE 1 # X: M1 front right, M2 rear left, M3 front left, M4 rear right param set MOT_PWM_TYPE 6 # DShot600: no ESC calibration param set BRD_IO_DSHOT 1 # DShot on the 6C's IO (MAIN) outputs param set BATT_MONITOR 4 # PM02: analog voltage and current param set BATT_CAPACITY 5000 # mAh param set MOT_BAT_VOLT_MAX 16.8 # 4.2 V x 4 cells: thrust stays the same as the pack drains param set MOT_BAT_VOLT_MIN 13.2 # 3.3 V x 4 cells param set AHRS_ORIENTATION 0 # Pixhawk arrow to the nose; 4 = Yaw180 if it points back # FRAME_CLASS, BRD_IO_DSHOT and AHRS_ORIENTATION take effect after a reboot

# SiK telemetry on TELEM1, ELRS on TELEM2 (not RCIN: CRSF needs a full UART), GPS on GPS1 param set SERIAL1_PROTOCOL 2 # MAVLink2 param set SERIAL1_BAUD 57 # 57600, the SiK radio's default param set SERIAL2_PROTOCOL 23 # RCIN: the ELRS receiver speaks CRSF here param set RSSI_TYPE 3 # link quality from the receiver protocol param set RC_OPTIONS 8192 # bit 13: 420 kbaud for ELRS param set SERIAL3_PROTOCOL 5 # GPS param set GPS1_TYPE 1 # auto-detect the u-blox M10 param set COMPASS_ORIENT 0 # GPS puck arrow forward

# A 6-position mode switch on channel 5 param set FLTMODE_CH 5 param set FLTMODE1 5 # Loiter param set FLTMODE2 2 # AltHold param set FLTMODE3 3 # Auto param set FLTMODE4 0 # Stabilize param set FLTMODE5 9 # Land param set FLTMODE6 6 # RTL

# A self-stabilising 2-axis brushless gimbal: ArduPilot only asks for an angle param set MNT1_TYPE 7 # BrushlessPWM (reboot); 1 = plain servo gimbal param set SERVO9_FUNCTION 8 # AUX 1: Mount1Roll param set SERVO10_FUNCTION 7 # AUX 2: Mount1Pitch param set MNT1_PITCH_MIN -90 # straight down param set MNT1_PITCH_MAX 25 param set MNT1_ROLL_MIN -30 param set MNT1_ROLL_MAX 30 param set RC6_OPTION 213 # the tilt knob on channel 6 moves the pitch param set MNT1_RC_RATE 90 # deg/s while the knob is off centre param set MNT1_DEFLT_MODE 3 # RC targeting

# Radio lost, battery low, battery critical, and a fence round home param set FS_THR_ENABLE 1 # radio lost: RTL param set FS_THR_VALUE 975 # throttle PWM below this counts as lost (PWM and SBUS receivers) param set BATT_LOW_VOLT 14 # 3.5 V per cell on 4S (the default 10.5 is a 3S value) param set BATT_CRT_VOLT 13.2 # 3.3 V per cell param set BATT_LOW_MAH 1000 # or 20 % of 5000 mAh left param set BATT_FS_LOW_ACT 2 # low: RTL param set BATT_FS_CRT_ACT 1 # critical: land where it is param set FENCE_ENABLE 1 param set FENCE_ALT_MAX 100 # m param set FENCE_RADIUS 300 # m round home

# Loiter: GPS holds the position too; the sticks ask for a speed param set LOIT_SPEED_MS 5 # m/s at full stick (default 12.5) param set LOIT_BRK_ACC_M 2.5 # m/s/s braking when the sticks centre param set LOIT_BRK_DELAY 1 # s before braking starts mode LOITER

# Return to launch: climb, fly home, wait, land param set RTL_ALT_M 20 # m above home: higher than the 18 m mast param set RTL_SPEED_MS 0 # 0 = fly home at WP_SPD param set RTL_LOIT_TIME 5000 # ms over home before it descends param set LAND_SPD_MS 0.5 # m/s for the last metres mode RTL

# The mast inspection: take off to 8 m, four photo points at 12 m, then RTL param set WP_SPD 4 # m/s between waypoints param set WP_RADIUS_M 2 # m: how close counts as reached param set WP_SPD_DN 1.5 # m/s descending # wp load inspection.txt (MAVProxy's wp module; Mission Planner: Plan > Load WP File) mode LOITER arm throttle # it refuses to arm in AUTO itself mode AUTO

Meet the GPS camera drone

Practice task

Build a GPS quad, calibrate its compass, then fly a photo mission round a mast

GPS camera drone

Design it

Calculated for this build

Checks

Cost

Build it

Try a real mistake

Selected part

Parts in the box

Wiring

Safety tests

Smoke stopper test

Motor test (props off)

Accelerometer calibration

Compass calibration

GPS lock

Radio failsafe (props off)

Gimbal test

Pre-arm checks

MAVProxy console

Configuration snippets

Frame, outputs and power after the build

Telemetry, receiver and GPS ports after the build

The mode switch after the build

Gimbal on AUX 1 and 2 after the build

Failsafes and fence after the build

Stabilize for Stabilize

AltHold for AltHold

Loiter for Loiter

Return to launch for RTL

AUTO: the mast inspection for AUTO mission

Check yourself · Fit the power module and capacitor

Check yourself · Stand the GPS mast at the rear

Check yourself · Hang the gimbal under the nose

Check yourself

Meet the GPS camera drone

Practice task

GPS camera drone

Design it

Calculated for this build

Checks

Cost

Build it

Try a real mistake

Selected part

Parts in the box

Wiring

Safety tests

Smoke stopper test

Motor test (props off)

Accelerometer calibration

Compass calibration

GPS lock

Radio failsafe (props off)

Gimbal test

Pre-arm checks

MAVProxy console

Configuration snippets

Frame, outputs and power after the build

Telemetry, receiver and GPS ports after the build

The mode switch after the build

Gimbal on AUX 1 and 2 after the build

Failsafes and fence after the build

Stabilize for Stabilize

AltHold for AltHold

Loiter for Loiter

Return to launch for RTL

AUTO: the mast inspection for AUTO mission

Check yourself · Fit the power module and capacitor

Check yourself · Stand the GPS mast at the rear

Check yourself · Hang the gimbal under the nose

Check yourself

Meet the GPS camera drone

Practice task