Settings
Pixhawk 4 (I/O PWM OUT is used, FMU PWM OUT is not used)
PX4 1.14.0
QGC 4.3.0
MATLAB R2023b
Question
I want to send rotor commands to Pixhawk from MATLAB through telemetry radio. After some search, I think MAV_CMD_DO_SET_ACTUATOR is the appropriate interface. I can arm Pixhawk from MATLAB using MAV_CMD_COMPONENT_ARM_DISARM. However, I cannot make MAV_CMD_DO_SET_ACTUATOR work. My code is as follows.
tele_com_port = "COM16";
device = serial(tele_com_port, "BaudRate", 57600);
dialect = mavlinkdialect("common.xml");
mavlink = mavlinkio(dialect);
% Arm, MAV_CMD_COMPONENT_ARM_DISARM
cmd_arm = createcmd(dialect, "long", 400);
cmd_arm.Payload.target_system = uint8(1);
cmd_arm.Payload.param1 = single(1);
buffer_cmd_arm = serializemsg(mavlink, cmd_arm);
% Set rotor input, MAV_CMD_DO_SET_ACTUATOR
cmd_set_actuator = createcmd(dialect, "long", 187);
cmd_set_actuator.Payload.target_system = uint8(1);
cmd_set_actuator.Payload.param1 = single(0.1);
cmd_set_actuator.Payload.param2 = single(0.1);
cmd_set_actuator.Payload.param3 = single(0.1);
cmd_set_actuator.Payload.param4 = single(0.1);
buffer_cmd_set_actuator = serializemsg(mavlink, cmd_set_actuator);
fclose(device);
fopen(device);
% Arm.
fwrite(device, buffer_cmd_arm, "uint8");
fprintf("Armed\n");
% Set rotor inputs.
for i = 0: 1000
thr = (0.8 - 0.2) / 1000 * i + 0.2;
cmd_set_actuator.Payload.param1 = single(thr);
cmd_set_actuator.Payload.param2 = single(thr);
cmd_set_actuator.Payload.param3 = single(thr);
cmd_set_actuator.Payload.param4 = single(thr);
buffer_cmd_set_actuator = serializemsg(mavlink, cmd_set_actuator);
% fwrite(device, buffer_cmd_set_actuator, "uint8");
fwrite(device, buffer_cmd_set_actuator);
pause(0.02);
end
fprintf("Done\n");
fclose(device);
Following https://docs.px4.io/main/en/config/actuators.html, I set the rotors as shown in https://github.com/PX4/PX4-user_guide/issues/3028 (sorry but I have not found a way to upload images here.
I can arm Pixhawk. In the code above, I set the rotor inputs to increase linearly. But the rotors’ speed seem does not change. And Pixhawk disarms even when the program above is still running. So I think the rotor commands are not sent to Pixhawk correctly.
Thanks in advance.