How to control the velocity in cflib backend?

[hbler99]

Now I need to control the velocity, I have using the cmdFullState() but the crazyflie didn’t move, however in crazyswarm1 I succeed, what commands can make it?

[hbler99]

Now I find the key problem is when I am subcribing the /cf1/pose topic then the motors stop,
`class Sub_pos1(Node):

def __init__(self):
    super().__init__('sub_pos')
    self.cf1 = Subscriber(self, PoseStamped, '/cf1/pose')
    # ts.registerCallback(self.getcurpos)
    self.cf1.registerCallback(self.getcurpos)

def getcurpos(self, msg):
    global pos
    self.get_logger().info('I heard: "%s"' % msg.pose.position)
    pos = np.round([msg.pose.position.x, msg.pose.position.y, msg.pose.position.z], 4)
    print(pos)`

Is there any way I can subscribe to topics and keep crazyflies hovering at the same time

[hbler99]

I have slolved the question, thx!

[knmcguire]

the cmdFullState() I don't think exists in the cflib backend yet. You can see that in the overview page: https://imrclab.github.io/crazyswarm2/overview.html

[hbler99]

And now new problem occurs: when there are 3 cfs controlled， I use allcfs.takeoff() and then send cmdFullState() to them one by one, cf1 keeps hovering but cf2 and cf3 fall suddenly where the motors of them stop rotating. However, when I use goTo() the problem doesn't occur. I suspect it has something to do with high-level and low-level commands，what do you think of it? Thx!

[whoenig]

Make sure you send cmdFullState at a high rate - if no message arrives within 500ms, the firmware has a safety power stop. One can switch back to the highlevel mode via notifysetpointstop, see teleop.cpp for an example.

[hbler99]

Thx! I set the interval time to 0.05s and then the cfs will not crash, and I find it's better to design multiple loops with samll interval time,for example:
`def my_vel(cf, timeHelper, position, vel, Ts):

position = [vel[0] * Ts + position[0], vel[1] * Ts + position[1], vel[2] * Ts + position[2]]
# print(position)
cf.cmdFullState(position, vel, acc0, 0.0, omega0)
return position
for i in range(20):
        position = my_vel(cf, timeHelper, position, v1, Ts)
        timeHelper.sleep(Ts)`

where the set velocity is approximately equal to the real velocity, whereas using cmdFullState in a single loop with bigger inerval time have poor performance. I really appreciate your advice！
Besides, I also want to know how to use multiple crazyradios at the same time, now I've inserted 3 crazyradios but only the first turned on the light. What steps do I need to take?

[whoenig]

Please open a new discussion for the question about multiple radios - thanks!

For the other topic, I am not sure if there is an additional question, or if you were able to solve your problem?

[hbler99]

Sorry for being late! The problem of topic has been solved, thx! I will open a new discussion for multiple radios.