Is it necessary to have the RC transmitter?


From looking at the dataflash log’s STRT (steering rate) message, the vehicle appears to be turning in the opposite direction from the way it should. Normally this is caused by a mistake in the setup of the motors (i.e. SERVOx_FUNCTION, SERVOx_REVERSED).

You’ve read the wiki’s configuration section including checking the direction of the motors and/or servos?

Also there’s an important section on tuning the steering controller here.