== Turntable Procedure ==
=== Hardware ===

== Pictures ==

<gallery>
File:Turntable rig.JPG|Turntable rig
Image:IMU_cradle_view_1.0.JPG|IMU cradle view 1.0
Image:IMU_cradle_view_1.1.JPG|IMU cradle view 1.1
Image:encoder_mount_base.JPG|Encoder mount base
Image:Olimex_lpc_H2148.JPG|Olimex LPC H2148
Image:rotary_encoder.JPG|Omron rotary encoder
</gallery>

== Components ==

* audio-technica [http://www.amazon.com/Audio-Technica-ATLP120-Professional-Turntable/dp/B002S1CJ2Q AT-LP120_USB] Direct Drive Professional Turntable
* Olimex LPC [http://www.olimex.com/dev/lpc-h2148.html H2148]
* [http://www.ebay.com/sch/i.html?_nkw=Omron+rotary+encoders&_sacat=0&_odkw=rotary+encoders&_osacat=0 Omron] rotary [http://www.omronexpress.com/product_pdf/197_0.pdf encoder]
* Lisa/L+IMU, Xbee 2.4Ghz modem set, fibreglass mounting plates and general wiring components
* Encoder mount hoop - engineering shop?

== Wiring ==
'''Encoder''' to '''LPC'''

* Black (common) to EXT2 GND

* Red 5~12 VDC to EXT2 Vin(5v)

* White OUTA to EXT1 PO.22

'''LPC''' to '''LPC'''

* EXT2 3.3v to EXT1 PO.22 (pull up resistor)

=== Software ===

== LPC Code Modifications ==

In case of USB 2.0 A-B cable operation, ~/conf/airframes/Poine/turntable.xml has to be amended, as follows, and saved as ~/turntable_dev_usb.xml:
{{Box Code|conf/airframes/Poine/turntable_dev_usb.xml|
<source lang="xml">
main.CFLAGS += -DUSE_USB_SERIAL
main.srcs += $(SRC_ARCH)/usb_ser_hw.c
main.srcs += $(SRC_ARCH)/lpcusb/usbhw_lpc.c $(SRC_ARCH)/lpcusb/usbinit.c
main.srcs += $(SRC_ARCH)/lpcusb/usbcontrol.c $(SRC_ARCH)/lpcusb/usbstdreq.c
main.CFLAGS += -DDOWNLINK -DDOWNLINK_TRANSPORT=PprzTransport -DDOWNLINK_DEVICE=UsbS

#main.CFLAGS += -DUSE_UART0 -DUART0_BAUD=B115200
#main.srcs += mcu_periph/uart.c
#main.srcs += $(SRC_ARCH)/mcu_periph/uart_arch.c
#main.CFLAGS += -DDOWNLINK -DDOWNLINK_TRANSPORT=PprzTransport -DDOWNLINK_DEVICE=Uart0

main.srcs += subsystems/datalink/downlink.c subsystems/datalink/pprz_transport.c

#main.CFLAGS += -DMB_TACHO
#main.srcs += $(MB)/mb_tacho.c

</makefile>

</airframe>
</source>
}}

A new turntable session has to be added to ~/conf/control_panel.xml:
{{Box Code|conf/control_panel.xml|
<source lang="xml">
<session name="Flight with USB-serial_TT modem">
<program name="Data Link">
<arg flag="-d" constant="/dev/ttyACM0"/>
<arg flag="-nouplink" constant=""/>
<arg flag="-s" constant="115200"/>
</program>
<program name="Server"/>
<program name="GCS"/>
</session>
</source>
}}

A new aircraft (A/C) named "TT" has to be built using the paparazzi centre:
{{Box Code|conf/conf.xml|
<source lang="xml">
<aircraft
name="TT"
ac_id="3"
airframe="airframes/Poine/turntable_dev_usb.xml"
radio="radios/cockpitSX.xml"
telemetry="telemetry/default_rotorcraft.xml"
flight_plan="flight_plans/dummy.xml"
settings=" settings/rotorcraft_basic.xml"
gui_color="blue"
/>
<aircraft
</source>
}}

