Servers by jDrones

Reverse control (PIXHAWK) - help to cofigure,pls!

(Andrey) #1

Hello! Please help to configure PIXHAWK to manage reverse (back) moving!
I am building boat with GPS cruising - trivial task (for begin), and I spent too much
time to find right config for MANUAL at first.
My boat has two motors with ESC.
I prefer to control power with analog voltage 0-5v (ordinal PWM, not RC PWM) and
control rotation direction through separate pin (‘relay’).
I’d like to try ‘like tank’ control: left and right control ‘pedals’, and
steering control: joystick left-right = steering, joystick middle-up = go forward, middle-down = go backward.
I’ve tried rover(1) and boat(2) config and never have reverse moving -
my throttle joystick always has ‘stop’ at down position (1100mS) and full throttle at up (1900mS).
And I see that motors has reverse rotation when I steer without throttle(or little throttle) - motors turn at different direction for boat turning around itself.
So help me - where can I set throttle joystick with reverse?

(rmackay9) #2

Hi Andrey,

It’s probably best to include a dataflash log file if possible.

When you say, “control power with analog voltage and control rotation direction through separate pin” are you talking about outputs to the motors or inputs? I think you probably mean outputs. I actually don’t know if we support the configuration you’re thinking about but the three outputs types we support are listed here on the wiki. It sounds like “Brushed With Relay” is the closest we have.

Have you seen the motor testing screen in the Mission Planner? It’s described on the wiki here.

For the input, I think you’ll want to set PILOT_INPUT_TYPE to “1” (aka “TwoPaddles”). It is described here on the wiki.

To get the reversing right, there are four parameters to check:

RC1_REVERSED, RC3_REVERSED <-- controls the reversing of the input from the transmitter/receiver. If the green bars move in the wrong direction for “roll” and “throttle” in the radio calibration screen then these parameters should be changed.
SERVO1_REVERSED, SERVO3_REVERSED <-- controls the reversing of the outputs from the back of the flight controller. If the motors don’t spin forward when doing the motor test then these parameters should be changed.

(Andrey) #3

Thank you, rmackay9! - in short - problem solved by going through all initial steps again :slight_smile:
You right: my mode for motor control output is
“Brushed With Relay”
it gives PWM output pulses with PWM frequency (16kHz) and duration (0%…99.9%) (1 and 3 main output)
and direction control AUX OUT 5 and 6.
so I really can use only one power MOSFET (logic gate) to regulate power for brushed motor with relay to change polarity. (tested - works!)

And now throttle stick works with middle “stop” and up forward and down backward.
Be kind tell me: where is definition of throttle stick neutral (stop motor) position?
(is it define in radio calibration last step, is it input channel TRIM or where is it)
My Q: how to tell system motor and stick mode - only one rotate dir(plane, dron) or back and force (car)?

(rmackay9) #4


Great! the throttle neutral is held in RC3_TRIM. So that’s probably 1500 by default (or something close to that)… and yes, this is stored by the mission planner at the last step of the radio calibration. it can be directly set using the Full Parameter List page in the groundstations as well.

I’m not sure if it answers your question but RCMAP can be used to change which channels control steering and throttle.

(Andrey) #5

Absolutely answered! Thanks.
I’ve noticed, usually TRIM=1500, in my case CH3 TRIM=1000.

1 Like
(B A Kanchuka) #6


I’m building an autonomous boat using Radiolink Pixhawk with GPS. the FC is loaded with Ardu Rover 3.5.0

But i need to configure the motor outputs. (Brushed Motor) because i couldn’t find any brushed bipolar ESC any time soon.
I am using Skid Steering.

These are the outputs needed:
Forward: Both the motors should turn forward
Back: Both the motors should turn backward
Right: Left motor powered up proportionately to the other (Applicable for both forward and reverse Likewise)
Left: Left motor powered up proportionately to the other (Applicable for both forward and reverse Likewise)

Progress: I have configured skid steering forward, left and right through a brush-less ESC driving a brush-less motor…

But Required: To drive brushed motors with both forward and reverse.

Issue: How to configure the pixhawk for brushed motors to connect with pixhawk for forward and reverse?

(Sebastian Schürmann) #7

Please just open a new thread for your questions/problems instead of reviving month old threads.
For skid steer to work, you must have setup two servo outputs with “throttle left” and “throttle right”, your throttle input should come from a self centering stick on your TX and your ESCs must support forwards and backwards operation. Most RC car ESCs (brushed or brushless) work this way, airplane/multicopter ESCs do not.

1 Like
(B A Kanchuka) #8

Hi Sebastian,

Thanks and i have now opened a new thread about the topic. Hope you’ll visit the following link…