Friday, June 14, 2013

32. How to #monitor the #Voltage and #Mode of #UAV Battery

We replaced some variables in ardustation programming in telemtry.c and then monitored it in HappyKill More GCS program in the Serial Data:

// The Ardupilot GroundStation protocol is mostly documented here:
//    http://diydrones.com/profiles/blogs/ardupilot-telemetry-protocol

///////////////////////// battery health testing code
if((udb_analogInputs[0].value<batt_min_value) && (mode ==3))
{
BATT_FLAG =1;
}
//////////////////////////////////////////////////////

if(mode<3)
{
BATT_FLAG =0;
}


if (udb_heartbeat_counter % 40 == 0)  // Every 8 runs (5 heartbeat counts per 8Hz)
{

serial_output("!!!LAT:%li,LON:%li,SPD:%.2f,CRT:%.2f,ALT:%li,ALH:%i,CRS:%.2f,BER:%i,WPN:%i,DS

T:%i,BTV:%.2f***\r\n"
 "+++THH:%i,RLL:%li,PCH:%li,STT:%i,***\r\n",
lat_gps.WW / 10 , long_gps.WW / 10 , (float)(sog_gps.BB / 100.0), 

(float)(climb_gps.BB / 100.0),
(alt_sl_gps.WW - alt_origin.WW) / 100, desiredHeight, 

(float)(cog_gps.BB / 100.0), desired_dir_deg,
waypointIndex, udb_analogInputs[0].value, (float)(voltage_milis.BB / 

100.0), 
(int16_t)((udb_pwOut[THROTTLE_OUTPUT_CHANNEL] - 

udb_pwTrim[THROTTLE_OUTPUT_CHANNEL])/20),
earth_roll, earth_pitch,
(BATT_FLAG+1) // So that flag is not discarded if it is 0
) ;
}
else if (udb_heartbeat_counter % 10 == 0)  // Every 2 runs (5 heartbeat counts per 

8Hz)
{
serial_output("+++THH:%i,RLL:%li,PCH:%li,STT:%i,***\r\n",
(int16_t)((udb_pwOut[THROTTLE_OUTPUT_CHANNEL] - 

udb_pwTrim[THROTTLE_OUTPUT_CHANNEL])/20),
earth_roll, earth_pitch,
mode
) ;
}
return ;
}

These can be viewed in the serial data screen of the Happy Kill More GCS program.

Friday, May 31, 2013

31. Further modifications in #Software for Battery Monitoring

We realized that by merely doing the flag int_flightplan 1 in telemetry.c will not direct our program in Return To Land Mode. We discovered in the programming that RTL mode can only be achieved when two conditions are met:
  1. Program/drone is in Auto-Pilot Mode, for this we need our gps to be locked &
  2. failSafePulses or the pulses coming from the transmitter are 0 i.e. we have lost the radio signal
This can be seen from the following program in states.c file:

/////// Come home state, entered when the radio signal is lost, and gps is locked.
void ent_returnS()
{
flags._.GPS_steering = 1 ;
flags._.pitch_feedback = 1 ;
flags._.altitude_hold_throttle = (ALTITUDEHOLD_WAYPOINT == AH_FULL) ;
flags._.altitude_hold_pitch = (ALTITUDEHOLD_WAYPOINT == AH_FULL || ALTITUDEHOLD_WAYPOINT == AH_PITCH_ONLY) ;
#if ( FAILSAFE_TYPE == FAILSAFE_RTL )
init_flightplan( 1 ) ;
#elif ( FAILSAFE_TYPE == FAILSAFE_MAIN_FLIGHTPLAN )
if ( stateS != &waypointS )
{
init_flightplan( 0 ) ; // Only reset non-rtl waypoints if not already following waypoints
}

