Large Rover - Sabertooth Trouble Turning

You are correct and I think that this was just overlooked when the MOT_SLEWRATE parameter was implemented. Technically you can turn a skid steer vehicle without applying any ‘throttle’ and currently the slew rate is only applied to the throttle request. I think that this parameter would more correctly be labelled THROTTLE_SLEWRATE or alternatively, be applied to all motor outputs after all other calculations.
Looking further into your motor controller, I can see that there is a ‘Ramping’ parameter on the motor output that can be set using the DEScribe software. I think that this is your best option and that you should disable any Ardurover motor rate limiting.

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yes, I agree with @jimovonz that the MOT_SLEWRATE should probably apply to the steering as well at least on a skid-steering rover. I suspect we didn’t support skid-steering rovers when the slew rate was originally added.

As a side note, I’m not very fond of the conventions we use for the slew rate parameter which are, “percentage of total range per second”. I’d prefer we use something similar to Copter’s MOT_SLEW_UP_TIME which specifies a time to achieve full throttle.

In any case, I’m happy to review, merge a PR to improve the motor slew feature.

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I will get the DELink 2 to program the Sabertooth’s “Ramping” feature. I must get Throttle and Steering tuned so I can apply the ATC_STR_ACC_MAX settings I believe? Again, you all have been great. I will update with video soon. Thx!!!


The ATC_STR_ACC_MAX parameter is used in all modes except Manual. Most users don’t need to set this parameter as part of tuning the steering but you might choose to in order to reduce the demands on the motors.

I had this number fairly high to get the smaller test ROVER to make precise/aggresive turns

I am using the same PH2 in this build. I will start with fresh settings to re-tune.
*Note: Applying rate curve in my Taranis radio had no effect on the problem.

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I did not mean any curve, dual rate or expo. Go to the mixer screen in OpenTX, there you select your steering channel, press enter, choose “edit”. In the screen that now opens, the last two options should be “slow up” and “slow dn” . You can enter a numerical value for how long the channel takes to follow the input/stick in X.X seconds. The menu item names might not be correct, my Jumper T16s menus are set to german.

Edit: I found a battery to power up my Taranis. The names should be correct.

If you want to perform skid steer, and not take advantage of all of the other advantages of ardurover, another option is to skip the flight controller altogether and use the “differential thrust” feature in opentx.

If the controller is mounted on the vehicle, the taranis can output sbus directly, so you don’t need a tx or rx.

I am in the process of making a off road wheelchair, and have been examining the options.

ps, wheelchair motors have an electronic brake, make sure you are not activating it when you attempt to put the wheelchair motors into reverse.

Thanks but the ultimate purpose of the rover is an autonomous drone. The wheelchair motors I buy have the brakes removed already. There are many eBay dealers selling them.

UPDATE: New 250a breaker and programming of Sabertooth 2x60’s

Thank you all again!!!