Turnigy 9x Mode 1 transmitter using Roll (Ch1) for steering and Throttle (Ch3) for speed. The speed controller is a Sabretooth 2x32 set to independent motor mode (not mixed mode).
The wheels will move forward with the throttle control ok and the rover will pivot and turn when stationary (ie with no throttle) but it does not seem to turn properly with any sort of throttle. It will turn left ok but when turning right the rover jerks, stops, goes into reverse momentarily before making a turn. I have attached the parameter file if anyone would like to check my configuration to see if I have missed anything obvious it would be greatly appreciated.
I think you’ve got a double-reversal going on. Reverse the motor directions on the Sabertooth (swap the output cables) and then reverse the roll channel on the RC transmitter.
I reversed the motor outputs from the Sabretooth to the motors and reversed the roll channel on the transmitter (tried changes one at a time and then both) however there was no change.
However I tried switching to mixing on the Sabretooth and set SERVO1_FUNCTION to RCIN1 and SERVO3_FUNCTION to RCIN3. (from a comment I read in a previous topic) It drove beautifully in manual and acro mode but when I hit auto mode nothing happened.
Also, I can’t seem to get the motor test to work, ie nothing happens when I hit motor C and motor D apart from the rover being disarmed.
setting the outputs to anything other then “throttle_left” and “throttle_right” will not result in a working setup.
I always setup my rovers, so that a PWM signal from 1500-2000us results in the wheels turning forward.
The transmitter is set to stick up, PWM 1500-2000us. Stick right, PWM 1500-2000us. And you need a self centering stick for throttle.
If you follow this, you should not have to reverse anything, reducing the possible causes of confusion.
The Sabertooth needs to be set to microcontroller PWM input, not RC transmitter input.
1-OFF 2-ON 3-OFF 4-OFF 5-ON 6-OFF
Thankyou for the advice. I have been using the right throttle stick on my transmitter for throttle which isn’t self centering and I have only been able to get my rover to work when I use the sabretooth to do the mixing, maybe this is why…Anyway I will change to a self centering stick for throttle tomorrow and see how I go.
I can now see the servo outputs on mission planner behaving as I think they should ie both servo1 and servo3 move together when I move the transmitter throttle stick up and down. And servo1 and servo3 move in opposite directions when I move the steering stick on the transmitter. Unfortunately the motors are still not behaving the same as the servo outputs indicate with jittery, jerky motion and they are spinning even with the sticks in the centered position. I’m pretty sure the sabretooth is ok as I bi-passed the cube and was able to operate the motors smoothly in the mixed mode of the sabretooth with the transmitter.
Tomorrow I’ll go through the configuration again and maybe even reload the firmware.
Hi again. This morning I upgraded the firmware 4.1.0 Beta (I wanted to try 3.5 again but can’t upload that on Cube Orange, fair enough)
Anyway no improvement however I did see that the the throttle seemed to be out of range, ie the wheels were spinning forward at full speed when the throttle stick is in the centered position (about 1500 pwm). When I pull the throttle stick back it goes into full reverse as it gets to the minimum (1000-1100 pwm) with a “dead” zone (very jittery and pulling a LOT of currant see file below) half way in between at about 1250 pwm. ie the throttle only seems to operating in the bottom half of it’s range (1000-1500pwm)
I have inlcluded the parameter and a data log files and I hope someone will have a chance to have a look at them.
I also monitored the sabretooth and have included a link to the CSV file of the sabretooth operating through the cube, which is a bit concerning as there were some very high currants being measured. For a comparison I then tried the sabretooth directly with the transmitter, which operated smoothly and have included this file as well.
Hi Stephen, thanks for taking the time to check my system out. I’m using 12v brushed dc motors which is why I selected MOT_PWM_TYP as 4. https://ardupilot.org/rover/docs/common-brushed-motors.html
But I’ll change it back to 1 and give it go as well as changing the servo settings as you suggested.
I’m beginning to wonder if the motors I am using are too old and worn out or if they are actually 24v motors as they seem to be drawing too much current.
I am very, very pleased to say after changing MOT_PWM_TYP to 1 (and 0) the servo1 and servo3 max, min and trim values to those suggested above I now seem to have the issue sorted and my rover is now behaving perfectly in manual mode.
When I first made the changes it would drive forward and turn left or right correctly when I moved the steering stick as it was moving but with no throttle and the rover was stationary it would pivot turn left if I moved the steering stick right and visa versa. However after I trimmed the throttle stick up slightly on the transmitter it all came good.
@dkemxr I just gave it a quick drive in Acro mode. It controls ok with very small movements of the sticks but tends to “run away” with sharper turns, which can be corrected with opposite movements of the sticks so hopefully some tuning will sort that out. Also I don’t have a spray tank mounted on it which will affect the dynamics as well. But I’m happy so far.
Yes, if it’s basically performing in Acro then the configuration is correct. Manual is passthrough no different than not having a flight controller at all.
Follow the tuning Wiki to get you there.
My project is very similar to yours. And the same problem occurs. I believe you use a Saberbooth right? I am using SYren 25. You can pass the configuration of your Dip Switch. What about its activation parameters? I went through the manual but mine didn’t trigger either.
