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Posted: **Mon Jan 28, 2019 4:54 pm**

Hi all

I have successfully completed the task of automatic swarm flight using the swarmSequence.py, but now I want to print the crazyflie's position.

I tried to change the code, but still failed.Here is the code I added

Code: Select all

def position_callback(timestamp, data, logconf):

    x = data['kalman.stateX']
    y = data['kalman.stateY']
    z = data['kalman.stateZ']
    print('pos: ({},{},{})'.format(x, y, z))
    with open('/home/gabriela/Área de Trabalho/Gabriel' +datetime.datetime.now().strftime('%Y-%m-%d-%H_')+'Callback_position.csv', 'a') as cvsfile:
        writer = csv.writer(csvfile,delimiter=',')
        writer.writerow([x, y, z, timestamp])
    csvfile.close()

def start_position_printing(scf):
    log_conf = LogConfig(name='Position', period_in_ms=50)
    log_conf.add_variable('kalman.stateX', 'float')
    log_conf.add_variable('kalman.stateY', 'float')
    log_conf.add_variable('kalman.stateZ', 'float')

    scf.cf.log.add_config(log_conf)
    log_conf.data_received_cb.add_callback(position_callback)
    log_conf.start()

However, i don't know how to to setup a different log callback for each Crazyflies

This is definitely wrong, someone can help me？I think a lot of people need this function.

thanks!

Posted: **Mon Feb 04, 2019 12:47 pm**

The code you have written so far looks good to start a log block.

If you call

Code: Select all

swarm.parallel(start_position_printing)

in the with swarm block, you will start to log position for all the drones in the swarm.

The scf.cf object contains the URI of the link, this would allow to identify each Crazyflie in "start_position_printing", then you can use a labmbda function as callback to save the position of each drone independently.

Posted: **Mon Feb 04, 2019 9:42 pm**

arnaud wrote: ↑Mon Feb 04, 2019 12:47 pm The code you have written so far looks good to start a log block.

If you call
Code: Select all
swarm.parallel(start_position_printing)
in the with swarm block, you will start to log position for all the drones in the swarm.

The scf.cf object contains the URI of the link, this would allow to identify each Crazyflie in "start_position_printing", then you can use a labmbda function as callback to save the position of each drone independently.

Hi Arnaud,

"The scf.cf object contains the URI of the link, this would allow to identify each Crazyflie in "start_position_printing"
Until here, okay.

But I can not understand how to use the lambda function ...

Through the start_position_printing function, could I create two position_callback? position_callback1 and position_calkback2

Thanks

Posted: **Tue Feb 05, 2019 11:19 am**

Hi!

Now, the acquisition is operating well!

I created two different callbacks: position_callback1 e position_callback2

Code: Select all

def start_position_printing(scf):
   
    if scf.cf.link_uri == 'radio://0/80/2M':
           
        log_conf = LogConfig(name='Position', period_in_ms=500)
        log_conf.add_variable('kalman.stateX', 'float')
        log_conf.add_variable('kalman.stateY', 'float')
        log_conf.add_variable('kalman.stateZ', 'float')

        scf.cf.log.add_config(log_conf)
        log_conf.data_received_cb.add_callback(position_callback1)
        log_conf.start()

    if scf.cf.link_uri == 'radio://0/81/2M':
         
        log_conf = LogConfig(name='Position', period_in_ms=500)
        log_conf.add_variable('kalman.stateX', 'float')
        log_conf.add_variable('kalman.stateY', 'float')
        log_conf.add_variable('kalman.stateZ', 'float')

        scf.cf.log.add_config(log_conf)
        log_conf.data_received_cb.add_callback(position_callback2)
        log_conf.start()

I don't know if there is a more appropriate form, but I guarantee separate reading

Posted: **Tue Feb 05, 2019 1:25 pm**

You can use lambda function, it is exactly what you need to make that cleaner

.

This is an example of how it works:

Code: Select all

def callback(uri, data):
    print("Uri: {}, Data: {}".format(uri, data))

def setup_and_call(uri):
    # Make a lambda function cb that takes one argument x, and call the callback with the value of uri as well as the argument
    cb = lambda x: callback(uri, x)
    
    # cb is only called with data
    cb("some data")

setup_and_call("uri1")  # Displays Uri: uri1, Data: Some data
setup_and_call("uri2")  # Displays Uri: uri2, Data: Some data

So in you case it could look something like:

Code: Select all

def position_callback(uri, timestamp, data, logconf):

(...)

log_conf.data_received_cb.add_callback(lambda t, d, l: position_callback(scf.cf.link_uri, t, d, l))

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How to print the position with the swarmSequence.py

How to print the position with the swarmSequence.py

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Re: How to print the position with the swarmSequence.py

Re: How to print the position with the swarmSequence.py

Re: How to print the position with the swarmSequence.py