I recently bought x joystick controller RB-Ins-12 and q believed could control two servos with freedom of movement but surprised me q to connect the servos always return to their initial position and something that did not want to leave because they pretended servos in the position I need. My question is if there is any solution oe made a purchase useless for my purpose.
Servos are made to go to a position based on a PWM signal, RB-Ins-12 will act like any other R/C servo controller and give you a position based on the position of the joystick.
This is the way almost all servo drivers work; they don’t send a request for movement in a direction and keep that position like you might expect.
Something like you want to achieve could be done but with some programming as there is not product doing this out of the box.
With a Slider Box the position would not go back to a defined centered one, maybe it could work for you.