RC Override data array full: how to add more motor control via joystick?

[bcdupree]

I am attempting to control an ROV with mavROS. I have Ardusub code running on a Pixhawk 4. On the topside I am running mavROS to facilitate camera input amongst other sensor streams and provide the ROS specific implementation of Mavlink. I am publishing messages to mavROS topics using an XBox controller.

My startup command in terminal is:

'roslaunch bluerov_ros_playground user_mav.launch'

I am getting perfect control of my 8 existing ROV thrusters using the 2 joysticks on the XBox controller. What I would like to do is add 2 more thrusters that only need stepwise speed control via 2 buttons on the controller (RB and RT). The commands would simply be step up speed in a clockwise direction on both thrusters or step up speed in the anticlockwise direction on both thrusters.

In 'src/bluerov/user.py', the commands for the 8 existing thrusters are sent to the Pixhawk via the ROS topic 'RCOverrideIn'. This data array for this topic is full however. How do I create an equivalent topic on which to publish the commands for my additional 2 thrusters?

I have tried adding in code like:

            if buttons[5] == 1: # Both Additional Motors Speed Up Clockwise
                thrust = [0.5] # THIS IS AN ARBITRARY VALUE BETWEEN 0 and 1 for now
                self.pub.set_data('/mavros/setpoint_attitude/thrust', thrust)

but I am not sure if the Thrust topic is the ideal one to be using.

Any help much appreciated! Also I am new to ROS, apologies for the noob questions in advance.

[patrickelectric]

Do you want to control the thrusters individually ?
That's not possible, it's only possible to send vertical and horizontal control reference to ArduSub.

[bcdupree]

Sorry im an idiot for calling them thrusters. They are actually extra motors that are not used for thrusting. The idea is that they would be controlled in unison.

[bcdupree]

Ardusub has a parameter called 'cam_tilit' in joystick.cpp that maybe we could use to send a pwm to 2 other motors? However I cannot find the equivalent parameter/data structure in the python libraries of the bluerov playground. how would we go about adding the appropriate python code on the topside?

[bcdupree]

sorry 'cam_tilt'