Presentacin de PowerPoint

David Melndez Cano@taiksontexas

Taiksonprojects.blogspot.com

TRASH ROBOTIC ROUTER PLATFORM

What is TRRP?

Low (or null) cost embedded platform

Internet of things

Use whatever is liying around

Trash can be useful

DO NOT RECYCLE!!! ->>> REUSE!!!

Use your old (or fancy new) router as robotic platform

No initial investion. You already have the router!

Change the firmware-> Embedded Linux OpenWRT

Created Robots using this philosiphy

ROVER Texas Ranger: Linksys WRT54GL

Drone ATROPOS:La Fonera 2201

Round one: ROV Texas Ranger

Round two!: Atropos Quadcopter

Fonera 2201

OpenWRT

Stabilization process

HTML5 telemetry and control

A-B-C for quad drones

Router platform: GPIOs for I2C

Led lights are driven by SoC CPU pins

Router platform: GPIOs for soft I2C and serial port

GPIO---> I2C / RS232

GPIO leds Serial port

Router platform: Module load

rm /etc/modules.d/59-i2c-gpio

echo "i2c-gpio-custom bus0=0,4,7 bus1=1,3,1" >/etc/modules.d/59-i2c-gpio-custom

echo "i2c-gpio" >/etc/modules.d/60-i2c-gpio

[reboot]

i2c-detect /dev/i2c0

Router platform: Serial port

stty -F /dev/ttyS0 raw stty -F /dev/ttyS0 speed 115200

Router platform: Gyroscope

Wii Motion Plus

Triaxial gyroscope

I2C port

Gives angular velocity on each axis

Real angle: angular velocity * time ? not so easy

Router platform: Accelerometer

Wii Nunchuck

Triaxial accelerometer

Puerto I2C

G forces in each axis.

Router platform: Magnetometer

- HMC5881L

-Units: Gauss

-Accelerometer only cancels gyro drif for pitch & roll

-Yaw gyro drif must be cancelled with a compass (magnetometer)

Router platform: Reading I2C sensors

#include

f_i2c0=open(I2C0, O_RDWR);

ioctl(f_i2c0, I2C_SLAVE, 0x52); write(f_i2c0, buff_out, data_size); --- read(f_i2c0, buffer,size);

. Ej Wii Motion+: 0x52

Peticin de datos escribiendo al dispositivo

Lectura de datos en buffer

Imagen: The Balance Filter MIT

Gyroscopes

Accelerometer

Obteniendo ngulos absolutos con respecto a la Tierra

Mejor: Matriz de Cosenos Directores (DCM)

We will work with:

Absolute angle: (rad) filtered value

Angular velocity : (rad/sec) from gyroscopes

Angullar acceleration: (rad/sec/sec) calculated from angular velocity

Proportional Integral Derivative Controller

Proportional

error=current_value-last_value

Proportional_term=Proportional_term*error

Integral

accumulated_error=accumulated_error+(error*time_between_samples)

Integral_term=Integral_term*accumulated_error

Derivative

error_speed=error-last_error/time_between_samples

Derivative_term=Derivative_term*error_speed

Nested PID

P ControllerPID controllerAngleAngularVelocity

Router Serial port

Router platform: Motor signal board (PWM)

-PIC Microcontroller receives motor speeds via router serial port-It converts those values into 4 time-fixed digital signals (PWM)

Fonera/dev/ttyS0PIC16f876AESCMotores

Router Platform: IMU (Inertial measurement Unit)

Critical process that has to be executed in a time-fixed ratiosetitimer(ITIMER_REAL,&i_int,NULL);(void)signal(SIGALRM ,timeout_real);

It compites with the rest of the process for CPU time

Changing priority with nice is not sufficent:

Real Time scheduling FIFO, Round Robin

#include

schedule.sched_priority=sched_get_priority_max(SCHED_FIFO);sched_setscheduler(pthread_self(), SCHED_FIFO,&schedule);

WATCHDOG process notifies to kernel that system is not hanged

It consumes SCHED_FIFO process time

What happens if router hangs during flight->

ioctl(/dev/watchdog, WDIOC_KEEPALIVE, &dummywd);

Actuator hardware

Electronic Speed controller (ESC)

Brushless motors Outrunner.

HTTP CONTROL

Httpd.c:[...]if (strncmp(tptr, "cgi-bin/ajaxinput", 17) == 0) {[...]strcpy((char *)shmat(shmget(9998, 30, IPC_CREAT | 0666), NULL, 0),g_query);exit(-1);}[...]

Pilot commands can be transmitted via AJAX or UDP packets
-AJAX uses DOM events and sends commands accordingly-A separate program reads USB Joypad and resends via UDP

http://atropos/cgi-bin/ajaxinput?QQZ[GAS]Z[ALABEO]Z[CABECEO]Z[GUIADA]Z

Router Httpd.c is tweaked to process the query faster.

USB Joypad control (GNU/Linux with joydev.ko)

cat /dev/input/js0

----

pad=open(/dev/input/js0,O_RDONLY);reads=read(pad,msg,MSG);

(msg[7]==2) gas=((analog+127))*GAS_FACTOR; [...] (msg[7]==4) yaw=-analog*YAW_FACTOR; [...] (msg[7]==1) pitch=-analog*PITCH_FACTOR; [...] (msg[7]==0) roll=-analog*ROLL_FACTOR; [...]

What about Android?

ZsunBully

HEADER

APATROP

COMMAND

PreambleGasPitchRollYaw

SEQUENCENUMBER

CHECKSUM

INIT.

VECTOR

Forged Beacon Frame injection

Protected with AES-128

BEACON FRAME PAYLOAD

HEADER

Demo?Vuelo Atropos Quadrocopter

Thank you!

David Melndez Cano

@TaiksonTexas

Taiksonprojects.blogspot.com

Taiksonprojects.blogspot.com

ROME 11-12 april 2014 Speaker's name