Smooth turning only works on one side

Rover 4.2.2 on old Pixhawk1m
SABERTOOTH 2x60 (linear, independent modes)

Testing driving in manual mode things are working, mostly.

Problem is when I try to make a slight turn while going forward it works fine for left, but trying right makes rover stop completely and turn hard in place. Opposite direction is affected when going in reverse.

Any ideas?

So I’ve removed the pixhawk from the setup and the machine works exactly as expected.

Since I now know that the pixhawk is part of, if not the entire problem, can anyone offer somewhere to look at parameters?

When going forward or backwards, left turning works fine (left wheel slows down) but turning right while going forward or backwards causes the right wheel to REVERSE direction immediately instead of just slowing down or stopping.

Thanks for any help offered!

Hi @cmorehouse,

If possible could you include an onboard log?

I wonder have you used the Motor Test feature of mission planner to confirm the outputs are working correctly?

its says the log files are too big to upload so i put them on my work website…

I have used the motor test multiple times and each time i change something to fix a problem i break something else…such as …
on motor test, motor C spins left motor forward , D spins right motor backwards.
so i change a servo1_reversed or servo3_reversed and fix it but then both wheels go the wrong way when manually controlling. I’ve swapped servo cables 1 and 3, ive swapped the wires to the motors, i feel like ive tried everything iwithout a good list of items to try in a particular order.
What would be helpful is an IF THIS, DO THAT type of set up.

When i moved servo cables the problem i am asking about moved to the other wheel, so i am sure its not a physical problem with my motors or Sabertooth.

Thanks for any help you can offer!

could this be because the brakes are not removed from my motors? im using an old motorized wheelchair with brakes but i have the levers in the PUSH position. and why would it only happen on one side if this is the problem?

nevermind…just removed the brakes and problem still happens…

This seems like a classic case of “it works in manual and I can’t figure out why it won’t work in auto/acro.”

If you got positive results when swapping servo direction but then had trouble in manual, keep the servo direction reversed and then reverse the appropriate RC transmitter channel to match.

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I agree with @Yuri_Rage’s suggestion that the input and output setup is being mixed up.

I recommend getting the Motor test working, then don’t touch the output setup. E.g. don’t change any wires to the ESCs or servos, don’t change any MOT_xx or SERVOx_xxx parameters. Instead focus on the input setup. To be more precise, go to Mission Planner’s Setup >> Mandatory Hardware >> Radio Calibration screen, uncheck all the “Reverse” checkboxes and then make sure that the green bars for Roll, Throttle and Yaw all move in the same direction as the physical sticks. For “Pitch”, the green bar should move in the opposite direction to the physical stick. If any of them move in the wrong direction, reverse the direction in the transmitter (not in the AP parameters).

The logs provided are tlogs but it would be much more useful if onboard logs (aka dataflash logs) were provided.

Hope this helps.


I followed your directions and got the right motors turning the right direction without anything reversed.
I had an A-HA moment when focusing on the Roll, Throttle, and Yaw moving in the correct direction. The throttle (up/down) movement came from left/right movement on the right stick and it was then i realized i had mapped the RCMAP parameters wrong. I was just changing settings there and not paying attention to exactly how they should be and instead just moved on once only the right stick controlled both wheels on the rover.

Thank you for your help and patience. Im sure i will have more questions and need more help and i thank you in advance for that help too!!
I’m truly grateful!!!


This is an unfortunately common issue (and one I struggled with, myself at first). It’s a little difficult to wrap one’s brain around the idea that the autopilot is not a way to augment RC control, but rather a nearly complete replacement for it.