Send MAVLink command with MATLAB

Hello, I'm searching if there is a way for interact and send commands to my quadcopter with MATLAB, instead of a Ground Control Station. I tried with MATMAV but seems not working. I also tried with MAVLink Support and also this seems not working for send command to my quadcopter. This is my code:

dialect = mavlinkdialect('common.xml');

mavlink = mavlinkio(dialect);

connect(mavlink, 'UDP', 'LocalPort', 14550);

%%

client = mavlinkclient(mavlink, 1, 1) % specify client (1 client = 1 drone)

connectionList = listConnections(mavlink)

clientsList = listClients(mavlink)

topicsList = listTopics(mavlink)

%%

message_num = 400;

cmdMsg = createcmd(dialect, 'int', message_num)

cmdMsg

num2enum(dialect,"MAV_CMD", message_num)

%%

sendudpmsg(mavlink, cmdMsg, '0.0.0.0', 14550)

There are other approaches to send commands to quadcopter through MATLAB?

Thanks in advance!

Answer 1

[Jianxin Sun]

Hi Paolo,

First the mavlink message needs to be refined:

For arm UAV:

cmd = dialect.createcmd("LONG", "MAV_CMD_COMPONENT_ARM_DISARM");

cmd.Payload.target_component(:) = 1;

cmd.Payload.target_system(:) = 1;

cmd.Payload.param1(:) = 1;

For disarm UAV

cmd = dialect.createcmd("LONG", "MAV_CMD_COMPONENT_ARM_DISARM");

cmd.Payload.target_component(:) = 1;

cmd.Payload.target_system(:) = 1;

cmd.Payload.param1(:) = 0;

Also since you are emulating a ground control station in MATLAB, you will need to keep sending out heartbeat from MATLAB to help the UAV find it:

heartbeat = createmsg(dialect,"HEARTBEAT");

heartbeat.Payload.type(:) = enum2num(obj.Dialect,'MAV_TYPE', 'MAV_TYPE_GCS');

heartbeat.Payload.autopilot(:) = enum2num(obj.Dialect,'MAV_AUTOPILOT', 'MAV_AUTOPILOT_INVALID');

heartbeat.Payload.system_status(:) = enum2num(obj.Dialect,'MAV_STATE',"MAV_STATE_STANDBY");

heartbeatTimer = timer;

heartbeatTimer.ExecutionMode = 'fixedRate';

heartbeatTimer.TimerFcn = @(~,~)sendmsg(obj.IO,heartbeat);

start(heartbeatTimer);

If UAV is also broadcasting its heartbeat, your listClient call should show UAV client as well, then you can send message to the uav client:

sendmsg(mavlink, client);

[Paolo]

Hi @Jianxin Sun, thanks for the reply. I figured out how the general mechanism. Thanks for the help!

[vahe]

Hi @Jianxin Sun, can you help me?

I have written the following codes to monitor gimbal variables for UAV through Mavlink codes in MATLAB:

--------------------------------------------------------------------

dialect = mavlinkdialect('common.xml');

sender = mavlinkio(dialect,'SystemID',1,'ComponentID',1,...
    'AutopilotType',"MAV_AUTOPILOT_GENERIC",...
    'ComponentType',"MAV_TYPE_FIXED_WING");

connect(sender,'UDP');

destinationPort = 14551;
destinationHost = '127.0.0.1';

receiver = mavlinkio(dialect);

connect(receiver,'UDP','LocalPort',destinationPort);

info = msginfo(dialect,"GIMBAL_DEVICE_ATTITUDE_STATUS");

msg = createmsg(dialect,info.MessageName);

info.Fields{:};

subscriber = mavlinksub(receiver,'GIMBAL_DEVICE_ATTITUDE_STATUS',...
                        'NewMessageFcn',@(~,msg)disp(msg.Payload));

for msgIdx = 1:10
    sendudpmsg(sender,msg,destinationHost,destinationPort);
    pause(1/50);
end

--------- in the command window ------

time_boot_ms: 0

q: [0 0 0 0]

angular_velocity_x: 0

angular_velocity_y: 0

angular_velocity_z: 0

failure_flags: 0

flags: 0

target_system: 0

target_component: 0

---------------------------------------------

--------- But how can I show only 'q' in the command window?

Because I want to convert it to Euler angles = quat2eul(q)