The condition to control the failSafePulses is mentioned in the background.c file:


if ( ( failSafePulses == 0 ) || ( noisePulses > MAX_NOISE_RATE ) )
{
if (udb_flags._.radio_on == 1) {
udb_flags._.radio_on = 0 ;
udb_callback_radio_did_turn_off() ;
}
LED_GREEN = LED_OFF ;
noisePulses = 0 ; // reset count of noise pulses
}
else
{
udb_flags._.radio_on = 1 ;
LED_GREEN = LED_ON ;
}
failSafePulses = 0 ;
}

Mode is mentioned in telemetry.c file and can be controlled from the receiver:

void serial_output_8hz( void )
{
uint16_t mode ;
struct relative2D matrix_accum ;
union longbbbb accum ;
int16_t desired_dir_deg ;  // desired_dir converted to a bearing (0-360)
int32_t earth_pitch ; // pitch in binary angles ( 0-255 is 360 degreres)
int32_t earth_roll ; // roll of the plane with respect to earth frame
//int32_t earth_yaw ; // yaw with respect to earth frame
accum.WW  = ( desired_dir * BYTECIR_TO_DEGREE ) + 32768 ;
desired_dir_deg  = accum._.W1 - 90 ; // "Convert UAV DevBoad Earth" to Compass Bearing
if ( desired_dir_deg < 0 ) desired_dir_deg += 360 ; 

if (flags._.GPS_steering == 0 && flags._.pitch_feedback == 0)
mode = 1 ;
else if (flags._.GPS_steering == 0 && flags._.pitch_feedback == 1)
mode = 2 ;
else if (flags._.GPS_steering == 1 && flags._.pitch_feedback == 1 && udb_flags._.radio_on == 1)
mode = 3 ;
else if (flags._.GPS_steering == 1 && flags._.pitch_feedback == 1 && udb_flags._.radio_on == 0)
mode = 0 ;
else
mode = 99 ; // Unknown
Hence to meet the above two conditions we created a flag BATT_FLAG which we defined in telemetry.c and declared as extern in defines.h file. When BATT_FLAG is set to 1 (in telemetry.c file) the int_flightplan  will become 0 (in background.c file) and thus enable out RTL Mode.

In telemetry.c file:

#define batt_min_value 16000
int BATT_FLAG =0;

if((udb_analogInputs[0].value<batt_min_value) && (mode = =3)) // if battery value goes below 16000 and is in Auto-Pilot Mode 
{
BATT_FLAG =1;
}
//////////////////////////////////////////////////////

if(mode<3) // if in Manual or Stabilized Mode then will never make BATT_FLAG 1 and int_flightplan 0
{
BATT_FLAG =0;
}

In background.c file:

// check to see if at least one valid pulse has been received,
// and also that the noise rate has not been exceeded
if(BATT_FLAG = =1)
{
failSafePulses =0;
}
if ( ( failSafePulses = = 0 ) || ( noisePulses > MAX_NOISE_RATE ) )
{
if (udb_flags._.radio_on == 1) {
udb_flags._.radio_on = 0 ;
udb_callback_radio_did_turn_off() ;
}
LED_GREEN = LED_OFF ;
noisePulses = 0 ; // reset count of noise pulses
}
else
{
udb_flags._.radio_on = 1 ;
LED_GREEN = LED_ON ;
}
failSafePulses = 0 ;
}

Here if we change from Auto-Pilot Mode to any other Mode then our BATT_FLAG will become 0 and our failSafePulses will start receiving real time signals from the transmitter on the drone.

How we monitored our changes, I will mention that in my next post.

30. Pictures - Voltage Divider Circuit for Battery Monitoring Circuit for #Unmanned AV #UAV








Thursday, May 30, 2013

29. Battery Monitoring Circuit for #UAV - #Software

Now we are working to create a program where we will guide our aircraft in case of insufficient battery. For this purpose we have added a voltage divider circuit, using 1k (R1) and .33k (R2) ohm resistances, to our existing UDB4 board and made the following changes in the telemetry.c file: 

#define batt_min_value 88

///////////////////////// battery health testing code
if(udb_analogInputs[0].value<batt_min_value)
{
init_flightplan( 1 );
}
//////////////////////////////////////////////////////

Here udb_analogInputs[0].value is real-time or current value that comes on one of our Analog pins of PIC controller (from AN15 to AN 18). If it goes below a certain value (for 3S LIPO battery - below 3.6 Volts each or net 10.8 Volts) then the program will switch to Return to Land (RTL) mode. 

