How to change neutral set point for motors

Blue Robotics Software
1

Hi,
I’m using an ESC where 1100 microsec is 0 throttle, so I’ve been trying to configure the neutral point for the motors to 1100, but I cant find the setting. Please could I have some help with this?

My application doesn’t require reversible motors.

Thanks,
Matt

2

Hi @Matt_D
What are you trying to configure to have that neutral point? ArduSub frame types all require reversible ESCs…

3

Hi @Matt_D,

You can try setting the SERVOn_TRIM parameters for your motor pins to be 1100, with MOT_PWM_TYPE set to PWMAngle (9).

That said, @tony-white is correct that ArduSub expects to be using reversible motors, so I’m unsure whether that will actually work properly / as expected, and am similarly curious what your application is.

4

I’m making a high speed ROV similar to the Simple ROV 3 frame. I’ve already got some decent ESCs, but they are not reversible and I don’t require turning on a single point.

@EliotBR I’ve set the trim parameter to 1100 microsecs, but that doesn’t change the output by itself so I will have go with MOT_PWM_TYPE and PWMAngle thank you.

As I have used the firmware more, ArduSub doesn’t quite fit the use case because it does not support servo outputs or fully support PWM passthru with unusual limits from 1300 - 1700 micosecs. The ROV is controlled with fins rather than motors, so I’ve moved over to using ArduPlane on the Navigator, but there’s some compatibility issues there so I’m currently working through that.

I’m going to use cockpit as I like the feature there (especially picture in picture), but it doesn’t always recognise my Radiomaster as a joystick, although it sometimes works.

5

I’m not sure what you mean by this. ArduSub definitely has servo motor support (it supports PWM outputs, and you can set their values directly or incrementally), and I’m not sure why you would want or need to change limits if you’re doing PWM passthrough - the output should match your input.

Fair enough. Proper control surface support for motion control is one of several advanced control mechanisms that ArduSub does not currently support.

That said, I suppose it would be possible to implement your own fin support via a Lua script if you wanted to…

I recommend you open a separate topic to discuss that, or a GitHub Issue. If you’re able to provide more information about the joystick, and some application logs we can likely help investigate and fix the problem.