== IMU Code Modifications ==

Similar files have to be created for the IMU cradle unit:
{{Box Code|conf/control_panel.xml|
<source lang="xml">
<session name="Flight USB-serial_TT @57600">
<program name="Data Link">
<arg flag="-d" constant="/dev/ttyUSB0"/>
<arg flag="-s" constant="57600"/>
</program>
</session>
</source>
}}

The airframe is a standard rotorcraft file with the appropriate IMU defined.
{{Box Code|conf/conf.xml|
<source lang="xml">
<aircraft
name="TTIMU"
ac_id="4"
airframe="airframes/Audax/slh_lisa_mkk_i2c_indoor_tt_asp1.0.xml"
radio="radios/cockpitSX.xml"
telemetry="telemetry/default_rotorcraft.xml"
flight_plan="flight_plans/rotorcraft_basic.xml"
settings=" settings/rotorcraft_basic.xml"
gui_color="blue"
/>
<aircraft
</source>
}}

== Encoder Code Modifications ==
Line 43 in ~/sw/airborne/firmwares/motor_bench/main_turntable.c has to be amended to reflect the encoder's factory pulses per revolution (P/R) setting from default "#define NB_STEP 256". The encoder above has a factory resolution set at "300" (P/R). The resolution setting has to relect turntable velocity message outputs of ~200deg/s (3.49065rad/s) and ~270deg/s (4.71239rad/s) for 33rpm and 45 rpm respectively.
{{Box Code|sw/airborne/firmwares/motor_bench/main_turntable.c|
<source lang="xml">
#define NB_STEP 300
</source>
}}

=== Calibration Session ===

== Data Collection Setup ==
'''In Paparazzi Centre:'''
* Build A/C "TT" using "main" target and the USB A-B lead detached from PC.
* Attach USB A-B lead to both LPC & PC and upload code.
* Start "Flight with USB-serial_TT modem" "session".
* Open default "Message" box and "Real-time Plotter" from the "Tools" menu. Choose "IMU_TURNTABLE" readout.
* Switch to A/C "TTIMU" in same "Paparazzi Centre" window, build and upload code.
* Start "Flight USB-serial_TT @57600" "session".
* In original "GCS" window change "Telemetry" to "raw_sensors".
* Open a new "Message" box and choose "IMU_GYRO_RAW" readout.
* Arrange placement of IMU cradle, for the chosen axis (p, q, r), on the side which reports the highest or positive reading.
* Start turntable @ 33rpm and drag "IMU_TURNTABLE" data from "Message" box to "Real-time Plotter".
* Restart "Server" 1 second before a full minute readout and record for four minutes.
* Halt "Data Link" for both A/Cs "TT" and "TTIMU" and change turntable speed to 45rpm.
* Restart - click both "Data Link" boxes and record for a further four minutes.
* Stop "Server"
[[Image:Imu_gyro_calib_ppzcentre.png|240px|IMU gyro calibration, Paparazzi Centre]]

== Data Analysis ==
* The captured turntable velocity and gyro axis data can be found date and time stamped at:
{{Box Code|var/logs/xx_xx_xx__xx_xx_xx.data|
<source lang="xml">
~/var/logs/12_06_05__18_11_00.data
</source>
}}
* Right click the file and open with "LibreOfficeCalc". Click column D and elect "Sort Ascending".
* Choose "Extend selection" box. Note the time stamps of the IMU_TURNTABLE outlier data in column A.
* Insert them in the search box of a separate open editor version of the log file and delete the offending prints.
* Save the file and run the following:
{{Box Code|~/paparazzi/sw/tools/calibration$|
<source lang="xml">
./calibrate_gyro.py --id 4 --tt_id 3 --axis r /home/stephen/paparazzi/var/logs/12_06_05__18_11_00.data

Linear regression using stats.linregress
regression: a=824.56 b=16.03, std error= 0.048
<define name="GYRO_X_NEUTRAL" value="16"/>
<define name="GYRO_X_SENS" value="4.967519" integer="16"/>
</source>
}}

The accompanying plots will also appear:
[[Image:Gyro_calib_plots.png|240px|Gyro calibration Plots]]