In order to read what exact value that will come at full charge i.e. 12.48 Volts on the Analog Pins we replaced our diff in telemetry.c with udb_analogInputs[0].value so that we may set our batt_min_value:

// The Ardupilot GroundStation protocol is mostly documented here:
//    http://diydrones.com/profiles/blogs/ardupilot-telemetry-protocol
///////////////////////// battery health testing code
if(udb_analogInputs[0].value<batt_min_value)
{
init_flightplan( 1 );
}
//////////////////////////////////////////////////////


if (udb_heartbeat_counter % 40 == 0)  // Every 8 runs (5 heartbeat counts per 8Hz)
{
serial_output("!!!LAT:%li,LON:%li,SPD:%.2f,CRT:%.2f,ALT:%li,ALH:%i,CRS:%.2f,BER:%i,WPN:%i,DST:%i,BTV:%.2f***\r\n"
 "+++THH:%i,RLL:%li,PCH:%li,STT:%i,***\r\n",
lat_gps.WW / 10 , long_gps.WW / 10 , (float)(sog_gps.BB / 100.0), (float)(climb_gps.BB / 100.0),
(alt_sl_gps.WW - alt_origin.WW) / 100, desiredHeight, (float)(cog_gps.BB / 100.0), desired_dir_deg,
waypointIndex, udb_analogInputs[0].value, (float)(voltage_milis.BB / 100.0), 
(int16_t)((udb_pwOut[THROTTLE_OUTPUT_CHANNEL] - udb_pwTrim[THROTTLE_OUTPUT_CHANNEL])/20),
earth_roll, earth_pitch,
mode
) ;
}

We will be able to monitor it on Happy Killmore GCS software as we did our diff variable earlier (Switch-out from Auto-Pilot Mode : Another function for #UAV)

Also, if init_flightplan( 1 ); is set to one as here, then we will be able to switch to RTL mode or else not as we can see in the flightplan-waypoints.c file:

// In the future, we could include more than 2 waypoint sets...
// flightplanNum is 0 for main waypoints, and 1 for RTL waypoints
void init_flightplan ( int16_t flightplanNum )
{
if ( flightplanNum == 1 ) // RTL waypoint set
{
currentWaypointSet = (struct waypointDef*)rtlWaypoints ;
numPointsInCurrentSet = NUMBER_RTL_POINTS ;
}
else if ( flightplanNum == 0 ) // Main waypoint set
{
currentWaypointSet = (struct waypointDef*)waypoints ;
    numPointsInCurrentSet = NUMBER_POINTS ;
    }

Wednesday, May 29, 2013

28. #Funny , #Hilarious n #Awkward

That awkward moment when in the middle of night (ripe time for a typical engineer to work) you are all set with your PCB, components - resistors, capacitors n controllers etc ..., the soldering rod to make your circuit, when suddenly you realize that you do not have soldering wire!!! Aww man!!!

Wednesday, May 22, 2013

26. Pictures - #Funny - #Ailerons going out of function for a while

As I had posted previously, we had to remove one of the servos of the drone. Reason being that in Auto-Pilot mode it was skipping a step. This was as shown earlier it had a broken step or tooth. We tried to repair that servo motor (like by exchanging its gear set with another ones, that was a metal one) but it could not be possible. Therefore we have decided to order a new one. 

But then we thought that how are we going to test our program in real time environment? For this purpose we have removed the other aileron's motor too and fixed both of them for a while.

So now we had to extend the rudder so that it may take on the role of ailerons too. Well this is funny, but it will work n its innovation at its best. This is how we did it: